BEFORE DOING PHYSICAL EXERCISE ... TO STRETCH OR NOT TO STRETCH? ... THAT IS THE QUESTION

The static stretching is held in a stretch of the muscle at rest until a certain position and maintaining the position for 15 - 30 seconds. It is commonly practiced by athletes as part of a routine prior to exercise and as part of a continuous exercise program.

Every weekend I can see that, before a race, a lot of athletes do this type of stretching, which makes me think if I should imitate them or not. With this article I want to scientifically verify if static stretches before physical exercise fulfill the benefits that most people believe they have:

· Improve flexibility,
· Improve physical performance and / or,
· Prevent injuries in the musculotendinous unit.

FLEXIBILITY

There is consistent evidence that static stretching increases flexibility in the short term, although gains in flexibility decrease relatively quickly, so that they are lost in 30 minutes 1-5. But there is also consistent evidence that stretches performed regularly over several weeks produce significant improvements in the range of motion ^6-11.

The mechanism of how this increase in range of motion occurs is subject to debate, which may be changes in neurophysiological factors (for example, changes in the tolerance to stretching) or mechanical factors (for example, viscoelastic changes).

Several studies have shown that static stretching does not change the mechanical properties of the musculotendinous unit ^10,12-18. This would suggest that the increase in range of motion is due to a greater tolerance to stretching, rather than to any mechanical alteration in the tissues.

In summary:
· Static stretching increases flexibility in both the short and long term.
· The mechanism through which static stretching achieves greater flexibility is still debatable. While a greater tolerance to stretching is likely and mechanical changes are very unlikely.

PHYSICAL PERFORMANCE

Effect on explosive strength, power and muscular performance.

Several recent reviews and meta-analyzes ^19-22 have agreed that, static stretching maintained for more than 45 seconds immediately before exercise:

· Influences negatively on maximum strength, power, explosive muscular performance (for example, jumping and running), balance and agility or,

· It has no effect on performance.

In other words, none of the reviews showed a beneficial effect of static stretching on explosive muscle performance.

Effect on endurance performance

The influence of stretching on activities such as running and cycling is less clear. A recent review 23 described how several studies ^24-27 show a negative influence, while others ^23,28-30 show no change in performance. Very few studies 60 report improvements in endurance performance after stretching.

In summary

· Stretching should be avoided for more than 45 seconds immediately prior to participation in activities where strength or power are important, since performance is likely to be reduced without any clear benefit to justify continued use.
· In endurance activities, stretching is difficult to justify immediately before participation, since performance can be reduced without clear benefits that justify continued use.

INJURY PREVENTION

It seems intuitively to make sense that stretching should help prevent injuries or help speed up the return to activity. However, the relationship between the reference flexibility and the future risk of injury is complex, and many studies ^31,32 show that there is no relationship between the two.

In fact, several systematic reviews have evaluated the effect of stretching on the risk of injury ^33-35, concluding that:

- "There is insufficient evidence to support or interrupt routine stretching before or after exercise to avoid injury among competitive or recreational athletes" ³³ and

- "In light of these findings, routine stretching exercises before the start of sports activities are not a proven and effective method to reduce injury rates" ³⁶.

In summary:

· Static stretching does not seem to reduce the risk of injury.

CLINICAL IMPLICATIONS

It is difficult to justify the use of stretching for any of the objectives examined in this article:

· Flexibility: stretching is very effective both in the short and long term. However, flexibility is not as important a factor in performance and injury prevention as was previously thought.

· Short term performance: stretching can decrease performance, especially when performed immediately before explosive activities.

· Injury prevention: there is very little evidence that stretching is effective.

Therefore, the only area in which static stretching seems to offer a specific advantage is in the one with the greatest flexibility. There may be times when the most important goal is to improve flexibility (for example, ballet) by being only in these isolated circumstances in which static stretching may be justifiable.

BIBLIOGRAPHY

1.            de Weijer VC, Gorniak GC, Shamus E. The effect of static stretch and warm-up exercise on hamstring length over the course of 24 hours. J Orthop Sports Phys Ther 2003; 33:727-733.

2.            DePino G, Webright W, Arnold B, Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol. J Athl Train 2 2000; 35:56-59.

3.            Spernoga SG, Uhl TL, Arnold BL, Gansneder BM. Duration of maintained hamstring flexibility after a one-time, modified hold-relax stretching protocol. J Athl Train 2001; 36:44-48.

4.            Ford P, McChesney J. Duration of maintained hamstring ROM following termination of three stretching protocols. J Sport Rehabil 2007; 16:18-27.

5.            O'Sullivan K, Murray E, Sainsbury D. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects. BMC Musculoskelet Disord 2009; 10:37.

6.            Harvey L, Herbert R, Crosbie J. Does stretching induce lasting increases in joint ROM? A systematic review. Physiother Res Int2002; 7:1-13.

7.            Radford JA, Burns J, Buchbinder R, Landorf KB, Cook C. Does stretching increase ankle dorsiflexion range of motion? A systematic review. Br J Sports Med 2006; 40:870-875.

8.            Bandy WD, Irion JM, Briggler M. The effect of static stretch and dynamic range of motion training on the flexibility of the hamstring muscles. J Orthop Sports Phys Ther 1998; 27:295-300.

9.          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 2001; 11:81-86.

10.          Reid DA, McNair PJ. Passive force, angle, and stiffness changes after stretching of hamstring muscles. Med Sci Sports Exerc 2004; 36:1944-1948.

11.          Decoster LC, Cleland J, Altieri C, Russell P. The effects of hamstring stretching on range of motion: a systematic literature review. J Orthop Sports Phys Ther 2005; 35:377-387.

12.          Halbertsma JP, Goeken LN. Stretching exercises: effect on passive extensibility and stiffness in short hamstrings of healthy subjects. Arch Phys Med Rehabil 1994; 75:976-981.

13.          Klinge K, Magnusson SP, Simonsen EB, Aagaard P, Klausen K, Kjaer M. The effect of strength and flexibility training on skeletal muscle electromyographic activity, stiffness, and viscoelastic stress relaxation response. Am J Sports Med 1997; 25:710-716.

14.          Magnusson SP, Simonsen EB, Aagaard P, Boesen J, Johannsen F, Kjaer M. Determinants of musculoskeletal flexibility: viscoelastic properties, cross‐sectional area, EMG and stretch tolerance. Scand J Med Sci Sports 1997; 7:195-202.

15.          Gajdosik RL, Allred JD, Gabbert HL, Sonsteng BA. A stretching program increases the dynamic passive length and passive resistive properties of the calf muscle-tendon unit of unconditioned younger women. Eur J Appl Physiol 2007; 99:449-454.

16.          Weppler CH, Magnusson SP. Increasing muscle extensibility: a matter of increasing length or modifying sensation? Phys Ther 2010; 90:438-449.

17.          Konrad A, Gad M, Tilp M. Effect of PNF stretching training on the properties of human muscle and tendon structures. Scand J Med Sci Sports 2014.

18.          Ben M, Harvey L. Regular stretch does not increase muscle extensibility: a randomized controlled trial. Scand J Med Sci Sports 2010; 20:136-144.

19.          Behm D, Bambury A, Farrel C, Power K. Effect of acute static stretching on force, balance, reaction time, and movement time. Med Sci Sports Exerc 2004; 36:1397-1402.

20.          Kay AD, Blazevich AJ. Effect of acute static stretch on maximal muscle performance: a systematic review. Med Sci Sports Exerc 2012; 44:154-164.

21.          Simic L, Sarabon N, Markovic G. Does pre‐exercise static stretching inhibit maximal muscular performance? A meta‐analytical review. Scand J Med Sci Sports 2013; 23:131-148.

22.          Winchester JB, Nelson AG, Landin D, Young MA, Schexnayder IC. Static stretching impairs sprint performance in collegiate track and field athletes. J Strength Cond Res 2008; 22:13-18.

23.          Peck E, Chomko G, Gaz DV, Farrell AM. The effects of stretching on performance. Curr Sports Med Rep 2014; 13:179-185.

24.          Wilson JM, Hornbuckle LM, Kim JS, Ugrinowitsch C, Lee S-R, Zourdos MC, et al. Effects of static stretching on energy cost and running endurance performance. J Strength Cond Res 2010; 24:2274-2279.

25.          Lowery RP, Joy JM, Brown LE, Oliveira de Souza E, Wistocki DR, Davis GS, et al. Effects of static stretching on 1-mile uphill run performance. J Strength Cond Res 2014; 28:161-167.

26.          Wolfe AE, Brown LE, Coburn JW, Kersey RD, Bottaro M. Time course of the effects of static stretching on cycling economy. J Strength Cond Res 2011; 25:2980-2984.

27.          Esposito F, Cè E, Limonta E. Cycling efficiency and time to exhaustion are reduced after acute passive stretching administration. Scand J Med Sci Sports 2012; 22:737-745.

28.          Mojock CD, Kim JS, Eccles DW, Panton LB. The effects of static stretching on running economy and endurance performance in female distance runners during treadmill running. J Strength Cond Res 2011; 25:2170-2176.

29.          Hayes PR, Walker A. Pre-exercise stretching does not impact upon running economy. J Strength Cond Res 2007; 21:1227-1232.

30.          Allison SJ, Bailey DM, Folland JP. Prolonged static stretching does not influence running economy despite changes in neuromuscular function. J Sports Sci 2008; 26:1489-1495.

31.          Bennell K, Tully E, Harvey N. Does the toe-touch test predict hamstring injury in Australian Rules footballers? Aust J Physiother 1999; 45:103-109.

32.          Wang HK, Chen CH, Shiang TY, Jan MH, Lin KH. Risk-factor analysis of high school basketball–player ankle injuries: a prospective controlled cohort study evaluating postural sway, ankle strength, and flexibility. Arch Phys Med Rehabil 2006; 87:821-825.

33.          Thacker SB, Gilchrist J, Stroup DF, Kimsey CJ. The impact of stretching on sports injury risk: a systematic review of the literature. Med Sci Sports Exerc 2004; 36:371-378.

34.          Herbert RD, Gabriel M. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. BMJ 2002; 325:468.

35.          Shrier I. Does stretching improve performance? A systematic and critical review of the literature. Clin J Sport Med 2004; 14:267-273.

36.          Schiff MA, Caine DJ, O'Halloran R. Injury prevention in sports. Am J Lifestyle Med 2010; 4:42-64.

stretch

stretch before or after exercise