"Stretching" The Truth
By Roy Stevenson
Stretching has always been considered a staple part of the sportsman’s and exerciser’s preparation and training program. Strident claims that it improves performance and reduces chance of injury have been made since the fitness boom started in the 1970’s. Other benefits are purported to be reducing post-competitive or post-training muscle soreness, relief of low back pain, to counteract muscle imbalances, and to relieve muscle cramps.
Yet, in the past 10 years, the relevance of stretching for these purposes has been challenged by exercise scientists--especially since one bombshell study found runners who stretched occasionally have a higher injury rate than runners who don’t stretch at all.
Another research paper got coaches’ attention when it showed overstretching is the third major cause of injuries to distance runners. Nevertheless, personal trainers, athletic trainers, physical therapists and coaches continue to recommend stretching, at least for rehabilitation and warm-up purposes, so the debate rages to this day.
The questions raised by new studies have triggered a truckload of research on the subject. As I write this I have a 3-inch thick stack of research papers sitting in front of me on the efficacy of stretching for performance improvement, reduced injury, reduction of muscle soreness, etc.
What the Experts Say
Most of the fitness gurus who’ve written books support stretching in rather general terms--even exercise physiology textbooks make similar claims. Given that authors have a certain amount of license to write what they think Vs what researchers find, let’s see what the exercise scientists have proven about this practice.
Here are twenty-four summaries and conclusions from over 20 different research papers published in respected and reputable research journals.
As you’ll see from scanning these tables the research on benefits are contradictory at the very best, many unfavorable. In particular, pay attention to the tables summarizing research against stretching — they’re eye-openers.
Stretching: Flexibility and Injury
What Research Shows about the Relationship between Flexibility and Injury Reduction—Conflicting Evidence
Research/Arguments in favor of Stretching for Injury Prevention
20. Improving flexibility through stretching is another important preparatory activity that has been advocated to improve physical performance.
20. Experts in the field of training and conditioning agree that good flexibility is essential to successful physical performance, although their ideas are based primarily on empirical rather than experimental evidence.
20. Maintaining good flexibility aids in the prevention of injuries to the musculoskeletal system.
8. Current sport research shows improving flexibility or increasing joint ROM is significant in its contribution to movement efficiency, amplitude of movement, and prevention of soft tissue injury.
20. Athletic trainers and physical therapists feel that maintaining good flexibility is important in prevention of injury to the musculotendinous unit.
4. Our statistical analysis indicates an association between the incorporation of a static stretching program and a decreased incidence of musculotendinous strains in Division III college football players.
Inconclusive Research for Stretching and Injury Prevention
6. No conclusive statements can be made about the relationship of flexibility to athletic injury.
20. Due to the paucity, heterogeneity and poor quality of the available studies no definitive conclusions can be drawn as to the value of stretching for reducing the risk of exercise-related injury.
18. There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes. Further research is urgently needed.
1. Static stretching decreased the incidence of muscle-related injuries but did not prevent bone or joint injuries.
Research against Stretching for Injury Prevention
6. In summary, we see no strong evidence proving that flexibility or stretching is associated with rates of strains, sprains, or overuse injuries that can be applied across all sports or levels of competition.
16. New evidence suggests that stretching immediately before exercise does not prevent overuse or acute injuries.
19. This intervention was not effective in reducing the number of running injuries.
9. There was no significant effect of pre-exercise stretching on all-injuries risk rate between the stretch group and the control group.
9. A typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits.
10. Injured runners were more likely to have stretched before running.
12. Although stretching to increase flexibility is widely recommended to prevent training injuries, data to support the practice are lacking. Our data indicate that both the most flexible and least flexible individuals are at higher risk of lower body injuries. Subjects in the least flexible and most flexible quintiles were 2.5 and 2.2 times more likely to get injured than subjects in the middle quintile.
2. The results of this review do not support the role of pre-exercise or postexercise stretching as an intervention addressing postexercise muscle soreness. In addition, the evidence presented in this review does not support the role of pre-exercise stretching in the reduction of lower extremity injury risk.
Stretching for Flexibility and Performance
What Research Shows about the Relationship between Flexibility and Performance—More Conflicting Evidence
Research/Arguments in favor of Stretching for Performance Improvement
7. Our results show that stretching may favorably influence the force-velocity relationship of the trained muscle as well as the shape of the torque curve during movements at a given velocity.
17. Regular stretching improves force, jump height, and speed, although there is no evidence that it improves running economy.
Research against Stretching for Performance Improvement
11. Greater flexibility may impair performance in sports that do not require a high degree of flexibility such as running. Runners with less flexibility are actually more efficient at running.
5. Intense static stretching may reduce maximum force production. The loss of voluntary strength and muscular power may last up to one hour after the static stretch.
3. Based on these results, performing stretching before a vertical jump test would be detrimental to performance.
13. Observations by coaches and athletes have called into question the universal prescription of stretching for the purpose of enhancing sport performance, and this skepticism is being supported by the growing body of empirical data.
Certainly many of these conclusions in the “against” columns, if true, are of concern to the personal trainer. The potential implications that (a) athletes are getting injured from stretching, (b) sportsmen who stretch seem to have a higher incidence of injury, (c) stretching may actually cause loss of muscular power and force production, (d) stretching does not appear to improve running economy, and (e) runners with increased range of motion may have impaired performance are undesirable outcomes for exercisers, athletes, or runners of any level.
What appears to be at the crux of the matter, according to researchers who venture an opinion is that, “When the type of sports activity contains low-intensity, or limited stretch shortening cycles (e.g. jogging, cycling and swimming) it is not necessary to have a very compliant muscle-tendon unit”(15).
This is because most of its power generation is derived from active (contractile) muscle work that is directly transferred (by the tendon) to the articular system to generate forward motion. Therefore, stretching (and thus making the tendon more compliant) may not be advantageous.
Thus it appears a lot of the purported benefits of stretching and improved flexibility may depend entirely on the nature of the sport or activity you compete in. And this may well have implications for the fitness and weight-training aficionado working out several times a week, who delights in pushing him or her-self as if they were athletes.
The evidence that static stretching before resistance training may affect one’s ability to use explosive power (because it causes the muscles to lose energy stored in its elastic tissue), is at least enough to make one reconsider the necessity of stretching before lifting weights.
Perhaps one researcher is close to the truth with this conjecture; “While increased flexibility is important for performance in some sports that rely on extremes of motion for movement, decreased flexibility may actually increase economy of movement in sports that only use the mid portion of range of motion such as running” (15).
So where does this leave the fitness buff or exerciser who is following a flexibility program now, or contemplating taking up a stretching program?
Perhaps common sense should help dictate whether we should recommend stretching, and how much we should stretch. Here’s what I mean. If your clients or athletes have been stretching and remain uninjured, then by all means continue with the stretching program. If they’ve been stretching consistently and getting injured consistently perhaps you should have them back off the stretching or reduce its intensity.
Proceed with Caution
Practical Advice
If your clients are contemplating starting up a stretching program, proceed with caution because it may not be the best thing for them, depending on why they’re exercising. Here’s some practical advice for start-up stretchers in the fitness club setting.
First, avoid overstretching—there are enough studies showing stretching may cause injuries or make you more prone to getting injured.
Second, warm-up before stretching with 5-10 minutes of easy aerobic activity. e.g. treadmill, bike, elliptical trainer, etc. And recent research shows you’re better off doing some easy stretches at the end of your workout, rather than in your warm-up before your training session.
Third, always stretch within your limits--without straining. Do not force your stretch to the point of pain! Straining at a painful stretch will not allow you to relax because if activates your stretch reflexes, exactly what you are trying to override. Perhaps this is why some studies show impaired performance and loss of muscular power from stretching.
Fourth, it’s probably not necessary to stretch every day, but 3-4 times each week will show an improvement in range of motion. But again, be warned, you might just get what you want—increased range of motion, which may reduce running, cycling or swimming economy, if those happen to be your client’s favorite activities.
Other Advice
You should be able to hold the stretch for 5-10 minutes. (You should not actually hold the stretch for this long, but the stretch should be mild enough to hold it this long). In light of the above studies, your clients are better off doing a few easy static stretching exercises for 10-30 seconds each, rather than a lengthy session.
It will takes a minimum of 2 weeks to 8 weeks for long-term improvements in your flexibility. Your short-term flexibility increases after stretching will last from 90 minutes up to 24 hours, according to research. But if you stop stretching, you’ll start to lose your newly gained flexibility in about 4 weeks.
Breathe calmly and relax when stretching. Avoid comparing your flexibility with other people. Develop a liking and routine for stretching.
What Regions Should be Stretched in a Warm-Up or Cool-Down?
Shoulders, chest, and arms can all be stretched with one or two common stretches.
Hip flexors and abdominals can be stretched with two common stretches.
The back, gluteals and hamstrings can be stretched with a few common stretches.
Stretch the quadriceps and calf with separate stretches.
Avoid these stretches: hurdler stretch, deep knee bend, standing toe touch, back arch and bridge, standing torso twist with broomstick, and Yoga plow.
It seems ironic that a sports technique that is now widely practiced was used, several centuries ago, as a technique to make hapless victims confess to crimes, clear up contradictory statements, discover other crimes for which they might be guilty, or to purge them of infamy. I’m referring here, of course, to the torture method of stretching on the dreaded rack.
Stretching may be appropriate for certain activities and sports that are performed through a wide range of motion, but we may want to reexamine its use for repetitive and rhythmic sports that involve a shorter range of motion.
References
1. Amako, M., T Oda, K Masuoka, H Yokoi and P Campisi (2003) Dept of Orthopedic Surgery, Japan Self-Defense Force Beppu Hospital, Effect of static stretching on prevention of injuries for military recruits. Military Medicine, June; 168(6): 442-6.
2. Andersen, J.C. Stretching Before and Afterv Exercise: effect on Muscle Soreness and Injury Risk (2005) Journal Athletic Training, Jul-Sep. 40(3); 218-220.
3. Church, J. Brian., Matthew S. Wiggins, F. Michael Moode, and Randall Crist. (2001) Effect of Warm-Up and Flexibility Treatments on Vertical Jump Performance, Journal of Strength and conditioning Research, 15 (3) 332-336.
4. Cross, Kevin M., Med, ATC and Ted W. Worrell, EdD, PT, ATC (1999) Effects of a Static Stretching Program on the incidence of Lower extremity Musculotendinous Strains, Journal Athletic Training, Jan-Mar; 34 (1): 11-14.
5. Evetovich, TK., NJ Nauman, DS Conley, JB Todd. Effect of static stretching of the biceps brachii on torque, electromyography, and mechanmyography during concentric isokinetic muscle actions, Journal Strength Conditioning Research. 17(3) pp 484-8.
6. Glein, Gilbert W. and Malachy P. McHugh (1997) Flexibility and Its Effects on Sports Injury and Performance, Sports Medicine, November. P. 289-299.
7. Handel, M, T., Horstmann, H. Dickhuth, R.W. Gulch. (1997) Effects of contract-relax stretching training on muscle performance in athletes, European Journal Applied physiology (1997) 76: 400-408.
8. Hartley-O’Brien, Sandra J (1980) University of British Columbia, Research Quarterly for Exercise and Sport. Vol.51, No.4, pp 625-635.
9. Herbert, RD, and Gabriel M (2002) Effects of stretching before and after exercise on muscle soreness and risk of injury: systematic review, BMJ. 325:468.
10. Jacobs, Stephen J., Md, and Burton L. Berson, MD. (1986) Injuries to runners: A study of entrants to a 10,000 meter race, The American Journal of Sports Medicine. Vol. 14, No. 2.
11. Jones, AM. Running economy is negatively related to sit-and-reach test performance in international-standard distance runners, International Journal Sports Medicine. 23 (10 40-3.
12. Jones, Bruce H., David N. Cowan, J.Pitt Tomlinson, John R. Robinson, David W. Polly, and Peter N.Frykman (1993) Epidemiology of injuries associated with physical training among young men in the army, Medicine & Science in Sports & Exercise, Vol. 25, No. 2, pp 197-203.
13. Neal, Jeni R., and William A. Sands. Dept of Physical Education, Health and Recreation, Eastern Washington University (2006) Stretching for performance enhancement, Current Sports Medicine Reports, Volume 5, Number 3. Pages 141-146.
14. Pope, Rodney Peter., Robert Dale Herbert, John Dennis Kirwan, and Bruce James Graham (2000) A randomized trial of preexercise stretching for prevention of lower-limb injury. Medicine & Science in Sports & Exercise, Vol. 32 No.2, pp. 271-277.
15. Shellock, Frank G. and William E. Prentice. Warming-Up and Stretching for Improved Performance and prevention of Sports-Related Injuries, Sports Medicine 2: 267-278.
16. Shrier, Ian., MD, PhD and Kav Gossal, MD (2000) Myths and Truths of Stretching. The Physician and Sportsmedicine, Vol. 28 No.8 August.
17. Shrier, Ian. MD, PhD. Does Stretching improve Performance?: A Systematic and Critical review of the Literature. Clinial Journal Sports Medicine. 14(5): 267-273, September 2004.
18. Thacker, Stephen B., Julie Gilchrist, Donna Stroup, C. Dexter Kimsey (2004) The Impact of Stretching on Sports Injury Risk: A Systematic review of the Literature, Medicine & Science in Sports & Exercise, 36, (3): 371-378, March.
19. van Mechelen, Wilhelm., MD, PhD, Hynek Hlobil, MD, Han C. Kemper, PhD, WIM J. Voorn, PhD, and H. Rob de Jongh, PhD (1993) Prevention of running injuries by warm-up, cool-down, and stretching exercises, American Journal of Sport Medicine. Vol. 21, No.5.
20. Weldon, S. The efficacy of stretching for prevention of exercise-related injury: a systematic review of the literature, Manual Therapy, Volume 8, Issue 3, Page 141.
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