[Effect of muscular work on the myosonogram].

AIM

The purpose of this study was to examine quantitatively the change of muscle thickness and echo intensity caused by muscle exercise in healthy persons.

METHOD

16 healthy volunteers (7 women, 9 men), aged 23 to 37 years, underwent static exercises of the rectus abdominis, rectus femoris/vastus intermedius, and tibialis anterior muscles. In addition, the rectus femoris/vastus intermedius muscles were exercised dynamically. Thicknesses of these muscles were measured before and during/after exercise using the electronic caliper and computer-assisted gray-scale analysis of the echo signals.

RESULTS

Short, maximal isometric contraction resulted in an increase of thickness by 5 to 18% depending on the examined muscle (p < 0.01). The echo intensity of the rectus femoris and vastus intermedius muscles decreased significantly (-8% and -26%, p < 0.01). The increase of muscle thickness immediately after isometric exercise for up to 90 s was significantly correlated to the duration of contraction (r = 0.26 to 0.49, p < 0.05). Muscle echo intensities did not significantly correlate with the duration of the contraction. After dynamic exercise on a bicycle ergometer both thickness of the rectus femoris/vastus intermedius muscles (+12.5%, p < 0.01) and echo intensity of the vastus intermedius muscle increased (+19.5%, p < 0.01). The change of echo intensity of the vastus intermedius muscle after static and dynamic exercise was significantly different (-26% vs. +18%, p < 0.001).

CONCLUSION

Muscle thickness increases during and after static as well as dynamic exercise. Echo intensity may be unchanged, decreased or increased, depending on the exercised muscle and mode of exercise.