Fractional utilization of ventilatory capacity during incremental cycle exercise at absolute and relative work rates in older men and women (A and C) as well as younger men and women (B and D). In C and D, the highest equivalent work rate achieved by all subjects was 80 W. Dashed lines within each group connect the 80 W data point to the peak exercise data point. All data are presented as means ± SE. V̇e/V̇eCAP, fractional utilization of ventilatory capacity. *P < 0.05, main effect of age, comparisons made between all older and all younger subjects, regardless of sex. No significant interaction effect was observed.