By Steven J. Fleck, Ph.D.
I’ve heard that you shouldn’t stretch right before a weight-training session because this will decrease your maximal strength and power. I’ve noticed, however, that the majority of the studies looking at the effects of stretching right before a training session have studied people with little or no stretching experience. I’ve been stretching for years and want to know if stretching right before a weight-training session will still decrease my maximal strength and power during the training session.
You’ve made a very astute observation. You’re correct in that the majority of studies looking at the effects of stretching prior to a weight-training session on strength and power have generally focused on people with little or no training history of stretching. However, one sports science research project addresses the possible effects of a stretching training history on whether or not stretching right before a resistance-training session affects maximal strength and power in a training session. You’ve been stretching for years; this study looked at college-aged males and females who had been stretching for at least 10 weeks in physical education classes. These students weren’t competitive athletes, but were recreationally active in a wide variety of sports such as basketball, volleyball, soccer, swimming, tennis and weight training. So they were at least “recreationally” physically fit. They also had pretty good flexibility, with all study participants having a sit-and-reach flexibility score greater than the 60th percentile.
In order to look at the effect of stretching on maximal strength, the college students performed a stretching routine for the hamstrings and quadriceps muscle groups right before determination of their one-repetition maximum in the knee curl and knee extension. The stretching routine consisted of five different stretches for the hamstrings and quadriceps. They repeated each stretch three times, holding for 15 seconds to the point of discomfort, and then taking a 15-second rest between successive stretches. The entire stretching routine took about 20 minutes. After stretching, their one-repetition maximum in both the knee curl and knee extension significantly decreased compared to no stretching. Knee curl one-repetition maximum decreased approximately 3.4 percent, while knee extension one-repetition maximum decreased approximately 5.6 percent after stretching, compared to no stretching.
The results indicate that even in people who have a stretching training history, stretching right before a training session would decrease maximal strength and power. The people in this study had a stretching training history of 10 weeks; you’ve been stretching for years, so there’s the possibility that with a longer stretching training history, the effect on maximal strength and power could be different. However, you can make physiological arguments either in favor of a longer stretching training history (resulting in less of a decrease in maximal strength and power) or increasing the decrease in maximal strength for power, compared to people with no or a relatively short-term stretching training history.
So, if you have a stretching training history of several years and are truly interested in expressing your maximal strength and power, you should probably err on the side of caution and not perform stretching prior to your resistance training sessions. Instead, perform your stretching routine after the training session, as the effect of stretching on maximal strength and power is an acute effect, and stretching after the training session won’t have any effect on your maximal strength and power in the following day’s training session.
It’s also important to remember that the effect of stretching on maximal strength and power only takes place in the muscle groups that are stretched. This means you can stretch your legs right before an arm workout and there wouldn’t be an effect on the maximum strength and power of your arms. I hope this gives you some guidance concerning your stretching routine.
Nelson AG, Kokkonen J, and Eldredge C. Strength inhibition following an acute stretch is not limited to novice stretchers. Res Quart Exerc Sport, 76:500-506.