Effect of Gravity Correction on Isokinetic Average Force of the Quadriceps and Hamstring Muscle Groups in Women Runners

Article type: Research Article

Authors: Perrin, David H.^{a; *; **} | Haskvitz, Esther M.^a | Weltman, Arthur^a

Affiliations: [a] Sports Medicine/Athletic Training Research Laboratory, Curry School of Education University of Virginia

Note: [*] This research was supported in part by a NIH Grant R01 DK38930.

Note: [**] Address reprint requests to Dr. Perrin at the Memorial Gymnasium, University of Virginia, Charlottesville, V A 22903.

Abstract: Previous investigations have examined the effect of gravity correction on hamstring and quadriceps force and reciprocal muscle group ratios when tested from a seated position. The effect of gravity correction on these values when knee extension is tested from supine and knee flexion from prone has not been determined. This study tested 48 females for concentric and eccentric average force of the quadriceps in the supine position and of the hamstring muscle group in the prone position with a Kin Com dynamometer. For the quadriceps and hamstring muscle groups, the gravity-corrected values were greater (p < .01) than gravity-uncorrected values for concentric and eccentric force. The gravity-corrected flexion/extension reciprocal muscle group ratios were also greater (p < .01) than uncorrected ratios when determined from both concentric and eccentric average force values. These findings indicate gravity correction had a significant effect on both quadriceps and hamstring force production and reciprocal muscle group ratios, regardless of the fact that both muscle groups were assessed against the effects of gravity. Furthermore, the effect of gravity correction on the hamstring muscle group was approximately twice as great as on the quadriceps. These findings support the need to correct for the effect of gravity when assessing knee extension from supine and knee flexion from prone. Thus, it is very important for clinicians to report how testing and gravity correction were accomplished to allow proper interpretation and analysis of the presented values.

Keywords: Gravity correction, concentric/eccentric ratio of hamstring/quadriceps, prone/supine positioning

DOI: 10.3233/IES-1991-1208

Journal: Isokinetics and Exercise Science, vol. 1, no. 2, pp. 99-102, 1991