There was considerable variability among subjects as several had dramatic improvements, particularly in SlowKE and FastKE, following the stretching treatment while others had minimal or even negative responses. The percent change from nonstretching to stretching trials for the 4 dependent variables for each subject is illustrated in Figure 7.
Despite a large amount of research on the effects of statically stretching the agonist musculature before rapid force production, this is the first published study to our knowledge that has examined the effects of statically stretching the antagonist musculature before a power movement. We hypothesized that a static stretch of the antagonists could inhibit this muscle group, allowing for greater expression of strength and power production of the agonists. Indeed, the primary finding of this study was that there were statistically significant increases in isokinetic knee extension torque at 300°.s−1 as well as VJheight and VJpower following static stretches of the antagonist musculature. However, these results are tempered by the fact that the magnitudes of the increases were small (8). Furthermore, there was no significant difference in EMG between stretching and nonstretching trials.
Decrements in torque production of 2–3% after static stretching of the agonists have been reported in several studies (10–12,23), whereas others have reported slightly larger drops in isokinetic peak torque of 5–12% (24,31,32,39). However, as Sobolewski et al. (32) observed, the magnitudes of these decrements were often within the standard error of measurement of isokinetic testing, and the effect sizes were small. Similarly, we observed an 8% increase for SlowKE and a 9% increase for FastKE after stretching of the antagonist, but the magnitudes of these increases exhibited small effect sizes (8). Thus, although there is a trend (and often a statistically significant difference) for static stretching to impact torque output, whether these differences between stretching and nonstretching conditions have practical meaning is not clear. Nevertheless, the magnitude of torque increase observed in the present study after static stretching of the antagonist was remarkably similar to the magnitude of decrease in torque output that has been reported after static stretching of the agonist.
It was hypothesized in the current study that stretching the antagonist musculature would result in an increased performance by increasing the neural drive to the agonist, decreasing neural drive to the antagonist, reducing stiffness of the antagonist and braking forces to the agonist, or a combination of these factors. Despite an increase in isokinetic peak torque for FastKE after hamstring stretching and a 9.7% increase in EMG activity of the vastus lateralis following the stretching trial compared with the nonstretching trial, the differences of EMG activity between test conditions were not statistically significant. Similarly, the EMG activity of the antagonist biceps femoris during FastKE was 16% lower after the stretching trial compared with the nonstretching trial, but again this difference was not statistically significant. The lack of a statistically significant finding for EMG activity suggests that the difference in torque observed was not related to increased activation of the prime movers.
With each measured variable, there was a large amount of subject-to-subject variability, as shown by the relatively large SDs (Table 1). The differences of interindividual strength and power responses to antagonist stretching may have been due to initial levels of flexibility. One of the limitations of this study is that there was no initial flexibility assessment taken. There is evidence that tight or short antagonist musculature may result in decreased function of the agonist musculature (29,34,35). It is possible that individuals with lower initial levels of flexibility in antagonist musculature experienced a greater training effect with stretching than those with higher initial levels. The researchers are not aware of any studies that have investigated whether initial levels of flexibility affect the magnitude of treatment effect from stretching, and this is a potential avenue of investigation.
Antagonist stretching of the hamstrings resulted in significantly greater torque during a high-velocity (300°.s−1) isokinetic knee extension. The take home message for the practitioner is that stretching the antagonist to the hip extensors (hip flexors) and plantarflexors (dorsiflexors) before jumping resulted in significantly greater VJheight and VJpower. These findings suggest that stretching the antagonist musculature immediately before a high-velocity activity may enhance the performance of that activity. Practitioners could apply the results of the current study in designing the warm-up procedures before plyometric training sessions or other training sessions that require high-velocity movements.
However, the findings of the current study are mitigated by the fact that the magnitude of improvement was small, and there was substantial interindividual variability in the response to antagonistic stretching. Furthermore, the difference in EMG activity after antagonistic stretching compared with a nonstretching trial was not significant, leaving the mechanism of improvement in doubt. Nevertheless, there is justification for practitioners to experiment with stretching the antagonist musculature to improve performance in high-velocity activity.
For the researcher, there is ample opportunity for further investigation on this topic. Future research should investigate other muscle groups and movement patterns. It should also be determined if initial levels of flexibility affect responses to antagonist stretching before strength and power–related performance. The effects of antagonist stretching using other stretching techniques (e.g., PNF, dynamic) should be investigated, as well as gender effects to antagonist stretching. Future research should also attempt to determine possible mechanisms, whether mechanical, neural, or a combination of both.
The authors thank the subjects for their effort and Dr. Dennis Dolny for his expertise and guidance with the Biopac EMG system. This study was conducted without external funding but was supported by the Human Movement Science Program at Utah State University.
1. Bandy WD, Irion JM, Briggler M. The effect of time and frequency of static stretching on flexibility
of the hamstrings muscles. Phys Ther 77: 1090–1096, 1997.
2. Baratta R, Solomomow M, Zhou B, Letson D, Chuinard R, D'Abrosia R. Muscular co-contraction. The role of antagonist musculature in maintaining knee stability. Am J Sports Med 16: 113–122, 1988.
3. Basmajian JV, DeLuca CJ. Muscles Alive: Their Function Revealed by Electromyography. Baltimore, MD: Willams & Wilkins, 1985.
4. Burden A. How should we normalize electromyograms obtained from healthy participants? What we have learned from over 25 years of research. J Electromyogr Kinesiol 20: 1023–1035, 2010.
5. Carolan B, Cafarelli E. Adaptations in coactivation after isometric training. J Appl Physiol 73: 911–917, 1992.
6. Chan SP, Hong Y, Robinson PD. Flexibility
and passive resistance of the hamstrings of young adults using two different static stretching protocols. Scand J Med Sci Sports 11: 81–86, 2001.
7. Church BJ, Wiggins MS, Moode M, Crist R. Effect of warm-up and flexibility
treatments on vertical jump performance. J Strength
Cond Res 15: 332–336, 2001.
8. Cohen J. Statistical Power
Analysis for Behavioral Sciences. Hillsdale, NJ: Erlbaum Associates, 1988.
9. Cornwell A, Nelson G, Sidaway B. Acute effects of stretching on the neuromechanical properties of the triceps surae muscle complex. Eur J Appl Physiol 86: 428–434, 2002.
10. Cramer JT, Beck TW, Housh TJ, Massey LL, Marek SM, Danglemeier S, Purkayastha S, Culbertson JY, Fitz KA, Egan AD. Acute effects of static stretching on characteristics of the isokinetic
angle-torque relationship, surface electromyography, and mechanomyography. J Sports Sci 25: 687–698, 2007.
11. Cramer JT, Housh TJ, Johnson GO, Miller JM, Coburn JW, Beck TW. Acute effects of static stretching on peak torque in women. J Strength
Cond Res 18: 236–241, 2004.
12. Cramer JT, Housh TJ, Weir JP, Johnson GO, Coburn JW, Beck TW. The acute effects of static stretching on peak torque, mean power
output, electromyography, and mechanomygraphy. Eur J Appl Physiol 93: 530–539, 2005.
13. DeLuca C. The use of surface electromyography in biomechanics. J Appl Biomech 13: 153–163, 1997.
14. Draganich LF, Jaeger RJ, Kralj AR. Coactivation of the hamstrings and the quadriceps during extension of the knee. J Bone Joint Surg 71: 1078–1081, 1989.
15. Feiring DC, Ellenbecker TS, Derscheid GL. Test-retest reliability of the biodex isokinetic
dynamometer. J Orthop Sports Phys Ther 11: 298–300, 1990.
16. Fowles JR, Sale DG, MacDougall JD. Reduced strength
after passive stretch of the human plantarflexors. J Appl Physiol 89: 1179–1188, 2000.
17. Häkkinen K, Kallinen M, Izquierdo M, Jokelainen K, Lassila H, Malkia E, Alen M. Change in agonist-antagonist EMG, muscle CSA, and force
training in middle aged and older people. J Appl Physiol 84: 1341–1349, 1998.
18. Harman E, Garhammer J, Pandorf C. Administration, scoring, and interpretation of selected tests. In: Essentials of Strength
Training and Conditioning (2nd ed.). Baechle TR, Earle RW, eds. Champaign IL: Human Kinetics, 2000. pp. 293.
19. Harman EA, Rosenstein MT, Frykman PN, Rosenstein RM, Kraemer WJ. Estimation of human power
output from vertical jump. J Appl Sport Sci 5: 116–120, 1991.
20. Herda TJ, Cramer JT, Ryan ED, McHugh MP, Stout JR. Acute effects of static versus dynamic stretching on isometric peak torque, electromyography, and mechanomyography of the biceps femoris muscle. J Strength
Cond Res 22: 809–817, 2008.
21. Johagen SG, Nemeth G, Eriksson E. Hamstring injuries in sprinters: The role of concentric and eccentric strength
. Am J Sports Med 22: 262–266, 1994.
22. Kokkonen J, Nelson AG, Cornwell A. Acute muscle stretching inhibits maximal strength
performance. Res Q Exerc Sport 69: 411–415, 1998.
23. Marek SM, Cramer JT, Fincher AL, Massey LL, Dangelmaier SM, Purkayastha S, Fitz KA, Culbertson JY. Acute effects of static and proprioceptive neuromuscular facilitation stretching on muscle strength
output. J Athletic Train 40: 94–103, 2005.
24. Nelson AG, Guillory IK, Cornwell A, Kokkonen J. Inhibition of maximal voluntary isokinetic
torque production following stretching is velocity-specific. J Strength
Cond Res 15: 241–246, 2001.
25. Nelson AG, Kokkonen J. Acute ballistic muscle stretching inhibits maximal strength
performance. Res Q Exerc Sport 72: 415–419, 2001.
K, Behm D, Cahill F, Carroll M, Young W. An acute bout of static stretching: effects on force
and jumping performance. Med Sci Sports Exerc 36: 1389–1396, 2004.
27. Robbins JW, Scheuermann BR. Varying amounts of acute static stretching and its effect on vertical jump performance. J Strength
Cond Res 22: 781–786, 2008.
28. Safran MR, Seaber AV, Garrett WE. Warm-up and muscular injury prevention: An update. Sports Med 8: 239–249, 1989.
29. Sahrmann SA. Diagnosis and Treatment of Movement Impairment Syndromes. St Louis, MI: Mosby, 2002.
30. Shrier I. Stretching before exercise does not reduce the risk of injury: A critical review of the clinical and basic scientific literature. Clin J Sports Med 9: 221–227, 1999.
31. Siatras TA, Mittas VP, Mameletzi DN, Eystroatios AV. The duration of the inhibitory effects with static stretching on quadriceps peak torque production. J Strength
Cond Res 22: 40–46, 2008.
32. Sobolewski EJ, Wagner DR, Bressel E. Effect of static stretching and jogging on knee extension isokinetic
peak torque. Isokinet Exerc Sci 19: 157–162, 2011.
33. Vujnovich AL, Dawson NJ. The effect of therapeutic muscle stretch on neural processing. J Orthop Sports Phys Ther 20: 145–153, 1994.
34. White SG, Sahrmann SA. A movement system balance approach to management of musculoskeletal pain. In: Physical Therapy of the Cervical and Thoracic Spine. Grant R, ed. New York, NY: Churchill Livingstone, 1994. pp. 339–357.
35. Winters MV, Blake CG, Trost JS, Marcello-Brinker TB, Lowe L, Garber MB, Wainner RS. Passive versus active stretching of the hip flexor muscles in subjects with limited hip extension: A randomized clinical trial. Phys Ther 84: 800–807, 2004.
36. Wordell TW, Smith TL, Winegardner J. Effect of hamstring stretching on hamstring performance. J Sport Phys Ther 20: 154–159, 1994.
37. Young W, Elliot 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.
38. Young W, MacDonald CH, Heggen T, Fitzpatrick J. An evaluation of the specificity, validity and reliability of jumping tests. J Sports Med Phys Fitness 37: 240–245, 1997.
39. Zakas A, Doganis G, Papakonstandinou V, Sentelidis T, Vamvakoudis E. Acute effects of static stretching duration on isokinetic
peak torque production of soccer players. J Bodywork Mov Ther 10: 89–95, 2006.