Physiological and muscle histochemical assessment of men and women 10 km runners matched for race performance or training volume.

Women have a disadvantage for performance in long-distance running compared with men. To elaborate on inherent characteristics, 12 subelite women were matched with 12 men for training volume (M-Tm) (56.6 ± 18 vs. 55.7 ± 17 km/wk). The women were also matched to other men for a 10 km staged outdoor time trial (M-Pm) (42:36 min:s) to determine which factors could explain equal running performance. Anthropometry and treadmill tests were done. Fiber type (% Type I and Type IIA) and citrate synthase activities were analyzed in muscle biopsy samples. Consistent sex differences for both comparisons included height, weight, % body fat ( P < 0.01), and hematocrit ( P < 0.05). Women had lower V̇o _2max and peak treadmill speed (PTS) compared with both M-Tm and M-Pm ( P < 0.01). Training matched pairs had no sex difference in % PTS at race pace but compared with M-Pm women ran at a higher % PTS ( P < 0.05) and %HR _max ( P < 0.01) at race pace. On average, the women trained 22.9 km/wk more than M-Pm (+67.5%, P < 0.01). This training was not associated with higher V̇o _2max or better running economy. Muscle morphology and oxidative capacity did not differ between groups. Percentage body fat remained significantly higher in women. In conclusion, women matched to men for training volume had slower 10 km performance (-10.5% P < 0.05). Higher training volume, more high-intensity sessions/wk, and time spent training in the 95%-100% HR _max zone may explain the higher % PTS and %HR _max at race pace in women compared with performance-matched men. NEW & NOTEWORTHY When subelite women 10 km runners were matched with male counterparts for 10 km race performance, inherent differences in % body fat, V̇o _2max , Hct, and peak treadmill speed were counteracted by significantly higher training volume, more time training at higher %HRmax and consequently, higher %HRmax and %PTS at race pace. Citrate synthase activity and muscle fiber types did not differ. When women and men matched for training, 10 km performance of men was 10.5% faster.