Isometric muscle strength and quantitative electromyography of back muscles in wrestlers and tennis players

Abstract

The isometric motor performance of the trunk muscles was studied in 10 male wrestlers and 9 male tennis players, all of whom were elite athletes. Isometric flex ion, extension, and lateral bending were performed. The motor output, including fatigue, was studied by means of a load cell and using electromyographγ. The wrestlers were found to have symmetrical strength and were stronger in all measured directions, especially in side bending (flexion, 852 N; extension, 951 N; right and left side bending, 759 N and 744 N, respectively), than the tennis players and normal sub jects of any published study. The development of fa tigue in the erector spinae muscles, as evaluated by spectral analysis of the myoelectric signal, was not symmetrical and was significant bilaterally at the lumbar level and on the right side at the thoracic level. As expected, the tennis players had asymmetrical isometric strength. They were stronger in left side bending than right side bending (643 N compared with 557 N, P < 0.01), and stronger in extension than flexion (835 N compared with 638 N, P < 0.01). The develop ment of fatigue in the erector spinae muscles was significant bilaterally at the lumbar level and on the left side at the thoracic level. The development of fatigue in the tennis players was less than that of the wrestlers except for the left tho racic measurement site. Our conclusions are that tennis players appear to be relatively weak in trunk flexion. The wrestlers displayed a development of fatigue that was asymmetrical and was of nearly the same degree as the tennis players, but on the opposite side.