B. Akova et al., Exercise-induced oxidative stress and muscle performance in healthy women:role of vitamin E supplementation and endogenous oestradiol, EUR J A PHY, 84(1-2), 2001, pp. 141-147
The purpose of this study was to investigate the individual and combined an
tioxidant effects of menstrual cycle phase-related alterations in blood ser
um oestradiol concentrations and of dietary vitamin E supplementation on ex
ercise-induced oxidative stress and muscle performance. A group of 18 seden
tary women, aged 19-35 years, were given supplements of 300 mg alpha -tocop
herol (n = 10) or placebo (n = 8) daily during the course of two menstrual
cycles. The subjects exercised the knee isokinetically to exhaustion after
cycling submaximally at 50% maximal oxygen uptake during the menstrual and
preovulatory phases of their menstrual cycles. Blood samples were taken bef
ore and after the exercise, to evaluate haematocrit, plasma lactic acid and
malondialdehyde concentrations, erythrocyte antioxidant enzymes superoxide
dismutase (SOD) and glutathione peroxidase (GPx) activities and apolipopro
tein B containing lipoprotein (non-high density lipoprotein, HDL, fraction)
oxidation. Serum vitamin E, follicle stimulating hormone, luteinizing horm
one and oestradiol concentrations were measured in pre-exercise blood sampl
es. Neither vitamin E supplementation nor oestradiol concentrations influen
ced SOD and GPx activities or the susceptibility of the non-HDL fraction to
oxidation while at rest. Plasma malondialdehyde concentration was unaffect
ed by exercise, however significant reductions in erythrocyte SOD and GPx a
ctivities and increased susceptibility of the non-HDL fraction to oxidation
were noted after exercise. Exercise-induced changes were reduced when oest
radiol concentration was high in the preovulatory phase, independent of the
serum vitamin E concentrations. In addition, both pre-(r = 0.58, P < 0.05)
and post-exercise (r = 0.73, P < 0.001) GPx activities in placebo administ
ered subjects were positively correlated with oestradiol concentrations. In
conclusion, these findings suggest a better protective role of oestradiol
against oxidative injury, compared to vitamin E. Exhausting muscle performa
nce was, however, not influenced by vitamin E supplementation and/or cycle-
phase related changes in oestradiol concentrations.