Improvement in muscle strength with low-load isotonic training depends on fascicle length but not joint angle

Abstract

Introduction: In this study we investigate whether low‐load isotonic training will elicit greater improvement in muscle strength at the same fascicle length, rather than at the same joint angle. Methods: Sixteen healthy men (24.1 ± 2.5 years of age) were randomly divided into intervention and control groups. Pre‐ and posttraining maximum isometric and isokinetic strengths and fascicle lengths of the medial gastrocnemius muscle were measured. Isotonic resistance training at 15 ° to 30 ° ankle plantarflexion at low intensity was conducted for 4 weeks. Results: The maximum isometric and isokinetic strength of the intervention group increased significantly only at 15 ° dorsiflexion and 8 ° to 12 ° dorsiflexion. Fascicle length during maximum voluntary contraction at 15 ° dorsiflexion to 0 ° was similar to fascicle length under training conditions. Discussion: It is possible that the improvement in muscle strength with low‐load training depends on fascicle length rather than joint angle.