Why Does Stretching Increase Strength?

By Angie Young

1. Reciprocal inhibition: when you strengthen/contract a muscle, it’s antagonist (opposite) muscle stretches. When you contract your bicep, your tricep stretches; when you contract your quad, your hamstring stretches, etc. Sometimes a muscle cannot strengthen/contract past its current limit because it’s antagonist muscle cannot stretch any further.
2. Sarcomere pliability: Your muscle fibers are made up of sarcomeres, which are like sliding doors – pulling together (strengthening/contracting the muscle) and pulling apart (stretching/lengthening the muscle). Stretching “loosens up” this movement so that the sarcomeres can contract and lengthen with more ease. (For the super nerds: look into the Sliding Filament Theory!).
3. Elongated fascia: fascia is highly-vascularized connective tissue that surrounds every muscle, nerve ending, blood vessel, bone, nerve fiber, and organ and keeps them all in place. If your muscle was a pillow, fascia would be the pillowcase. Your muscle (the pillow) cannot grow larger than the fascia (the pillowcase). In fact, research from the Journal of Applied Physiology shows that stretching your fascia consistently and correctly for 28 days can increase your muscle mass by 318% – no joke! (That does not equate to 318% increase in strength- it’s just the size of the muscle. Strength increases by about 20%, which is still very significant).