Resistance exercise enhances joint flexibility as well as muscle strength, and static stretching exercise performed after resistance exercise enhances muscle strength as well as joint flexibility.
Muscle is an amazing tissue that has both the ability to contract and shorten to about 50 percent less than its resting length and the ability to relax and lengthen to about 50 percent more than its resting length. As you know, the best way to increase a muscle’s strength capacity is to perform progressive resistance exercise.
The recommended strength-training protocol is to use a weight load that you can lift for 8 to 12 repetitions in good form. When you can complete 12 repetitions with proper technique, you increase the weight load by about 5 percent for the next exercise session. This is known as the double-progressive training procedure in which you first increase the exercise repetitions and then you increase the exercise resistance. In addition to being highly effective for incremental strength gains, the double-progressive training procedure greatly reduces the risk of doing too much too soon and experiencing a musculoskeletal injury.
This same double-progressive training protocol can be applied to improving a muscle’s capacity to stretch. Begin by stretching the target muscles to the point where they have lengthened to their comfort limit and hold this position for about 10 seconds. Do not stretch your muscles to the point of discomfort or pain, as this can be counterproductive.
As an example, if you sit on the floor with your legs straight in front, you may be able to flex your hips far enough to grasp your shins just below the knees without feeling discomfort in your rear thigh (hamstrings) muscles. You may maintain this stretched position for 10 seconds, relax for 10 seconds, and repeat. After a few sessions when this procedure becomes more comfortable, you may hold the stretched position for 15 seconds and repeat. The final progression at this position is to maintain the stretch for 20 seconds and repeat.
Completing 20-second stretches (without discomfort) is an indication that you can safely increase the muscle elongation. You may therefore grasp your shins an inch farther from your knees and progressively increase your stretch time from 10 to 15 to 20 seconds. In this double-progressive training protocol, your hamstring muscles should gradually increase their elasticity for improved hip flexibility.
In our previous research studies, we have repeatedly found that performing muscle-stretching exercise in conjunction with muscle-strengthening exercise results in a win-win situation. Our results have demonstrated that full-range resistance exercise enhances joint flexibility as well as muscle strength, and that static stretching exercise performed after resistance exercise enhances muscle strength as well as joint flexibility.
In three separate studies, research participants who stretched their muscles after each resistance exercise experienced 19 percent greater strength gains than those who did not incorporate the stretches. As examples of combined training, the chest press exercise was followed by a 20-second stretch for the chest muscles, and the low back exercise was followed by a 20-second stretch for the low back muscles.
In addition to the physiological benefits of combining muscle-strengthening and muscle-stretching activity, most of our fitness program participants like to do so simply because they find that it feels really good to stretch each muscle group after performing a resistance exercise.
Other research has revealed static stretches should not be performed prior to doing resistance exercise. This being the case, we recently conducted a study in which participants performed a carefully controlled dynamic stretch before each resistance exercise. For example, just before doing the chest-press exercise, the participants performed five slow and progressively larger arm circles to stretch the chest muscles without holding a stretched position.
In general, our study participants were pleased with the pre-exercise dynamic stretches. However, when given the choice to do pre-exercise dynamic stretches or post-exercise static stretches, almost everyone opted to perform 20 seconds of static stretching after the resistance exercise.
Based on our research and experience, it seems the preferred protocol of combining stretching and strengthening activity is to do static stretches shortly after performing your resistance exercises.
Wayne L. Westcott, Ph.D., teaches exercise science and directs the Health & Fitness Center at Quincy College in Massachusetts.