title: Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production.
abstract: This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque. Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s(-1). The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested. Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s(-1) by 12-13% (P < 0.05). Muscle size increased in LL only, the changes were correlated (r = 0.73-0.93, P < 0.05) with the changes in concentric torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group. Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.
authors.affiliation: a School of Exercise and Health Sciences, Centre for Exercise and Sports Science Research , Edith Cowan University , Joondalup , Australia.
authors.forename: Marika
authors.initials: M
authors.lastname: Noorkõiv
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nosaka
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Blazevich
mesh_terms: D000328:Adult; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D010806:Physical Education and Training / Q000379:methods; D052097:Quadriceps Muscle / Q000033:anatomy & histology* / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D019415:Torque; D055815:Young Adult
keywords: angular velocity; dynamic torque; length-specificity