Abstract
Fifteen recreational male cyclists (VO2max = 48.35 ml/kg/min ± 6.20) participated in an investigation aimed to determine how varying cycling workrates influence electromyographic (EMG) spectral parameters and if these parameters relate to the resulting exercise efficiency. Gross efficiency (GE% = work output/energy input × 100) was assessed from steady-rate VO2 readings obtained when cycling (Monark ergometer) at 60, 80, and 100 rpm, with a force setting of 1.0 kp and 2.5 kp. Surface EMG records of the vastus lateralis (VL) and gastrocnemius (GA) muscles were used to derive the integrated EMG (IEMG), and the mean (MPF) and median power frequency (MedPF) of the signals' frequency spectrum. Repeated measures ANOVA revealed that regardless of pedaling rate., IEMG scores for the VL were greater (p < 0.05) when pedaling at 2.5 kp. For the GA muscle, this wa also true except when comparisons were made at 60 rmp. Also, for both muscles, IEMG values increased along with pedaling rate (p < 0.05) regardless of ergometer force setting. However, for both muscles the respective MPF and MedPF remained unchanged across all experimental conditions. Thus, the degree of muscle recruitment (IEMG) had no affect on the EMG frequency spectrum content. Additionally, no correlations were established between MPF and GE%, nor MedPF and GE% for the VL. For the GA, correlations between MPF and GE% (r = −.647; p < 0.05), and MedPF and GE% (r = −.628; p < 0.05) were established but only for one experimental condition (60 rpm and 2.5 kp). It was concluded that the GE% of cycle ergometry does not seem to be influenced by the frequency spectrum (MPF, MedPF) of the surface EMG signal. These frequency variables were not dependent on mechanical workrates.
Published Version
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