Differences in ultra-endurance exercise in performance-matched male and female runners

Abstract

Our study investigated endurance performances in a performance-matched (running 42.2 km) group of females (N = 10) and males (N = 10). The distances examined were 10 km, 21.1 km, 42.2 km, and 90 km. Measurements included VO2max, running economy, lactate accumulation, and running speeds. Although our female subjects performed as well as their male counterparts at 42.2 km (194.8 +/- 12.9 m.min-1 vs 192.6 +/- 16.3 m.min-1), the performance for 90 km was significantly better (P < 0.05) in the female group (171.0 +/- 11.7 m.min-1 vs 155.2 +/- 14.7 m.min-1). The average fraction of the VO2max (F) sustained by each subject indicated that the females achieved their performances by working at a higher (P < 0.01) F (73.4 +/- 5.5% vs 66.3 +/- 3.7% for 42.2 km and 59.8 +/- 6.2% vs 50.2 +/- 3.1% for 90 km). The degree of decline in the fraction of the VO2max sustained as the distance of running increased was significantly less (P < 0.05) in the females. The better performance by the females at 90 km was not related to greater maximal aerobic capacity, running economy, training level, or fatty acid metabolism.

Plasma lactate accumulation is reduced during incremental exercise in untrained women compared with untrained men

“…The clear picture to emerge in the present study was that plasma [La -1 ] was lower in women at all relative intensities between 30 and 100% _ VO 2peak : One consequence of this rightward displacement of the plasma [La -1 ] profile would be to allow women to perform sustained exercise at higher relative intensities than men, and to some extent, offset the performance disadvantage of their lower _ VO 2peak values. That this concept has merit is supported by reports of greater endurance capacity in women when men and women of similar aerobic power have been compared (Helgerud 1994;Speechly et al 1996). The rightward displacement of the plasma [La -1 ] profile in women compared with men is not dissimilar from that reported to occur in any given individual, of either sex, in response to an endurancetraining program (Coyle et al 1985) and it could be argued that the women in the present study were not truly untrained.…”

Menstrual cycle phase and sex influence muscle glycogen utilization and glucose turnover during moderate-intensity endurance exercise

“…The role of estrogen in regulating fuel selection during exercise was first hypothesized when women began to overtake men during longer endurance events (42). Women can complete a 90-km run in less time than men, which has been attributed to women being better able to sustain a higher percentage of their V O 2 peak compared with men (42).…”

Advantages of a smaller bodymass in humans when distance-running in warm, humid conditions

“…If that is the case, it may explain why smaller and lighter runners can progressively compensate for their lower peak exercise intensities by running at higher relative intensities over increasing race distances (Bam et al 1997;Bosch et al 1990;Coetzer et al 1993;Speechly et al 1996). At any given speed, the absolute metabolic heat production of lighter runners is less than that of heavier runners and that may be one reason why smallness of stature is an asset in distance running.…”