EMG, ventilatory and hr thresholds in elite rowers

Aims of this study was to verify the existence of a EMG threshold in four muscle (Vastus Lateralis, Biceps Femoris, Gastrocnemius Lateralis, and Tibialis Anterioris) of lower limb of rower and to correlate it with Ventilatory and Hearth rate parameters. We tested 9 elite rowers with a ramp test on the Concept II remoergometer until exhaustion. Start power was 40 watt, and was increased with steps of 20 watt/min. Hearth rate was measured on-line with a Polar hearth rate monitor, while O2 consumption was measured with a MedGraphics telemetric system. Emg surface signal was measured with a full wawe RMS technique with a time costant of 10 seconds using a Mega Electronics system working at a sampling rate of 1000 Hz. Hearth rate threshold (HRth) and EMG threshold (EMGth) were established by two independent experts, with the referee of a third expert in the case of disagreement between them. Ventilatory threshold (Ath) was determined with the V-slope method. Results shows the existence of the EMG threshold in all four leg muscle, with the EMGths of VL and BF showing the higher correlation with Ath and HRth (0.78 and 0.71 , p< 0.05). HRth was at 243 Watt (+/- 34) and EMGth was at a mean of 243 (+/- 35) for BF and GL, while ATh was at 273 (+/- 27) watt. Results are in accordance with previous findings, and confirm the EMG as a non invasive method for local thresholds determination