title: Effects of power training on muscle structure and neuromuscular performance.
abstract: The present study examines changes in muscle structure and neuromuscular performance induced by 15 weeks of power training with explosive muscle actions. Twenty-three subjects, including 10 controls, volunteered for the study. Muscle biopsies were obtained from the gastrocnemius muscle before and after the training period, while maximal voluntary isometric contractions (MVC) and drop jump tests were performed once every fifth week. No statistically significant improvements in MVC of the knee extensor (KE) and plantarflexor muscles were observed during the training period. However, the maximal rate of force development (RFD) of KE increased from 18,836+/-4282 to 25,443+/-8897 N (P<0.05) during the first 10 weeks of training. In addition, vertical jump height (vertical rise of the center of body mass) in the drop jump test increased significantly (P<0.01). Simultaneously, explosive force production of KE muscles measured as knee moment and power increased significantly; however, there was no significant change (P>0.05) in muscle activity (electromyography) of KE. The mean percentage for myosin heavy chain and titin isoforms, muscle fiber-type distributions and areas were unchanged. The enhanced performance in jumping as a result of power training can be explained, in part, by some modification in the joint control strategy and/or increased RFD capabilities of the KE.
authors.affiliation: Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyväskylä, Jyväskylä, Finland. heikki@sport.jyu.fi
authors.forename: H
authors.initials: H
authors.lastname: Kyröläinen
authors.forename: J
authors.initials: J
authors.lastname: Avela
authors.forename: J M
authors.initials: JM
authors.lastname: McBride
authors.forename: S
authors.initials: S
authors.lastname: Koskinen
authors.forename: J L
authors.initials: JL
authors.lastname: Andersen
authors.forename: S
authors.initials: S
authors.lastname: Sipilä
authors.forename: T E S
authors.initials: TE
authors.lastname: Takala
authors.forename: P V
authors.initials: PV
authors.lastname: Komi
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001706:Biopsy; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods*; D010809:Physical Fitness / Q000502:physiology; D014142:Track and Field / Q000502:physiology