Comparison of the histochemical and contractile properties of human triceps surae

Abstract

The purpose of the study was to compare the contractile properties determined from an electrically stimulated twitch with histochemically determined fibre type parameters of the human triceps surae. Muscle samples were obtained from the medial head of the gastrocnemius of ten male athletes. Ages ranged from 20 to 29 years. Muscle samples from the belly of the medial gastrocnemius muscle were obtained using the needle biopsy technique. The samples were treated histochemically for myosin ATPase to classify the fibres as either slow twitch (ST) or fast twitch (FT) and to determine fibre areas. Surface electrical stimulation was used to determine muscle twitch parameters. The contractile variables of the muscle twitch were latency (L), time to peak force (TPF), peak force (PF), half-contraction time (1/2 CT) and half-relaxation time (1/2 RT). Backward elimination procedures for dependent variables were used to determine which contractile properties best represented the histochemical profile of the muscles. Prediction formulas were developed for FT and ST percentages (R2 = 0.98, p < 0.001), relative area percentage (R2 = 0.87, p < 0.001), and ST area (R2 = 0.85, p < 0.01). It was concluded that the use of the electrotensiometer (ETM) protocol was a valid testing procedure when studying physiological relationships of histochemical properties in intact human skeletal muscle.

Probabilistic modeling of selective stimulation of the human sciatic nerve with a flat interface nerve electrode

“…Application of this equation resulted in the non-linear relationship wherein the small population of large motor units contributed to the majority of force generated by a muscle and the large population of small motor units contributed a relatively small percentage to the total force generated by the muscle. Muscle-specific parameters were collected from the literature (Botterman and Cope 1988; Boyd 1968; Enoka and Fuglevand 2001; Feiereisen et al 1997; Gordon et al 1990; Holmback et al 2003; Ito et al 2003; Kernell et al 1983; Macefield et al 1996; Moss 1992; Ohira et al 2000; Powers and Binder 1991; Ward et al 2009; Winter 2009). …”