A new device to study isoload eccentric exercise
Résumé
A new device to study isoload eccentric exercise. J Strength Cond Res 24(X): 000–000, 2010—This study was designed to develop a new device allowing mechanical analysis of eccentric exercise against a constant load, with a view in mind to compare isoload (IL) and isokinetic (IK) eccentric exercises. A plate-loaded resistance training device was integrated to an IK dynamom-eter, to perform the acquisition of mechanical parameters (i.e., external torque, angular velocity). To determine the muscular torque produced by the subject, load torque was experimentally measured (T Lexp) at 11 different loads from 30° to 90° angle (0° = lever arm in horizontal position). T Lexp was modeled to take friction effect and torque variations into account. Validity of modeled load torque (T Lmod) was tested by determining the root mean square (RMS) error, bias, and 2SD between the descending part of T Lexp (from 30° to 90°) and T Lmod. Validity of T Lexp was tested by a linear regression and a Passing–Bablok regression. A pilot analysis on 10 subjects was performed to determine the contribution of the torque because of the moment of inertia to the amount of external work (W). Results showed the validity of T Lmod (bias = 0%; RMS error = 0.51%) and T Lexp SEM = 4.1 NÁm; Intraclass correlation coefficient (ICC) = 1.00; slope = 0.99; y-intercept = 20.13). External work calculation showed a satisfactory reproducibility (SEM = 38.3 J; ICC = 0.98) and moment of inertia contribution to W showed a low value (3.2 6 2.0%). Results allow us to validate the new device developed in this study. Such a device could be used in future work to study IL eccentric exercise and to compare the effect of IL and IK eccentric exercises in standardized conditions.
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