VALIDITY OF FAT-FREE WEIGHT EQUATIONS FOR PREDICTING ISOKINETIC PEAK TORQUE IN YOUNG WRESTLERS

Clayton L. Camic1, Terry J. Housh, Michelle Mielke, Jorge Zuniga, C. Russell Hendrix, Glen O. Johnson, Dona J. Housh, Richard J. Schmidt

Abstract

The purpose of this investigation was to determine the validity of fat-free weight (FFW) equations derived on non-athletic children and adolescents for predicting concentric, isokinetic peak torque (PT) in young wrestlers. Seventy-one male wrestlers (mean age ± SD = 12.6 ± 1.1 years) volunteered to perform concentric, isokinetic leg extensions at 180 and 300°·s-1 on a Cybex II dynamometer to measure PT (Nm) and underwater weighing to determine FFW. Predicted PT values at 180 and 300°·s-1 were also estimated from FFW using the following equations: EQ1: Leg Extension PT at 180°·s-1 in Nm = 3.3(FFW) – 54.4 EQ2: Leg Extension PT at 300°·s-1 in Nm = 2.4(FFW) – 38.5 The validity of the equations was determined by examining the constant error (CE), correlation coefficient (r), standard error of estimate (SEE), and total error (TE) values for measured PT versus predicted PT. There were significant (p < 0.05) mean differences (CE) between the measured PT (mean ± SD: 180°·s-1 = 69.3 ± 23.7 Nm; 300°·s-1 = 44.9 ± 16.9 Nm) and predicted PT (180°·s-1 = 79.6 ± 33.7 Nm; 300°·s-1 = 58.9 ± 24.5 Nm) at 180 and 300°·s-1. The r, SEE, and TE values at 180°·s-1 were 0.92, 9.5 Nm, and 18.3 Nm, respectively. The r, SEE, and TE values at 300°·s-1 were 0.92, 6.6 Nm, and 17.8 Nm, respectively. Although measured PT and predicted PT were highly correlated at both 180 and 300°·s-1, the TE values associated with the equations ranged from 26.4 to 39.6% of the mean measured PT values. It is likely that the magnitude of the errors was due to the fact that the equations cross-validated in the present study were derived on a non-athletic sample that included older subjects with greater PT per unit of FFW than the current sample of young wrestlers.

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