To investigate whether the larger reduction in
mechanical work observed during repeated-sprint exercise
(RSE) in men versus women represents a true, physiological
sex dimorphism or is the consequence of the higher
initial mechanical work performed by men. Male and
female team-sport athletes (n = 35) performed 20, 5-s
cycle sprints interspersed with 25 s of rest. Mechanical
work and surface electromyograms (EMG) of four muscles
were recorded in every sprint. Mechanical work achieved
in one sprint (20.7%, P = 0.0006), total work accumulated
over the 20 sprints (21.1%, P = 0.009) and percent work
decrement (32.2%, P = 0.008) were larger in men than in
women. When both sexes were plotted together, there was
a positive relationship between the initial-sprint work and
the work decrement across sprint repetitions (r = 0.89,
P = 0.002). The RSE induced larger (P = 0.009) absolute
EMG amplitude changes in men (-155.2 ± 60.3 mVs)
than in women (-102.5 ± 45.1 mVs). Interestingly, in a
subset of men and women (n = 7 per group) matched for
initial-sprint work, the sex difference in percent work
decrement (men: –29.5 ± 1.5%; women: –27.2 ± 3.2%;
P = 0.72) and EMG changes (men: –17.7 ± 6.9% vs.
women: –15.3 ± 7.1%; P = 0.69) no longer persisted.
Results show that the proposed greater fatigue in men is
likely to be a consequence of their greater absolute initial-sprint
performance, rather than a sex difference in fatigue
resistance per se. We conclude that, on the basis of the absolute mechanical work completed, women are not more
fatigue resistant than men and use comparable muscle
recruitment strategies to perform RSE.