Soy intake plus moderate weight resistance exercise: effects on serum concentrations of lipid peroxides in young adult women.

AIM

Exercise can conceivably increase concentrations of lipid peroxides (by producing oxidant stress) or decrease their concentrations (by accelerating peroxide breakdown). The net effect could depend on exercise intensity and nutritional antioxidant intake.

METHODS

Recreationally trained, young adult women (n=18) consumed antioxidant-rich soy protein or antioxidant-poor whey protein for 4 weeks (40 g protein/day). A moderate intensity, weight resistance exercise session was done before and after the 4 week period. Blood was drawn before each exercise session and postexercise at 0, 3 and 24 h. Serum from the pre-exercise draw was analyzed for antioxidant status (based on radical scavenging capacities); serum from pre- and postexercise draws were analyzed for concentrations of lipid peroxides as well as creatine kinase activities (which are affected by oxidant damage to muscles).

RESULTS

Soy, but not whey intake, increased pre-exercise serum antioxidant status values and inhibited exercise-induced increases in creatine kinase activities. Before soy or whey intake, serum values for lipid peroxides rose at two of the three postexercise times. After whey intake, values for lipid peroxides showed no increase at the three postexercise times. After soy treatment, values for lipid peroxides actually showed a decrease at the three postexercise times.

CONCLUSIONS

Moderate intensity exercise exerted variable effects on serum lipid peroxides with decreases occurring with 4 weeks of soy intake, which also produced other antioxidant effects.