Back muscle endurance during remote muscle contraction

Eleven healthy male subjects were studied during the trunk holding test without grip power and with 20% and 50% grip power. Surface electrodes were placed over each erector spinae muscle at L1 level. Median frequency (MF) and mean power frequency (MPF) were evaluated by the spectral analysis program. The rate of change was determined for each parameter during the test. Both MF and MPF decreases with 20% grip power were significantly faster than without grip power. Both indices decreases with 50% grip power were significantly slower than with 20% grip. We found that back muscle endurance with 20% grip power was lower than without remote muscle contraction