Changes in lumbopelvic motion and trunk muscle activity during 2000 m rowing ergometer trial

Abstract

1 The changes in lumbopelvic motion and trunk muscle activity occurring during 2000 2 m rowing in elite collegiate rowers (five men and three women with rowing careers of 3 5.6±2.1 years) were investigated. The pelvic inclination and the lumbar angle were 4 calculated. Surface electrodes were attached to the rectus abdominis, external oblique, 5 internal oblique, multifidus, erector spinae, latissimus dorsi, rectus femoris, and biceps 6 femoris. Three consecutive strokes at the 20% and 80% time-points of a 2000 m race 7 simulation were analyzed. The root-mean-square was calculated during the early drive 8 phase, late drive phase, and recovery phase. Root-mean-square amplitude was 9 normalized by maximum voluntary contraction. Between two time-points, paired t-tests 10 for each angle and Wilcoxon signed-rank tests for each muscle were performed. 11 Biceps femoris activity during the late drive phase and rectus abdominis activity during 12 the recovery phase decreased significantly in prolonged rowing. Posterior inclination of 13 the pelvis at the catch and middle positions, lumbar flexion at the catch position, and 14 activity of the erector spinae and multifidus during the early drive phase increased 15 significantly in prolonged rowing. The inability to maintain the set position during the 16 recovery phase owing to decreased rectus abdominis activity may lead to excessive 17 posterior pelvic tilt in the catch position. Since an increase in the posterior inclination 18 of the pelvis and lumbar flexion occurred in apparent opposition to erector spinae and 19 multifidus function, repetitive rowing may have decreased the control of the 20 intersegmental motion of the lumbar spine.