New research has found that muscle fibers in bodybuilders and power athletes generate a higher isometric force (muscle contraction generates tension without changing its length) compared to controls, but the peak muscle power only increases in the power athletes.
Researchers took small muscle samples from the thigh of 12 male bodybuilders, 6 power athletes and 14 non-competitive controls and isolated single muscle cells from them. Individual small muscle cells were connected to a force transducer, the size of the cells was measured, and the cell then activated to produce maximal force.
The research showed that not only the muscles, but also individual muscle cells of bodybuilders are extraordinarily large and can generate forces that exceed those of other people. The surprising thing, however, was that a gram of muscle from bodybuilders produced less force than that from non-bodybuilders, and it thus seems that the 'muscle quality' is less in bodybuilders.
It thus appears that excessive muscle growth may have detrimental effects on quality of the muscle, and one may well be better off with normal-sized muscles than with metabolically expensive large muscles. However, in power athletes, the muscle quality was improved with their training methods seemingly having an impact on muscle quality, which is of great importance for trainers and coaches interested in enhancing either performance of athletes.
Researchers say they had no indication that the proteins generating force (muscle motor proteins) work less in bodybuilders, but it could be that they have fewer motor proteins per gram muscle. It would be interesting to see what aspect in the training of bodybuilders causes this decrease in muscle quality, they added.