International Journal of Sports Physiology and Performance, 2015, 10, 498 -503 http://dx.doi.org/10.1123/ijspp.2014-0338 © 2015 Human Kinetics, Inc.
Original Investigation
High-Intensity Warm-Ups: Effects During Subsequent Intermittent Exercise James Zois, David Bishop, and Rob Aughey High-intensity, short-duration warm-up techniques improve acute physical performance, but sparse research has examined their consequence when followed by intermittent activity, which is pertinent to team sports. The authors compared a 5-repetitionmaximum (5RM) leg-press, a small-sided game (SSG), and a current team-sport warm-up in 10 semiprofessional soccer players after 2 intermittent-activity protocols consisting of 15 repetitions of a 60-s circuit that included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities. There was a large improvement in countermovement-jump height in the 5RM after the 1st intermittent-activity protocol (mean, ±90% CL 6.0, ±4.0%, P = .03) and a small improvement after the 2nd (4.6, ±4.0%, P = .04) compared with team sport. Reactive agility was moderately faster via 5RM after the 1st intermittent-activity protocol (3.1, ±2.6%: P = .04) and the 2nd (5.7, ±2.7%, P = .001) than via SSG. There was a small improvement in reactive agility after the 1st intermittent-activity protocol in the 5RM, compared with team sport (3.3, ±2.9%, P = .04). There was a small improvement in mean 20-m-sprint times after both intermittent-activity protocols in the 5RM, compared with SSG (4.2, ±2.0%, P = .01, and 4.3, ±2.0%, P = .01) and, after the 1st intermittent-activity protocol only, compared with team sport (4.2, ±2.1%, P = 0.02). Small increases in blood lactate concentration were observed (46.7, ±18.6%, P = .01) in the 5RM compared with the SSG after the 2nd intermittent-activity protocol. Improved performances after the 5RM warm-up should encourage practitioners to reduce activity time and include high-intensity tasks in team-sport warmups aimed at inducing a potentiating effect. Keywords: postactivation potentiation, soccer, football, team sports In professional team sports such as football (soccer), it is imperative that the warm-up enhance acute performance but not contribute to performance decrements in the latter stages of a half or a match. We have recently established that warm-up routines including a 5-repetition-maximum (5RM) leg-press or a small-sided game (SSG) are superior to currently implemented team-sport warm-up routines, improving the performance of acute team-sport-specific tasks.1 However, it is also important to identify the effects of these warm-up routines on team-sport-related physical performance after prolonged periods of intermittent exercise. Extended periods of intermittent exercise can reduce the physical performance of elite soccer players.2 At the conclusion of a soccer match, 30-m-sprint performance decreases by 2% compared with prematch,3 while high-speed running (>15 km/h) is reduced by ~40% in the last 15 minutes of a match.2 These decreases could be related to low-frequency fatigue experienced in team sports4 and the accompanying reduction in calcium sensitivity via the sarcoplasmic reticulum in skeletal muscles.5 Warm-up routines exacerbating these physiological changes may provoke greater decreases in subsequent performance. For example, routines lasting 10 to 16 minutes (at ~60–70% of VO2max) can decrease time to exhaustion in subsequent intermittent-exercise tasks compared with prior rest.6 Despite this, and recommendations in the literature,7 professional team-sport warm-up routines typically include moderate- to high-intensity activities lasting ~30 to 40 minutes.3,8 These warm-up routines may negatively affect team-sport performance by exacerbatThe authors are with the College of Sport and Exercise Science, Victoria University, Melbourne, Victoria, Australia. Address author correspondence to James Zois at [email protected]. 498
ing fatigue-inducing mechanisms. This has important implications for team-sport athletes relying on their ability to maintain highintensity exercise throughout a match.9 An alternative to current team-sport warm-up routines may be a high-intensity, short-duration warm-up aimed at inducing a postactivation potentiation (PAP) effect (eg, loaded squat exercises). Evidence suggests that such warm-ups can acutely enhance countermovement-jump height,10 sprint ability,11 and other team-sportspecific performance tasks.1 However, their effect on prolonged team-sport-specific physical performance has not yet been investigated. Given that these warm-up routines would not provoke major perturbations in fatigue-inducing mechanisms, it may be hypothesized that they would be superior to typical, prolonged warm-up routines for maintaining team-sport-related physical performance. SSG warm-ups can also be high in intensity and short in duration and acutely improve countermovement-jump/reactive agility tasks while replicating the specific skills of a sport.1 However, the effects of an SSG warm-up on prolonged intermittent-sprint performance and repeated-sprint ability, tasks typical of team-sport athletes, have not been investigated. The purpose of this study was to compare the effects of a, SSG, a 5RM leg-press, and a typical team-sport warmup on team-sport-related performance during and after prolonged periods of intermittent exercise.
Methods Ten healthy, semiprofessional, male football (soccer) players gave written informed consent to participate in this study, which was granted ethical approval by the Victoria University Human Research Ethics Committee, in accordance with the Declaration of Helsinki.
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The mean age, height, body mass, and maximum heart rate (HRmax) of the participants were 23.3 ± 2.5 years, 1.78 ± 0.04 m, 69.1 ± 4.1 kg, and 191 ± 8 beats/min, respectively. At the time of this study, all participants competed in the third division (Serie C) of the Italian Soccer League, had an extended period of physical-training experience (≥5 y), and had recently completed their competitive season (within 3 wk).
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Experimental Design The 3 experimental sessions were completed in a random, counterbalanced order at similar times (within 1 h) to minimize circadian influences.12 All experimental sessions were completed on a naturalgrass soccer field. Environmental conditions (degrees Celsius, humidity, and wind speed) were accessed and recorded via a local meteorology station (Golosine, Verona). Mean temperature, humidity, and wind speed were 26.4°C ± 3.3°C, 46.9% ± 18.9%, and 2.2 ± 1.3 m/s, respectively. Participants attended 1 familiarization session, 1 baseline session, and 3 experimental sessions, all separated by ≥72 hours. The familiarization session included a 5-minute baseline jog warm-up maintaining HR at 60% of the predicted HRmax, followed by habituation with all physiological (blood lactate and HR) and performance (countermovement jump, reactive agility, repeated-sprint ability) measures. After 5 minutes of rest, participants’ highest level attained during the Yo-Yo Intermittent Recovery test was recorded to characterize their intermittent-exercise capacity, as was HRmax. During the subsequent baseline session, participants repeated all physiological and performance tests and, after another 5 minutes of rest, completed a seated 5RM leg-press test. At the completion of the 5RM, participants individually rehearsed the SSG and team-sport warm-up protocols. Finally, after a 5-minute rest, they completed a familiarization of the 1 × 15-minute intermittent-activity protocol described following.
On completion of each warm-up intervention, participants received a 4-minute passive rest followed by a 15-minute intermittent-activity protocol that included locomotor tasks representative of team-sport activity.1 A 4-minute passive rest period is preferred when investigating the transfer of PAP effects from high-intensity warm-up protocols in subsequent team-sport tasks.1,13 The intermittent-activity protocol consisted of 15 repetitions of a 60-second circuit included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities (see Figure 1). The intermittent-activity protocol was performed twice, with performance and physiological measures taken immediately after each 15-minute period, followed by an 8-minute passive recovery period.8 The work–rest periods within the intermittentactivity protocol were based on previous pilot work performed to assess adequate team-sport-related fatigue, while minimizing the occurrence of a pacing strategy implemented by participants. At the beginning of each 60-second circuit of the intermittent-activity protocol, 20-m-sprint times were recorded as measures of specific sprint ability using Photocells (Lynx Systems Developers, USA); a coefficient of variation (CV) for mean time of 0.8% was established.
Performance Measures Performance measures recorded after both 15-minute intermittentactivity protocols included vertical-jump height, reactive agility, and repeated-sprint ability (measured in this order), with ~60 seconds of recovery between measures. Vertical-jump height was calculated via Opto Jump (Lynx System Developers, USA) with a previously established day-to-day CV of 2.7%.1 The reactive agility test has a CV of 2.8% and is described in detail elsewhere.14 Briefly, the reactive agility test requires a rapid whole-body movement with a change of velocity or direction in response to a stimulus. We used Photocells (Lynx Systems Developers, USA) to measure time taken
Experimental Procedures During experimental sessions participants completed a 5-minute baseline jog warm-up at 60% HRmax, followed immediately by 1 of the 3 warm-up interventions: SSG, 5RM leg-press, or professional team-sport warm-up routine. The SSG warm-up has been previously described1 and included a 3-versus-3 soccer game with 2 minutes of play interspersed with 2 minutes of passive rest (×3) (~10 min duration). The SSG warm-up encourages high-intensity activity with minimal recovery (excluding designated recovery periods), conducted in an open-skill environment. The acute physiological effects of the SSG warm-up have been reported elsewhere.1 On a separate day, as previously described,1 a 5RM leg-press (Techno gym, Italy) warm-up lasting 15 seconds was investigated. Briefly, the seated 5RM leg-press consisted of 5 unassisted leg-press movements with full flexion/extension ranges of the lower limbs. Finally, a currently implemented premier-league football (Serie A division: soccer) warm-up routine lasting ~23 minutes, previously described in detail,1 was implemented. Briefly, the warm-up included general activities (high-knees, butt-kicks, and body-weight squats performed at medium intensity [submaximal velocity] for 6 min), specific movements (back-and-forth sprinting, lateral skipping, and changeof direction-movements performed at high intensity [maximal velocity] for 9 min), and ball-control activities (dribbling, passing, and run-throughs performed at high intensity for 6 min). One 60-second and two 30-second passive recovery periods were interspersed in the routine. The premier-league warm-up is a common soccer warm-up routine that was familiar to all participants in this study.
Figure 1 — Intermittent-activity protocol consisting of 60-s circuit × 15 repetitions per set.
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to complete the reactive agility test. A previously used repeat-sprintability test15 incorporating 6 × 30-m sprints starting on 20 seconds was implemented, with mean sprint times measured via Photocells (Lynx Systems Developers, USA) and a day-to-day CV of 0.8%.
The mean Yo-Yo score and 5RM leg-press strength of the participants were 1640 ± 104 m and 88 ± 8 kg, respectively. There were no between-trials differences in temperature, humidity, or wind speed observed during this study (P > .05). Compared with the team-sport warm-up, there was a moderate beneficial difference in countermovement-jump height in the 5RM
warm-up (6.0, ±4.0%: mean, ±90% confidence limits; P = .03) after the first intermittent-activity protocol and a small beneficial difference (4.6, ±4.0%: P = .04) after the second. There were no differences when countermovement-jump height was compared between the 5RM warm-up and the SSG warm-up after either the first or second intermittent-activity protocol (P > .05). There were also no differences observed when comparing the SSG with team-sport warm-ups after the first and second intermittent-activity protocols (P > .05) (Figure 2[a]). Reactive agility in the 5RM warm-up was moderately faster after the first (3.1, ±2.6%: P = 0.04) and second intermittent-activity protocols (5.7, ±2.7%: P = .001) than with the SSG warm-up. A small improvement in reactive agility was observed after only the first intermittent-activity protocol in the 5RM warm-up, compared with the team-sport warm-up (3.3, ±2.9%: P = .04) (Figure 2[b]). There were no observed differences for reactive agility between the SSG and team-sport warm-ups after either the first or second intermittent-activity protocol (P > .05). Mean repeat-sprint-ability times after the second intermittent-activity protocol were moderately faster in the 5RM warm-up than in the team-sport warm-up (4.4, ±2.2%: P = .01) but not after the first intermittent-activity protocol when compared with the team sport or the SSG warm-up (P > .05). There were also no differences for mean repeat-sprint-ability times in the SSG warm-up after the second intermittent-activity protocol compared with the team-sport warm-up (P > 0.05). In the 5RM warm-up there were small improvements observed in mean 20-m-sprint performance after both the first (4.2, ±2.0%: P = .01) and second intermittent activity protocols (4.3, ±2.0%: P = .01) compared with the SSG warm-up. Similarly, a small improvement was observed in mean 20-m-sprint performance in the 5RM warmup after the first intermittent-activity protocol compared with the team-sport warm-up (4.2, ±2.1%: P = .02) (Figure 3). There was a small increase in [Lac–]b after the second intermittent-activity protocol in the 5RM warm-up compared with the SSG warm-up (46.7, ±18.6%: P = .01) but no other differences reported (P > .05) (Figure 4). There were also no differences in HR measures after the first (SSG 171 ± 8, 5RM 174 ± 9, team sport 172 ± 8 beats/
(a)
(b)
Physiological Measures Blood lactate concentration ([Lac–]b) and HR were measured immediately after both 15-minute intermittent-activity protocols. Approximately 30 μL of blood was sampled from the ear lobe and analyzed for [Lac–]b using Biosen C Line (EKF Diagnostics, Germany). HR was recorded every 5 seconds during testing using short-range-telemetry HR-monitoring systems (VantageNV, S710, and Xtrainer models, Polar Electro, Kempele, Finland).
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Statistical Analysis Data are expressed as mean ± SD and were analyzed using PASW Statistics version 21 (SPSS Inc, Chicago, IL, USA) with a 2-factor repeated-measures ANOVA design (group × time). The least significant difference was employed for post hoc multiple comparisons. Magnitudes of changes were assessed via standardization with 90% confidence intervals16 to investigate the practical importance relevant to a sporting context. Changes were analyzed when there was a ≥75% likelihood of the effect being equal to or greater than the smallest worthwhile change (estimated as 0.2 × between-subjects SD). Effect sizes were classified as small (ES 0.2–0.59), moderate (ES 0.6–1.19), large (ES 1.2–1.9), or very large (ES 2.0–4.0).
Results
Figure 2 — (a) Countermovement-jump height and (b) reactive agility measured after each of the two 15-minute intermittent-activity protocols (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10. IJSPP Vol. 10, No. 4, 2015
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Figure 3 — The average time for the 15 × 20-m sprints imbedded in each of the intermittent-activity protocols (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10.
Figure 4 — Blood lactate concentration measured immediately after each 15-minute intermittent-activity protocol (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10.
min) or second (SSG 172 ± 10, 5RM 173 ± 10, team sport 172 ± 10 beats/min) intermittent-activity protocol between the 3 warm-up conditions (P > .05).
Discussion The major findings from this study were that a range of teamsport-related performance measures were improved after a 5RM warm-up compared with the 2 alternative warm-ups. After at least 1 of the 15-minute periods of intermittent activity, jump height and reactive agility were improved in the 5RM warm-up compared
with both the team-sport and SSG warm-ups. In addition, mean 20-m-sprint performance was faster after the 5RM warm-up after the first intermittent-activity protocol compared with the alternative warm-up interventions, as well as average 30-m repeat-sprint-ability times (5RM faster than the team-sport warm-up) after the second intermittent-activity protocol. In the current study, a 5RM warm-up, which produces a PAP effect,17 was associated with faster 20-m-sprint and repeat-sprintability performance during, and after, bouts of intermittent exercise. Although no previous study has investigated the prolonged effects of PAP on subsequent team-sport-related intermittent activity, 1 study reported an increase in peak power and average power in rebound jump performance (~3%) 18.5 minutes after a warm-up aimed at inducing PAP (5 × 1RM back squat).18 These findings suggest that warm-up protocols invoking a PAP effect (such as a 5RM warm-up) may be better suited than traditional team-sport warm-ups for the maintenance of sprint performance during subsequent intermittent activities, which is of high relevance to team sports such as soccer. Better sprint performances via the 5RM warm-up in the current study may be attributed to mechanisms associated with PAP, such as increased neuromuscular efficiency, a decrease in the required motor-unit firing rate for subsequent tasks, and the offsetting of low-frequency fatigue.19 For example, low-frequency fatigue can result from the impairment of excitation–contraction coupling,20 which may include a reduced Ca2+ release from the sarcoplasmic reticulum per action potential.5 However, in some circumstances this may be minimized or even reversed via PAP.19,21 It is therefore possible that the observed performance improvements via the 5RM warm-up may be attributable to an increase in phosphorylation of myosin light chains, leading to an increase in protein sensitivity to Ca2+,22 which in turn would counteract the negative effects associated with low-frequency fatigue. However, due to the performance nature of this study, further mechanistic research is required to confirm whether aforementioned mechanisms contributed to the enhanced performance observed during and after the intermittentexercise bouts. Enhanced neuromuscular efficiency is another mechanism of PAP that may provide beneficial effects to explosive tasks such as reactive agility. After selected periods of intermittent activity, reactive agility was faster (~3–6%) in the 5RM warm-up than in either of the alternative warm-ups. Sustained higher-order motor-neuron recruitment can be achieved in the presence of a decreasing firing rate via PAP.23 This particular mechanism may provide economies pertaining to membrane excitability and excitation–contraction coupling efficiency after the 5RM warm-up, both possible factors involved in delaying the onset of fatigue during intermittent exercise20 and enhancing the performance of subsequent explosive tasks.24 Although further research is required to confirm the timecourse effects of PAP during intermittent exercise, it seems plausible that PAP induced via a 5RM warm-up could minimize performance decrements in subsequent high-intensity explosive tasks. Alternative explanations for observed differences in the current study pertain to the negative effects of prolonged warm-ups on subsequent intermittent-sprint performance. Warm-up protocols employing similar intensities (60–80% VO 2max) and durations (15–30 min) to those of both the team-sport and the SSG warm-up used in the current study have been associated with decrements in subsequent performance.6,25 Similarly, we observed slower mean 20-m-sprint times and mean repeat-sprint-ability times after both the team-sport and the SSG warm-ups than with the 5RM warmup. The mechanism responsible for these observations may include the inhibition of anaerobic glycolysis and/or an increase in thermal
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strain via prolonged periods of active warm-up.26 We have previously reported greater increases in both [Lac–]b and core temperature after the team-sport and SSG warm-ups than with a 5RM.1 Other team-sport research has suggested that a decrease in muscle glycogen stores may also be responsible for the onset of fatigue during intermittent team-sport activity (eg, soccer).27 Although the current study did not investigate muscle glycogen content, the performance results support the hypothesis that prolonged warm-up routines may not be as beneficial for subsequent team-sport-related physical performance as high-intensity, short-duration warm-ups. These findings have important implications for team-sport coaches interested in designing efficient warm-up protocols to prepare athletes for subsequent competition. We have previously reported an acute 6% improvement in countermovement-jump performance after a similar SSG warmup intervention.1 In contrast, the current study reported enhanced countermovement-jump performance in the 5RM warm-up after both 15-minute periods of intermittent activity but no improvements after the SSG warm-up in comparison with the team-sport warm-up. The disparities in countermovement-jump performance suggest that the findings from studies investigating the effects of warm-up on acute performance may not be applicable to teamsport performance, which is characterized by prolonged periods of intermittent activity. Approximately 10 minutes of SSG activity may be beneficial for acute power performance but potentially too long when combined with 2 × 15-minute intermittent exercise. In support of this, 20-m-sprint performance decreased by ~5% (during sprints 7–15) after an SSG warm-up compared with a 5RM warmup.1 Small to moderate decreases in the latter stages of intermittentsprint performance may be associated with the onset of fatigue after the SSG warm-up.1 Similar decrements in sprint performance (4%) have been reported after high-intensity, 5-minute periods during a soccer match and may also be related to the temporary onset of fatigue.27 It should be noted that the varied nature of SSG tasks and associated work-rate levels may partly explain observed changes. Therefore, future research using SSG warm-up activities should endeavor to control, or closely monitor, work-rate profiles during SSG warm-ups. The physiological responses to the 3 warm-up interventions in this study were similar across both periods of the intermittentactivity protocol, with the exception of [Lac–]b. In the 5RM warm-up, [Lac–]b was higher after the second intermittent-activity protocol (46.7%) than with the SSG warm-up. These findings may be attributable to faster 20-m-sprint times observed during the intermittent-activity tasks after the 5RM warm-up compared with the SSG (4.2% and 4.3% faster) and the team-sport warm-up (4.2% and 5.1% faster). Despite the current findings, feedback from participants showed a distinct preference for warm-up protocols that included some skill component (eg, ball-control tasks). Acute improvements in soccer passing performance (Loughborough soccer passing test) after SSG warm-ups aimed at skill execution have been reported.13 However, these effects have not yet been investigated when the warm-up is preceded by soccer-specific intermittent exercise and therefore warrant further investigation It should be noted that in the current study the team-sport warmup acted as the control warm-up, as similar warm-up protocols are typically implemented in soccer. The variable nature of warm-up protocols currently used at the elite level makes selecting 1 generic control protocol to replicate all warm-up procedures impossible, while choosing a simplified generic protocol would not provide prac-
titioners with an ecologically valid comparison with potential new strategies. Furthermore, the administration of an optimal recovery period after high-intensity warms ups, such as that implemented in the current study, may be reliant on sport/competition regulations (ie, time/recovery-period restraints). Therefore, practitioners should review the team-sport warm-up protocol used in this study for similarities to their own currently implemented warm-up regimens, as well as governing regulations, to identify avenues for individual program improvements and efficiencies.
Conclusion A 5RM warm-up was associated with improved countermovementjump height, 20-m-sprint ability, reactive agility, and repeat-sprint ability during and after two 15-minute periods of intermittent activity compared with alternative warm-ups. This may be attributable to smaller physiological perturbations provoked by the 5RM warm-up, compared with the alternative warm-ups, and/or the induction of a PAP effect that was maintained during subsequent intermittent activities. These results have important implications for athletes, coaches, and physical-training staff. Of particular interest should be the design of the warm-up period to aid subsequent intermittent performance and to minimize the potential counterproductive effects of current warm-ups. Practitioners should explore the inclusion of short periods of high-intensity warm-up tasks before subsequent intermittent team-sport activity, which may benefit from a potentiation effect.
Practical Implications • A 5RM warm-up can enhance soccer-specific physical performance during 30 minutes of intermittent field-based exercise, compared with a premier-league soccer warm-up routine. • Changes in performance may be related to a potentiation effect via a high-intensity, short-duration 5RM warm-up or reduced physiological perturbations via fatigue-inducing mechanisms. • Future research should investigate the practicality and subsequent effect of including a 5RM warm-up before competitive scenarios.
References 1. Zois J, Bishop DJ, Ball K, Aughey RJ. High-intensity warm-ups elicit superior performance to a current soccer warm-up routine. J Sci Med Sport. 2011;14(6):522–528. PubMed doi:10.1016/j.jsams.2011.03.012 2. Mohr M, Krustrup P, Bangsbo J. Match performance of highstandard soccer players with special reference to development of fatigue. J Sports Sci. 2003;21(7):519–528. PubMed doi:10.1080/0264041031000071182 3. Mohr M, Krustrup P, Nybo L, Nielsen JJ, Bangsbo J. Muscle temperature and sprint performance during soccer matches—beneficial effect of re-warm-up at half-time. Scand J Med Sci Sports. 2004;14(3):156– 162. PubMed doi:10.1111/j.1600-0838.2004.00349.x 4. Fowles JR. Technical issues in quantifying low-frequency fatigue in athletes. Int J Sports Physiol Perform. 2006;1(2):169–171. PubMed 5. Hill CA, Thompson MW, Ruell PA, Thom JM, White MJ. Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans. J Physiol. 2001;531(Pt 3):871–878. PubMed doi:10.1111/j.1469-7793.2001.0871h.x
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6. Gregson WA, Batterham A, Drust B, Cable NT. The influence of prewarming on the physiological responses to prolonged intermittent exercise. J Sports Sci. 2005;23(5):455–464. PubMed doi:10.1080/02 640410410001730214 7. Bishop D. Warm up II: performance changes following active warm up and how to structure the warm up. Sports Med. 2003;33(7):483–498. PubMed doi:10.2165/00007256-200333070-00002 8. Towlson C, Midgley AW, Lovell R. Warm-up strategies of professional soccer players: practitioners’ perspectives. J Sports Sci. 2013;31(13):1393–1401. PubMed doi:10.1080/02640414.2013.792 946 9. Bangsbo J, Mohr M, Krustrup P. Physical and metabolic demands of training and match-play in the elite football player. J Sports Sci. 2006;24(7):665–674. PubMed doi:10.1080/02640410500482529 10. Kilduff LP, Bevan HR, Kingsley MI, et al. Postactivation potentiation in professional rugby players: optimal recovery. J Strength Cond Res. 2007;21(4):1134–1138. PubMed 11. Chatzopoulos DE, Michailidis CJ, Giannakos AK, et al. Postactivation potentiation effects after heavy resistance exercise on running speed. J Strength Cond Res. 2007;21(4):1278–1281. PubMed 12. Racinais S, Connes P, Bishop D, Blonc S, Hue O. Morning versus evening power output and repeated-sprint ability. Chronobiol Int. 2005;22(6):1029–1039. PubMed doi:10.1080/07420520500397918 13. Zois J, Bishop D, Fairweather I, Ball K, Aughey RJ. High-intensity re-warm-ups enhance soccer performance. Int J Sports Med. 2013;34(9):800–805. PubMed doi:10.1055/s-0032-1331197 14. Sheppard JM, Young WB, Doyle TL, Sheppard TA, Newton RU. An evaluation of a new test of reactive agility and its relationship to sprint speed and change of direction speed. J Sci Med Sport. 2006;9(4):342–349. PubMed doi:10.1016/j.jsams.2006.05.019 15. Pyne DB, Saunders P, Montgomery P, Hewitt A, Sheehan K. Relationships between repeated sprint testing, speed, and endurance. J Strength Cond Res. 2008;22(5):1633–1637. PubMed doi:10.1519/ JSC.0b013e318181fe7a 16. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science.
Med Sci Sports Exerc. 2009;41(1):3–13. PubMed doi:10.1249/ MSS.0b013e31818cb278 17. Mitchell CJ, Sale DG. Enhancement of jump performance after a 5-RM squat is associated with postactivation potentiation. Eur J Appl Physiol. 2011;111(8):1957–1963. PubMed doi:10.1007/s00421-010-1823-x 18. Chiu LZ, Fry AC, Weiss LW, Schilling BK, Brown LE, Smith SL. Postactivation potentiation response in athletic and recreationally trained individuals. J Strength Cond Res. 2003;17(4):671–677. PubMed 19. Green HJ, Jones SR. Does post-tetanic potentiation compensate for low frequency fatigue? Clin Physiol. 1989;9(5):499–514. PubMed doi:10.1111/j.1475-097X.1989.tb01003.x 20. Edwards RH, Hill DK, Jones DA, Merton PA. Fatigue of long duration in human skeletal muscle after exercise. J Physiol. 1977;272(3):769– 778. PubMed doi:10.1113/jphysiol.1977.sp012072 21. Bigland-Ritchie B, Johansson R, Lippold OC, Woods JJ. Contractile speed and EMG changes during fatigue of sustained maximal voluntary contractions. J Neurophysiol. 1983;50(1):313–324. PubMed 22. Moore RL, Stull JT. Myosin light chain phosphorylation in fast and slow skeletal muscles in situ. Am J Physiol. 1984;247(5 Pt 1):C462– C471. PubMed 23. Sale DG. Postactivation potentiation: role in human performance. Exerc Sport Sci Rev. 2002;30(3):138–143. PubMed doi:10.1097/00003677200207000-00008 24. Gullich A, Schmidtbleicher D. MVC-induced short-term potentiation of explosive force. New Stud Athl. 1996;11(4):67–81. 25. Gregson WA, Drust B, Batterham A, Cable NT. The effects of prewarming on the metabolic and thermoregulatory responses to prolonged submaximal exercise in moderate ambient temperatures. Eur J Appl Physiol. 2002;86(6):526–533. PubMed doi:10.1007/s00421-002-0580-x 26. Hermansen L. Effect of metabolic changes on force generation in skeletal muscle during maximal exercise. Ciba Found Symp. 1981;82:75–88. PubMed 27. Krustrup P, Mohr M, Steensberg A, Bencke J, Kjaer M, Bangsbo J. Muscle and blood metabolites during a soccer game: implications for sprint performance. Med Sci Sports Exerc. 2006;38(6):1165–1174. PubMed doi:10.1249/01.mss.0000222845.89262.cd
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Original Investigation
High-Intensity Warm-Ups: Effects During Subsequent Intermittent Exercise James Zois, David Bishop, and Rob Aughey High-intensity, short-duration warm-up techniques improve acute physical performance, but sparse research has examined their consequence when followed by intermittent activity, which is pertinent to team sports. The authors compared a 5-repetitionmaximum (5RM) leg-press, a small-sided game (SSG), and a current team-sport warm-up in 10 semiprofessional soccer players after 2 intermittent-activity protocols consisting of 15 repetitions of a 60-s circuit that included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities. There was a large improvement in countermovement-jump height in the 5RM after the 1st intermittent-activity protocol (mean, ±90% CL 6.0, ±4.0%, P = .03) and a small improvement after the 2nd (4.6, ±4.0%, P = .04) compared with team sport. Reactive agility was moderately faster via 5RM after the 1st intermittent-activity protocol (3.1, ±2.6%: P = .04) and the 2nd (5.7, ±2.7%, P = .001) than via SSG. There was a small improvement in reactive agility after the 1st intermittent-activity protocol in the 5RM, compared with team sport (3.3, ±2.9%, P = .04). There was a small improvement in mean 20-m-sprint times after both intermittent-activity protocols in the 5RM, compared with SSG (4.2, ±2.0%, P = .01, and 4.3, ±2.0%, P = .01) and, after the 1st intermittent-activity protocol only, compared with team sport (4.2, ±2.1%, P = 0.02). Small increases in blood lactate concentration were observed (46.7, ±18.6%, P = .01) in the 5RM compared with the SSG after the 2nd intermittent-activity protocol. Improved performances after the 5RM warm-up should encourage practitioners to reduce activity time and include high-intensity tasks in team-sport warmups aimed at inducing a potentiating effect. Keywords: postactivation potentiation, soccer, football, team sports In professional team sports such as football (soccer), it is imperative that the warm-up enhance acute performance but not contribute to performance decrements in the latter stages of a half or a match. We have recently established that warm-up routines including a 5-repetition-maximum (5RM) leg-press or a small-sided game (SSG) are superior to currently implemented team-sport warm-up routines, improving the performance of acute team-sport-specific tasks.1 However, it is also important to identify the effects of these warm-up routines on team-sport-related physical performance after prolonged periods of intermittent exercise. Extended periods of intermittent exercise can reduce the physical performance of elite soccer players.2 At the conclusion of a soccer match, 30-m-sprint performance decreases by 2% compared with prematch,3 while high-speed running (>15 km/h) is reduced by ~40% in the last 15 minutes of a match.2 These decreases could be related to low-frequency fatigue experienced in team sports4 and the accompanying reduction in calcium sensitivity via the sarcoplasmic reticulum in skeletal muscles.5 Warm-up routines exacerbating these physiological changes may provoke greater decreases in subsequent performance. For example, routines lasting 10 to 16 minutes (at ~60–70% of VO2max) can decrease time to exhaustion in subsequent intermittent-exercise tasks compared with prior rest.6 Despite this, and recommendations in the literature,7 professional team-sport warm-up routines typically include moderate- to high-intensity activities lasting ~30 to 40 minutes.3,8 These warm-up routines may negatively affect team-sport performance by exacerbatThe authors are with the College of Sport and Exercise Science, Victoria University, Melbourne, Victoria, Australia. Address author correspondence to James Zois at [email protected]. 498
ing fatigue-inducing mechanisms. This has important implications for team-sport athletes relying on their ability to maintain highintensity exercise throughout a match.9 An alternative to current team-sport warm-up routines may be a high-intensity, short-duration warm-up aimed at inducing a postactivation potentiation (PAP) effect (eg, loaded squat exercises). Evidence suggests that such warm-ups can acutely enhance countermovement-jump height,10 sprint ability,11 and other team-sportspecific performance tasks.1 However, their effect on prolonged team-sport-specific physical performance has not yet been investigated. Given that these warm-up routines would not provoke major perturbations in fatigue-inducing mechanisms, it may be hypothesized that they would be superior to typical, prolonged warm-up routines for maintaining team-sport-related physical performance. SSG warm-ups can also be high in intensity and short in duration and acutely improve countermovement-jump/reactive agility tasks while replicating the specific skills of a sport.1 However, the effects of an SSG warm-up on prolonged intermittent-sprint performance and repeated-sprint ability, tasks typical of team-sport athletes, have not been investigated. The purpose of this study was to compare the effects of a, SSG, a 5RM leg-press, and a typical team-sport warmup on team-sport-related performance during and after prolonged periods of intermittent exercise.
Methods Ten healthy, semiprofessional, male football (soccer) players gave written informed consent to participate in this study, which was granted ethical approval by the Victoria University Human Research Ethics Committee, in accordance with the Declaration of Helsinki.
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The mean age, height, body mass, and maximum heart rate (HRmax) of the participants were 23.3 ± 2.5 years, 1.78 ± 0.04 m, 69.1 ± 4.1 kg, and 191 ± 8 beats/min, respectively. At the time of this study, all participants competed in the third division (Serie C) of the Italian Soccer League, had an extended period of physical-training experience (≥5 y), and had recently completed their competitive season (within 3 wk).
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Experimental Design The 3 experimental sessions were completed in a random, counterbalanced order at similar times (within 1 h) to minimize circadian influences.12 All experimental sessions were completed on a naturalgrass soccer field. Environmental conditions (degrees Celsius, humidity, and wind speed) were accessed and recorded via a local meteorology station (Golosine, Verona). Mean temperature, humidity, and wind speed were 26.4°C ± 3.3°C, 46.9% ± 18.9%, and 2.2 ± 1.3 m/s, respectively. Participants attended 1 familiarization session, 1 baseline session, and 3 experimental sessions, all separated by ≥72 hours. The familiarization session included a 5-minute baseline jog warm-up maintaining HR at 60% of the predicted HRmax, followed by habituation with all physiological (blood lactate and HR) and performance (countermovement jump, reactive agility, repeated-sprint ability) measures. After 5 minutes of rest, participants’ highest level attained during the Yo-Yo Intermittent Recovery test was recorded to characterize their intermittent-exercise capacity, as was HRmax. During the subsequent baseline session, participants repeated all physiological and performance tests and, after another 5 minutes of rest, completed a seated 5RM leg-press test. At the completion of the 5RM, participants individually rehearsed the SSG and team-sport warm-up protocols. Finally, after a 5-minute rest, they completed a familiarization of the 1 × 15-minute intermittent-activity protocol described following.
On completion of each warm-up intervention, participants received a 4-minute passive rest followed by a 15-minute intermittent-activity protocol that included locomotor tasks representative of team-sport activity.1 A 4-minute passive rest period is preferred when investigating the transfer of PAP effects from high-intensity warm-up protocols in subsequent team-sport tasks.1,13 The intermittent-activity protocol consisted of 15 repetitions of a 60-second circuit included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities (see Figure 1). The intermittent-activity protocol was performed twice, with performance and physiological measures taken immediately after each 15-minute period, followed by an 8-minute passive recovery period.8 The work–rest periods within the intermittentactivity protocol were based on previous pilot work performed to assess adequate team-sport-related fatigue, while minimizing the occurrence of a pacing strategy implemented by participants. At the beginning of each 60-second circuit of the intermittent-activity protocol, 20-m-sprint times were recorded as measures of specific sprint ability using Photocells (Lynx Systems Developers, USA); a coefficient of variation (CV) for mean time of 0.8% was established.
Performance Measures Performance measures recorded after both 15-minute intermittentactivity protocols included vertical-jump height, reactive agility, and repeated-sprint ability (measured in this order), with ~60 seconds of recovery between measures. Vertical-jump height was calculated via Opto Jump (Lynx System Developers, USA) with a previously established day-to-day CV of 2.7%.1 The reactive agility test has a CV of 2.8% and is described in detail elsewhere.14 Briefly, the reactive agility test requires a rapid whole-body movement with a change of velocity or direction in response to a stimulus. We used Photocells (Lynx Systems Developers, USA) to measure time taken
Experimental Procedures During experimental sessions participants completed a 5-minute baseline jog warm-up at 60% HRmax, followed immediately by 1 of the 3 warm-up interventions: SSG, 5RM leg-press, or professional team-sport warm-up routine. The SSG warm-up has been previously described1 and included a 3-versus-3 soccer game with 2 minutes of play interspersed with 2 minutes of passive rest (×3) (~10 min duration). The SSG warm-up encourages high-intensity activity with minimal recovery (excluding designated recovery periods), conducted in an open-skill environment. The acute physiological effects of the SSG warm-up have been reported elsewhere.1 On a separate day, as previously described,1 a 5RM leg-press (Techno gym, Italy) warm-up lasting 15 seconds was investigated. Briefly, the seated 5RM leg-press consisted of 5 unassisted leg-press movements with full flexion/extension ranges of the lower limbs. Finally, a currently implemented premier-league football (Serie A division: soccer) warm-up routine lasting ~23 minutes, previously described in detail,1 was implemented. Briefly, the warm-up included general activities (high-knees, butt-kicks, and body-weight squats performed at medium intensity [submaximal velocity] for 6 min), specific movements (back-and-forth sprinting, lateral skipping, and changeof direction-movements performed at high intensity [maximal velocity] for 9 min), and ball-control activities (dribbling, passing, and run-throughs performed at high intensity for 6 min). One 60-second and two 30-second passive recovery periods were interspersed in the routine. The premier-league warm-up is a common soccer warm-up routine that was familiar to all participants in this study.
Figure 1 — Intermittent-activity protocol consisting of 60-s circuit × 15 repetitions per set.
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to complete the reactive agility test. A previously used repeat-sprintability test15 incorporating 6 × 30-m sprints starting on 20 seconds was implemented, with mean sprint times measured via Photocells (Lynx Systems Developers, USA) and a day-to-day CV of 0.8%.
The mean Yo-Yo score and 5RM leg-press strength of the participants were 1640 ± 104 m and 88 ± 8 kg, respectively. There were no between-trials differences in temperature, humidity, or wind speed observed during this study (P > .05). Compared with the team-sport warm-up, there was a moderate beneficial difference in countermovement-jump height in the 5RM
warm-up (6.0, ±4.0%: mean, ±90% confidence limits; P = .03) after the first intermittent-activity protocol and a small beneficial difference (4.6, ±4.0%: P = .04) after the second. There were no differences when countermovement-jump height was compared between the 5RM warm-up and the SSG warm-up after either the first or second intermittent-activity protocol (P > .05). There were also no differences observed when comparing the SSG with team-sport warm-ups after the first and second intermittent-activity protocols (P > .05) (Figure 2[a]). Reactive agility in the 5RM warm-up was moderately faster after the first (3.1, ±2.6%: P = 0.04) and second intermittent-activity protocols (5.7, ±2.7%: P = .001) than with the SSG warm-up. A small improvement in reactive agility was observed after only the first intermittent-activity protocol in the 5RM warm-up, compared with the team-sport warm-up (3.3, ±2.9%: P = .04) (Figure 2[b]). There were no observed differences for reactive agility between the SSG and team-sport warm-ups after either the first or second intermittent-activity protocol (P > .05). Mean repeat-sprint-ability times after the second intermittent-activity protocol were moderately faster in the 5RM warm-up than in the team-sport warm-up (4.4, ±2.2%: P = .01) but not after the first intermittent-activity protocol when compared with the team sport or the SSG warm-up (P > .05). There were also no differences for mean repeat-sprint-ability times in the SSG warm-up after the second intermittent-activity protocol compared with the team-sport warm-up (P > 0.05). In the 5RM warm-up there were small improvements observed in mean 20-m-sprint performance after both the first (4.2, ±2.0%: P = .01) and second intermittent activity protocols (4.3, ±2.0%: P = .01) compared with the SSG warm-up. Similarly, a small improvement was observed in mean 20-m-sprint performance in the 5RM warmup after the first intermittent-activity protocol compared with the team-sport warm-up (4.2, ±2.1%: P = .02) (Figure 3). There was a small increase in [Lac–]b after the second intermittent-activity protocol in the 5RM warm-up compared with the SSG warm-up (46.7, ±18.6%: P = .01) but no other differences reported (P > .05) (Figure 4). There were also no differences in HR measures after the first (SSG 171 ± 8, 5RM 174 ± 9, team sport 172 ± 8 beats/
(a)
(b)
Physiological Measures Blood lactate concentration ([Lac–]b) and HR were measured immediately after both 15-minute intermittent-activity protocols. Approximately 30 μL of blood was sampled from the ear lobe and analyzed for [Lac–]b using Biosen C Line (EKF Diagnostics, Germany). HR was recorded every 5 seconds during testing using short-range-telemetry HR-monitoring systems (VantageNV, S710, and Xtrainer models, Polar Electro, Kempele, Finland).
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Statistical Analysis Data are expressed as mean ± SD and were analyzed using PASW Statistics version 21 (SPSS Inc, Chicago, IL, USA) with a 2-factor repeated-measures ANOVA design (group × time). The least significant difference was employed for post hoc multiple comparisons. Magnitudes of changes were assessed via standardization with 90% confidence intervals16 to investigate the practical importance relevant to a sporting context. Changes were analyzed when there was a ≥75% likelihood of the effect being equal to or greater than the smallest worthwhile change (estimated as 0.2 × between-subjects SD). Effect sizes were classified as small (ES 0.2–0.59), moderate (ES 0.6–1.19), large (ES 1.2–1.9), or very large (ES 2.0–4.0).
Results
Figure 2 — (a) Countermovement-jump height and (b) reactive agility measured after each of the two 15-minute intermittent-activity protocols (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10. IJSPP Vol. 10, No. 4, 2015
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Figure 3 — The average time for the 15 × 20-m sprints imbedded in each of the intermittent-activity protocols (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10.
Figure 4 — Blood lactate concentration measured immediately after each 15-minute intermittent-activity protocol (IAP), mean ± SD. Abbreviations: SSG, small-sided game; 5RM, 5-repetition maximum; TS, team sport. *P < .05, N = 10.
min) or second (SSG 172 ± 10, 5RM 173 ± 10, team sport 172 ± 10 beats/min) intermittent-activity protocol between the 3 warm-up conditions (P > .05).
Discussion The major findings from this study were that a range of teamsport-related performance measures were improved after a 5RM warm-up compared with the 2 alternative warm-ups. After at least 1 of the 15-minute periods of intermittent activity, jump height and reactive agility were improved in the 5RM warm-up compared
with both the team-sport and SSG warm-ups. In addition, mean 20-m-sprint performance was faster after the 5RM warm-up after the first intermittent-activity protocol compared with the alternative warm-up interventions, as well as average 30-m repeat-sprint-ability times (5RM faster than the team-sport warm-up) after the second intermittent-activity protocol. In the current study, a 5RM warm-up, which produces a PAP effect,17 was associated with faster 20-m-sprint and repeat-sprintability performance during, and after, bouts of intermittent exercise. Although no previous study has investigated the prolonged effects of PAP on subsequent team-sport-related intermittent activity, 1 study reported an increase in peak power and average power in rebound jump performance (~3%) 18.5 minutes after a warm-up aimed at inducing PAP (5 × 1RM back squat).18 These findings suggest that warm-up protocols invoking a PAP effect (such as a 5RM warm-up) may be better suited than traditional team-sport warm-ups for the maintenance of sprint performance during subsequent intermittent activities, which is of high relevance to team sports such as soccer. Better sprint performances via the 5RM warm-up in the current study may be attributed to mechanisms associated with PAP, such as increased neuromuscular efficiency, a decrease in the required motor-unit firing rate for subsequent tasks, and the offsetting of low-frequency fatigue.19 For example, low-frequency fatigue can result from the impairment of excitation–contraction coupling,20 which may include a reduced Ca2+ release from the sarcoplasmic reticulum per action potential.5 However, in some circumstances this may be minimized or even reversed via PAP.19,21 It is therefore possible that the observed performance improvements via the 5RM warm-up may be attributable to an increase in phosphorylation of myosin light chains, leading to an increase in protein sensitivity to Ca2+,22 which in turn would counteract the negative effects associated with low-frequency fatigue. However, due to the performance nature of this study, further mechanistic research is required to confirm whether aforementioned mechanisms contributed to the enhanced performance observed during and after the intermittentexercise bouts. Enhanced neuromuscular efficiency is another mechanism of PAP that may provide beneficial effects to explosive tasks such as reactive agility. After selected periods of intermittent activity, reactive agility was faster (~3–6%) in the 5RM warm-up than in either of the alternative warm-ups. Sustained higher-order motor-neuron recruitment can be achieved in the presence of a decreasing firing rate via PAP.23 This particular mechanism may provide economies pertaining to membrane excitability and excitation–contraction coupling efficiency after the 5RM warm-up, both possible factors involved in delaying the onset of fatigue during intermittent exercise20 and enhancing the performance of subsequent explosive tasks.24 Although further research is required to confirm the timecourse effects of PAP during intermittent exercise, it seems plausible that PAP induced via a 5RM warm-up could minimize performance decrements in subsequent high-intensity explosive tasks. Alternative explanations for observed differences in the current study pertain to the negative effects of prolonged warm-ups on subsequent intermittent-sprint performance. Warm-up protocols employing similar intensities (60–80% VO 2max) and durations (15–30 min) to those of both the team-sport and the SSG warm-up used in the current study have been associated with decrements in subsequent performance.6,25 Similarly, we observed slower mean 20-m-sprint times and mean repeat-sprint-ability times after both the team-sport and the SSG warm-ups than with the 5RM warmup. The mechanism responsible for these observations may include the inhibition of anaerobic glycolysis and/or an increase in thermal
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strain via prolonged periods of active warm-up.26 We have previously reported greater increases in both [Lac–]b and core temperature after the team-sport and SSG warm-ups than with a 5RM.1 Other team-sport research has suggested that a decrease in muscle glycogen stores may also be responsible for the onset of fatigue during intermittent team-sport activity (eg, soccer).27 Although the current study did not investigate muscle glycogen content, the performance results support the hypothesis that prolonged warm-up routines may not be as beneficial for subsequent team-sport-related physical performance as high-intensity, short-duration warm-ups. These findings have important implications for team-sport coaches interested in designing efficient warm-up protocols to prepare athletes for subsequent competition. We have previously reported an acute 6% improvement in countermovement-jump performance after a similar SSG warmup intervention.1 In contrast, the current study reported enhanced countermovement-jump performance in the 5RM warm-up after both 15-minute periods of intermittent activity but no improvements after the SSG warm-up in comparison with the team-sport warm-up. The disparities in countermovement-jump performance suggest that the findings from studies investigating the effects of warm-up on acute performance may not be applicable to teamsport performance, which is characterized by prolonged periods of intermittent activity. Approximately 10 minutes of SSG activity may be beneficial for acute power performance but potentially too long when combined with 2 × 15-minute intermittent exercise. In support of this, 20-m-sprint performance decreased by ~5% (during sprints 7–15) after an SSG warm-up compared with a 5RM warmup.1 Small to moderate decreases in the latter stages of intermittentsprint performance may be associated with the onset of fatigue after the SSG warm-up.1 Similar decrements in sprint performance (4%) have been reported after high-intensity, 5-minute periods during a soccer match and may also be related to the temporary onset of fatigue.27 It should be noted that the varied nature of SSG tasks and associated work-rate levels may partly explain observed changes. Therefore, future research using SSG warm-up activities should endeavor to control, or closely monitor, work-rate profiles during SSG warm-ups. The physiological responses to the 3 warm-up interventions in this study were similar across both periods of the intermittentactivity protocol, with the exception of [Lac–]b. In the 5RM warm-up, [Lac–]b was higher after the second intermittent-activity protocol (46.7%) than with the SSG warm-up. These findings may be attributable to faster 20-m-sprint times observed during the intermittent-activity tasks after the 5RM warm-up compared with the SSG (4.2% and 4.3% faster) and the team-sport warm-up (4.2% and 5.1% faster). Despite the current findings, feedback from participants showed a distinct preference for warm-up protocols that included some skill component (eg, ball-control tasks). Acute improvements in soccer passing performance (Loughborough soccer passing test) after SSG warm-ups aimed at skill execution have been reported.13 However, these effects have not yet been investigated when the warm-up is preceded by soccer-specific intermittent exercise and therefore warrant further investigation It should be noted that in the current study the team-sport warmup acted as the control warm-up, as similar warm-up protocols are typically implemented in soccer. The variable nature of warm-up protocols currently used at the elite level makes selecting 1 generic control protocol to replicate all warm-up procedures impossible, while choosing a simplified generic protocol would not provide prac-
titioners with an ecologically valid comparison with potential new strategies. Furthermore, the administration of an optimal recovery period after high-intensity warms ups, such as that implemented in the current study, may be reliant on sport/competition regulations (ie, time/recovery-period restraints). Therefore, practitioners should review the team-sport warm-up protocol used in this study for similarities to their own currently implemented warm-up regimens, as well as governing regulations, to identify avenues for individual program improvements and efficiencies.
Conclusion A 5RM warm-up was associated with improved countermovementjump height, 20-m-sprint ability, reactive agility, and repeat-sprint ability during and after two 15-minute periods of intermittent activity compared with alternative warm-ups. This may be attributable to smaller physiological perturbations provoked by the 5RM warm-up, compared with the alternative warm-ups, and/or the induction of a PAP effect that was maintained during subsequent intermittent activities. These results have important implications for athletes, coaches, and physical-training staff. Of particular interest should be the design of the warm-up period to aid subsequent intermittent performance and to minimize the potential counterproductive effects of current warm-ups. Practitioners should explore the inclusion of short periods of high-intensity warm-up tasks before subsequent intermittent team-sport activity, which may benefit from a potentiation effect.
Practical Implications • A 5RM warm-up can enhance soccer-specific physical performance during 30 minutes of intermittent field-based exercise, compared with a premier-league soccer warm-up routine. • Changes in performance may be related to a potentiation effect via a high-intensity, short-duration 5RM warm-up or reduced physiological perturbations via fatigue-inducing mechanisms. • Future research should investigate the practicality and subsequent effect of including a 5RM warm-up before competitive scenarios.
References 1. Zois J, Bishop DJ, Ball K, Aughey RJ. High-intensity warm-ups elicit superior performance to a current soccer warm-up routine. J Sci Med Sport. 2011;14(6):522–528. PubMed doi:10.1016/j.jsams.2011.03.012 2. Mohr M, Krustrup P, Bangsbo J. Match performance of highstandard soccer players with special reference to development of fatigue. J Sports Sci. 2003;21(7):519–528. PubMed doi:10.1080/0264041031000071182 3. Mohr M, Krustrup P, Nybo L, Nielsen JJ, Bangsbo J. Muscle temperature and sprint performance during soccer matches—beneficial effect of re-warm-up at half-time. Scand J Med Sci Sports. 2004;14(3):156– 162. PubMed doi:10.1111/j.1600-0838.2004.00349.x 4. Fowles JR. Technical issues in quantifying low-frequency fatigue in athletes. Int J Sports Physiol Perform. 2006;1(2):169–171. PubMed 5. Hill CA, Thompson MW, Ruell PA, Thom JM, White MJ. Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans. J Physiol. 2001;531(Pt 3):871–878. PubMed doi:10.1111/j.1469-7793.2001.0871h.x
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6. Gregson WA, Batterham A, Drust B, Cable NT. The influence of prewarming on the physiological responses to prolonged intermittent exercise. J Sports Sci. 2005;23(5):455–464. PubMed doi:10.1080/02 640410410001730214 7. Bishop D. Warm up II: performance changes following active warm up and how to structure the warm up. Sports Med. 2003;33(7):483–498. PubMed doi:10.2165/00007256-200333070-00002 8. Towlson C, Midgley AW, Lovell R. Warm-up strategies of professional soccer players: practitioners’ perspectives. J Sports Sci. 2013;31(13):1393–1401. PubMed doi:10.1080/02640414.2013.792 946 9. Bangsbo J, Mohr M, Krustrup P. Physical and metabolic demands of training and match-play in the elite football player. J Sports Sci. 2006;24(7):665–674. PubMed doi:10.1080/02640410500482529 10. Kilduff LP, Bevan HR, Kingsley MI, et al. Postactivation potentiation in professional rugby players: optimal recovery. J Strength Cond Res. 2007;21(4):1134–1138. PubMed 11. Chatzopoulos DE, Michailidis CJ, Giannakos AK, et al. Postactivation potentiation effects after heavy resistance exercise on running speed. J Strength Cond Res. 2007;21(4):1278–1281. PubMed 12. Racinais S, Connes P, Bishop D, Blonc S, Hue O. Morning versus evening power output and repeated-sprint ability. Chronobiol Int. 2005;22(6):1029–1039. PubMed doi:10.1080/07420520500397918 13. Zois J, Bishop D, Fairweather I, Ball K, Aughey RJ. High-intensity re-warm-ups enhance soccer performance. Int J Sports Med. 2013;34(9):800–805. PubMed doi:10.1055/s-0032-1331197 14. Sheppard JM, Young WB, Doyle TL, Sheppard TA, Newton RU. An evaluation of a new test of reactive agility and its relationship to sprint speed and change of direction speed. J Sci Med Sport. 2006;9(4):342–349. PubMed doi:10.1016/j.jsams.2006.05.019 15. Pyne DB, Saunders P, Montgomery P, Hewitt A, Sheehan K. Relationships between repeated sprint testing, speed, and endurance. J Strength Cond Res. 2008;22(5):1633–1637. PubMed doi:10.1519/ JSC.0b013e318181fe7a 16. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science.
Med Sci Sports Exerc. 2009;41(1):3–13. PubMed doi:10.1249/ MSS.0b013e31818cb278 17. Mitchell CJ, Sale DG. Enhancement of jump performance after a 5-RM squat is associated with postactivation potentiation. Eur J Appl Physiol. 2011;111(8):1957–1963. PubMed doi:10.1007/s00421-010-1823-x 18. Chiu LZ, Fry AC, Weiss LW, Schilling BK, Brown LE, Smith SL. Postactivation potentiation response in athletic and recreationally trained individuals. J Strength Cond Res. 2003;17(4):671–677. PubMed 19. Green HJ, Jones SR. Does post-tetanic potentiation compensate for low frequency fatigue? Clin Physiol. 1989;9(5):499–514. PubMed doi:10.1111/j.1475-097X.1989.tb01003.x 20. Edwards RH, Hill DK, Jones DA, Merton PA. Fatigue of long duration in human skeletal muscle after exercise. J Physiol. 1977;272(3):769– 778. PubMed doi:10.1113/jphysiol.1977.sp012072 21. Bigland-Ritchie B, Johansson R, Lippold OC, Woods JJ. Contractile speed and EMG changes during fatigue of sustained maximal voluntary contractions. J Neurophysiol. 1983;50(1):313–324. PubMed 22. Moore RL, Stull JT. Myosin light chain phosphorylation in fast and slow skeletal muscles in situ. Am J Physiol. 1984;247(5 Pt 1):C462– C471. PubMed 23. Sale DG. Postactivation potentiation: role in human performance. Exerc Sport Sci Rev. 2002;30(3):138–143. PubMed doi:10.1097/00003677200207000-00008 24. Gullich A, Schmidtbleicher D. MVC-induced short-term potentiation of explosive force. New Stud Athl. 1996;11(4):67–81. 25. Gregson WA, Drust B, Batterham A, Cable NT. The effects of prewarming on the metabolic and thermoregulatory responses to prolonged submaximal exercise in moderate ambient temperatures. Eur J Appl Physiol. 2002;86(6):526–533. PubMed doi:10.1007/s00421-002-0580-x 26. Hermansen L. Effect of metabolic changes on force generation in skeletal muscle during maximal exercise. Ciba Found Symp. 1981;82:75–88. PubMed 27. Krustrup P, Mohr M, Steensberg A, Bencke J, Kjaer M, Bangsbo J. Muscle and blood metabolites during a soccer game: implications for sprint performance. Med Sci Sports Exerc. 2006;38(6):1165–1174. PubMed doi:10.1249/01.mss.0000222845.89262.cd
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