TRAINING-INDUCED CHANGES IN MUSCLE ARCHITECTURE AND SPECIFIC TENSION

Five men underwent unilateral resistance training of elbow extensor (t riceps brachii) muscles for 16 weeks. Before and after training, muscl e layer thickness and fascicle angles of the long head of the triceps muscle were measured in vivo using B-mode ultrasound, and fascicle len gths were estimated. Series anatomical cross-sectional areas (ACSA) of the triceps brachii muscle were measured by magnetic resonance imagin g, from which muscle volume (V-m) was determined and physiological cro ss-sectional area (PCSA) was calculated. Elbow extension strength (iso metric; concentric and eccentric at 30, 90 and 180 degrees . s(-1)) wa s measured using an isokinetic dynamometer to determine specific tensi on. Muscle volumes, ACSA, PCSA, muscle layer thickness and fascicle an gles increased after training and their relative changes were similar, while muscle and fascicle length did not change. Muscle strength incr eased at all velocities; however, specific tension decreased after tra ining. Increase in fascicle angles, which would be the result of incre ased V-m and PCSA, would seem to imply the occurrence of changes in mu scle architecture. This might have given a negative effect on the forc e-generating properties of the muscles.