Sunday, February 9, 2014

The effect of prior eccentric exercise on heavy-intensity cycling: the role of gender and oral contraceptives.


PURPOSE: To determine if gender and/or the use of oral contraceptives alter
cycling performance with exercise-induced muscle damage (EiMD).
METHODS: Nine male adults (MEN), nine normally menstruating female adults
(WomenNM), and nine female adults using oral contraceptives (WomenOC)
participated. Gas exchange and time to exhaustion were measured during continuous
cycling performed at three distinct power outputs before (pre) and 48 h after
(post) 240 maximal effort eccentric contractions of the quadriceps muscles
designed to induce muscle damage (i.e., EiMD).
RESULTS: The change in muscle damage (i.e., range of motion about the knee joint 
and serum creatine kinase activity) from pre- compared to post-EiMD was greater
in MEN and WomenOC compared to the WomenNM. Time to exhaustion decreased after
EiMD in MEN (5.19 ± 4.58 min, p = 0.01) and in WomenOC (2.86 ± 2.83 min,
p = 0.02) but did not change in WomenNM (0.98 ± 2.28 min, p = 0.43). Accordingly,
the slow component of O2 uptake, expressed relative to time to exhaustion (i.e., 
 % min(-1)), was greater in post- compared to pre-EiMD for MEN (p = 0.02) and the
WomenOC (p = 0.03), but not for the WomenNM (p = 0.12).
CONCLUSION: The preservation of exercise tolerance during heavy-intensity cycling
performed after intense eccentric exercise is improved in women compared to men. 
Furthermore, the preservation of exercise tolerance is exclusive to 17β-estradiol
and cannot be replicated with an exogenous synthetic estrogen replacement
delivered in an oral contraceptive.
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