Stephen B. Thacker, Julie Gilchrist, Donna F. Stroup, C.Dexter Kimsey, Jr.
Epidemiology Program Office, National Center for Injury Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta
Some investigators have questioned the routine practice of stretching and contend that there is little evidence that stretching pre-or post participation prevents injury and that it might affect performance negatively.
A recent systematic review concluded that hte best available evidence indicates that stretching before or after exercise does not prevent muscle soreness or injury and that there is insufficient evidence to assess effect on performance.
There are several methods of stretching to increase flexibility including passive, static, isometric, ballistic, and proprioceptive neuromuscular facilitation (PNF).
Although stretching before activity might improve performance for some sports that require an increased range of motion (e.g., gymnastics or swimming), increased flexibility might compromise muscle performance for up o 1h.
Literature reviews and analytic studies concerning injuriy enumerate many risk factors such age, extremes in body, mass index, etc...
Close examination, of these studies, howevery finds that stretching has not been shown to prevent injury.
Stretching to improve flexibility
Alternative methods of stretching, including passive stretching, static stretching, ballistic stretching, isometric contractions, and PNF, have been compared for their effects on flexibility.
Stretching was demonstrated to increased joint flexibility about the knee (including hamstring/quadriceps muscles), hip, trunk and shoulder and ankle joints (soleus/gastrocnemius muscles). Although there is evidence that PNF stretching is more effective in improving flexibility, this has not been demonstrated consistently.
A 15s or 30s passive stretch is more effective thar shorter duration stretches and as effective as stretches of longer duration. Passive stretching is more effective than dynamic stretching of the hamstring, although no diference was found in active versus passive stretching of the hip joint.
Adverse effects of stretching/flexibility
Recent studies of passive stretching shows significant adverse effects on jump performance and plantar flexion. Increased flexibility decreases running economy and peak performance, but these findings are not consistent and there is some evidence that increased flexibility enhances performance.
Warm-up to prevent injury
Warm-up together with stretching increases the flexibility of the ankle, hip, and knee joints but has not been shown to prevent muscle soreness.
Several programs that combine warm-up, strenght, and balance training with stretching have demonstrated effectiveness in the prevention of knee and ankle injuries, but the independent effects of warm-up and stretching were not determined.
A positive attitude toward warm-up was associated with a significant improvement in performance.
Risk factors for injury
Questionnaire surveys and/or personal logs of groups of runners and other athletes have asked about stretching and have shown either no association with injury, no protective effective, or no increased injury rates.
But in order studies, stretching before or after exercise had no effect in the prevention of postexercise pain.
Recently, the President's Council for Physical Fitness and Sports reported that Stretching not only might not prevent injuries but also might compromise performance.
Stronger evidence demonstrates that various approaches to conditioning that include warm-up and stretching along with other techinques, such as strenght training, plyometrics, and proprioception training both enhance performance and prevent certain kinds of injury. This suggests that strenght training, conditioning, and warm-up play an important role in injury prevention. In addition, stretching of specific muscles and joints for specific activities might enhance the effectiveness of these other preexercise activities, an approach consistent with a multifactorial model for prevention. At the same time, there might also be a risk of injury and impaired performance associated with a stretching without adequate conditioning and/or warm-up.
Some have argued that warm-up is more important than stretching in the prevention of injuries in sports.
Based on this review, we can recommend neither the endorsement not the discontinuation of stretching, which has been a basic tenet of preparation for athletic participation. The evidence demonstrates that stretching clearly increases flexibility and, to the degree that flexibility might benefit performance or decrease the risk of injury, stretching might be desirable. It is also evident that strenght training conditioning, and warm-up have an important role in injury prevention, and we suggest that when stretching is done, it should be conducted in the context of adequate conditioning and appropriate warm-up.
In conclusion, there is not sufficient evidence to endorse or discontinue routine pre-or postevent stretching to prevent injury among competitive or recreational athletes. Better research is needed to determine the proper role of stretching in sports, especially as there are increasing numbers of athletes and growing recognition that all people need to increase their physical activity to improve their health and quality of life.
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