PERRINE, JAMES J. and V. REGGIE EDGERTON. Muscle force-velocity relationships under isokinetic loading. Med. Sci. Sports. Vol. 10, No. 3, pp. 159-166, 1978.—Various studies have indicated that human muscles in-vivo manifest a substantially similar, if not the identical force-velocity relationship established for isolated, maximally stimulated animal muscles. In the present study, fifteen healthy males and females, 18 to 38 years old and representing varied activity patterns from sedentary to athletic, performed maximal dynamic knee extensions on an isokinetic loading dynamometer. Maximal torque forces attained at a specific point in the range (30° before full extension) and at seven loading velocities from 0 (isometric) to 288° /sec were recorded. The maximum 30° torques exhibited by the various subjects ranged from 29 to 245 Newton-meters. However, over the four lower test velocities (0, 48, 96 & 144° /sec), all subjects exhibited less than a 15% deviation from their respective maximum 30° torque values, which occurred most often at the 96° /sec test velocity. Maximal instantaneous power output at the 30° position ranged from 98 to 680 Watts. In all 15 subjects this was attained at and remained generally constant over the three highest test velocities (192 to 288° /sec). A neural mechanism that restricts a muscle's maximal tension in-vivo is postulated as being responsible for the marked difference between the force-velocity relationship found for human muscles in-vivo and that exhibited by isolated animal muscles.
FORCE-VELOCITY VS. LOAD-VELOCITY, POSITION AND VELOCITY-SPECIFIC FORCES, INSTANTANEOUS POWER OUTPUT, EXCITATION INTENSITY, NEUROMUSCULAR INHIBITION