title: Adaptive changes in motor control of rhythmic movement after maximal eccentric actions.
abstract: Effects of an exhaustive eccentric exercise (EE) on the motor control of maximal velocity rhythmic elbow extension/flexion movement (RM) were examined in eight male students. The exhaustive EE consisted of 100 maximal eccentric actions of the elbow flexor muscles. Movement range was 40-170 degrees in EE at an angular velocity of 2rads(-1). A directive scaled RM of 60 degrees with visual feedback was performed in a sitting position, with the right forearm fixed to the lever arm in horizontal plane above protractor. Surface electromyographic activity (EMG) was recorded from the biceps brachii (BB) and triceps brachii (TB) muscles. Maximal isokinetic eccentric and concentric tests and RM test were conducted before, after, 0.5h, 2 days and 7 days after the exercise. Dynamic force production was deteriorated after EE (P<.001), and did not recover fully within 7 days. The delayed recovery phase was characterized by delayed onset of muscle soreness (DOMS) and elevated serum creatine kinase (CK) activity. The RM test revealed a delayed increase of the fatigued BB muscle EMG activity, but the maximal RM velocity could be preserved. The present results emphasize the capacity of the neuromuscular system to compensate for prolonged eccentric-induced contractile failure by optimizing antagonistic muscles coordination in a demanding rhythmic task. The underlying compensatory mechanisms could be related to increased sensitization of small diameter muscle nerve endings.
authors.affiliation: University of Jyväskylä, Neuromuscular Research Center, Department of Biology of Physical Activity, PO Box 35, 40014 Jyväskylä, Finland. reijo.bottas@sport.jyu.fi
authors.forename: Reijo
authors.initials: R
authors.lastname: Bottas
authors.forename: Caroline
authors.initials: C
authors.lastname: Nicol
authors.forename: Paavo V
authors.initials: PV
authors.lastname: Komi
authors.forename: Vesa
authors.initials: V
authors.lastname: Linnamo
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D004551:Elbow Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000502:physiology; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010507:Periodicity; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult