International Journal of Sports Physiology and Performance, 2015, 10, 509 -515 http://dx.doi.org/10.1123/ijspp.2014-0334 © 2015 Human Kinetics, Inc.
Original Investigation
Five-Meter Rope-Climbing: A Commando-Specific Power Test of the Upper Limbs Wissem Dhahbi, Anis Chaouachi, Johnny Padulo, David G. Behm, and Karim Chamari Purpose: To examine the concurrent validity and absolute and relative reliabilities of a commando-specific power test. Participants: 21 antiterrorism commandos. Methods: All participants were assessed on a 5-m rope-climbing test (RCT) and the following tests: pull-ups, push-ups, estimated-1-repetition-maximum (est-1RM), medicine-ball put, and handgrip-strength test. The stopwatch method related to the execution time (ET) was validated by comparison with video motion analysis. The best individual attempt of 3 trials was kept for analysis, and the performance was expressed in absolute power output (APO) and body-mass relative power output (RPO). Results: Stopwatch assessment had an excellent criterion validity (r = .99, P < .001), intraclass correlation coefficient (ICC3,1) of .98, standard errors of measurement (SEM%) of 1.19%, bias ± the 95% limits of agreement of 0.03 ± 0.26 s, and minimal detectable change (MDC95) of 0.51 s. The ET, APO, and RPO were significantly correlated (P < .05) with all cited tests (absolute-value r range .55–.98), while est-1RM was not significantly correlated with the other tests. Test–retest reliability coefficients were excellent for ET, APO, and RPO (ICC3,1 > .90). The SEM% values for the ET, APO, and RPO were all under 5% (range 3.73–4.52%), all being smaller than the corresponding smallest worthwhile change. The coefficients of variation for the ET, APO, and RPO were all under 10%. %MDC95 ranged from 10.37% to 12.53%. Conclusions: Considering the strong concurrent validity and excellent test–retest reliability, the RCT is simple to administer, has ecological validity, and is a valid specific field test of upper-body power for commandos and, in addition, can be accurately assessed with a stopwatch. Keywords: field test, muscle strength, sport army, upper-limb power test, validity and reliability Since the events of September 11, 2001, most countries in the world increased the pace of the process of training Special Forces units to combat terrorism in their territory. They also participated in sending international missions to combat terrorism in vulnerable areas in the world.1 Commandos are elite Special Operations soldiers who possess a high level of fitness; are specialized in combat skills, sky diving, parachuting (static line and free fall), and scuba training; and master various weapon qualifications.2 These soldiers are ground combatant forces, and they must maintain optimal physical attributes of strength, power, stamina, and endurance to be efficient.3 Identifying selection measures of Special Forces combatants is complex, but physical capability, motivation, and spatial ability have been recognized as key performance factors.3,4 Combat ability has been linked to the Army Physical Fitness Test, which has been used to determine fitness levels and promote health. To be successful in this test, each soldier must attain a minimum standard score for each individual subtest.5 According to the analysis of physical requirements of Special Forces soldiers,3 strength and power of the upper-limb muscles is required. During the diverse operations/tasks performed by the commando soldiers in their daily activities, they
Dhahbi, Chaouachi, and Padulo are with the Tunisian Research Laboratory “Sport Performance Optimization,” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia. Behm is with the School of Human Kinetics and Recreation, Memorial University of Newfoundland, St John’s, NL, Canada. Chamari is with Aspetar, Qatar Orthopedic and Sports Medicine Hospital, Doha, Qatar. Address author correspondence to Wissem Dhahbi at [email protected].
have to bear their body mass (and the relatively heavy equipment they wear) with their upper limbs. Therefore, the latter performance is of paramount importance for their overall physical performance. These motor-ability requirements dictate that physiological assessment of elite soldiers is the only way to examine the extreme human adaptations to specific types of exercise and training and to accurately track changes in performance over time. Power is defined as the amount of work performed per unit of time; therefore, it is a combination of strength and speed.6 The majority of tests and training protocols for soldiers emphasize lower-extremity muscle power. The upper-body Wingate anaerobic test and the medicine-ball put are most commonly used to examine maximal upper-extremity anaerobic capacity and power for most sports and physical activities. Each of these tests has been validated numerous times and has proven to be reliable across multiple populations.7 Upper-limb power is a highly desirable fitness component for commandos.5 Historically, the usual methods for assessing power for the Special Forces have been pull-ups,8 push-ups,9,10 estimated 1-repetition-maximum bench press (est-1RM),10,11 and medicine-ball put tests.12 The handgrip test is also widely used as an adjunct index of upper-limb physical qualities in soldiers.13 Nevertheless, handgrip performance concerns the finger flexors, which are requisite for body-hanging performance, and does not elicit the entire upper limbs. In this context, to our knowledge, there is no commando-specific power test to assess the upper limbs of soldiers. Therefore, the purpose of this study was to develop and refine the methodology for administering a 5-m rope-climbing power test (RCT), to determine concurrent validity by determining the relationship between RCT scores and upper-limb power tests, and to assess the reliability of the measurements.
509
510 Dhahbi et al
Methods
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
Subjects Participants were 21 antiterrorism soldiers from the Tunisian National Guard commandos, 1st level (BS1), who voluntarily participated in the study (age 24.1 ± 1.8 y, body mass 74.9 ± 5.1 kg, body height 179.5 ± 4.0 cm, and body-mass index 23.3 ± 1.7 kg/m2). The inclusion criteria were having regularly trained for 17 weeks in the National Guard School of Commandos for ~32 h/wk, divided into ~14 h/wk for fitness training and ~18 h/wk dedicated to technical and tactical training. All the participants were free from any injury or pain that would prevent maximal effort during performance testing. All gave their written informed consent to the study after receiving a thorough explanation of the protocol. This protocol conformed to internationally accepted policy statements regarding the use of human subjects and was approved by the university ethics committee in accordance with the Helsinki declaration.
Design A cohort study design was used. The experimental protocol consisted of performing the RCT 3 times. One session was carried out to familiarize the participants with the measurement protocol 1 week before baseline testing. The first session of baseline testing was dedicated to the assessment tests: 5-m RCT, handgrip strength (HGS), pull-ups 15 seconds, push-ups 15 seconds, est-1RM bench press, and medicine-ball put. The protocol consisted of performing the 6 tests in random order (3 trials for each test), with 5 minutes rest between trials and 10 minutes recovery between tests. The best attempt of the 3 trials was kept for analysis of the test performance. The same protocol was used in both the first and the second testing sessions, to keep the same conditions between test and retest. In order to study the criterion-related validity of the RCT, only the first session’s data were analyzed. To examine the test–retest reliability of the RCT, the best scores of testing sessions 1 and 2 were analyzed.
Methodology Before starting the tests, the participants performed ~15 minutes of warm-up, which included circumduction and flexion/extension of
the upper limbs with self-selected intensity and dynamic stretching (pectorals, trapezius, arm flexor and extensor, flexors and extensors of the hand/fingers). After the warm-up, the participants recovered for ~5 minutes and then began tests. Test data were collected at approximately the same time of day (morning) in both sessions (between 9:00 and 11:00 AM) to eliminate any influence of circadian variations on performance.14 Participants performed the tests with clothes and shoes, without their usual specially designed bulletproof vest (the mass of the equipment was of ~5 kg and consistent during the 2 test sessions). They were also asked to follow their normal diet, eat a light meal at least 3 hours before each session, sleep normally, and stop any strenuous activity during the 24 hours before the test. The experimenter provided strong verbal encouragement during the tests to obtain maximum efforts on all tests from the participants. RCT global ratings of perceived exertion (RPEs) were recorded immediately after the RCTs using the Borg scale (RPE 1–10).15 The test was performed outdoors in the following conditions (measurements taken every 30 min during the experiment): 17.4°C ± 0.9°C and 15.6°C ± 0.8°C for temperature, 56.0% ± 1.8% and 56.8% ± 1.3% for humidity, monitored by a digital environmental station (VaisalaOyj, Helsinki, Finland) during the test and the retest sessions, respectively. In both sessions, wind velocity was light (under 10 km/h).
Five-Meter Rope-Climbing Test The participants climbed the rope as fast as possible and hit the finish mark (see Figure 1). The timer was triggered at the signal of the assessor and stopped when the participant touched the mark that was situated at a height of 5 m above the starting mark. The RCT began with the participant sitting on his buttocks (the seated position) with the rope between his legs, both hands placed on the rope without exceeding the starting mark situated at 1 m above the ground. The climbing was performed without skipping (without momentum), without the use of any gloves, and without using the lower limbs (ie, the legs were not allowed to touch the rope to help climbing but were free for movement). Polyamide rope (4 strands wrapped together from left to right, length 9 m, diameter 40 mm; these features allow climbing without hand sliding but requiring high prehensile strength) attached to a rod
Figure 1 — The 5-m rope-climbing power test: (A) start, (B) execution, and (C) finish position. IJSPP Vol. 10, No. 4, 2015
Rope Climbing: Commando-Specific Field Test 511
fixed through 8 m height was marked with a node mark at departure (1-m height) and taped mark at the finish (6-m height). For safety reasons, a carpet was present (3 × 2 × 0.3 m), with the distance between the upper surface of the carpet and the starting mark ~70 cm. The parameter to be evaluated in this study was power—more precisely, a selected expression of upper-body power as determined by climbing a rope at maximum speed over a set distance. The argument for logical validity was based on the concept that to successfully execute a rope climb, strength is required, and, in addition, work is accomplished by the upper body. If time is factored into the work performance (ie, how quickly the repetition is executed), strength measures can legitimately be transformed to power measures using the formula
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
Power (W) =
body mass ( kg ) × 9.81 × rope distance (m) ET (s)
where ET = execution time. The determination of ET allowed the estimation of the absolute (APO) and relative power output (RPO) developed by the participant according to the following equations:
instructed to limit head and trunk motion.18 The maximal-effort trials were performed for 15 seconds.
Est-1RM Bench Press Participants were asked to grasp the bar at approximately shoulder width apart and lift it off the rack. Spotters were in place throughout the testing. The participants then performed each repetition by lowering the bar to within ~2.5 cm of the chest and then raising it until the elbows reached full extension. The amount of weight that could be moved no more than 6 repetitions was recorded. The participants were not accustomed to training using the bench-press exercise.19 They had a total of 3 attempts to adjust the weight, with 5 minutes of rest between attempts. Est-1RM was calculated using tables provided by the National Strength and Conditioning Association and the American College of Sports Medicine.20
Medicine-Ball Put
A 45° inclined bench was used for the medicine-ball put to facilitate an optimal trajectory of 45°. The medicine ball’s mass was 9 body mass (kg) × 9.81 × 5 m 49.05 × body mass (kg) kg. The ball was covered with carbonate of magnesia before each APO (W) = = attempt to facilitate the accurate measurement of thrown distances ET (s) ET (s) on contact with the floor. The test was conducted in a room with a ceiling clearance of 8 m. A measuring tape was placed on the APO (W) 49.05 RPO (W/kg) = = floor with the near end positioned under the frame of the bench to body mass (kg) ET (s) anchor it. The tip of the tape was oriented so that it would coincide Climbing duration was assessed by manual timing (by a simple approximately with the posterior portion of the medicine ball as it stopwatch) accompanied by a video recording (40 frames/s). Video rested on each participant’s chest in the ready position. The tape sequences were treated with VirtualDub software (1.10.4) to verify extended outward 7.6 m, well beyond the capabilities of all particithe validity of manual timing of ET. ET was defined as the time pants, and was secured to the floor for increased stability. On each between the start signal and the noise of the slap at the finish mark. side of the measuring tape, a border was created with duct tape that determined a band of 0.6 m within which the ball had to land to be considered a regular throw. Any throw that landed outside the Handgrip Strength band was not counted and had to be repeated after a minimum of This test was performed following the HGS protocol with the elbow 5 minutes of passive recovery. Balls landing within the band were flexed described by España-Romero et al.16 Both hands (left and considered legitimate, and the distances were recorded to the nearest right) were evaluated with 3 consecutive trials per hand (with 1-min inch (2.5 cm). The near edge of the chalk mark (in the direction of rest between trials). The hand to be tested first was randomly chosen. the bench) was used to measure the thrown distance.21 The Takei handgrip dynamometer (Takei A5401 digital hand grip dynamometer; error 0.001 g) is a digital tool with an adjustable grip Statistical Analyses span to fit a wide range of hand sizes. Data analyses were performed using SPSS version 18.0 for Windows. Means ± SD were calculated after verifying the normality of Pull-Up Test distributions using Kolmogorov-Smirnov statistics. Systematic bias Participants hung from a horizontal bar (diameter 5 cm), hands at was investigated using a dependent t test. Estimates of effect size, least shoulder width apart (but no more than 1.5 shoulder width apart mean differences, and 95% confidence intervals (CIs) protected from the outsides of the hands) with pronated grip (palms turned against type 2 errors. Concurrent validity of the chronograph device was examined away from the face) and arms fully extended. For a successful pullup, the chin cleared the bar; attempts associated with body swing- using intraclass correlation coefficients (ICC3,1) with 95% CIs, staning, absence of full arm extension when returning to the starting dard errors of measurement (SEM), minimal detectable change at position, or lifting the chin (neck extension) were excluded.17 The 95% CI (MDC95), Bland-Altman plots and systematic bias ± random errors using the 95% limits of agreement (LOA),22 and Pearson maximal-effort trials were performed for 15 seconds. correlation coefficients (r) were also used. Pearson correlation coefficients and stepwise regression tested the validity of RCT data. Push-Up Test The relative reliability of the ET, APO, and RPO was determined by Participants were positioned prone with hands about shoulder width calculating ICC, and the absolute reliability was expressed in terms apart with the trunk held in a rigid, straight position. Push-ups were of SEM and coefficients of variation (CV). The sensitivity of the performed as quickly as possible. Participants began in the “up” test was assessed by comparing the smallest worthwhile change and position with their elbows fully extended. When descending the SEM, using the thresholds proposed by Liow and Hopkins.23 In both body toward the ground, participants flexed their elbows until the validity and reliability analyses, heteroscedasticity was examined. upper arm was parallel to the testing surface. The participants were Significance for all the statistical tests was accepted at P ≤ .05. IJSPP Vol. 10, No. 4, 2015
512 Dhahbi et al
Results Validity of Stopwatch Measurements Compared With Video Timer
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
The mean ± SD of ET recorded by stopwatch and video timer during the RCT were 15.55 ± 3.48 and 15.52 ± 3.38 seconds, respectively. The pairwise analysis revealed no significant difference between the 2 tools (P = .68, dz = 0.10 [trivial]), with a low systematic bias (0.18 s) and low CI (–0.10 < 95% CI < 0.15 s). Moreover, coefficient of correlation between the 2 methods was r = .99 (P < .001). The ET showed a high degree of ICC between the 2 methods (ICC3,1 = .98). SEM was 0.18 (1.19%) second, the MDC95 was small (0.51 s), and the mean difference (bias) ± 95% LOA was 0.03 ± 0.26 second (Figure 2) for the ET between the 2 methods. Moreover, there was no heteroscedasticity in the raw data (r = –.04).
Concurrent Validity of the RCT Descriptive variables including both the mean and SD of the test scores are presented in Table 1. Pearson product correlations between all functional-performance variables for participants are shown in Table 2. The ET, APO, and RPO were significantly correlated (P < .05) with right and left HGS, pull-ups, push-ups, and medicine-ball put (absolute value of r .55–.98, P ≤ .05 and lower), while est-1RM had no significant correlation with the other tests. The corresponding regression equations are shown in Table 3.
Absolute and Relative Reliability of the RCT Relative and absolute reliability indices are presented in Table 4. Dependent t tests evaluating the equality of means showed no significant test–retest bias for ET (s) (t = –0.82, P = .427, dz = 0.18 [trivial]), APO (W) (t = 0.08, P = .94, dz = 0.02 [trivial]), RPO (W/ kg) (t = 0.11, P = .92, dz = 0.02 [trivial]), and RPE (t = 1.52, P = .14, dz = 0.34 [moderate]). Except for RPE, the estimated effect sizes (dz) were trivial. Heteroscedasticity coefficients for ET and RPE
were all small and nonsignificant (r = .10, P = .67, and r = .21, P = .36, respectively), while the heteroscedasticity coefficients were statistically significant for APO and RPO (r = .66, P = .001, and r = .66, P = .001, respectively).
Discussion The aims of this study were to establish concurrent validity and absolute and relative reliability of a 5-m RCT by measuring the ET with a stopwatch. To our knowledge, this is the first time that such evaluation of this commando-specific upper-limb power field test has been reported. The main findings of this study suggest that the stopwatch is a valid tool for measuring ET of RCT performance in commandos. The RCT performance is highly reliable and strongly correlated with valid tests that assess muscle power of the upper limbs. The use of automatic timers to record ET is very difficult to consider because the eventual setting of photocells along the rope (which is not rigid) may lead to erroneous measurements in addition to the practical issues arising from such a measurement process. Video recording is probably much more accurate for recording ET. Nevertheless, this method requires specific equipment and settings and further computerized treatment to collect ET. The stopwatch, on the other hand, is a more accessible instrument and often used in both sport and research settings to record ET for calculations of effort indicators.24 The results of the current study indicate excellent agreement both within and between stopwatch and video-timer assessments across 5-m rope-climbing distance in commando soldiers, with very little difference in SEM value (1.19%;
Original Investigation
Five-Meter Rope-Climbing: A Commando-Specific Power Test of the Upper Limbs Wissem Dhahbi, Anis Chaouachi, Johnny Padulo, David G. Behm, and Karim Chamari Purpose: To examine the concurrent validity and absolute and relative reliabilities of a commando-specific power test. Participants: 21 antiterrorism commandos. Methods: All participants were assessed on a 5-m rope-climbing test (RCT) and the following tests: pull-ups, push-ups, estimated-1-repetition-maximum (est-1RM), medicine-ball put, and handgrip-strength test. The stopwatch method related to the execution time (ET) was validated by comparison with video motion analysis. The best individual attempt of 3 trials was kept for analysis, and the performance was expressed in absolute power output (APO) and body-mass relative power output (RPO). Results: Stopwatch assessment had an excellent criterion validity (r = .99, P < .001), intraclass correlation coefficient (ICC3,1) of .98, standard errors of measurement (SEM%) of 1.19%, bias ± the 95% limits of agreement of 0.03 ± 0.26 s, and minimal detectable change (MDC95) of 0.51 s. The ET, APO, and RPO were significantly correlated (P < .05) with all cited tests (absolute-value r range .55–.98), while est-1RM was not significantly correlated with the other tests. Test–retest reliability coefficients were excellent for ET, APO, and RPO (ICC3,1 > .90). The SEM% values for the ET, APO, and RPO were all under 5% (range 3.73–4.52%), all being smaller than the corresponding smallest worthwhile change. The coefficients of variation for the ET, APO, and RPO were all under 10%. %MDC95 ranged from 10.37% to 12.53%. Conclusions: Considering the strong concurrent validity and excellent test–retest reliability, the RCT is simple to administer, has ecological validity, and is a valid specific field test of upper-body power for commandos and, in addition, can be accurately assessed with a stopwatch. Keywords: field test, muscle strength, sport army, upper-limb power test, validity and reliability Since the events of September 11, 2001, most countries in the world increased the pace of the process of training Special Forces units to combat terrorism in their territory. They also participated in sending international missions to combat terrorism in vulnerable areas in the world.1 Commandos are elite Special Operations soldiers who possess a high level of fitness; are specialized in combat skills, sky diving, parachuting (static line and free fall), and scuba training; and master various weapon qualifications.2 These soldiers are ground combatant forces, and they must maintain optimal physical attributes of strength, power, stamina, and endurance to be efficient.3 Identifying selection measures of Special Forces combatants is complex, but physical capability, motivation, and spatial ability have been recognized as key performance factors.3,4 Combat ability has been linked to the Army Physical Fitness Test, which has been used to determine fitness levels and promote health. To be successful in this test, each soldier must attain a minimum standard score for each individual subtest.5 According to the analysis of physical requirements of Special Forces soldiers,3 strength and power of the upper-limb muscles is required. During the diverse operations/tasks performed by the commando soldiers in their daily activities, they
Dhahbi, Chaouachi, and Padulo are with the Tunisian Research Laboratory “Sport Performance Optimization,” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia. Behm is with the School of Human Kinetics and Recreation, Memorial University of Newfoundland, St John’s, NL, Canada. Chamari is with Aspetar, Qatar Orthopedic and Sports Medicine Hospital, Doha, Qatar. Address author correspondence to Wissem Dhahbi at [email protected].
have to bear their body mass (and the relatively heavy equipment they wear) with their upper limbs. Therefore, the latter performance is of paramount importance for their overall physical performance. These motor-ability requirements dictate that physiological assessment of elite soldiers is the only way to examine the extreme human adaptations to specific types of exercise and training and to accurately track changes in performance over time. Power is defined as the amount of work performed per unit of time; therefore, it is a combination of strength and speed.6 The majority of tests and training protocols for soldiers emphasize lower-extremity muscle power. The upper-body Wingate anaerobic test and the medicine-ball put are most commonly used to examine maximal upper-extremity anaerobic capacity and power for most sports and physical activities. Each of these tests has been validated numerous times and has proven to be reliable across multiple populations.7 Upper-limb power is a highly desirable fitness component for commandos.5 Historically, the usual methods for assessing power for the Special Forces have been pull-ups,8 push-ups,9,10 estimated 1-repetition-maximum bench press (est-1RM),10,11 and medicine-ball put tests.12 The handgrip test is also widely used as an adjunct index of upper-limb physical qualities in soldiers.13 Nevertheless, handgrip performance concerns the finger flexors, which are requisite for body-hanging performance, and does not elicit the entire upper limbs. In this context, to our knowledge, there is no commando-specific power test to assess the upper limbs of soldiers. Therefore, the purpose of this study was to develop and refine the methodology for administering a 5-m rope-climbing power test (RCT), to determine concurrent validity by determining the relationship between RCT scores and upper-limb power tests, and to assess the reliability of the measurements.
509
510 Dhahbi et al
Methods
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
Subjects Participants were 21 antiterrorism soldiers from the Tunisian National Guard commandos, 1st level (BS1), who voluntarily participated in the study (age 24.1 ± 1.8 y, body mass 74.9 ± 5.1 kg, body height 179.5 ± 4.0 cm, and body-mass index 23.3 ± 1.7 kg/m2). The inclusion criteria were having regularly trained for 17 weeks in the National Guard School of Commandos for ~32 h/wk, divided into ~14 h/wk for fitness training and ~18 h/wk dedicated to technical and tactical training. All the participants were free from any injury or pain that would prevent maximal effort during performance testing. All gave their written informed consent to the study after receiving a thorough explanation of the protocol. This protocol conformed to internationally accepted policy statements regarding the use of human subjects and was approved by the university ethics committee in accordance with the Helsinki declaration.
Design A cohort study design was used. The experimental protocol consisted of performing the RCT 3 times. One session was carried out to familiarize the participants with the measurement protocol 1 week before baseline testing. The first session of baseline testing was dedicated to the assessment tests: 5-m RCT, handgrip strength (HGS), pull-ups 15 seconds, push-ups 15 seconds, est-1RM bench press, and medicine-ball put. The protocol consisted of performing the 6 tests in random order (3 trials for each test), with 5 minutes rest between trials and 10 minutes recovery between tests. The best attempt of the 3 trials was kept for analysis of the test performance. The same protocol was used in both the first and the second testing sessions, to keep the same conditions between test and retest. In order to study the criterion-related validity of the RCT, only the first session’s data were analyzed. To examine the test–retest reliability of the RCT, the best scores of testing sessions 1 and 2 were analyzed.
Methodology Before starting the tests, the participants performed ~15 minutes of warm-up, which included circumduction and flexion/extension of
the upper limbs with self-selected intensity and dynamic stretching (pectorals, trapezius, arm flexor and extensor, flexors and extensors of the hand/fingers). After the warm-up, the participants recovered for ~5 minutes and then began tests. Test data were collected at approximately the same time of day (morning) in both sessions (between 9:00 and 11:00 AM) to eliminate any influence of circadian variations on performance.14 Participants performed the tests with clothes and shoes, without their usual specially designed bulletproof vest (the mass of the equipment was of ~5 kg and consistent during the 2 test sessions). They were also asked to follow their normal diet, eat a light meal at least 3 hours before each session, sleep normally, and stop any strenuous activity during the 24 hours before the test. The experimenter provided strong verbal encouragement during the tests to obtain maximum efforts on all tests from the participants. RCT global ratings of perceived exertion (RPEs) were recorded immediately after the RCTs using the Borg scale (RPE 1–10).15 The test was performed outdoors in the following conditions (measurements taken every 30 min during the experiment): 17.4°C ± 0.9°C and 15.6°C ± 0.8°C for temperature, 56.0% ± 1.8% and 56.8% ± 1.3% for humidity, monitored by a digital environmental station (VaisalaOyj, Helsinki, Finland) during the test and the retest sessions, respectively. In both sessions, wind velocity was light (under 10 km/h).
Five-Meter Rope-Climbing Test The participants climbed the rope as fast as possible and hit the finish mark (see Figure 1). The timer was triggered at the signal of the assessor and stopped when the participant touched the mark that was situated at a height of 5 m above the starting mark. The RCT began with the participant sitting on his buttocks (the seated position) with the rope between his legs, both hands placed on the rope without exceeding the starting mark situated at 1 m above the ground. The climbing was performed without skipping (without momentum), without the use of any gloves, and without using the lower limbs (ie, the legs were not allowed to touch the rope to help climbing but were free for movement). Polyamide rope (4 strands wrapped together from left to right, length 9 m, diameter 40 mm; these features allow climbing without hand sliding but requiring high prehensile strength) attached to a rod
Figure 1 — The 5-m rope-climbing power test: (A) start, (B) execution, and (C) finish position. IJSPP Vol. 10, No. 4, 2015
Rope Climbing: Commando-Specific Field Test 511
fixed through 8 m height was marked with a node mark at departure (1-m height) and taped mark at the finish (6-m height). For safety reasons, a carpet was present (3 × 2 × 0.3 m), with the distance between the upper surface of the carpet and the starting mark ~70 cm. The parameter to be evaluated in this study was power—more precisely, a selected expression of upper-body power as determined by climbing a rope at maximum speed over a set distance. The argument for logical validity was based on the concept that to successfully execute a rope climb, strength is required, and, in addition, work is accomplished by the upper body. If time is factored into the work performance (ie, how quickly the repetition is executed), strength measures can legitimately be transformed to power measures using the formula
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
Power (W) =
body mass ( kg ) × 9.81 × rope distance (m) ET (s)
where ET = execution time. The determination of ET allowed the estimation of the absolute (APO) and relative power output (RPO) developed by the participant according to the following equations:
instructed to limit head and trunk motion.18 The maximal-effort trials were performed for 15 seconds.
Est-1RM Bench Press Participants were asked to grasp the bar at approximately shoulder width apart and lift it off the rack. Spotters were in place throughout the testing. The participants then performed each repetition by lowering the bar to within ~2.5 cm of the chest and then raising it until the elbows reached full extension. The amount of weight that could be moved no more than 6 repetitions was recorded. The participants were not accustomed to training using the bench-press exercise.19 They had a total of 3 attempts to adjust the weight, with 5 minutes of rest between attempts. Est-1RM was calculated using tables provided by the National Strength and Conditioning Association and the American College of Sports Medicine.20
Medicine-Ball Put
A 45° inclined bench was used for the medicine-ball put to facilitate an optimal trajectory of 45°. The medicine ball’s mass was 9 body mass (kg) × 9.81 × 5 m 49.05 × body mass (kg) kg. The ball was covered with carbonate of magnesia before each APO (W) = = attempt to facilitate the accurate measurement of thrown distances ET (s) ET (s) on contact with the floor. The test was conducted in a room with a ceiling clearance of 8 m. A measuring tape was placed on the APO (W) 49.05 RPO (W/kg) = = floor with the near end positioned under the frame of the bench to body mass (kg) ET (s) anchor it. The tip of the tape was oriented so that it would coincide Climbing duration was assessed by manual timing (by a simple approximately with the posterior portion of the medicine ball as it stopwatch) accompanied by a video recording (40 frames/s). Video rested on each participant’s chest in the ready position. The tape sequences were treated with VirtualDub software (1.10.4) to verify extended outward 7.6 m, well beyond the capabilities of all particithe validity of manual timing of ET. ET was defined as the time pants, and was secured to the floor for increased stability. On each between the start signal and the noise of the slap at the finish mark. side of the measuring tape, a border was created with duct tape that determined a band of 0.6 m within which the ball had to land to be considered a regular throw. Any throw that landed outside the Handgrip Strength band was not counted and had to be repeated after a minimum of This test was performed following the HGS protocol with the elbow 5 minutes of passive recovery. Balls landing within the band were flexed described by España-Romero et al.16 Both hands (left and considered legitimate, and the distances were recorded to the nearest right) were evaluated with 3 consecutive trials per hand (with 1-min inch (2.5 cm). The near edge of the chalk mark (in the direction of rest between trials). The hand to be tested first was randomly chosen. the bench) was used to measure the thrown distance.21 The Takei handgrip dynamometer (Takei A5401 digital hand grip dynamometer; error 0.001 g) is a digital tool with an adjustable grip Statistical Analyses span to fit a wide range of hand sizes. Data analyses were performed using SPSS version 18.0 for Windows. Means ± SD were calculated after verifying the normality of Pull-Up Test distributions using Kolmogorov-Smirnov statistics. Systematic bias Participants hung from a horizontal bar (diameter 5 cm), hands at was investigated using a dependent t test. Estimates of effect size, least shoulder width apart (but no more than 1.5 shoulder width apart mean differences, and 95% confidence intervals (CIs) protected from the outsides of the hands) with pronated grip (palms turned against type 2 errors. Concurrent validity of the chronograph device was examined away from the face) and arms fully extended. For a successful pullup, the chin cleared the bar; attempts associated with body swing- using intraclass correlation coefficients (ICC3,1) with 95% CIs, staning, absence of full arm extension when returning to the starting dard errors of measurement (SEM), minimal detectable change at position, or lifting the chin (neck extension) were excluded.17 The 95% CI (MDC95), Bland-Altman plots and systematic bias ± random errors using the 95% limits of agreement (LOA),22 and Pearson maximal-effort trials were performed for 15 seconds. correlation coefficients (r) were also used. Pearson correlation coefficients and stepwise regression tested the validity of RCT data. Push-Up Test The relative reliability of the ET, APO, and RPO was determined by Participants were positioned prone with hands about shoulder width calculating ICC, and the absolute reliability was expressed in terms apart with the trunk held in a rigid, straight position. Push-ups were of SEM and coefficients of variation (CV). The sensitivity of the performed as quickly as possible. Participants began in the “up” test was assessed by comparing the smallest worthwhile change and position with their elbows fully extended. When descending the SEM, using the thresholds proposed by Liow and Hopkins.23 In both body toward the ground, participants flexed their elbows until the validity and reliability analyses, heteroscedasticity was examined. upper arm was parallel to the testing surface. The participants were Significance for all the statistical tests was accepted at P ≤ .05. IJSPP Vol. 10, No. 4, 2015
512 Dhahbi et al
Results Validity of Stopwatch Measurements Compared With Video Timer
Downloaded by Australian Catholic University on 09/25/16, Volume 10, Article Number 4
The mean ± SD of ET recorded by stopwatch and video timer during the RCT were 15.55 ± 3.48 and 15.52 ± 3.38 seconds, respectively. The pairwise analysis revealed no significant difference between the 2 tools (P = .68, dz = 0.10 [trivial]), with a low systematic bias (0.18 s) and low CI (–0.10 < 95% CI < 0.15 s). Moreover, coefficient of correlation between the 2 methods was r = .99 (P < .001). The ET showed a high degree of ICC between the 2 methods (ICC3,1 = .98). SEM was 0.18 (1.19%) second, the MDC95 was small (0.51 s), and the mean difference (bias) ± 95% LOA was 0.03 ± 0.26 second (Figure 2) for the ET between the 2 methods. Moreover, there was no heteroscedasticity in the raw data (r = –.04).
Concurrent Validity of the RCT Descriptive variables including both the mean and SD of the test scores are presented in Table 1. Pearson product correlations between all functional-performance variables for participants are shown in Table 2. The ET, APO, and RPO were significantly correlated (P < .05) with right and left HGS, pull-ups, push-ups, and medicine-ball put (absolute value of r .55–.98, P ≤ .05 and lower), while est-1RM had no significant correlation with the other tests. The corresponding regression equations are shown in Table 3.
Absolute and Relative Reliability of the RCT Relative and absolute reliability indices are presented in Table 4. Dependent t tests evaluating the equality of means showed no significant test–retest bias for ET (s) (t = –0.82, P = .427, dz = 0.18 [trivial]), APO (W) (t = 0.08, P = .94, dz = 0.02 [trivial]), RPO (W/ kg) (t = 0.11, P = .92, dz = 0.02 [trivial]), and RPE (t = 1.52, P = .14, dz = 0.34 [moderate]). Except for RPE, the estimated effect sizes (dz) were trivial. Heteroscedasticity coefficients for ET and RPE
were all small and nonsignificant (r = .10, P = .67, and r = .21, P = .36, respectively), while the heteroscedasticity coefficients were statistically significant for APO and RPO (r = .66, P = .001, and r = .66, P = .001, respectively).
Discussion The aims of this study were to establish concurrent validity and absolute and relative reliability of a 5-m RCT by measuring the ET with a stopwatch. To our knowledge, this is the first time that such evaluation of this commando-specific upper-limb power field test has been reported. The main findings of this study suggest that the stopwatch is a valid tool for measuring ET of RCT performance in commandos. The RCT performance is highly reliable and strongly correlated with valid tests that assess muscle power of the upper limbs. The use of automatic timers to record ET is very difficult to consider because the eventual setting of photocells along the rope (which is not rigid) may lead to erroneous measurements in addition to the practical issues arising from such a measurement process. Video recording is probably much more accurate for recording ET. Nevertheless, this method requires specific equipment and settings and further computerized treatment to collect ET. The stopwatch, on the other hand, is a more accessible instrument and often used in both sport and research settings to record ET for calculations of effort indicators.24 The results of the current study indicate excellent agreement both within and between stopwatch and video-timer assessments across 5-m rope-climbing distance in commando soldiers, with very little difference in SEM value (1.19%;
