Effects of Age, Power Output, and Cadence on Energy Cost and Lower Limb Antagonist Muscle Co-Activation during Cycling.

It is unknown if higher antagonist muscle coactivation is a factor contributing to greater energy expenditure of cycling in older adults. We determined how age, power output, and cadence affect energy expenditure and lower limb antagonist muscle coactivation during submaximal cycling. Thirteen younger and 12 older male participants completed 6-min trials at four power output-cadence conditions (75 W-60 rpm, 75 W-90 rpm, 125 W-60 rpm, and 125 W-90 rpm) while electromyographic and metabolic energy consumption data were collected. Knee and ankle coactivation indices were calculated using vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior electromyography data. Energy expenditure of cycling was greater in older compared with younger participants at 125 W (p = .002) and at 90 rpm (p = .026). No age-related differences were observed in the magnitude or duration of coactivation about the knee or ankle (p > .05). Our results indicated that the knee and ankle coactivation is not a substantive factor contributing to greater energy expenditure of cycling in older adults.