Can simply flexing a muscle cause greater growth? Bryan Haycock PH.D.
What if tension can be developed in the muscle without lifting something? When posing, for example, both agonist and antagonist muscle groups are flexed at the same time, generating tension in the muscle. Could this be enough to cause muscle growth?
Researchers from the University of Mississippi wanted to know if muscle growth could occur simply by moving your arms through a full range of motion while flexing. Subjects completed four sets of 20 flexing reps with 30 seconds’ rest between sets. In the other arm, they completed four sets of 8–12 repetitions on arm curls with 90 seconds’ rest between sets at 70% of their 1RM.
After six weeks both biceps grew an equal amount whether using no load or 70% 1RM. Interestingly, the triceps of the group using actual weights shrank during the course of the study while the no-load group saw a small increase. Strength, however, was a different matter with the 70% 1RM group making significantly greater increases.
Flexing your arm muscles through a full range of motion with no external load increases muscle size similar to high-load training. In addition, high-load training produced larger increases in strength compared with contracting with no external load.
This is a very interesting study. It comes on the heels of other recent studies showing similar growth from low loads compared with traditional loads, given that the low-load sets are taken to failure. The most practical application of this research is for situations where heavy loads are not possible (such as in a hotel room) or not recommended, such as after injury. It would be interesting to see what would happen using blood-flow restriction protocols with no loads. I speculate results might be even better.