Is Stretching Worth It? The Classic Debate
Current research has not proven whether stretching helps improve performance or reduce injury. Why? Today we're covering the problem behind current evidence, how stretching affects performance and injury, and conclusions we can draw from the evidence.
THE PROBLEM
McHugh & Cosgrave (2010) show that current research is ambiguous for the following three reasons:- No RCT with 4 specific groups: (1) stretching alone (2) warm-up alone (3) stretching with warm-up (4) control
- No optimal stretching routine (intensity, frequency, duration)
- Few studies examining the different types of stretching (dynamic, active, passive, PNF, ballistic) in combination with warm-up and their relationship to performance and injury
There are nine different possible ways stretching affects performance and injury. Stretching can improve, do nothing, or decrease performance. Stretching can reduce, do nothing, increase injury rates, or do any combination of the above. A review of the literature yields a mixed bag of results.
HOW STRETCHING AFFECTS PERFORMANCE
Stretching can either increase, do nothing, or decrease performance. Stretching has two effects on the body: viscoelastic and neural. Viscoelastic effects include changes to range of motion and resistance to stretching. Neural effects include decreased motor neuron excitability and muscle contractions (Guissard et al., 1988; Magnusson et al., 1995).
Stretching may reduce maximal strength. Stretch-induced strength loss is determined by stretching technique, type of contraction, and the length of the muscle being measured. Several studies have shown that stretch-induced strength loss is a neural effect with decreased EMG amplitude measured during MVC after stretching (Avela et al., 1999, 2004). However, the type of stretching matters. Herda et al. (2008) found dynamic stretching produced no stretch-induced strength loss.
Furthermore, the loss of strength is typically greater than the reduction in performance. Reviewing 36 studies, McHugh & Cosgrave (2010) found that the average stretch-induced strength loss was 22% for 30-60 minute stretching times. Conversely, the average stretch-induced decreases in performance were only 3-4% for the vertical jump and 0-2% for sprint speed. Stretching may reduce strength and decrease performance to a far lesser degree.
Stretching may reduce maximal strength. Stretch-induced strength loss is determined by stretching technique, type of contraction, and the length of the muscle being measured. Several studies have shown that stretch-induced strength loss is a neural effect with decreased EMG amplitude measured during MVC after stretching (Avela et al., 1999, 2004). However, the type of stretching matters. Herda et al. (2008) found dynamic stretching produced no stretch-induced strength loss.
Furthermore, the loss of strength is typically greater than the reduction in performance. Reviewing 36 studies, McHugh & Cosgrave (2010) found that the average stretch-induced strength loss was 22% for 30-60 minute stretching times. Conversely, the average stretch-induced decreases in performance were only 3-4% for the vertical jump and 0-2% for sprint speed. Stretching may reduce strength and decrease performance to a far lesser degree.
HOW STRETCHING AFFECTS INJURY
Stretching can either increase, do nothing to, or reduce rates of injury. McHugh & Cosgrave (2010) theorize that stretching may reduce incidents of muscle strain because a stretched muscle can resist excessive muscle elongation. The scientific literature is ambiguous, most likely because the type of stretching (intensity, frequency, and duration) widely varies between studies. The optimal stretching routine to avoid injury has yet to be discovered.
Three specific studies found that stretching did not affect injury rates (van Mechelen et al., 1993; Pope et al., 1998, 2000). A major shortcoming of these studies is the duration of the stretching routine. Prolonged decreases in passive resistance to stretching are the result of routines that are at least 5-6 minutes in length rather than the 1-2 minutes that were used in the three studies mentioned above (Ryan et al., 2008).
Four specific studies found that stretching when compared to a control group greatly reduced rates of muscle strains (Ekstrand et al., 1983; Bixler & Jones, 1992; Amako et al., 2003; Hadala & Barrios, 2009).
Preparticipation stretching may help reduce specific muscle strain injuries. When studies used longer stretching times (i.e > 5 minutes) the risk of muscle strain was far less in the groups that stretched before exercise than in the groups that did not.
Three specific studies found that stretching did not affect injury rates (van Mechelen et al., 1993; Pope et al., 1998, 2000). A major shortcoming of these studies is the duration of the stretching routine. Prolonged decreases in passive resistance to stretching are the result of routines that are at least 5-6 minutes in length rather than the 1-2 minutes that were used in the three studies mentioned above (Ryan et al., 2008).
Four specific studies found that stretching when compared to a control group greatly reduced rates of muscle strains (Ekstrand et al., 1983; Bixler & Jones, 1992; Amako et al., 2003; Hadala & Barrios, 2009).
- 23 injuries in control, 6 in intervention (Ekstrand et al., 1983)
- 13 injuries in control, 1 in intervention (Bixler & Jones, 1992)
- 16 injuries in control, 7 in intervention (Amako et al., 2003)
- 22 injuries in control, 4 in intervention (Hadala & Barrios, 2009)
CONCLUSION
McHugh & Cosgrave (2010) observe preparticipation stretching reduces maximal force. However, the reduction in force may be less or even nonexistent when stretching is combined with a dynamic warmup. Additionally, the decreases in strength may be greater than any decrease in performance.Preparticipation stretching may help reduce specific muscle strain injuries. When studies used longer stretching times (i.e > 5 minutes) the risk of muscle strain was far less in the groups that stretched before exercise than in the groups that did not.
These findings are far from conclusive due to the difficulty in isolating the effects of stretching, the lack of knowledge about optimal stretching routines, and the difficulty of tracking participant adherence over time.
BOTTOM LINE: Stretching may reduce strength but from the available data it appears it either has a very small negative effect on performance or no effect at all. Stretching may help prevent muscle strains during certain activities when the total duration of stretching is ≥ 5 minutes.
RESOURCES
RESOURCES
Amako M, Oda T, Masuoka K, Yokoi H, Campisi P. Effect of static stretching on prevention of injuries for military recruits. Mil Med 2003: 168: 442–446.
Avela J, Finni T, Liikavainio T, Niemela E, Komi PV. Neural and mechanical responses of the triceps surae muscle group after 1 h of repeated fast passive stretches. J Appl Physiol 2004: 96: 2325–2332.
Avela J, Kyro ̈ la ̈ inen H, Komi PV. Altered reflex sensitivity after repeated and prolonged passive muscle stretching. J Appl Physiol 1999: 86: 1283–1291.
Hadala M, Barrios C. Different strategies for sports injury prevention in an America’s Cup Yachting Crew. Med Sci Sports Exerc 2009: 41: 1587–1596.
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 2008: 22: 809–817.
Bixler B, Jones RL. High-school football injuries: effects of a post-halftime arm- up and stretching routine. Fam Pract Res J 1992: 12(2): 131–139.
Ekstrand J, Gillquist J, Liljedahl SO. Prevention of soccer injuries. Supervision by doctor and physiotherapist. Am J Sports Med 1983: 11: 116–120.
Guissard N, Duchateau J, Hainaut K. Muscle stretching and motoneuron excitability. Eur J Appl Physiol Occup Physiol 1988: 58: 47–52.
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 2008: 22: 809–817.
Magnusson SP, Simonsen EB, Aagaard P, Kjaer M. Biomechanical responses to repeated stretches in human hamstring muscle in vivo. Am J Sports Med 1996a: 24(5): 622–628.
McHugh, M. P., & Cosgrave, C. H. (2010). To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian journal of medicine & science in sports, 20(2), 169-181.
Pope R, Herbert R, Kirwan J. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Aust J Physiother 1998: 44: 165–172.
Pope RP, Herbert RD, Kirwan JD, Graham BJ. A randomized trial of pre-exercise stretching for prevention of lower-limb injury. Med Sci Sports Exerc 2000: 32: 271–277.
Ryan ED, Beck TW, Herda TJ, Hull HR, Hartman MJ, Stout JR, Cramer JT. Do practical durations of stretching alter muscle strength? A dose-response study. Med Sci Sports Exerc 2008b: 40: 1529–1537.
van Mechelen W, Hlobil H, Kemper HC, Voorn WJ, de Jongh HR. Prevention of running injuries by warm-up, cool-down, and stretching exercises. Am J Sports Med 1993: 21: 711–719.
Avela J, Finni T, Liikavainio T, Niemela E, Komi PV. Neural and mechanical responses of the triceps surae muscle group after 1 h of repeated fast passive stretches. J Appl Physiol 2004: 96: 2325–2332.
Avela J, Kyro ̈ la ̈ inen H, Komi PV. Altered reflex sensitivity after repeated and prolonged passive muscle stretching. J Appl Physiol 1999: 86: 1283–1291.
Hadala M, Barrios C. Different strategies for sports injury prevention in an America’s Cup Yachting Crew. Med Sci Sports Exerc 2009: 41: 1587–1596.
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 2008: 22: 809–817.
Bixler B, Jones RL. High-school football injuries: effects of a post-halftime arm- up and stretching routine. Fam Pract Res J 1992: 12(2): 131–139.
Ekstrand J, Gillquist J, Liljedahl SO. Prevention of soccer injuries. Supervision by doctor and physiotherapist. Am J Sports Med 1983: 11: 116–120.
Guissard N, Duchateau J, Hainaut K. Muscle stretching and motoneuron excitability. Eur J Appl Physiol Occup Physiol 1988: 58: 47–52.
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 2008: 22: 809–817.
Magnusson SP, Simonsen EB, Aagaard P, Kjaer M. Biomechanical responses to repeated stretches in human hamstring muscle in vivo. Am J Sports Med 1996a: 24(5): 622–628.
McHugh, M. P., & Cosgrave, C. H. (2010). To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian journal of medicine & science in sports, 20(2), 169-181.
Pope R, Herbert R, Kirwan J. Effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Aust J Physiother 1998: 44: 165–172.
Pope RP, Herbert RD, Kirwan JD, Graham BJ. A randomized trial of pre-exercise stretching for prevention of lower-limb injury. Med Sci Sports Exerc 2000: 32: 271–277.
Ryan ED, Beck TW, Herda TJ, Hull HR, Hartman MJ, Stout JR, Cramer JT. Do practical durations of stretching alter muscle strength? A dose-response study. Med Sci Sports Exerc 2008b: 40: 1529–1537.
van Mechelen W, Hlobil H, Kemper HC, Voorn WJ, de Jongh HR. Prevention of running injuries by warm-up, cool-down, and stretching exercises. Am J Sports Med 1993: 21: 711–719.
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