Research has shown a long time ago that stretching statically the antagonists potentiates the strength of the agonists.
Swiss elite strength coach Jean-Pierre Egger was the first one to popularize this method when training elite shot putter Werner Günthör
So if you stretch the quadriceps statically between hamstring leg curls sets, the force produced by the hamstrings will increase, hence it will create more overload on these muscles.
There are two mechanisms responsible for that:
- The quadriceps actually relax because of the static stretch, thus creating less friction.
- More motor units are recruited when the antagonist is stretched statically.
What would be the best way to stretch the quads?
Laying on the leg curl, have a partner bring your heels towards your buttocks, and hold the stretch for a full 5 minutes before doing your first set of leg curls. A five minute static hold has been shown recently to be the best to stretch statically. From a clinical standpoint, I find that a single 5 minutes stretch works better than 15 seconds inserted between all sets.
Coach Charles R. Poliquin