title: Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.
abstract: Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.
authors.affiliation: 1Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan; and 2Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Kyoto, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Tome
authors.initials: T
authors.lastname: Ikezoe
authors.forename: Jun
authors.initials: J
authors.lastname: Umehara
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Umegaki
authors.forename: Takuya
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Satoru
authors.initials: S
authors.lastname: Nishishita
authors.forename: Kosuke
authors.initials: K
authors.lastname: Fujita
authors.forename: Kojiro
authors.initials: K
authors.lastname: Araki
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ichihashi
mesh_terms: D000328:Adult; D000843:Ankle Joint; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D011897:Random Allocation; D055070:Resistance Training; D055815:Young Adult