Should You Stretch to Grow?

Many recent studies have cast doubt on the value of stretching. While flexibility is vital for overall fitness, the notion that an extensive stretching program will help prevent injuries has been repudiated by some studies. Other studies show that engaging in lengthy stretching before or during strength training leads to a significant loss of muscular strength.

What haven’t been examined, however, are the effects of doing extensive stretching routines alone; that is, not prior to a bodybuilding workout or athletic event. Studies that have looked at stretching alone found such benefits as increased range of joint motion—even increased muscle strength. A new study sought to answer the question of how a discrete stretching program affects muscular strength, endurance and power. 

In it, 38 college students were randomly divided into a stretching group, consisting of eight men and 11 women, and a control group, consisting of the same numbers of men and women. The study lasted 10 weeks and focused on a program of static stretching—assuming a stretch position, then holding for 10 to 30 seconds—made up of various stretches designed to work the lower body for 40 minutes per session, three times a week. Each subject was measured before and after the study for flexibility, power, strength and strength endurance.

At the conclusion of the study, subjects in the stretching group showed an average 23.9 percent increase in muscular strength and a 29.5 percent increase in muscular endurance. They also had an average 18.1 percent increase in flexibility. The control group, who did no training or stretching, showed zero improvement. The study appears to confirm that stretching all by itself increases flexibility, strength, endurance and power. The authors suggest that the improvements in power and endurance in the stretching group are related to the increase in strength that resulted from the extensive stretching sessions.

The gains in power are related to increases in muscle length, which lead to increases in muscle contractile velocity and force generation—all of which equates to more muscle power.

The authors also note that the results of the study may not apply to a situation where stretching is combined with strength training. On the other hand, the study does show that stretching is beneficial—but perhaps as a workout in itself, not as part of a strength-training session.

A similar scenario exists for aerobic training. Done prior to or immediately following a weight workout, aerobic training can interfere with muscle and strength gains, but done at a separate time, it causes no interference.

The study also shows that a stretching routine may be an effective way to exercise for those who, for one reason or another, cannot lift weights. That includes older people who are too feeble to lift any kind of weights. Research shows a clear connection between muscular fitness and mortality, and a stretching program for those too weak to lift weights can prove lifesaving. For all others, incorporating a stretching program distinct from weight training may supplement a bodybuilding program, leading to better overall results. IM

Kokkonen, J., et al. (2007). Chronic static stretching improves exercise performance. Med Sci Sports Exer. 39:1825-31.