Stretching has always been considered a staple part of the triathlete’s preparation and training. Strident claims that it improves triathlon performance and reduces chance of injury have been made since the triathlon boom started in the 1980’s. Stretching, we’re told, reduces post-race or post-training muscle soreness, relieves low back pain, counteracts muscle imbalances and relieves 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 overstretching is the third major cause of injuries to distance runners.
Another research paper got coaches attention when it showed runners who stretched occasionally have a higher injury rate than runners who don’t stretch at all. Nevertheless, athletic trainers, physiotherapists and coaches continue to recommend stretching, at least for rehabilitation and warm-up purposes, so the debate rages to this day.
This ongoing question has triggered a truckload of research on the subject. As I write this I have a three-inch thick stack of research papers sitting in front of me on the efficacy of stretching for performance improvement, reduced injury, etc.
What the Experts Say
Most of the experts who’ve written books on running support stretching in rather general terms. Bob Glover and Pete Schuder in their book The Competitive Runner’s Handbook state, “Stretching increases your athletic ability and efficiency.” Hal Higdon in Marathon-The Ultimate Training and Racing Guide says, “Stretching and strengthening is another way to minimize injury.”
Given that authors have a certain amount of license to write what they think versus what researchers may believe, let’s see what the exercise scientists have proven about this practice.
Here are summaries and conclusions from 26 different research papers published in reputable research journals (See table at end of this article for the names of these journals). As you’ll see from scanning these tables, the research on benefits of stretching are contradictory, at the very best, and many are unfavorable. In particular, pay attention to the table summarizing research against stretching-it’s an eye-opener.
What Research Shows about the Relationship between Flexibility and Injury Reduction.
|Research/Arguments in favor of Stretching for Injury Prevention
|Improving flexibility through stretching is another important preparatory activity that has been advocated to improve physical performance.|
|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.|
|Maintaining good flexibility aids in the prevention of injuries to the musculoskeletal system.|
|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.|
|Athletic trainers and physical therapists feel that maintaining good flexibility is important in prevention of injury to the musculotendinous unit.|
|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
|No conclusive statements can be made about the relationship of flexibility to athletic injury.|
|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.|
|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.|
|Static stretching decreased the incidence of muscle-related injuries but did not prevent bone or joint injuries.|
|Research against Stretching for Injury Prevention
|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.|
|New evidence suggests that stretching immediately before exercise does not prevent overuse or acute injuries.|
|Incidence of injury was not significantly different for the experimental and control groups.|
|This intervention was not effective in reducing the number of running injuries.|
|There was no significant effect of pre-exercise stretching on injury risk rate between the stretch group and the control group.|
|A typical muscle stretching protocol performed during pre-exercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits.|
|In this study the number of lower extremity overuse injuries was significantly increased in infantry basic trainees with increased hamstring flexibility.|
|Injured runners were more likely to have stretched before running.|
|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.|
|The results of this review do not support the role of pre-exercise or post-exercise stretching as an intervention addressing post-exercise 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.|
What Research Shows about the Relationship between Flexibility and Performance.
|Research/Arguments in favor of Stretching for Performance Improvement|
|Our results show that stretching may favourably influence the force-velocity relationship of the trained muscle as well as the shape of the torque curve during movements at a given velocity.|
|Regular stretching improves force, jump height, and speed, although there is no evidence that it improves running economy.|
|Research against Stretching for Performance Improvement|
|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.|
|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.|
|Based on these results, performing stretching before a vertical jump test would be detrimental to performance.|
|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 the conclusions in the “against” columns, if true, are damning. After examining these tables, what is of concern to triathletes and runners are the potential implications that, (a) runners are getting injured from stretching, (b) runners who stretch seem to have a higher incidence of injury, (c) stretching does not appear to improve running economy, (d) runners with increased range of motion may have impaired performance, and (e) stretching may actually cause loss of muscular power. These are unsatisfactory outcomes for triathletes and runners of any level.
What appears to be at the crux of the matter, according to the 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.”
This is because most of the power generation for these activities 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.
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”.
So where does this leave the triathlete who is following a flexibility program now, or contemplating taking up a stretching program?
I believe we’ve now come to a point where the evidence has tilted towards the negative benefits of stretching for runners and cyclists. So, common sense should dictate whether we should stretch or not and how much we should stretch. Here’s what I mean. If you’ve been stretching and remain uninjured, then by all means continue your stretching program. If you’ve been stretching consistently, and getting injured consistently, perhaps you should back off the stretching or reduce its intensity.
If, however, you are contemplating starting up a stretching program, proceed with caution because it may not be the best thing for you. Here’s some practical advice for start-up stretchers:
1) Avoid overstretching-there are enough studies now showing stretching may cause injuries or make you more prone to getting injured.
2) Warm-up before you stretch with five to 10 minutes of easy aerobic activity (treadmill, bike, elliptical trainer, etc.). And recent research shows you may be better off doing some easy stretches at the end of your workout, rather than in your warm-up before running.
3) 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, and causes your muscles to contract.
4) It’s probably not necessary to stretch every day, but three to four times each week will show an improvement in your range of motion. But, again, be warned, you might just get what you want-increased range of motion that may reduce your running and cycling economy.
Other Stretching Advice
- You should be able to hold the stretch for five to10 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, you’d be better off doing a few easy static stretching exercises for 10 to 30 seconds each, rather than a lengthy session.
- It will take you from two to eight weeks for long-term improvements in your flexibility. Your short-term flexibility gains 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 four weeks.
- Breathe calmly and relax when you stretch and develop a liking and routine for stretching. Also, avoid comparing your flexibility with others.
What Regions Should you stretch in a Warm-Up?
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.
Roy Stevenson teaches exercise science at Seattle University in Washington State and has coached hundreds of serious and recreational runners and triathletes in the Seattle area.
He held the NZ under-20 marathon record in 1974 when he ran his first marathon in 2:42:28.