M.T.G. Pain and S.E. Forrester (UK)
Strength parameters; isovelocity dynamometer; activation.
This study aimed to determine whether EMG amplitude from maximum voluntary contractions can be used to estimate the tetanic force – velocity relationship. Five subjects performed maximal knee extensions over a range of eccentric and concentric velocities on an isovelocity dynamometer and EMG from the quadriceps was recorded. A muscle model of the knee extensions allowed the maximum voluntary (MVC) force – length – velocity data to be estimated from the dynamometer data. Normalised root mean square (RMS) amplitude – length – velocity data were obtained from the EMG signals. Dividing the MVC forces by these normalised RMS amplitudes generated EMG corrected force – length – velocity data. A Hill-type tetanic force function covering eccentric and concentric velocities was fitted to both the MVC and EMG corrected force data. Based on a number of comparative scores, the EMG corrected forces provided a significantly better fit to the tetanic force function compared to the MVC forces (p ”0.05), suggesting that EMG amplitude can be used to estimate tetanic forces from in vivo MVC measurements.
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