Velocity-spectrum testing using a closed kinetic chain

Abstract

Two force and two power variables were monitored during standardized multiple-joint, closed-chain, velocity-spectrum tests to ascertain if contiguous velocities produced discrete or redundant output. Measurements were obtained from 52 men and 50 women during squats performed at six velocities ranging from 0.51 to 2.04 m·s⁻¹. Main effects as well as the sex-by-main-effects interaction were significant (P<0.001) for all four variables. Therefore, post hoc tests were performed separately for men and women. Maximal squatting forces over the velocity spectrum produced force-velocity curves resembling classical single-joint ones. The highest force output occurred at the slowest test velocity as expected and signifcantly decreased (P<0.05) for each increment in velocity for both men and women. Concurrently, maximal squatting power over the velocity spectrum produced power-velocity curves resembling classical single-joint ones. The highest power output ( $\overline{x}=1.26\mbox{ m}\cdot s^{-1}$ ) occurred as part of a plateau at intermediate velocities as expected and was signifcantly less at faster and slower velocities. However, maximal power output generally materialized at faster velocities for men ( $\overline{x}=1.54\mbox{ m}\cdot s^{-1}$ ) than for women ( $\overline{x}=0.97\mbox{ m}\cdot s^{-1}$ ). It appears the six squatting velocities used in this investigation elicit discrete force data for both men and women, and results for force and power resemble what would be expected for isolated single-joint testing protocols. However, it remains unclear why an apparent gender difference exists in the velocity at which the highest peak power is produced.