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

Women have a disadvantage for performance in long-distance running compared to men. To elaborate on inherent characteristics, 12 sub-elite 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 10km 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 VO2 max 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 to M-Pm women ran at a higher % PTS (P < 0.05) and % HRmax (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 VO2 max 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 10km performance (-10.5% p<0.05). Higher training volume, more high intensity sessions/wk and time spent training in the 95-100% HRmax zone, may explain the higher % PTS and % HRmax at race pace in women compared to performance matched men.