title: The effects of two forms of isometric training on the mechanical properties of the triceps surae in man.
abstract: 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.
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D007537:Isometric Contraction; D007866:Leg; D008297:Male; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D010806:Physical Education and Training / Q000379:methods*