Effect of physical exercise on serum lipid peroxide related to exercise intensity

It is becoming a greater interest for scientists whether exercise should increase production of free radicals and lipid peroxidation which are considered to be related to many clinical problems and aging. Conflicting results concerning effect of exercise on lipid peroxidation have been reported, because of different experimental conditions. Therefore, we tried to make it clear how the exercise intensities are related to lipid peroxidation or whether there is a threshold of the exercise intensity for the increase in lipid peroxidation. Five healthy male subjects performed 4 different intencities of treadmill running for 25 min on different days, viz. 40%, 60%, 80%, and 100% of VO₂max. Blood samples at rest, 13 min of exercise, immediately after exercise, 10 min, 30 min, and 60 min after exercise were analyzed for serum lipid peroxides (TBAR) and plasma lactate. The results of the present study are as follows; Serum lipid peroxides during exercise and immediately after exercise showed significant increases from rest at every intensity of exercise. These increases, however, were considered to be the result of hemoconcentration with exercise. During recovery period, serum lipid peroxides showed significant increases from rest only at 30 min and 60 min after the maximal intensity of exercise. These increases were not due to hemoconcentration with exercise. Negative relationship (r= -0.847, 0.05<P<0.1) was observed between VO₂max and increasing rate of serum lipid peroxides corrected with hematocrit after maximal exercise. These results seem to suggest that lipid peroxidation is well controled during and after submaximal exercise up to 80% of VO₂max but increases after maximal exercise, and that physical training may have a beneficial effect on controling system of lipid peroxidation.