Agreement of three vs. eight isokinetic preset velocities to determine knee extensor torque- and power-velocity relationships

Abstract

BACKGROUND: Torque and power-velocity relationships obtained during isokinetic evaluation can be useful for rehabilitation program. Nevertheless, their determination requires a substantial number of measures using different velocities, inducing time-consuming protocols.

OBJECTIVE: The aim of the present study was to assess the agreement between a short isokinetic protocol, including three angular velocities ( $P_{3}$ ) and a longer one including eight angular velocities ( $P_{8}$ ).

METHODS: Sixteen healthy male subjects performed isokinetic knee extensions at several preset velocities during two protocols. The first included eight velocities ranging from 60 to 270°/s ( $P_{8}$ ), whereas the second ( $P_{3}$ ) consisted of three velocities (90, 180 and 240°/s). Mechanical parameters: theoretical maximal isometric torque $T_{0}$ , theoretical maximal velocity $V_{0}$ , and maximal power $P_{max}$ , were extrapolated from torque- and power-velocity relationships for both $P_{8}$ and $P_{3}$ .

RESULTS: The torque- and power velocity relationships drawn from each protocol were in agreement since no significant differences were found for either each extrapolated mechanical parameters, between the slopes of the torque-velocity relationships, or between the polynomial regression coefficients of the power-velocity relationships resulting from $P_{8}$ and $P_{3}$ .

CONCLUSION: The agreement between the short and long protocols allows reduction of fatigue and loss of motivation that may occur during full velocities testing particularly during rehabilitation program.