Study after study has found that doing static stretching before your strength training will decrease the quality of your workout. But that doesn't mean that static stretching is worthless for strength athletes. Quite the opposite, says sports scientist J. Kokkonen of Brigham Young University, Hawaii. Stretching, if done the right way, can unlock growth and strength gains.
There are two kinds of stretching that are commonly used by athletes: Dynamic and Static.
Dynamic stretching means 'pumping' your muscles, and isn’t what we normally consider as “stretching”. You adopt a stretch pose, then keep gently pushing the stretch to the point where you feel it in your muscle, and then release so that the muscle returns quickly to its original length. This type of stretching has been shown to improve explosive performance, such as before a sprint training session.
Static stretching is what most of us having in mind when we think of stretching. With static stretching, you stretch until you feel the stretch in the muscle, and then you hold that position for a longer amount of time.
This type of stretching is safer than dynamic stretching. However, consider yourself warned: while countless gym-gurus recommend it, study after study has confirmed static stretching just before a lifting session will reduce strength (muscle will temporarily be unable to generate maximal power).
What’s more, there is surprisingly little evidence that stretching reduces the occurrence of injuries at all.
Because it can boost muscle growth, if done right. Research has shown that stretching has the same effect on muscles as weight training does (although on a smaller scale – don’t trade your wrist wraps for a yoga mat just yet!).
Both stretching and lifting weights cause microscopic tears in muscle tissue – called Z-line ruptures – which stimulate the muscle cells to produce growth factors. These growth factors in turn prompt the manufacture of new muscle fibers.
Consider: there are animal studies in which rats gained 13 percent more calf muscle mass when the researchers did nothing but stretch their soleus (calf) muscle 3 times a week for a period of 4 weeks. [J. Appl. Physiol. 1994 Jul; 77(1): 58-62.]
Hell, if you can get calves to grow, you’ve got to be onto something.
This brings us back to sports scientist J. Kokkonen from BYU Hawaii. Kokkonen studied the effects of stretching after lifting weights, rather than before. He divided his athletes into two groups: Weight training only (WT) vs. weight training followed by static stretching (WT+ST).
After 8 weeks, Kokkonen found that the athletes in the WT+ST group who stretched post-workout gained significantly more strength than the athletes who only lifted.