The temporal relationship of thresholds between muscle activity and ventilation during bicycle ramp exercise in community dwelling elderly males

Abstract

[Purpose] To compare the appearance time of the ventilatory threshold point and the electromyo graphic threshold in the activity of the vastus lateralis, rectus femoris, biceps femoris long head and gastrocnemius lateral head muscles during ramp cycling exercise in elderly males. [Subjects and Methods] Eleven community dwelling elderly males participated in this study. Subjects performed exercise testing with an expiratory gas analyzer and surface electromyography to evaluate the tested muscle activities during ramp exercise. [Results] The electromyo graphic threshold for rectus femoris was not valid because the slope after electromyo graphic threshold was not significant as compared to that before electromyo graphic threshold. The slope of the regression line for vastus lateralis was significantly decreased after electromyo graphic threshold while biceps femoris and gastrocnemius were increased. The electromyo graphic threshold appearance times for vastus lateralis and gastrocnemius were significantly earlier than ventilatory threshold point. There were no difference in electromyo graphic threshold appearance times among three muscles. [Conclusion] These results suggest that the increase in the slope of the regression line after electromyo graphic threshold for vastus lateralis was decreased, possibly indicating to postpone muscular fatigue resulting from the activation of biceps femoris and gastrocnemius as biarticular antagonists. This recruitment pattern might be an elderly-specific strategy.