Contractile properties of two human lower limb muscle groups: The quadriceps and triceps Surae

The purpose of this study was to differentiate between the contractile characteristics of the quadriceps femoris (QF) and triceps surae (TS) muscle groups within the same individual independently of volitional effort. Electrically evoked isometric contractions of the QF and TS muscle groups were recorded from the dominant leg of 13 men and women (28.8 ±2.1 years). The electrical stimulation protocol performed included: supramaximal twitches; contractions evoked at 10, 20, 50 and 100 Hz stimulation; and a two minute fatigue test. Compared with the QF, the TS contractile properties were found to have: (1) prolonged twitch TPT and ½RT; (2) a larger relative torque production at low frequencies of stimulation; and (3) a greater resistance to fatigue. These results indicate: (1) that the TS is a functionally slower and less fatiguable muscle group than the QF; and (2) that electrical stimulation is a sensitive and non‐invasive technique for determining the contractile characteristics of human muscle.