Abstract

Human tremor amplitude has been shown to be sensitive to fatigue offering a measure for neuro-muscular functioning. Effects of adaptation to strength training on fatigue-induced changes in tremor amplitude were studied in 9 male subjects participating in a five-week training program comprising 13 training units of bilateral, dynamic elbow flexions. Each training unit consisted for four sets, each performed to the state of fatigue. A free-moving barbell training load was progressively increased with growing strength abilities during the course of training. Forearm tremor was measured with an accelerometer on the right forearm after warming up at the beginning of each training unit and seven minutes after the last set. Two different springs were subsequently used as a load at tremor measurements. A power spectrum density function for tremor was calculated and changes in tremorr induced by fatigue were analysed in a frequency domain (range 9-20 Hz) for each subject over the 13 training units. Results: The increase in tremor log-amplitude induced by the fatiguing effect of a single strength training unit did not depend on training phase, remaining relatively constant during the five-week training period. In this study the volume of work done during a single training unit as well as utilised load had no effect on the increase in tremor log-amplitude. The possible contribution to the stretch reflex and/or synchronisation of motor units firing to fatigue-induced tremor variability is discussed. Verf.-Referat (gekuerzt)