Athletes traditionally include static stretching (SS) as part of a preactivity warm-up to improve performance and decrease the risk of injury. Despite this common practice, no conclusive evidence exists supporting the theory that SS before exercise reduces injury risk (23). Additionally, SS has recently been purported to decrease maximal force production (9,10,16,18,21), jump height (4,27,33), and sprint speed (12,15), while increasing reaction time and impairing balance (3). As a result, strength and conditioning professionals have started shifting away from prepractice SS in favor of a functional, dynamic warm-up (2). Dynamic stretching (DS) theoretically provides the same flexibility benefits as SS without compromising performance and may even improve performance in activities involving explosive power (14,30).
Performance reductions after SS have been explained by a combination of mechanical and neural factors. Mechanically, SS results in a longer and more compliant musculotendinous unit (28). Contractile elements must then contract more rapidly and over a greater distance to “pick up the slack,” resulting in reduced peak torque and a slower rate of force development (28). Neurologically, SS appears to decrease motor unit activation (1,5,16,21). Cramer et al. reported that SS performed on the dominant leg resulted in decreased peak torque and motor unit activation (as measured by electromyographic amplitude) in both the stretched and unstretched legs (9,10). They suggest that because deficits in maximal force production were observed in both the stretched and the unstretched leg, a central nervous system inhibitory mechanism must be at least partially responsible for the observed changes (10).
The DS routines incorporate skipping, directional running, shuffling, and various calisthenics of increasing intensity that simulate the movement patterns necessary for success in a particular sport. Performance improvements after DS have been documented in sprinting (11), jumping (14), and peak force-generating capacity (30). Because of its active nature, DS before activity may improve performance by providing an opportunity for movement rehearsal (15) and by increasing blood flow to the muscles, the latter resulting in enhanced oxygen delivery and waste removal and faster nerve-impulse conduction (24). Recent guidelines recommend that strength and conditioning professionals replace SS with DS in their preactivity warm-ups (2).
In athletic activity, it is common for a warm-up to include SS followed by a period of sport-specific activity practice before the beginning of competition (19). Currently, only a limited number of studies have attempted to determine whether the performance decrements associated with SS persist after activity commences. Woolstenhulme et al. (29) reported no difference when comparing vertical jump height immediately after SS and after 20 minutes of supplemental basketball play. Conversely, Fletcher and Anness (11) reported that athletes' sprint times improved when SS was removed from a combination warm-up consisting of jogging, SS, and DS. Thus, there remains a need to further investigate the time course of static stretch-induced performance deficits to determine both the magnitude and duration of any potential lingering effects.
Successful performance in sport often requires explosive power and quick reaction time. In elite competition, where success may be affected by very small performance differences, it is essential for the athlete to maximize benefits from the warm-up. The purpose of this research was to compare the effects of a warm-up with static vs. DS on jump height and reaction time during a series of countermovement jumps (CMJs). We sought to determine whether any observed performance decrements or benefits would persist throughout a series of CMJs. We hypothesized that a warm-up that included SS would reduce jump height and increase reaction time, whereas a warm-up with DS would improve jump height and decrease reaction time. We also hypothesized that potential performance differences may be less obvious by the end of the series of jumps, compared to the first jumps. Additionally, we sought to compare the effects of both stretch treatments on hamstring flexibility. We hypothesized that both warm-ups would be equally effective at increasing hamstring flexibility.
Experimental Approach to the Problem
There is a growing body of evidence to suggest that SS may acutely impact performance, whereas DS may acutely improve performance. However, in real-world athletic settings, these treatments are not often used in isolation. In many competitive settings, a warm-up may include SS followed by some other sort of dynamic activity. Thus, the acute detrimental effects of SS may not persist through a series of CMJs, because the early jumps may function as a secondary “dynamic warm-up,” thereby improving the later jumps. The purpose of this study was to compare the effects of a warm-up with static vs. DS on jump height and reaction time during a series of CMJs. We sought to determine whether any observed differences persisted throughout the series of CMJs. Additionally, we sought to compare hamstring flexibility after each stretch treatment.
The CMJ height was selected as an outcome measure because successful performance involves a coordinated movement of all major muscle groups of the lower extremity. The CMJ height has been shown to have very high reliability with low within-subject variation (17). Additionally, CMJ ability is highly related to other performance measures such as peak power output, agility, sprint velocity, and sprint acceleration (20), making it a robust measure applicable to a wide variety of sports. Additionally, we sought to measure reaction time because it has not extensively been studied and because reaction time is critically important in athletic tasks such as reacting to a shot on goal or to a change in direction by an attacking player. Because athletes also stretch to improve flexibility, we also included a measure of low-back and hamstring flexibility to compare the effectiveness of both stretch treatments on acute flexibility.
Participants completed 3 testing sessions, each consisting of a general warm-up followed by 1 of 3 treatments: no stretching (NS), SS, or DS. After the general warm-up and treatment, the participant was measured on each of the outcome variables. First, the participant performed a sit-and-reach test to assess low-back and hamstring flexibility. Next, participants completed a set of 10 maximal-effort CMJs, on each of which they were to jump as quickly as possible after seeing a visual stimulus (light). The onset of movement and CMJ height were determined from measured ground reaction force data. The order of treatments was counterbalanced by rotating which treatment was performed first (i.e., one-third of participants experienced NS first, one-third experienced SS first, etc.), and the 3 sessions were scheduled 3-7 days apart.
Twenty-one recreationally active male university students (mean ± SD age: 24.4 ± 4.5 years; height: 1.80 ± 0.06 m; mass: 81.1 ± 14.0 kg) volunteered for this study. The study was approved by the university's Institutional Review Board for the protection of human subjects, and all participants gave their informed consent. Inclusion criteria included regular participation (minimum of 30 min·d−1, 3 d·wk−1) in physical activity that included resistance training, sprinting, jumping, or quick changes in direction. Individuals who reported low-back or lower-extremity injury (i.e., strain, sprain, or fracture) in the past 6 months were excluded. Participants were asked to abstain from resistance training for at least 24 hours before testing.
Participants completed 3 testing sessions, scheduled at approximately the same time of day. A general warm-up was performed at the start of each testing session. The general warm-up consisted of a 5-minute treadmill jog at a self-selected pace (8.6 ± 1.4 km·h−1) that was kept constant across testing sessions, followed by 2 submaximal practice CMJs. After completing the general warm-up, participants completed 1 of the 3 treatments (NS, SS, or DS). During the NS treatment, subjects sat quietly for 15 minutes. The SS treatment consisted of 7 lower-extremity stretching exercises (Table 1), each held for 2 repetitions of 30 seconds. The selected stretches are representative of those commonly recommended to target major muscle groups of the lower extremity (2). Mean time to complete the SS treatment was 14.8 ± 0.4 minutes. The DS treatment consisted of 11 exercises of increasing intensity (Table 2), performed on a regulation-size volleyball court (18.3 m in length). Mean time to complete the DS treatment was 13.8 ± 1.7 minutes, and participants rated the intensity of the treatment as 5.2 ± 1.2 on the Borg CR10 Scale (7).
After completing the designated treatment, low-back/hamstring flexibility was assessed using a sit-and-reach box (Novel Products, Inc., Rockton, IL, USA), following a standard protocol (2,8,29). The best of 3 trials was retained. Next, participants performed a series of 10 CMJs. Participants stood on a portable force plate (Kistler USA, Amherst, NY, USA) with hands akimbo and were instructed to perform a maximal-height CMJ as quickly as possible after seeing a visual stimulus (red light of 1-cm diameter) that was at eye level approximately 2 m in front of the participant. Participants were precued for the next trial between 5 and 15 seconds before illumination of the light. A total of 10 CMJs were performed with a 1-minute rest between jumps. Ground reaction forces were recorded from the force plate at 2,000 Hz, filtered with a fourth-order no-lag Butterworth filter (low-pass cutoff 25 Hz) and processed using a custom program (LabVIEW 8.5, National Instruments, Austin TX, USA).
Recorded ground reaction forces were used to calculate CMJ height and reaction time. To calculate CMJ height, the vertical velocity and height of the participant's center of mass at take-off were first calculated by single and double integration, respectively, of the ground reaction force minus body weight from the onset of movement to the instant of take-off. Projectile motion equations were then used to calculate jump height as the peak height of the center of mass during the jump with respect to its height at the onset of motion. The onset of motion (i.e., start of the unloading phase of the CMJ) was determined to be the instant when the vertical ground reaction force fell 3SDs below its baseline value. The instant of take-off was determined to be the instant when the vertical ground reaction force fell to within 2SDs of the mean value recorded on the unloaded force plate (i.e., while the participant was in the air). Finally, reaction time was defined as the elapsed time from the presentation of the visual stimulus to the onset of motion.
The purpose of this study was to compare the effects of a warm-up with static vs. DS on the following dependent variables: CMJ height, reaction time, and low-back and hamstring flexibility. Data from jumps 1 and 10 of each testing session were excluded from the analysis to reduce intrajump variability (it was observed that during the first jump, participants were so focused on getting off the ground quickly that they did not perform a maximal jump; during the last jump, participants' jump heights increased relative to the previous jumps, potentially because they knew they were finishing the trial). Two participants were excluded because of multiple missing data points and extreme variation (>20% difference in mean jump height) between testing sessions. The CMJ height and reaction time were analyzed with separate (3 [treatment] × 8 [jump]) repeated-measures analyses of variance (ANOVAs). Because flexibility was measured only after each treatment, 1-way ANOVA was used to identify differences in flexibility posttreatment. Post hoc analyses of the effects of treatment were conducted using Bonferroni-adjusted 1-tailed paired t-tests, based on the hypothesized effects (DS > NS; DS > SS; NS > SS). Post hoc analyses of selected jump pairs (early jumps vs. late jumps) were conducted using Bonferroni-adjusted 2-tailed t-tests. All statistical analyses were conducted using SPSS version 15 for Windows (SPSS Inc., Chicago, IL, USA) and significance was set at p ≤ 0.05.
Results of the ANOVA for CMJ height revealed main effects of stretch treatment (p = 0.004; Table 3) and jump (p = 0.005), with no interaction between treatment and jump (p = 0.57). Post hoc comparisons revealed that mean CMJ height was significantly higher after DS compared to after NS and SS (p = 0.005 and p = 0.044, respectively). However, the mean CMJ height was not lower for SS than for NS (p = 0.46). Post hoc comparisons of early (jumps 2 and 3) and late (jumps 8 and 9) jump height revealed that jumps at the end of the series were significantly lower than jumps at the beginning of the series (jump 2 > jump 9, p = 0.045; jump 3 > jumps 8 and 9; p = 0.03 and p = 0.042) (Figure 1). The ANOVA for reaction time revealed no main effects of stretch treatment (p = 0.08) or jump (p = 0.58) and no interaction between treatment and jump (p = 0.88).
Finally, 1-way ANOVA revealed a significant main effect of stretch treatment on sit-and-reach flexibility (p < 0.001; Table 3). Post hoc analyses revealed that both SS and DS resulted in significantly greater flexibility compared to NS (SS: p = 0.002; DS: p < 0.001). No difference in sit-and-reach scores was observed between SS and DS (p = 0.53).
The purpose of this investigation was to compare the effects of a warm-up including static vs DS on jump height and reaction time over a series of CMJs. Additionally, we sought to determine whether different stretch treatments would affect hamstring flexibility. Using a repeated-measures design, the results revealed that CMJ height was significantly higher after DS than after NS (3.9% improvement) or SS (2.6% improvement). These results are consistent with those of previous research that reported increases in CMJ height after a warm-up consisting of progressive-resistance half-squats (13). Additional studies have revealed that warm-ups that included a combination of jogging, DS and practice jumps resulted in higher CMJ height than warm-ups that included SS (26,33). Dynamic stretching has also been shown to improve sprint times and agility drill performance. Little and Williams (15) reported that lower-body dynamic exercises resulted in reduced 10- and 20-m sprint times and a reduced zig-zag drill time but no change in CMJ performance. Additional research suggests that dynamic exercise performed at a jogging pace can improve sprint performance; however, comparable improvements were not observed when these exercises were performed while stationary (12). Collectively, these previous studies and the present findings suggest that DS exercises, particularly those performed at a jogging pace as opposed to stationary, can improve performance in measures of power such as sprinting and jumping.
Our results also showed that SS did not decrease CMJ height in comparison to NS. Many studies investigating the effects of SS on performance have reported decreases in peak torque (9,10,16,18,21) and jump height (4,6,27,33). However, consistent with the present findings, several authors (8,15,21,25) have reported no change in jump performance after performing lower-extremity SS ranging from 3 repetitions of 15 seconds (25) up to 3 repetitions of 45 seconds (21). The static stretch treatment in this study consisted of a moderate amount of stretching (2 repetitions of 30 seconds for 7 lower-extremity stretches). It is possible that this was not a sufficient stretch duration to induce performance deficits. Robbins and Scheuermann (22) reported that squat jump performance was affected by 6 sets of quadriceps, hamstring, and plantarflexor stretches but unaffected by 2 or 4 sets of the stretches. Their research, however, examined the concentric-only squat jump, which does not rely on the stretch-shortening cycle to enhance lower-extremity power production and may therefore be less susceptible to stretch-induced force decrements (31). It is also possible that, in the present study, the 15-minute waiting period after the general warm-up in the NS condition resulted in a performance deficit equivalent to that induced by SS. Another surprising finding was that overall, the highest mean jump height across all conditions occurred during SS (trial 3, Figure 1). Although mean jump height during SS trial 3 was not significantly higher than DS trial 3, this phenomenon is interesting and warrants further exploration. Examination of the data revealed that the observed higher mean during SS trial 3 was not because of any single jumper performing exceptionally well; rather, 9 of the 19 participants recorded their best SS jump during trial 3. One plausible explanation for this observation could be the fact that the first 2 jumps may have provided a movement rehearsal leading to (temporary) better performance. However, the mean jump height of the subsequent trial was substantially lower and in line with other trials. It seems unlikely that any benefit of movement rehearsal would have such a fleeting effect on performance. Despite the unusually high mean jump height during SS trial 3, the overall pattern of jump performance suggests that jumpers performed worse after SS than after DS.
Counter to our expectations, CMJ height decreased from the early to the late jumps, regardless of stretch treatment. One mechanism by which DS may improve performance is by providing an opportunity for rehearsal of specific movement patterns (12,15). In this case, participants' peak performance would be expected to occur during the last several jumps in the series, because the earlier jumps would provide more opportunity for skill-specific rehearsal. Instead, our results showed a progressive decrease in CMJ height across jumps, consistent with fatigue. This gradual decrease in jump height is particularly interesting after SS, because it is a common athletic practice to include SS followed by sport-specific dynamic activity during the warm-up (32). We expected to see mean jump height increase progressively during the jump series, because the first several jumps had the potential to function as a secondary warm-up that might gradually increase mean CMJ height up to the level reached after DS. However, Pearce et al. observed a similar phenomenon to the present while examining the performance impact of a secondary dynamic warm-up after SS (19). They found that performance deficits observed after SS continued to worsen for up to 30 minutes after 10-12 minutes of secondary dynamic movement drills. From a performance perspective, our results and theirs suggest that deficits in performance after SS are not easily overcome or reversed through additional activity.
Beyond their influences on CMJ height, it was hypothesized that DS would improve reaction time, whereas SS would impair it. The effects of DS on reaction time had not been reported previously; however, Behm et al. (3) reported a 4.0% slowing (impairment) of reaction time to a light stimulus after SS. In contrast, our results did not reveal statistically significant differences in reaction time between DS, SS, and NS. Large inter and intrasubject variability in reaction time may have resulted in an inability to detect possible subtle changes in reaction time.
The observed differences in CMJ height reveal a clear performance advantage in choosing DS before exercise. However, a second important consideration in warm-up design is whether the chosen stretching method produces the desired acute increase in flexibility. Our results suggest that static and DS are equally effective at improving sit-and-reach performance. Thus, DS may be particularly beneficial in sports requiring a combination of flexibility and explosive force, because it appears to provide the greatest performance benefits without sacrificing acute flexibility in the process.
Limitations of this study include the fact that all participants were recreationally active but participated in different sports and trained at different intensity levels, ranging from 30 minutes of activity, 3 d wk−1 to 2 hours of intense activity, most days of the week. Additionally, some reported stretching regularly after exercising, whereas others reported no regular stretching practice. Some participants also reported that the dynamic stretch treatment, designed based on a typical collegiate-level warm-up, was intense enough to potentially cause fatigue. Participants' rating of their level of exertion during DS ranged from a 3 (“Moderate”) to 6 (“Strong” to “Very Strong”) on the Borg CR10 scale (7).
Our study, in combination with previous work, suggests that DS before exercise can provide a performance advantage in jump height, sprint speed, and agility. Additionally, our results provide additional evidence that potential performance deficits incurred after SS may not easily be overcome through additional activity. In designing effective warm-up routines for athletes requiring strength, speed, or power, coaches and strength and conditioning professionals should prescribe a general aerobic warm-up followed by DS that increases muscle temperature and blood flow, while providing the opportunity for sport-specific movement rehearsal. SS immediately before activity should be avoided because it confers no performance benefit. A well-designed warm-up including DS can serve the dual purposes of enhancing acute flexibility while also priming the athlete for peak performance.
1. Avela, J, Kyrolainen, H, and Komi, PV. Altered reflex sensitivity after repeated and prolonged passive muscle stretching. J Appl Physiol
86: 1283-1291, 1999.
2. Baechle, TR and Earle, RW. Essentials of Strength Training and Conditioning
. (3rd ed.). Champaign, IL: Human Kinetics, 2008.
3. Behm, DG, Bambury, A, Cahill, F, and Power, K. Effect of acute static stretching on force, balance, reaction time and movement time. Med Sci Sports Exerc
36: 1397-1402, 2004.
4. Behm, DG, Bradbury, EE, Haynes, AT, Hodder, JN, Leonard, AM, and Paddock, NR. Flexibility is not related to stretch-induced deficits in force or power. J Sports Sci Med
5: 33-42, 2006.
5. Behm, DG, Button, DC, and Butt, JC. Factors affecting force loss with prolonged stretching. Can J Appl Physiol
26: 261-272, 2001.
6. Behm, DG and Kibele, A. Effects of differing intensities of static stretching on jump performance
. Eur J Appl Physiol
101: 587-594, 2007.
7. Borg, G. Borg's Perceived Exertion and Pain Scales
. Champaign, IL: Human Kinetics, 1998.
8. Church, JB, Wiggins, MS, Moode, FM, and Crist, R. Effect of warm-up and flexibility treatments on vertical jump performance
. J Strength Cond Res
15: 331-336, 2001.
9. Cramer, JT, Housh, TJ, Johnson, GO, Miller, JM, Coburn, JW, and Beck, TW. Acute effects of static stretching on peak torque in women. J Strength Cond Res
18: 236-241, 2004.
10. Cramer, JT, Housh, TJ, Weir, JP, Johnson, GO, Coburn, JW, and Beck, TW. The acute effects of static stretching on peak torque, mean power output, electromyography, and mechanomyography. Eur J Appl Physiol
93: 530-539, 2005.
11. Fletcher, IM and Anness, R. The acute effects of combined static and dynamic stretch protocols on fifty-meter sprint performance
in track-and-field athletes. J Strength Cond Res
21: 784-787, 2007.
12. Fletcher, IM and Jones, B. The effect of different warmup stretch protocols on 20 meter sprint performance
in trained rugby union players. J Strength Cond Res
18: 885-888, 2004.
13. Gourgoulis, V, Aggeloussis, N, Kasimatis, P, Mavromatis, G, and Garas, A. Effect of a submaximal half-squats warm-up program on vertical jumping ability. J Strength Cond Res
17: 342-344, 2003.
14. Holt, BW and Lambourne, K. The impact of different warm-up protocols on vertical jump performance
in male collegiate athletes. J Strength Cond Res
22: 226-229, 2008.
15. Little, T and Williams, AG. Effects of differential stretching protocols during warm-ups on high-speed motor capacities in professional soccer players. J Strength Cond Res
20: 203-207, 2006.
16. Marek, SM, Cramer, JT, Fincher, AL, Massey, LL, Dangelmaier, SM, Purkayastha, S, Fitz, KA, and Culbertson, JY. Acute effects of static and proprioceptive neuromuscular facilitation stretching on muscle strength and power output. J Athl Train
40: 94-103, 2005.
17. Markovic, G, Dizdar, D, Jukic, I, and Cardinale, M. Reliability and factorial validity of squat and countermovement jump tests. J Strength Cond Res
: 551-555, 2004.
18. Papadopoulos, G, Siatras, T, and Kellis, S. The effect of static and dynamic stretching exercises on the maximal isokinetic strength of the knee extensors and flexors. Isokin Exerc Sci
13: 285-291, 2005.
19. Pearce, A, Kidgell, D, Zois, J, and Carlson, J. Effects of secondary warm up following stretching. Eur J Appl Physiol
105: 175-183, 2009.
20. Peterson, MD, Alvar, BA, and Rhea, MA. The contribution of maximal force production to explosive movement among young collegiate athletes. J Strength Cond Res
20: 867-873, 2006.
21. Power, K, Behm, D, Cahill, F, Carroll, M, and Young, W. An acute bout of static stretching: effects on force and jumping performance
. Med Sci Sports Exerc
36: 1389-1396, 2004.
22. Robbins, JW and Scheuermann, BW. Varying amounts of acute static stretching and its effect on vertical jump performance
. J Strength Cond Res
22: 781-786, 2008.
23. Shrier, I. Does stretching help prevent injuries? In: Evidence-Based Sports Medicine
. MacAuley, D and Best, T, eds. (2nd ed.). Malden, MA: Blackwell Publishing, 2007.
24. Thacker, SB, Gilchrist, J, Stroup, DF, and Kimsey, CJ Jr. The impact of stretching on sports injury risk: A systematic review of the literature. Med Sci Sports Exerc
36: 371-378, 2004.
25. Unick, J, Kieffer, HS, Cheesman, W, and Feeney, A. The acute effects of static and ballistic stretching on vertical jump performance
in trained women. J Strength Cond Res
19: 206-212, 2005.
26. Vetter, RE. Effects of six warm-up protocols on sprint and jump performance
. J Strength Cond Res
21: 819-823, 2007.
27. Wallmann, HW, Mercer, JA, and McWhorter, JW. Surface electromyographic assessment of the effect of static stretching of the gastrocnemius on vertical jump performance
. J Strength Cond Res
19: 684-688, 2005.
28. Witvrouw, E, Mahieu, N, Danneels, L, and McNair, P. Stretching and injury prevention: An obscure relationship. Sports Med
34: 443-449, 2004.
29. Woolstenhulme, MT, Griffiths, CM, Woolstenhulme, EM, and Parcell, AC. Ballistic stretching increases flexibility and acute vertical jump height when combined with basketball activity. J Strength Cond Res
20: 799-803, 2006.
30. Yamaguchi, T, Ishii, K, Yamanaka, M, and Yasuda, K. Acute effects of dynamic stretching exercise on power output during concentric dynamic constant external resistance leg extension. J Strength Cond Res
21: 1238-1244, 2007.
31. Young, W and Elliott, S. Acute effects of static stretching, proprioceptive neuromuscular facilitation stretching, and maximum voluntary contractions on explosive force production and jumping performance
. Res Q Exerc Sport
72: 273-279, 2001.
32. Young, WB. The use of static stretching in warm-up for training and competition. Int J Sports Physiol Perform
2: 212-216, 2007.
33. Young, WB and Behm, DG. Effects of running, static stretching and practice jumps on explosive force production and jumping performance
. J Sports Med Phys Fitness
43: 21-27, 2003.