Static stretching and workouts

Bodybuilders sometimes use static stretches to stimulate additional muscle growth. Static stretches can be done either [1] before a workout, [2] during a workout (such as between sets of exercises that involve the same muscle group), or [3] after a workout. Which approach is best?

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#1. Static stretching does cause muscle growth

First of all, let us establish that research is clear that static stretching can indeed cause meaningful muscle growth in humans (despite claims to the contrary). Even so, our ability to create muscle growth by means of passive mechanical tension is limited by both our personal tolerance to the stretch sensation and also by the number of sarcomeres inside the stretched muscle fibers (read more).

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Importantly, the increase in muscle size that is stimulated by the passive mechanical tension produced during static stretching is solely an increase in sarcomeres in series (read more)

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#2. Static stretching also causes fatigue

In addition to producing hypertrophy, static stretching also causes calcium ion-related fatigue. This means that the fatigue has a negative impact on mechanical tension, and thereby impairs the stimulus for hypertrophy of any subsequent exercise (read more).

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#3. Static stretching before a workout

The fatiguing effects of static stretching are very apparent when we look at the literature examining the effects of pre-workout static stretches. There is a clear reduction in the number of reps that can be performed in the strength training sets of a workout, when static stretching is performed beforehand. This most likely reduces the number of stimulating reps, because the calcium ion-related fatigue reduces mechanical tension.

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#4. Static stretching during a workout

The fatiguing effects of static stretching are also likely to be present when stretches are performed between strength training sets. Yet, the hypertrophic effects of static stretching seem to overpower its fatiguing effects in this context, and the overall impact of inter-set static stretches seems to be positive (although bear in mind that the positive effect will occur by means of sarcomerogenesis and the negative effect will be imposed upon myofibrillar addition).

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This phenomenon has been observed in more than one study, giving confidence that the balance of hypertrophy stimulus and fatigue is likely towards the hypertrophy stimulus, at least in those muscles like the quadriceps and soleus that [1] very easily experience a passive tension stimulus, and which [2] do not easily experience calcium ion-related fatigue.

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#5. Static stretching after a workout

Generally, most research into post-workout static stretching has focused on the ability of static stretches to ameliorate the fatigue produced by strength training, which is absurd because static stretching also produces fatigue. Yet, since the passive mechanical tension in static stretching is not affected by the fatigue produced by strength training, post-workout stretching can produce the same stimulus hypertrophy as either pre-workout stretching or inter-set stretching, without causing any reduction in the number of stimulating reps produced in the strength training part of the workout.

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Conclusions

Bodybuilders sometimes use static stretches to stimulate additional muscle growth. Static stretches can be done either [1] before a workout, [2] during a workout (such as between sets of exercises that involve the same muscle group), or [3] after a workout. Which approach is best? First of all, it is important to note that the passive mechanical tension produced by static stretching does indeed stimulate muscle growth (by means of sarcomerogenesis) in humans as well as in animals (despite claims to the contrary). Yet, static stretching also produces calcium ion-related fatigue, owing to the opening of stretch-activated ion channels. This fatigue mechanism is both relatively long-lasting and also reduces the ability of the muscle fibers to generate active mechanical tension by crossbridge formation. Indeed, when static stretches are performed prior to strength training sets, they do reduce the number of reps that can be performed (which very likely reduces the hypertrophic stimulus caused by the strength training set). Therefore, when static stretches are performed either pre-workout or between sets, the passive tension generated will stimulate an increase in muscle size (by means of sarcomerogenesis), but the fatigue produced will reduce the active mechanical tension stimulus for myofibrillar addition produced by subsequent strength training sets. This suggests that the optimal strategy for incorporating static stretching into a bodybuilding program is to perform it at the very end of the workout.