COMPARISON OF RUNNING CHARACTERISTICS AND HEART RATE RESPONSE OF INTERNATIONAL AND NATIONAL FEMALE RUGBY SEVENS PLAYERS DURING COMPETITIVE MATCHES JAVIER PORTILLO,1,4 JOSE´ Ma GONZA´LEZ-RAVE´,1 DANIEL JUA´REZ,1 JOSE´ M. GARCI´A,1 LUIS SUA´REZ-ARRONES,2 AND ROBERT U. NEWTON3 1
Sport Training Laboratory, Faculty of Sport Sciences, University of Castilla La Mancha, Spain; 2Faculty of Sport Sciences, University of Pablo de Olavide, Spain; 3School of Exercise, Biomedical and Health Sciences, Edith Cowan University Australia; and 4Strength and Conditioning Spanish Rugby Federation, Spain
ABSTRACT Portillo, J, Mª Gonza´lez-Rave´, J, Jua´rez, D, Garcı´a, JM, Sua´rezArrones, L, and Newton, RU. Comparison of running characteristics and heart rate response of international and national female rugby sevens players during competitive matches. J Strength Cond Res 28(8): 2281–2289, 2014—This study compared the activity profile of national and international female rugby sevens players during competitive matches. Twenty rugby sevens female players were recruited, 10 were members of the Spanish National Team (26.27 6 4.05 years, 65.39 6 5.01 kg, 166.72 6 6.70 cm) and 10 were amateur athletes from a Spanish rugby championship (32.12 6 6.40 years, 66.48 6 5.38 kg of body mass, 167.37 6 3.02 cm). Data collection was conducted over 4 matches in each of the 2 tournaments, national and international. Distance, velocity, and heart rate (HR) were recorded using global positioning system devices for all participants throughout each match. There were significant differences (p , 0.01) in total distance (1642 6 171 vs. 1363 6 222 m), average speed (6.0 6 0.3 vs. 5.2 6 0.6 km$h21), number of sprints (6.1 6 3.1 vs. 1.9 6 1.4 sprints), and distance covered in sprinting (118.8 6 61.4 vs. 47.0 6 38.8 m). Significant differences were found at .95% maximum HR (HRmax), both for the first (p , 0.01) and second half (p # 0.05). The work-rest ratio was significantly different (p , 0.01) between international (1:0.3) and national players (1:0.4). Significant differences were found in accelerations above 2 m$s22 in the first and second half between the 2 groups. These findings suggest that distance covered in a match and speed are considerably different between international and national rugby sevens players, and this is reflected Address correspondence to Javier Portillo Yabar, [email protected]. 28(8)/2281–2289 Journal of Strength and Conditioning Research Ó 2014 National Strength and Conditioning Association
as higher intensity of play with consequently higher HR. Coaches may use this information to design specific running drills for this athlete population to match the requirements of national or international game play.
KEY WORDS elite, GPS, performance, competition INTRODUCTION
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ugby sevens has gained great popularity in recent years, is now recognized as an Olympic sport and will make its debut in the 2016 Summer Olympics (15), which will contribute to even greater popularity of the sport. The game is substantially the same as full rugby union, with some rule changes and shorter games. Matches have 2 halves of 7 minutes except the finals of a tournament in which each half is 10 minutes. Rugby sevens is characterized by the combination of efforts of high intensity with frequent intense bouts of running and tackling, interspersed with short bouts of recovery. As a result of the physical demands of the game, physiological qualities of players are highly developed with players requiring high levels of aerobic fitness, speed, repeat sprint ability, neuromuscular strength and power, and agility (13). A number of studies have focused on analyzing the physical demands in rugby union (2,9,11,12,14,29) and rugby league (24,25,30,34) using video recordings of matches or the global positioning system (GPS), but a lack of studies exist regarding physical demands of rugby sevens (20,32), which should be quite different given the duration and environment of the game. Although several studies have documented the physiological capacities of male international rugby players (14,17,23), there is a dearth of research examining rugby 7s athletes and in particular comparing international vs. national female rugby players under actual game conditions. Previously, Baker (3) reported that levels of upper-body maximal power seem to be a potent discriminator of playing ability between national rugby league VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players professionals, state league semiprofessionals, and younger college-age players. Jennings et al. (21) have investigated the activity demands of national level competition and compared these with the top-level international competition in field hockey. In addition to this, Gabbett (16) investigated the physiological characteristics of sub-elite junior and senior rugby league players and established performance standards for these athletes. By understanding the activity profiles between national and international tournaments, coaches could improve their fitness programs based on the requirements of each competition level and game characteristics targeting training at performance demands. Furthermore, the transition between levels could be facilitated by understanding such differences (30). As the first stage investigation of female rugby sevens athletes, it would seem critical to assess the running demands and subsequent physiological load of the game and determine if there are differences depending on level of competition, international vs. national. Knowledge of the distance, velocity, number of sprints, accelerations, and impacts required by rugby sevens players during competition would facilitate coaches to develop specific training programs to enhance the playing performance of these athletes to meet the demands of national and international competition. To our knowledge, there are currently no comparative studies that investigate differences in physical demands during a match in female rugby sevens players of national and international levels. With this in mind, the purposes of this study were to investigate the distance and speed demands and subsequent heart rate (HR) responses of female rugby sevens players competing at international and national levels and to establish running training program recommendations for these athletes. Furthermore, we hypothesize that players competing in international games will cover greater distances and at higher speeds than exhibited during national level competition, and this intensity will be reflected in higher HR response.
METHODS Experimental Approach to the Problem
We investigated the running characteristics, impacts, and heart response of female players during international vs. national rugby sevens competition using a cross-sectional research design. Specifically, game motion characteristics of distance, velocity and acceleration of running, impacts and physiological response as determined from HR were investigated during international vs. national women’s rugby sevens matches. Dependent variables were measured by mean of GPS receivers (incorporating accelerometers) and HR monitors. Data collection was conducted in 2 tournaments. The International Cisneros tournament held on June 12, 2011 and Region of Madrid Tournament held on June 27, 2011. The competition model was similar with the first group stage in 2 groups of 4 teams and 1 semifinal and final knockout round. All matches were played on the same standard
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outdoor natural grass fields. Playing time was 2 halves of 7 minutes each. All matches were played on the same day between 10:00 and 20:00. Additionally, all the players were provided with a consistent nutrition and hydration protocol between all matches. The data were gathered from 20 players (10 international and 10 national players) during 4 matches in both levels of player. Obtaining measures of player’s workload and physiological demands between different levels of performance in rugby sevens female players during the competition match enabled us to determine how these athletes responded to a competition and if differences exist between game workload and physiological response in both groups. Our dependent variables were distance traveled during the match and divided into halves and quarters, distance covered in 6 player speed zones, maximum HR categorized into player speed zones, average speed and maximal speed, number of sprints completed during the match, work-rest ratio, impacts, and acceleration. Our independent variable was the competition level (National or International). We believe this study is unique because of the level of athletes investigated, actual international competition was the setting and that they were women, an under-investigated population in this sport. In addition, an understanding of the workload and physiological requirements of national and international players during tournament play is important for monitoring performance and effectively planning training programs. Subjects
Twenty rugby sevens female players were recruited: 10 were members of the Spanish National Team (26.27 6 4.05 years, range 21–28, 65.39 6 5.01 kg of body mass, 166.7 6 6.7 cm height, percentage body fat 19.3 6 4.1, and 10.8 6 3.9 years of playing history in the national league at the end of the study) and defined as international. The female Spanish national team had been European champions in 2010 and the second in the European Championship in 2011 and 2012. A further 10 participants were amateur athletes from a Spanish rugby championship (32.12 6 6.40 years, range 20–41, 66.48 6 5.38 kg of body mass, 167.4 6 3.0 cm height, percentage body fat 21.5 6 5.1, and 10.4 6 2.5 years of playing history in the national league at the end of the study), being the third highest competitive level in European female rugby sevens championships (the 2 strongest rugby sevens female leagues are located in England and France) and defined as National level. All players completed 2 hours of training including warm-up and cool-down, 3 days per week. International players also completed an additional 4 hours of training per week with the Spanish National Team. Before participation, the experimental procedures and risk of the research were explained to all participants, who gave their voluntary written informed consent and understood that they were free to withdraw from the study at any time. The study was conducted in accordance with the Declaration of Helsinki, and all procedures were approved by the Research
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TABLE 1. Distance and speed during national and international competition. National (n = 21) Mean 6 SD Total distance (m) Average speed (km$h21) Average number of sprints (.20 km$h21) Distance (m) speed zone (0–6 km$h21) Distance (m) speed zone (6.1–12 km$h21) Distance (m) speed zone (12.1–14 km$h21) Distance (m) speed zone (14.1–18 km$h21) Distance (m) speed zone (18.1–20 km$h21) Distance (m) speed zone (.20 km$h21)
1363.4 5.2 1.9 523.6 437.1 157.0 199.4 46.2 47.0
6 6 6 6 6 6 6 6 6
221.8 0.6 1.4 137.0 96.8 50.5 78.9 32.7 38.8
International (n = 29) Mean 6 SD
Cohen’s Effect Size
6 6 6 6 6 6 6 6 6
1.37 1.63 1.58 0.27 1.26 0.16 0.92 1.42 1.47
1642.2 6.0 6.1 496.3 549.0 164.6 275.0 102.6 118.8
171.2* 0.3* 3.1* 69.1 73.6* 44.0 87.5* 48.2* 61.4*
*p , 0.01.
Ethics Committee at Castilla La Mancha University. All were given a medical examination before participation to assess their state of health and detect any medical condition, which might result in injury during the study.
ability of GPS has been established sampling at both 1 and 5 Hz (6,10,18,22,27). These studies report that GPS analysis is a valid and reliable method for tracking movement patterns in athletes during field sports. The players also wore an HR transmitter chest belt (Polar Electro, Kempele, Finland) to record Procedures HR data. Devices were switched on 5 minutes before the start The players’ running profile and impacts were assessed durof the game and turned off immediately after the game was ing competitive matches using a GPS device (mass: 76 g; completed. Data stored included time, distance, position, dimensions: 48 3 20 3 87 mm; SPI Pro X; GPSports Systems, speed, direction, HR, and the number and intensity of player Canberra, Australia) that enabled speed and distance to be impacts measured as peak acceleration in multiples of “g” (9.81 recorded at a sampling frequency of 15 Hz. Players’ accelerm$s22). The unit was worn in a small harness on the player’s upper back. After the data had been gathered, it was downations were also recorded using a triaxial accelerometer with loaded to a personal computer where additional analysis was an operational sampling rate of 100 Hz. The validity and relicarried out using the system software provided by the manufacturer (Team AMS; GPSports, V. R2 2010, Australia). The frequency and duration of running efforts were evaluated using the distance covered in 6 player speed zones. These were as follows: zone 1: standing and walking (0–6 km$h21), zone 2: jogging (6.1–12 km$h21), zone 3: cruising (12.1–14 km$h21), zone 4: striding (14.1–18 km$h21), zone 5: high-intensity running (18.1– 20 km$h21), and zone 6: sprinting (.20 km$h21). Allocations of speed zones were those considered to be typical of varying running categories during intermittent team sport (11). Movement speed was also Figure 1. Work to rest ratio in international and national rugby players. *p # 0.05. divided into categories to determine work to rest ratios: VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players
TABLE 2. Distance and speed during national and international competition comparing the first and second halves. First half National (n = 27) Mean 6 SD Total distance (m) Average speed (km$h21) Maximum speed (km$h21) Average number of sprints (.20 km$h21) Distance (m) speed zone (0–6 km$h21) Distance (m) speed zone (6.1–12 km$h21) Distance (m) speed zone (12.1–14 km$h21) Distance (m) speed zone (14.1–18 km$h21) Distance (m) speed zone (18.1–20 km$h21) Distance (m) speed zone (.20 km$h21) Average time spent in sprint
719.0 5.5 20.8 0.6 258.5 236.6
6 6 6 6 6 6
147.7 0.9 2.6 0.9 63.2 66.5
Second half
International (n = 36) Mean 6 SD 883.4 6.1 24.4 2.9 237.8 305.8
6 6 6 6 6 6
122.0* 0.3* 2.0* 1.8* 33.8 48.3
National (n = 22) Mean 6 SD 615.1 5.1 22.3 1.0 250.7 213.1
6 6 6 6 6 6
145.6 0.4 2.5 1.0 77.5 51.7
International (n = 30) Mean 6 SD 725.2 5.9 24.9 3.6 261.4 241.3
6 6 6 6 6 6
157.1* 0.4* 1.6† 2.0* 45.5 63.3
86.0 6 34.0
91.3 6 29.0
71.1 6 25.0
72.5 6 21.5
106.2 6 44.9
134.7 6 44.9*
88.0 6 45.5
114.4 6 49.8*
26.4 6 24.3
51.9 6 23.8*
19.3 6 15.1
46.4 6 19.3*
15.0 6 20.7 4.3 6 3.0
62.0 6 37.6* 9.0 6 5.7*
27.2 6 28.2 5.7 6 3.9
61.9 6 37.9† 1 6 5.8*
*p , 0.01.
(a) low-intensity activity (0–6 km$h21) and (b) moderateintensity and high-intensity activity (.6 km$h21). Acceleration was evaluated in 4 zones: zone 1: .1.5 m$s22, zone 2: .2 m$s22, zone 3: .2.5 m$s22, and zone 4: .2.75 m$s22. This categorization was based on similar previous work with rugby union players using GPS technology (11). Player impact data (intensity, number, and distribution) were determined from accelerometer data. Impact intensity was graded according to the following scaling system provided by the system manufacturer and in accordance with the work of Cunniffe et al. (11): 5–6 g: light impact, hard acceleration/deceleration/change of direction; 6–6.5 g: light to moderate impact (player collision, contact with the ground); 6.5–7 g: moderate to heavy impact (tackle); 7–8 g: heavy
impact (tackle); 8–10 g: very heavy impact (scrum engagement, tackle); and +10 g: severe impact/tackle/collision. To define efforts and analyze physical and physiological demands, the protocol proposed by Cunniffe et al. (11) was used. Recorded game HRs were grouped into 6 HR zones based on each player’s known maximum HR (HRmax). Heart rate zones were as follows: zone 1: ,60% HRmax, zone 2: 61–70% HRmax, zone 3: 71–80% HRmax, zone 4: 81–90% HRmax, zone 5: 91–95% HRmax, and zone 6: .95% HRmax. Maximum HR was estimated using the formula proposed by Tanaka et al. (33). For those players who had higher HRs during the match than that determined by the above estimation, actual maximum HR was used as the reference for calculating percentages.
TABLE 3. Summary of accelerations completed during the first and second halves. First half National Mean 6 SD No. No. No. No.
of of of of
accelerations accelerations accelerations accelerations
over over over over
1.5 m$s22 2.0 m$s22 2.5 m$s22 2.75 m$s22
6.0 3.0 0.4 0.2
6 6 6 6
2.2 2.30 0.6 0.5
Second half
International Mean 6 SD 6.0 4.3 1.3 1.7
6 6 6 6
2.7 1.7* 1.2* 1.2†
National Mean 6 SD 4.5 2.21 0.5 0.2
6 6 6 6
2.2 1.63 0.9 0.4
International Mean 6 SD 4.9 3.9 1.2 1.5
6 6 6 6
2.4 2.0† 1.2† 1.2†
*p # 0.05. †p , 0.01.
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differences in mean total distance, average speed, average number TABLE 4. Heart rate attained during national and international competition.* of sprints and distance covered in sprinting, and distances covNational (n = 26) International (n = 23) Mean 6 SD Mean 6 SD ered in speed zones: 6.1–12 km$h21, 14.1–18 km$h21, 18.1– 21 178.4 6 11.6 186.2 6 9.1 Maximum HR (b$min ) 20 km$h21, and .20 km$h21. Mean HR (b$min21) 154.5 6 14.3 163.6 6 9.2 The international women players *HR = heart rate. covered 17% higher mean total distance during a game than the national women players. In addition, the distance covered in high intensity (.18.1 km$h21) was Statistical Analyses 2.3 times that of the national players. The number of sprints (6.1 All results were analyzed using Statistical Package for Social 6 3.1 sprints in international vs. 1.9 6 1.4 sprints in nationals), Sciences (SPSS v. 19.0 for Windows). Data are presented as and the average speed (6.0 6 0.3 vs. 5.2 6 0.6 km$h21) was mean 6 SD. The t-test was applied to analyze differences higher for international compared with national tournaments. between groups for the different parameters recorded during For these variables, the Cohen’s effect size was large (Table 1). the match. A repeated-measures analysis of variance The player’s work to rest ratio in international games was 1:0.3 (ANOVA) was initially performed to identify differences in (i.e., for every 1 minute of work, there were 0.3 minutes of rest), variables over time (the first and second half). The alpha level whereas for national games, the ratio was 1:0.4 (Figure 1). These for criterion of statistical significance was set at p # 0.05. were significant differences (p , 0.01; Cohen’s ES: 1.24) between Additionally, Cohen’s effect size (Cohen’s d) (8) was calcuinternational and national players. lated as an index of effect in relation to the differences ob2 Results from the movement analysis of the first and second tained by applying the t-test, whereas eta squared partial (h ) half in international and national tournaments are presented was calculated as an index of effect size in relation to the in Table 2. Significant differences were observed between differences obtained after the application of ANOVA. For halves and groups in mean total distance (p , 0.01; h2 = effect size, the following categories were applied: 0.2 (small), 2 0.28), average speed (p , 0.01; h2 = 0.38), number of sprints 0.5 (moderate), and 0.8 (large), whereass for h , categorization 2 = 0.38), and distances covered in the following h (p , 0.01; was based on: 0.01 (small), 0.06 (moderate), and 0.14 (large). speed zones: 14.1–18 km$h21 (p , 0.01; h2 = 0.87); 18.1– RESULTS 20 km$h21 (p , 0.01; h2 = 0.36); .20 km$h21 (p , 0.01; h2 = 0.40), and maximal speed (p , 0.01; h2 = 0.40). The Results of the game analysis of national and international interaction between both factors was nonsignificant, so the initial competition are presented in Table 1. There were significant differences were maintained until the end of the match. The international players covered more distance than national in terms TABLE 5. Percent (%) time spent in each HR zone comparing halves and of mean total distance (18.7% in competition level.* first half and 15.2% in the second First half Second half half). The average number of National International National International sprints (.20 km$h21) of interMean 6 SD Mean 6 SD Mean 6 SD Mean 6 SD national players was higher Zone 1: ,60% HRmax 0.2 6 0.9 0.3 6 0.8 0.5 6 2.4 0.0 6 0.0 (p , 0.01) in the first and secZone 2: 61–70% 6.2 6 7.6 2.3 6 3.2 3.5 6 7.0 0.9 6 1.4 ond half (2.9 6 1.8 and 3.6 6 HRmax 2.0) than national players Zone 3: 71–80% 18.2 6 12.6 8.6 6 7.3 17.9 6 13.5 7.4 6 6.4 (0.6 6 0.9 and 1.0 6 1.0). HRmax Zone 4: 81–90% 41.6 6 13.1 29.4 6 12.7 36.9 6 16.7 31.7 6 13.0 Average speed and maximum HRmax speed of international players Zone 5: 91–95% 22.9 6 11.9 33.8 6 10.9 26.3 6 16.0 31.6 6 7.4 were higher in comparison HRmax with nationals for both first Zone 6: .95% HRmax 10.7 6 9.4 25.0 6 14.8† 15.3 6 11.8 28.3 6 17.8z and second half as shown *HRmax = maximum heart rate. Table 2. However, the distan†p , 0.01. ces covered in speed zones zp # 0.05. above (.18.1 km$h21) for the international players were VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players in a match. Our hypothesis was players in international games TABLE 6. Average speed for each quarter of the match. will cover greater distances and at higher speeds than national First half Second half level competition, and these reFirst quarter Second quarter Third quarter Fourth quarter sults confirm our hypothesis. Mean 6 SD Mean 6 SD Mean 6 SD Mean 6 SD This study characterizes the running demands of national and International 6.2 6 0.4 6.1 6 0.4 6.1 6 0.6 5.8 6 0.6 National 5.4 6 1.2 5.5 6 0.9 5.5 6 0.7 4.7 6 0.4 international women rugby sevens game play and provides important parameters for training program design. Rugby sevens is a contact 2.7 times higher than national in the first half and 2.3 times team sport that demands a variety of physiological requirehigher in the second. ments reflecting the high-intensity nature of the sport, which The number of accelerations in each half is provided in involves short repeated sprints combined with short efforts Table 3. No significant differences were found in acceleraof maximal strength and power expression through high tions between 1.5 and 2.0 m$s22. Significant differences (p # frequency body contact. It is typically a very fast game 0.05; h2 = 0.29) were found in accelerations above 2.0 m$s22 played at high speed with wide-open spaces. This is because in the first and second half, between internationals and nathe game is still played on a full size rugby pitch but with tionals, above 2.5 m$s22 (p , 0.01 in the first half and p # a reduced number of players. This has been supported 0.05 in the second; h2 = 0.19), and above 2.75 m$s22 (p , empirically by this GPS analysis indicating high-intensity 0.01 in both halves, h2 = 0.49). However, no significant running interspersed with short rest periods. These findings differences were found in impacts between international indicate that international players exhibit higher perforand national players. mance in competition, and that international games, as The mean and maximum HR during competition for the expected, are at higher intensity than national games. It is international players was higher than national during both reasonable to expect that international female rugby players halves as shown in Table 4. Percentage of time spent in each have developed higher performance capacity through HR zone during each half is presented in Table 5. There greater improvement in fitness so as to achieve international were significant differences only in zone 6 (.95% HRmax) selection and also to be able to meet the game demands. for both the first (p , 0.01) and second half (p # 0.05; h2 = This is likely because of better-developed physiological 0.14) between international and national players. characteristics of international players, and other factors Finally, the average speed during the matches is presented such as skills and tactics that determine success in rugby and in Table 6. For ease of interpretation, each half was divided these characteristics would be superior to national level into average speed for each of the 4 quarters, 2 in the first rugby players (20). half and 2 in the second half. No significant differences were This study shows that average distances covered (6SD) found between international and national players; however, was higher in international players (1642 6 171 m) than data indicate that average speed was stable in the first, secnationals (1363 6 221 m). This finding coincides with the ond, and third quarters and observed a decline in the fourth work of Suarez-Arrones et al. (32), using GPS technology quarter for national level. However, we found no significant with international women rugby sevens players obtaining differences in the international players among the 4 quarters, similar values (1556.2 6 189.3 m) to our study. Differences whereas significant differences were found in the fourth in distance covered in our study would be due to factors quarter in national players (p # 0.05 with the first quarter, such as fitness, agility, coordination, technical, and tactical p , 0.01 with the second and third quarters). abilities of the sample of international women rugby sevens players in combination with the higher intensity of compeDISCUSSION tition. It seems that measurement of these game running To our knowledge, this study is the first to investigate the characteristics and HR response are providing a valuable running velocities, impacts, and HR response of female rugby description of the differences between international and sevens players competing at international and national levels. women rugby sevens players as shown other studies in difWe found significant differences between distances covered in ferent sports (1,19,21,28). a match, average speed, distance covered in sprinting, and Jennings et al. (21) affirm that 1 explanation of the differdistances covered in speed zones: 6.1–12 km$h21, 14.1–18 ences in the activity demands between international and nakm$h21, 18.1–20 km$h21, and .20 km$h21. In addition, our tionals is the greater physical fitness in hockey. In addition to results confirm significant differences between international and this, Higham et al. (20) explained that observed increase in national female rugby 7 players for both first and second halves match intensity would be probably influenced by other
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Journal of Strength and Conditioning Research factors not measured in this current study as the greater experience of elite players, the level of skills, match tactics, or higher physical conditioning. There were significant differences in distance covered in speed zones 5 and 6, and number of sprints produced in competition between the 2 groups. For example, distance covered in the high-intensity zone (.18.1 km$h21) was greater for international players. Other parameters such as average and maximal speed were higher in international competition, and these findings are in agreement with Higham et al. (20). In addition, significant differences were observed between halves and groups in mean total distance, average speed, number of sprints and distances covered in the following speed zones: 14.1–18 km$h21; 18.1–20 km$h21; .20 km$h21, and maximal speed. These findings are in agreement with previous studies that reported higher speed, number of sprints, and distance covered in Australian Football (7), male rugby sevens (20), field hockey (21), and soccer (26). The finding of greater running performance, exercise intensity, and acceleration to the body for international female players in comparison with national players is in agreement with previous studies in rugby sevens (20) and hockey (21). Although our study did not include tests of fitness, other studies have found differences in fitness between international and national level players assessed with tests of fitness for example Baker and Newton (3–5) in rugby league. Our results indicate that rugby sevens generate high physiological stress as indicated by HR. The results of maximal (186.2 6 9.1 b$min21; 178.4 6 11.6 b$min21) and mean (163.6 6 9.2 b$min21; 154.5 6 14.3 b$min21) HR during the match showed a higher HR attained in international than nationals players because of level of intensity dictated by the speed of play being higher in international competition. We only found significant differences in zone 6 (96–100% HRmax), in the first (p , 0.01) and second half (p # 0.05) between nationals and internationals, so the international players maintain a higher intensity during the game compared with the national counterparts. The assessment of the external (i.e., running demands) and internal (HR responses) loads imposed during the actual competition is the first step preceding the design of specific conditioning programs and physical fitness testing protocols in rugby sevens. High-intensity running is of great importance in rugby sevens because the effect of this type of activity may well be a factor in deciding the final outcome of the match. Our results indicate that the intensity of the game is higher in international competition than national. However, although successful performance in rugby is dependent (at least in part) on welldeveloped physiological capacities, players also require the ability to exhibit high levels of skill under pressure and fatigue. In this study, the running performance during the match was also analyzed in relation to the mean velocity during the match. To achieve this, the match was divided into 4 quarters, 2 quarters for each half of the match. Nonsignificant differences were observed between international and
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national players in the mean velocity. In both player groups, the mean velocity was decreasing during the match, being slower during the last quarter compared with the first (p # 0.05) and the second and the third (p , 0.01) quarters. However, nonsignificant differences were found in the mean velocities of each quarter in the international players. The differences in running velocity over the course of the game have been studied in other sports such as soccer (26,28), Australian rules football (1), hockey (21), and rugby sevens (20). In rugby union, the studies of Cunniffe et al. (11) and Roberts et al. (29) did not report differences in running performance between the first and second half. The disparity between our results of a decline in velocity during rugby sevens competition and these 2 studies on traditional fullteam rugby may be explained by the different rules of each game, and the physiological demands imposed (31) and possibly the fitness level of the female athletes in this study. It does seem that the short-sided game causes greater fatigue requiring a reduction in running velocity as the game progresses. Thus, training strategies that reduce this decline should result in better game performance against opposition that does not develop this capacity. However, there is also evidence to suggest that the physiological capacities of players may deteriorate as the match progresses as affirmed Gabbett et al. (17). The differences in performance between national and international games could be because of other factors such as technical and tactical performance being higher in internationals and a higher level of physical fitness as shown in other studies (7,14,31). Work to rest ratio was significantly higher (p , 0.01) for international (1:0.3) vs. national players (1:0.4). These results are in agreement with the study of Suarez-Arrones et al. (32), in female rugby sevens. The work to rest ratio values reported in this study are substantially higher than any of those previously reported in other rugby codes (14,24,29), ranging from 1:5 to 1:7 depending on position of the player. This provides additional support to the notion that rugby sevens is played at a much higher intensity with quite high work:rest ratio compared with that of full-sided games. However, the work to rest ratio reflects the total highintensity running compared with the total time of the game under low-intensity exercise (0–6 km$h21), which does not accurately reflect the intensity generally associated with other nonlocomotor actions during the game such as push/pull in rucks, mauls, and scrums. This may explain this higher work to rest ratio reported in this study (11). Regardless, the small-sided rugby game seems to have much higher intensity than the 15 aside game, and this has relevance for strength and conditioning practice in terms of designing work:rest ratios into repeat sprint training. Such results also support the application of short-sided games for fitness training of athletes playing the 15 aside game. A limitation of this study is small sample size (n = 20 divided in 2 groups of 10) and heterogeneity of players, because the characteristics of players vary markedly with VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players different positions. As the sample size was small, the subjects in the 2 groups could not be subdivided into backs and forwards to compare the influence of playing position. In conclusion, the results of this study indicate significant differences between international and national competition for distance covered in a match, average speed, and distance covered in different speed zones (from walking to sprinting). International competition as hypothesized is of much higher intensity and training practices should reflect this. Running performance measured in meters covered and velocity tracked across the game demonstrated a slowing down for both national and international competition with significant decline particularly in the last quarter of the game. The higher intensity of rugby 7s compared with that of full-sided games has relevance for strength and conditioning of these athletes, and it is recommended that similar work:rest ratios as measured during competition should be applied in some aspects of their training program.
PRACTICAL APPLICATIONS The physiological model of competition described in this article can be used to predict and guide the prescription of future training loads during pre-season and in-season training phases for a female professional rugby team. Specifically, contemporary training regimes for rugby sevens need to meet the apparent increased overall running demands, including high-intensity running training and an emphasis on reduced work to rest ratios. In particular, strategies should be implemented to minimize the decline in running speed, which we observed over the course of the game, as this would provide considerable competitive advantage. From a practical perspective, additional study is warranted to address and determine the optimum quantity and quality of training for rugby players during a season from an analysis of competition. Based on the hypothesis that this study confirmed, the distances covered in highspeed zones and the average number of sprints are the defining factors in international competitive matches. These findings suggested the importance of developing the capacity to generate high-speed running capacity and an emphasis on the importance of sprint performance for female rugby sevens. In this regard, the results of this study can be used to inform multiple sprint intervals in conditioning programs. This study provides the first game descriptive data for these 2 levels of competition in this sport, which can be used for training program design by other teams and coaches. We believe the greatest practical application is that strength and conditioning specialists may design running programs that simulate the game characteristics reported from this study, which will provide more specific development of physiological capacities required for women rugby sevens competition.
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ACKNOWLEDGMENTS This study was partially supported by a grant from the Consejo Superior de Deportes, Spain.
REFERENCES 1. Aughey, RJ. Australian football player work rate: evidence of fatigue and pacing? Int J Sports Physiol Perform 5: 394–405, 2010. 2. Austin, D, Gabbett, T, and Jenkins, D. The physical demands of Super 14 rugby union. J Sci Med Sport 14: 259–263, 2011. 3. Baker, D. Comparison of upper-body strength and power between professional and college-aged rugby league players. J Strength Cond Res 15: 30–35, 2001. 4. Baker, D. Differences in strength and power among junior-high, senior-high, college-aged, and elite professional rugby league players. J Strength Cond Res 16: 581–585, 2002. 5. Baker, DG and Newton, RU. Comparison of lower body strength, power, acceleration, speed, agility, and sprint momentum to describe and compare playing rank among professional rugby league players. J Strength Cond Res 22: 153–158, 2008. 6. Barbero-Alvarez, JC, Coutts, A, Granda, J, Barbero-Alvarez, V, and Castagna, C. The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes. J Sci Med Sport 13: 232–235, 2010. 7. Brewer, C, Dawson, B, Heasman, J, Stewart, G, and Cormack, S. Movement pattern comparisons in elite (AFL) and sub-elite (WAFL) Australian football games using GPS. J Sci Med Sport 13: 618–623, 2010. 8. Cohen, J. Statistical Power Analysis for the Behavioral Sciences. Hillsdale, NJ: Lawrence Erlbaum Associates, 1988. 9. Coughlan, GF, Green, BS, Pook, PT, Toolan, E, and O’Connor, SP. Physical game demands in elite rugby union: a global positioning system analysis and possible implications for rehabilitation. J Orthop Sports Phys Ther 41: 600–605, 2011. 10. Coutts, AJ and Duffield, R. Validity and reliability of GPS devices for measuring movement demands of team sports. J Sci Med Sport 13: 133–135, 2010. 11. Cunniffe, B, Proctor, W, Baker, JS, and Davies, B. An evaluation of the physiological demands of elite rugby union using Global Positioning System tracking software. J Strength Cond Res 23: 1195– 1203, 2009. 12. Deutsch, MU, Kearney, GA, and Rehrer, NJ. Time—motion analysis of professional rugby union players during match-play. J Sports Sci 25: 461–472, 2007. 13. Duthie, G, Pyne, D, and Hooper, S. Applied physiology and game analysis of rugby union. Sports Med 33: 973–991, 2003. 14. Duthie, G, Pyne, D, and Hooper, S. Time motion analysis of 2001 and 2002 Super 12 rugby. J Sports Sci 23: 523–530, 2005. 15. Engebretsen, L and Steffen, K. Rugby in Rio in 2016! Br J Sports Med 44: 157, 2010. 16. Gabbett, T. Physiological characteristics of junior and senior rugby league players. Br J Sports Med 36: 334–339, 2002. 17. Gabbett, T, King, T, and Jenkins, D. Applied physiology of rugby league. Sports Med 38: 119–138, 2008. 18. Gray, AJ, Jenkins, D, Andrews, MH, Taaffe, DR, and Glover, ML. Validity and reliability of GPS for measuring distance travelled in field-based team sports. J Sports Sci 28: 1319–1325, 2010. 19. Hoff, J and Helgerud, J. Endurance and strength training for soccer players: physiological considerations. Sports Med 34: 165–180, 2004. 20. Higham, DG, Pyne, DB, Ansond, JM, and Eddyc, A. Movement patterns in rugby sevens: Effects of tournament level, fatigue and substitute players. J Sci Med Sport 15: 277–282, 2012.
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Journal of Strength and Conditioning Research 21. Jennings, DH, Cormack, SJ, Coutts, AJ, and Aughey, RJ. International field hockey players perform more high-speed running than nationallevel counterparts. J Strength Cond Res 26: 947–952, 2012. 22. Jennings, D, Cormack, S, Coutts, AJ, Boyd, L, and Aughey, RJ. The validity and reliability of GPS units for measuring distance in team sport specific running patterns. Int J Sports Physiol Perform 5: 328– 341, 2010.
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28. Rampinini, E, Impellizzeri, FM, Castagna, C, Coutts, AJ, and Wisloff, U. Technical performance during soccer matches of the Italian Serie A league: effect of fatigue and competitive level. J Sci Med Sport 12: 227–233, 2009. 29. Roberts, SP, Trewartha, G, Higgitt, RJ, El-Abd, J, and Stokes, KA. The physical demands of elite English rugby union. J Sports Sci 26: 825–833, 2008.
23. King, D, Hume, P, Milburn, P, and Guttenbeil, D. A review of the physiological and anthropometrical characteristics of rugby league players. South Afr J Res Sport Phys Educ Recreation 31: 49–67, 2009.
30. Sirotic, AC, Coutts, AJ, Knowles, H, and Catterick, C. A comparison of match demands between elite and semi-elite rugby league competition. J Sports Sci 27: 203–211, 2009.
24. King, T, Jenkins, D, and Gabbett, T. A time-motion analysis of professional rugby league match-play. J Sports Sci 27: 213–219, 2009.
31. Stone, NM and Kilding, AE. Aerobic conditioning for team sport athletes. Sports Med 39: 615–642, 2009.
25. McLellan, CP, Lovell, DI, and Gass, GC. Performance analysis of elite rugby league match play using global positioning systems. J Strength Cond Res 25: 1703–1710, 2011.
32. Suarez-Arrones, L, Nun˜ez, F, Portillo, J, and Mendez-Villanueva, A. Match running performance and exercise intensity in elite female rugby sevens. J Strength Cond Res 26: 1858–1862, 2012.
26. Mohr, M, Krustrup, P, and Bangsbo, J. Match performance of highstandard soccer players with special reference to development of fatigue. J Sports Sci 21: 519–528, 2003.
33. Tanaka, H, Monahan, KD, and Seals, DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 37: 153–156, 2001.
27. Petersen, C, Pyne, D, Portus, M, and Dawson, B. Validity and reliability of GPS units to monitor cricket-specific movement patterns. Int J Sports Physiol Perform 4: 381–393, 2009.
34. Waldron, M, Twist, C, Highton, J, Worsfold, P, and Daniels, M. Movement and physiological match demands of elite rugby league using portable global positioning systems. J Sports Sci 29: 1223– 1230, 2011.
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Sport Training Laboratory, Faculty of Sport Sciences, University of Castilla La Mancha, Spain; 2Faculty of Sport Sciences, University of Pablo de Olavide, Spain; 3School of Exercise, Biomedical and Health Sciences, Edith Cowan University Australia; and 4Strength and Conditioning Spanish Rugby Federation, Spain
ABSTRACT Portillo, J, Mª Gonza´lez-Rave´, J, Jua´rez, D, Garcı´a, JM, Sua´rezArrones, L, and Newton, RU. Comparison of running characteristics and heart rate response of international and national female rugby sevens players during competitive matches. J Strength Cond Res 28(8): 2281–2289, 2014—This study compared the activity profile of national and international female rugby sevens players during competitive matches. Twenty rugby sevens female players were recruited, 10 were members of the Spanish National Team (26.27 6 4.05 years, 65.39 6 5.01 kg, 166.72 6 6.70 cm) and 10 were amateur athletes from a Spanish rugby championship (32.12 6 6.40 years, 66.48 6 5.38 kg of body mass, 167.37 6 3.02 cm). Data collection was conducted over 4 matches in each of the 2 tournaments, national and international. Distance, velocity, and heart rate (HR) were recorded using global positioning system devices for all participants throughout each match. There were significant differences (p , 0.01) in total distance (1642 6 171 vs. 1363 6 222 m), average speed (6.0 6 0.3 vs. 5.2 6 0.6 km$h21), number of sprints (6.1 6 3.1 vs. 1.9 6 1.4 sprints), and distance covered in sprinting (118.8 6 61.4 vs. 47.0 6 38.8 m). Significant differences were found at .95% maximum HR (HRmax), both for the first (p , 0.01) and second half (p # 0.05). The work-rest ratio was significantly different (p , 0.01) between international (1:0.3) and national players (1:0.4). Significant differences were found in accelerations above 2 m$s22 in the first and second half between the 2 groups. These findings suggest that distance covered in a match and speed are considerably different between international and national rugby sevens players, and this is reflected Address correspondence to Javier Portillo Yabar, [email protected]. 28(8)/2281–2289 Journal of Strength and Conditioning Research Ó 2014 National Strength and Conditioning Association
as higher intensity of play with consequently higher HR. Coaches may use this information to design specific running drills for this athlete population to match the requirements of national or international game play.
KEY WORDS elite, GPS, performance, competition INTRODUCTION
R
ugby sevens has gained great popularity in recent years, is now recognized as an Olympic sport and will make its debut in the 2016 Summer Olympics (15), which will contribute to even greater popularity of the sport. The game is substantially the same as full rugby union, with some rule changes and shorter games. Matches have 2 halves of 7 minutes except the finals of a tournament in which each half is 10 minutes. Rugby sevens is characterized by the combination of efforts of high intensity with frequent intense bouts of running and tackling, interspersed with short bouts of recovery. As a result of the physical demands of the game, physiological qualities of players are highly developed with players requiring high levels of aerobic fitness, speed, repeat sprint ability, neuromuscular strength and power, and agility (13). A number of studies have focused on analyzing the physical demands in rugby union (2,9,11,12,14,29) and rugby league (24,25,30,34) using video recordings of matches or the global positioning system (GPS), but a lack of studies exist regarding physical demands of rugby sevens (20,32), which should be quite different given the duration and environment of the game. Although several studies have documented the physiological capacities of male international rugby players (14,17,23), there is a dearth of research examining rugby 7s athletes and in particular comparing international vs. national female rugby players under actual game conditions. Previously, Baker (3) reported that levels of upper-body maximal power seem to be a potent discriminator of playing ability between national rugby league VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players professionals, state league semiprofessionals, and younger college-age players. Jennings et al. (21) have investigated the activity demands of national level competition and compared these with the top-level international competition in field hockey. In addition to this, Gabbett (16) investigated the physiological characteristics of sub-elite junior and senior rugby league players and established performance standards for these athletes. By understanding the activity profiles between national and international tournaments, coaches could improve their fitness programs based on the requirements of each competition level and game characteristics targeting training at performance demands. Furthermore, the transition between levels could be facilitated by understanding such differences (30). As the first stage investigation of female rugby sevens athletes, it would seem critical to assess the running demands and subsequent physiological load of the game and determine if there are differences depending on level of competition, international vs. national. Knowledge of the distance, velocity, number of sprints, accelerations, and impacts required by rugby sevens players during competition would facilitate coaches to develop specific training programs to enhance the playing performance of these athletes to meet the demands of national and international competition. To our knowledge, there are currently no comparative studies that investigate differences in physical demands during a match in female rugby sevens players of national and international levels. With this in mind, the purposes of this study were to investigate the distance and speed demands and subsequent heart rate (HR) responses of female rugby sevens players competing at international and national levels and to establish running training program recommendations for these athletes. Furthermore, we hypothesize that players competing in international games will cover greater distances and at higher speeds than exhibited during national level competition, and this intensity will be reflected in higher HR response.
METHODS Experimental Approach to the Problem
We investigated the running characteristics, impacts, and heart response of female players during international vs. national rugby sevens competition using a cross-sectional research design. Specifically, game motion characteristics of distance, velocity and acceleration of running, impacts and physiological response as determined from HR were investigated during international vs. national women’s rugby sevens matches. Dependent variables were measured by mean of GPS receivers (incorporating accelerometers) and HR monitors. Data collection was conducted in 2 tournaments. The International Cisneros tournament held on June 12, 2011 and Region of Madrid Tournament held on June 27, 2011. The competition model was similar with the first group stage in 2 groups of 4 teams and 1 semifinal and final knockout round. All matches were played on the same standard
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outdoor natural grass fields. Playing time was 2 halves of 7 minutes each. All matches were played on the same day between 10:00 and 20:00. Additionally, all the players were provided with a consistent nutrition and hydration protocol between all matches. The data were gathered from 20 players (10 international and 10 national players) during 4 matches in both levels of player. Obtaining measures of player’s workload and physiological demands between different levels of performance in rugby sevens female players during the competition match enabled us to determine how these athletes responded to a competition and if differences exist between game workload and physiological response in both groups. Our dependent variables were distance traveled during the match and divided into halves and quarters, distance covered in 6 player speed zones, maximum HR categorized into player speed zones, average speed and maximal speed, number of sprints completed during the match, work-rest ratio, impacts, and acceleration. Our independent variable was the competition level (National or International). We believe this study is unique because of the level of athletes investigated, actual international competition was the setting and that they were women, an under-investigated population in this sport. In addition, an understanding of the workload and physiological requirements of national and international players during tournament play is important for monitoring performance and effectively planning training programs. Subjects
Twenty rugby sevens female players were recruited: 10 were members of the Spanish National Team (26.27 6 4.05 years, range 21–28, 65.39 6 5.01 kg of body mass, 166.7 6 6.7 cm height, percentage body fat 19.3 6 4.1, and 10.8 6 3.9 years of playing history in the national league at the end of the study) and defined as international. The female Spanish national team had been European champions in 2010 and the second in the European Championship in 2011 and 2012. A further 10 participants were amateur athletes from a Spanish rugby championship (32.12 6 6.40 years, range 20–41, 66.48 6 5.38 kg of body mass, 167.4 6 3.0 cm height, percentage body fat 21.5 6 5.1, and 10.4 6 2.5 years of playing history in the national league at the end of the study), being the third highest competitive level in European female rugby sevens championships (the 2 strongest rugby sevens female leagues are located in England and France) and defined as National level. All players completed 2 hours of training including warm-up and cool-down, 3 days per week. International players also completed an additional 4 hours of training per week with the Spanish National Team. Before participation, the experimental procedures and risk of the research were explained to all participants, who gave their voluntary written informed consent and understood that they were free to withdraw from the study at any time. The study was conducted in accordance with the Declaration of Helsinki, and all procedures were approved by the Research
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TABLE 1. Distance and speed during national and international competition. National (n = 21) Mean 6 SD Total distance (m) Average speed (km$h21) Average number of sprints (.20 km$h21) Distance (m) speed zone (0–6 km$h21) Distance (m) speed zone (6.1–12 km$h21) Distance (m) speed zone (12.1–14 km$h21) Distance (m) speed zone (14.1–18 km$h21) Distance (m) speed zone (18.1–20 km$h21) Distance (m) speed zone (.20 km$h21)
1363.4 5.2 1.9 523.6 437.1 157.0 199.4 46.2 47.0
6 6 6 6 6 6 6 6 6
221.8 0.6 1.4 137.0 96.8 50.5 78.9 32.7 38.8
International (n = 29) Mean 6 SD
Cohen’s Effect Size
6 6 6 6 6 6 6 6 6
1.37 1.63 1.58 0.27 1.26 0.16 0.92 1.42 1.47
1642.2 6.0 6.1 496.3 549.0 164.6 275.0 102.6 118.8
171.2* 0.3* 3.1* 69.1 73.6* 44.0 87.5* 48.2* 61.4*
*p , 0.01.
Ethics Committee at Castilla La Mancha University. All were given a medical examination before participation to assess their state of health and detect any medical condition, which might result in injury during the study.
ability of GPS has been established sampling at both 1 and 5 Hz (6,10,18,22,27). These studies report that GPS analysis is a valid and reliable method for tracking movement patterns in athletes during field sports. The players also wore an HR transmitter chest belt (Polar Electro, Kempele, Finland) to record Procedures HR data. Devices were switched on 5 minutes before the start The players’ running profile and impacts were assessed durof the game and turned off immediately after the game was ing competitive matches using a GPS device (mass: 76 g; completed. Data stored included time, distance, position, dimensions: 48 3 20 3 87 mm; SPI Pro X; GPSports Systems, speed, direction, HR, and the number and intensity of player Canberra, Australia) that enabled speed and distance to be impacts measured as peak acceleration in multiples of “g” (9.81 recorded at a sampling frequency of 15 Hz. Players’ accelerm$s22). The unit was worn in a small harness on the player’s upper back. After the data had been gathered, it was downations were also recorded using a triaxial accelerometer with loaded to a personal computer where additional analysis was an operational sampling rate of 100 Hz. The validity and relicarried out using the system software provided by the manufacturer (Team AMS; GPSports, V. R2 2010, Australia). The frequency and duration of running efforts were evaluated using the distance covered in 6 player speed zones. These were as follows: zone 1: standing and walking (0–6 km$h21), zone 2: jogging (6.1–12 km$h21), zone 3: cruising (12.1–14 km$h21), zone 4: striding (14.1–18 km$h21), zone 5: high-intensity running (18.1– 20 km$h21), and zone 6: sprinting (.20 km$h21). Allocations of speed zones were those considered to be typical of varying running categories during intermittent team sport (11). Movement speed was also Figure 1. Work to rest ratio in international and national rugby players. *p # 0.05. divided into categories to determine work to rest ratios: VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players
TABLE 2. Distance and speed during national and international competition comparing the first and second halves. First half National (n = 27) Mean 6 SD Total distance (m) Average speed (km$h21) Maximum speed (km$h21) Average number of sprints (.20 km$h21) Distance (m) speed zone (0–6 km$h21) Distance (m) speed zone (6.1–12 km$h21) Distance (m) speed zone (12.1–14 km$h21) Distance (m) speed zone (14.1–18 km$h21) Distance (m) speed zone (18.1–20 km$h21) Distance (m) speed zone (.20 km$h21) Average time spent in sprint
719.0 5.5 20.8 0.6 258.5 236.6
6 6 6 6 6 6
147.7 0.9 2.6 0.9 63.2 66.5
Second half
International (n = 36) Mean 6 SD 883.4 6.1 24.4 2.9 237.8 305.8
6 6 6 6 6 6
122.0* 0.3* 2.0* 1.8* 33.8 48.3
National (n = 22) Mean 6 SD 615.1 5.1 22.3 1.0 250.7 213.1
6 6 6 6 6 6
145.6 0.4 2.5 1.0 77.5 51.7
International (n = 30) Mean 6 SD 725.2 5.9 24.9 3.6 261.4 241.3
6 6 6 6 6 6
157.1* 0.4* 1.6† 2.0* 45.5 63.3
86.0 6 34.0
91.3 6 29.0
71.1 6 25.0
72.5 6 21.5
106.2 6 44.9
134.7 6 44.9*
88.0 6 45.5
114.4 6 49.8*
26.4 6 24.3
51.9 6 23.8*
19.3 6 15.1
46.4 6 19.3*
15.0 6 20.7 4.3 6 3.0
62.0 6 37.6* 9.0 6 5.7*
27.2 6 28.2 5.7 6 3.9
61.9 6 37.9† 1 6 5.8*
*p , 0.01.
(a) low-intensity activity (0–6 km$h21) and (b) moderateintensity and high-intensity activity (.6 km$h21). Acceleration was evaluated in 4 zones: zone 1: .1.5 m$s22, zone 2: .2 m$s22, zone 3: .2.5 m$s22, and zone 4: .2.75 m$s22. This categorization was based on similar previous work with rugby union players using GPS technology (11). Player impact data (intensity, number, and distribution) were determined from accelerometer data. Impact intensity was graded according to the following scaling system provided by the system manufacturer and in accordance with the work of Cunniffe et al. (11): 5–6 g: light impact, hard acceleration/deceleration/change of direction; 6–6.5 g: light to moderate impact (player collision, contact with the ground); 6.5–7 g: moderate to heavy impact (tackle); 7–8 g: heavy
impact (tackle); 8–10 g: very heavy impact (scrum engagement, tackle); and +10 g: severe impact/tackle/collision. To define efforts and analyze physical and physiological demands, the protocol proposed by Cunniffe et al. (11) was used. Recorded game HRs were grouped into 6 HR zones based on each player’s known maximum HR (HRmax). Heart rate zones were as follows: zone 1: ,60% HRmax, zone 2: 61–70% HRmax, zone 3: 71–80% HRmax, zone 4: 81–90% HRmax, zone 5: 91–95% HRmax, and zone 6: .95% HRmax. Maximum HR was estimated using the formula proposed by Tanaka et al. (33). For those players who had higher HRs during the match than that determined by the above estimation, actual maximum HR was used as the reference for calculating percentages.
TABLE 3. Summary of accelerations completed during the first and second halves. First half National Mean 6 SD No. No. No. No.
of of of of
accelerations accelerations accelerations accelerations
over over over over
1.5 m$s22 2.0 m$s22 2.5 m$s22 2.75 m$s22
6.0 3.0 0.4 0.2
6 6 6 6
2.2 2.30 0.6 0.5
Second half
International Mean 6 SD 6.0 4.3 1.3 1.7
6 6 6 6
2.7 1.7* 1.2* 1.2†
National Mean 6 SD 4.5 2.21 0.5 0.2
6 6 6 6
2.2 1.63 0.9 0.4
International Mean 6 SD 4.9 3.9 1.2 1.5
6 6 6 6
2.4 2.0† 1.2† 1.2†
*p # 0.05. †p , 0.01.
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differences in mean total distance, average speed, average number TABLE 4. Heart rate attained during national and international competition.* of sprints and distance covered in sprinting, and distances covNational (n = 26) International (n = 23) Mean 6 SD Mean 6 SD ered in speed zones: 6.1–12 km$h21, 14.1–18 km$h21, 18.1– 21 178.4 6 11.6 186.2 6 9.1 Maximum HR (b$min ) 20 km$h21, and .20 km$h21. Mean HR (b$min21) 154.5 6 14.3 163.6 6 9.2 The international women players *HR = heart rate. covered 17% higher mean total distance during a game than the national women players. In addition, the distance covered in high intensity (.18.1 km$h21) was Statistical Analyses 2.3 times that of the national players. The number of sprints (6.1 All results were analyzed using Statistical Package for Social 6 3.1 sprints in international vs. 1.9 6 1.4 sprints in nationals), Sciences (SPSS v. 19.0 for Windows). Data are presented as and the average speed (6.0 6 0.3 vs. 5.2 6 0.6 km$h21) was mean 6 SD. The t-test was applied to analyze differences higher for international compared with national tournaments. between groups for the different parameters recorded during For these variables, the Cohen’s effect size was large (Table 1). the match. A repeated-measures analysis of variance The player’s work to rest ratio in international games was 1:0.3 (ANOVA) was initially performed to identify differences in (i.e., for every 1 minute of work, there were 0.3 minutes of rest), variables over time (the first and second half). The alpha level whereas for national games, the ratio was 1:0.4 (Figure 1). These for criterion of statistical significance was set at p # 0.05. were significant differences (p , 0.01; Cohen’s ES: 1.24) between Additionally, Cohen’s effect size (Cohen’s d) (8) was calcuinternational and national players. lated as an index of effect in relation to the differences ob2 Results from the movement analysis of the first and second tained by applying the t-test, whereas eta squared partial (h ) half in international and national tournaments are presented was calculated as an index of effect size in relation to the in Table 2. Significant differences were observed between differences obtained after the application of ANOVA. For halves and groups in mean total distance (p , 0.01; h2 = effect size, the following categories were applied: 0.2 (small), 2 0.28), average speed (p , 0.01; h2 = 0.38), number of sprints 0.5 (moderate), and 0.8 (large), whereass for h , categorization 2 = 0.38), and distances covered in the following h (p , 0.01; was based on: 0.01 (small), 0.06 (moderate), and 0.14 (large). speed zones: 14.1–18 km$h21 (p , 0.01; h2 = 0.87); 18.1– RESULTS 20 km$h21 (p , 0.01; h2 = 0.36); .20 km$h21 (p , 0.01; h2 = 0.40), and maximal speed (p , 0.01; h2 = 0.40). The Results of the game analysis of national and international interaction between both factors was nonsignificant, so the initial competition are presented in Table 1. There were significant differences were maintained until the end of the match. The international players covered more distance than national in terms TABLE 5. Percent (%) time spent in each HR zone comparing halves and of mean total distance (18.7% in competition level.* first half and 15.2% in the second First half Second half half). The average number of National International National International sprints (.20 km$h21) of interMean 6 SD Mean 6 SD Mean 6 SD Mean 6 SD national players was higher Zone 1: ,60% HRmax 0.2 6 0.9 0.3 6 0.8 0.5 6 2.4 0.0 6 0.0 (p , 0.01) in the first and secZone 2: 61–70% 6.2 6 7.6 2.3 6 3.2 3.5 6 7.0 0.9 6 1.4 ond half (2.9 6 1.8 and 3.6 6 HRmax 2.0) than national players Zone 3: 71–80% 18.2 6 12.6 8.6 6 7.3 17.9 6 13.5 7.4 6 6.4 (0.6 6 0.9 and 1.0 6 1.0). HRmax Zone 4: 81–90% 41.6 6 13.1 29.4 6 12.7 36.9 6 16.7 31.7 6 13.0 Average speed and maximum HRmax speed of international players Zone 5: 91–95% 22.9 6 11.9 33.8 6 10.9 26.3 6 16.0 31.6 6 7.4 were higher in comparison HRmax with nationals for both first Zone 6: .95% HRmax 10.7 6 9.4 25.0 6 14.8† 15.3 6 11.8 28.3 6 17.8z and second half as shown *HRmax = maximum heart rate. Table 2. However, the distan†p , 0.01. ces covered in speed zones zp # 0.05. above (.18.1 km$h21) for the international players were VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players in a match. Our hypothesis was players in international games TABLE 6. Average speed for each quarter of the match. will cover greater distances and at higher speeds than national First half Second half level competition, and these reFirst quarter Second quarter Third quarter Fourth quarter sults confirm our hypothesis. Mean 6 SD Mean 6 SD Mean 6 SD Mean 6 SD This study characterizes the running demands of national and International 6.2 6 0.4 6.1 6 0.4 6.1 6 0.6 5.8 6 0.6 National 5.4 6 1.2 5.5 6 0.9 5.5 6 0.7 4.7 6 0.4 international women rugby sevens game play and provides important parameters for training program design. Rugby sevens is a contact 2.7 times higher than national in the first half and 2.3 times team sport that demands a variety of physiological requirehigher in the second. ments reflecting the high-intensity nature of the sport, which The number of accelerations in each half is provided in involves short repeated sprints combined with short efforts Table 3. No significant differences were found in acceleraof maximal strength and power expression through high tions between 1.5 and 2.0 m$s22. Significant differences (p # frequency body contact. It is typically a very fast game 0.05; h2 = 0.29) were found in accelerations above 2.0 m$s22 played at high speed with wide-open spaces. This is because in the first and second half, between internationals and nathe game is still played on a full size rugby pitch but with tionals, above 2.5 m$s22 (p , 0.01 in the first half and p # a reduced number of players. This has been supported 0.05 in the second; h2 = 0.19), and above 2.75 m$s22 (p , empirically by this GPS analysis indicating high-intensity 0.01 in both halves, h2 = 0.49). However, no significant running interspersed with short rest periods. These findings differences were found in impacts between international indicate that international players exhibit higher perforand national players. mance in competition, and that international games, as The mean and maximum HR during competition for the expected, are at higher intensity than national games. It is international players was higher than national during both reasonable to expect that international female rugby players halves as shown in Table 4. Percentage of time spent in each have developed higher performance capacity through HR zone during each half is presented in Table 5. There greater improvement in fitness so as to achieve international were significant differences only in zone 6 (.95% HRmax) selection and also to be able to meet the game demands. for both the first (p , 0.01) and second half (p # 0.05; h2 = This is likely because of better-developed physiological 0.14) between international and national players. characteristics of international players, and other factors Finally, the average speed during the matches is presented such as skills and tactics that determine success in rugby and in Table 6. For ease of interpretation, each half was divided these characteristics would be superior to national level into average speed for each of the 4 quarters, 2 in the first rugby players (20). half and 2 in the second half. No significant differences were This study shows that average distances covered (6SD) found between international and national players; however, was higher in international players (1642 6 171 m) than data indicate that average speed was stable in the first, secnationals (1363 6 221 m). This finding coincides with the ond, and third quarters and observed a decline in the fourth work of Suarez-Arrones et al. (32), using GPS technology quarter for national level. However, we found no significant with international women rugby sevens players obtaining differences in the international players among the 4 quarters, similar values (1556.2 6 189.3 m) to our study. Differences whereas significant differences were found in the fourth in distance covered in our study would be due to factors quarter in national players (p # 0.05 with the first quarter, such as fitness, agility, coordination, technical, and tactical p , 0.01 with the second and third quarters). abilities of the sample of international women rugby sevens players in combination with the higher intensity of compeDISCUSSION tition. It seems that measurement of these game running To our knowledge, this study is the first to investigate the characteristics and HR response are providing a valuable running velocities, impacts, and HR response of female rugby description of the differences between international and sevens players competing at international and national levels. women rugby sevens players as shown other studies in difWe found significant differences between distances covered in ferent sports (1,19,21,28). a match, average speed, distance covered in sprinting, and Jennings et al. (21) affirm that 1 explanation of the differdistances covered in speed zones: 6.1–12 km$h21, 14.1–18 ences in the activity demands between international and nakm$h21, 18.1–20 km$h21, and .20 km$h21. In addition, our tionals is the greater physical fitness in hockey. In addition to results confirm significant differences between international and this, Higham et al. (20) explained that observed increase in national female rugby 7 players for both first and second halves match intensity would be probably influenced by other
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Journal of Strength and Conditioning Research factors not measured in this current study as the greater experience of elite players, the level of skills, match tactics, or higher physical conditioning. There were significant differences in distance covered in speed zones 5 and 6, and number of sprints produced in competition between the 2 groups. For example, distance covered in the high-intensity zone (.18.1 km$h21) was greater for international players. Other parameters such as average and maximal speed were higher in international competition, and these findings are in agreement with Higham et al. (20). In addition, significant differences were observed between halves and groups in mean total distance, average speed, number of sprints and distances covered in the following speed zones: 14.1–18 km$h21; 18.1–20 km$h21; .20 km$h21, and maximal speed. These findings are in agreement with previous studies that reported higher speed, number of sprints, and distance covered in Australian Football (7), male rugby sevens (20), field hockey (21), and soccer (26). The finding of greater running performance, exercise intensity, and acceleration to the body for international female players in comparison with national players is in agreement with previous studies in rugby sevens (20) and hockey (21). Although our study did not include tests of fitness, other studies have found differences in fitness between international and national level players assessed with tests of fitness for example Baker and Newton (3–5) in rugby league. Our results indicate that rugby sevens generate high physiological stress as indicated by HR. The results of maximal (186.2 6 9.1 b$min21; 178.4 6 11.6 b$min21) and mean (163.6 6 9.2 b$min21; 154.5 6 14.3 b$min21) HR during the match showed a higher HR attained in international than nationals players because of level of intensity dictated by the speed of play being higher in international competition. We only found significant differences in zone 6 (96–100% HRmax), in the first (p , 0.01) and second half (p # 0.05) between nationals and internationals, so the international players maintain a higher intensity during the game compared with the national counterparts. The assessment of the external (i.e., running demands) and internal (HR responses) loads imposed during the actual competition is the first step preceding the design of specific conditioning programs and physical fitness testing protocols in rugby sevens. High-intensity running is of great importance in rugby sevens because the effect of this type of activity may well be a factor in deciding the final outcome of the match. Our results indicate that the intensity of the game is higher in international competition than national. However, although successful performance in rugby is dependent (at least in part) on welldeveloped physiological capacities, players also require the ability to exhibit high levels of skill under pressure and fatigue. In this study, the running performance during the match was also analyzed in relation to the mean velocity during the match. To achieve this, the match was divided into 4 quarters, 2 quarters for each half of the match. Nonsignificant differences were observed between international and
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national players in the mean velocity. In both player groups, the mean velocity was decreasing during the match, being slower during the last quarter compared with the first (p # 0.05) and the second and the third (p , 0.01) quarters. However, nonsignificant differences were found in the mean velocities of each quarter in the international players. The differences in running velocity over the course of the game have been studied in other sports such as soccer (26,28), Australian rules football (1), hockey (21), and rugby sevens (20). In rugby union, the studies of Cunniffe et al. (11) and Roberts et al. (29) did not report differences in running performance between the first and second half. The disparity between our results of a decline in velocity during rugby sevens competition and these 2 studies on traditional fullteam rugby may be explained by the different rules of each game, and the physiological demands imposed (31) and possibly the fitness level of the female athletes in this study. It does seem that the short-sided game causes greater fatigue requiring a reduction in running velocity as the game progresses. Thus, training strategies that reduce this decline should result in better game performance against opposition that does not develop this capacity. However, there is also evidence to suggest that the physiological capacities of players may deteriorate as the match progresses as affirmed Gabbett et al. (17). The differences in performance between national and international games could be because of other factors such as technical and tactical performance being higher in internationals and a higher level of physical fitness as shown in other studies (7,14,31). Work to rest ratio was significantly higher (p , 0.01) for international (1:0.3) vs. national players (1:0.4). These results are in agreement with the study of Suarez-Arrones et al. (32), in female rugby sevens. The work to rest ratio values reported in this study are substantially higher than any of those previously reported in other rugby codes (14,24,29), ranging from 1:5 to 1:7 depending on position of the player. This provides additional support to the notion that rugby sevens is played at a much higher intensity with quite high work:rest ratio compared with that of full-sided games. However, the work to rest ratio reflects the total highintensity running compared with the total time of the game under low-intensity exercise (0–6 km$h21), which does not accurately reflect the intensity generally associated with other nonlocomotor actions during the game such as push/pull in rucks, mauls, and scrums. This may explain this higher work to rest ratio reported in this study (11). Regardless, the small-sided rugby game seems to have much higher intensity than the 15 aside game, and this has relevance for strength and conditioning practice in terms of designing work:rest ratios into repeat sprint training. Such results also support the application of short-sided games for fitness training of athletes playing the 15 aside game. A limitation of this study is small sample size (n = 20 divided in 2 groups of 10) and heterogeneity of players, because the characteristics of players vary markedly with VOLUME 28 | NUMBER 8 | AUGUST 2014 |
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Comparison Between Female Rugby Sevens Players different positions. As the sample size was small, the subjects in the 2 groups could not be subdivided into backs and forwards to compare the influence of playing position. In conclusion, the results of this study indicate significant differences between international and national competition for distance covered in a match, average speed, and distance covered in different speed zones (from walking to sprinting). International competition as hypothesized is of much higher intensity and training practices should reflect this. Running performance measured in meters covered and velocity tracked across the game demonstrated a slowing down for both national and international competition with significant decline particularly in the last quarter of the game. The higher intensity of rugby 7s compared with that of full-sided games has relevance for strength and conditioning of these athletes, and it is recommended that similar work:rest ratios as measured during competition should be applied in some aspects of their training program.
PRACTICAL APPLICATIONS The physiological model of competition described in this article can be used to predict and guide the prescription of future training loads during pre-season and in-season training phases for a female professional rugby team. Specifically, contemporary training regimes for rugby sevens need to meet the apparent increased overall running demands, including high-intensity running training and an emphasis on reduced work to rest ratios. In particular, strategies should be implemented to minimize the decline in running speed, which we observed over the course of the game, as this would provide considerable competitive advantage. From a practical perspective, additional study is warranted to address and determine the optimum quantity and quality of training for rugby players during a season from an analysis of competition. Based on the hypothesis that this study confirmed, the distances covered in highspeed zones and the average number of sprints are the defining factors in international competitive matches. These findings suggested the importance of developing the capacity to generate high-speed running capacity and an emphasis on the importance of sprint performance for female rugby sevens. In this regard, the results of this study can be used to inform multiple sprint intervals in conditioning programs. This study provides the first game descriptive data for these 2 levels of competition in this sport, which can be used for training program design by other teams and coaches. We believe the greatest practical application is that strength and conditioning specialists may design running programs that simulate the game characteristics reported from this study, which will provide more specific development of physiological capacities required for women rugby sevens competition.
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ACKNOWLEDGMENTS This study was partially supported by a grant from the Consejo Superior de Deportes, Spain.
REFERENCES 1. Aughey, RJ. Australian football player work rate: evidence of fatigue and pacing? Int J Sports Physiol Perform 5: 394–405, 2010. 2. Austin, D, Gabbett, T, and Jenkins, D. The physical demands of Super 14 rugby union. J Sci Med Sport 14: 259–263, 2011. 3. Baker, D. Comparison of upper-body strength and power between professional and college-aged rugby league players. J Strength Cond Res 15: 30–35, 2001. 4. Baker, D. Differences in strength and power among junior-high, senior-high, college-aged, and elite professional rugby league players. J Strength Cond Res 16: 581–585, 2002. 5. Baker, DG and Newton, RU. Comparison of lower body strength, power, acceleration, speed, agility, and sprint momentum to describe and compare playing rank among professional rugby league players. J Strength Cond Res 22: 153–158, 2008. 6. Barbero-Alvarez, JC, Coutts, A, Granda, J, Barbero-Alvarez, V, and Castagna, C. The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes. J Sci Med Sport 13: 232–235, 2010. 7. Brewer, C, Dawson, B, Heasman, J, Stewart, G, and Cormack, S. Movement pattern comparisons in elite (AFL) and sub-elite (WAFL) Australian football games using GPS. J Sci Med Sport 13: 618–623, 2010. 8. Cohen, J. Statistical Power Analysis for the Behavioral Sciences. Hillsdale, NJ: Lawrence Erlbaum Associates, 1988. 9. Coughlan, GF, Green, BS, Pook, PT, Toolan, E, and O’Connor, SP. Physical game demands in elite rugby union: a global positioning system analysis and possible implications for rehabilitation. J Orthop Sports Phys Ther 41: 600–605, 2011. 10. Coutts, AJ and Duffield, R. Validity and reliability of GPS devices for measuring movement demands of team sports. J Sci Med Sport 13: 133–135, 2010. 11. Cunniffe, B, Proctor, W, Baker, JS, and Davies, B. An evaluation of the physiological demands of elite rugby union using Global Positioning System tracking software. J Strength Cond Res 23: 1195– 1203, 2009. 12. Deutsch, MU, Kearney, GA, and Rehrer, NJ. Time—motion analysis of professional rugby union players during match-play. J Sports Sci 25: 461–472, 2007. 13. Duthie, G, Pyne, D, and Hooper, S. Applied physiology and game analysis of rugby union. Sports Med 33: 973–991, 2003. 14. Duthie, G, Pyne, D, and Hooper, S. Time motion analysis of 2001 and 2002 Super 12 rugby. J Sports Sci 23: 523–530, 2005. 15. Engebretsen, L and Steffen, K. Rugby in Rio in 2016! Br J Sports Med 44: 157, 2010. 16. Gabbett, T. Physiological characteristics of junior and senior rugby league players. Br J Sports Med 36: 334–339, 2002. 17. Gabbett, T, King, T, and Jenkins, D. Applied physiology of rugby league. Sports Med 38: 119–138, 2008. 18. Gray, AJ, Jenkins, D, Andrews, MH, Taaffe, DR, and Glover, ML. Validity and reliability of GPS for measuring distance travelled in field-based team sports. J Sports Sci 28: 1319–1325, 2010. 19. Hoff, J and Helgerud, J. Endurance and strength training for soccer players: physiological considerations. Sports Med 34: 165–180, 2004. 20. Higham, DG, Pyne, DB, Ansond, JM, and Eddyc, A. Movement patterns in rugby sevens: Effects of tournament level, fatigue and substitute players. J Sci Med Sport 15: 277–282, 2012.
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Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
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Journal of Strength and Conditioning Research 21. Jennings, DH, Cormack, SJ, Coutts, AJ, and Aughey, RJ. International field hockey players perform more high-speed running than nationallevel counterparts. J Strength Cond Res 26: 947–952, 2012. 22. Jennings, D, Cormack, S, Coutts, AJ, Boyd, L, and Aughey, RJ. The validity and reliability of GPS units for measuring distance in team sport specific running patterns. Int J Sports Physiol Perform 5: 328– 341, 2010.
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28. Rampinini, E, Impellizzeri, FM, Castagna, C, Coutts, AJ, and Wisloff, U. Technical performance during soccer matches of the Italian Serie A league: effect of fatigue and competitive level. J Sci Med Sport 12: 227–233, 2009. 29. Roberts, SP, Trewartha, G, Higgitt, RJ, El-Abd, J, and Stokes, KA. The physical demands of elite English rugby union. J Sports Sci 26: 825–833, 2008.
23. King, D, Hume, P, Milburn, P, and Guttenbeil, D. A review of the physiological and anthropometrical characteristics of rugby league players. South Afr J Res Sport Phys Educ Recreation 31: 49–67, 2009.
30. Sirotic, AC, Coutts, AJ, Knowles, H, and Catterick, C. A comparison of match demands between elite and semi-elite rugby league competition. J Sports Sci 27: 203–211, 2009.
24. King, T, Jenkins, D, and Gabbett, T. A time-motion analysis of professional rugby league match-play. J Sports Sci 27: 213–219, 2009.
31. Stone, NM and Kilding, AE. Aerobic conditioning for team sport athletes. Sports Med 39: 615–642, 2009.
25. McLellan, CP, Lovell, DI, and Gass, GC. Performance analysis of elite rugby league match play using global positioning systems. J Strength Cond Res 25: 1703–1710, 2011.
32. Suarez-Arrones, L, Nun˜ez, F, Portillo, J, and Mendez-Villanueva, A. Match running performance and exercise intensity in elite female rugby sevens. J Strength Cond Res 26: 1858–1862, 2012.
26. Mohr, M, Krustrup, P, and Bangsbo, J. Match performance of highstandard soccer players with special reference to development of fatigue. J Sports Sci 21: 519–528, 2003.
33. Tanaka, H, Monahan, KD, and Seals, DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 37: 153–156, 2001.
27. Petersen, C, Pyne, D, Portus, M, and Dawson, B. Validity and reliability of GPS units to monitor cricket-specific movement patterns. Int J Sports Physiol Perform 4: 381–393, 2009.
34. Waldron, M, Twist, C, Highton, J, Worsfold, P, and Daniels, M. Movement and physiological match demands of elite rugby league using portable global positioning systems. J Sports Sci 29: 1223– 1230, 2011.
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