The effects of two forms of isometric training on the mechanical properties of the triceps surae in man

• Published in: Pflügers Archiv Vol. 405; no. 4; pp. 384 - 388
• Main Authors: YOUNG, K, MCDONAGH, M. J. N, DAVIES, C. T. M
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-12-1985
• Subjects: Adult; Biological and medical sciences; Biomechanical Phenomena; Fundamental and applied biological sciences. Psychology; Humans; Isometric Contraction; Leg; Male; Muscle Contraction; Muscles - physiology; Physical Education and Training - methods; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system; Physical exercise; Human; Triceps surae muscle; Isometric muscular contraction; Fatigue; Endurance; Striated muscle; Electrical simulation
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/BF00595692

The training effects of rhythmic and sustained isometric contractions on the contractile characteristics of the triceps surae have been investigated in four healthy subjects over a period of 8 weeks. One leg (ST) of each subject was trained by performing repeated daily sustained (1 min) isometric contractions at 30% of maximal voluntary contraction force (MVC), and the other using rhythmic isometric contractions at 100% of MVC. The protocol was so arranged that the total area under the training force/time curves was the same for each limb. Electrically evoked maximal twitch (Pt) and tetanic (Po) tensions of the triceps surae were measured weekly on both legs using a standard procedure. The results showed that the rhythmic regime increased the MVC at the rate of 5.5% per week and the sustained training increased MVC at the rate of 3.3% per week. Twitch and tetanic tensions were not altered by either regime. However, only training using sustained contractions produced a progressive increase in endurance as measured by performance in a fatigue test. The results suggest that increases in voluntary strength resulting from short term isometric training are not necessarily associated with a rise in the intrinsic involuntary capacity of muscle fibres to generate force.