Are indices of free radical damage related to exercise intensity

Abstract

The possibility that plasma levels of malonaldehyde (MDA) are altered by exercise has been examined. The presence of MDA has been recognized to reflect peroxidation of lipids resulting from reactions with free radicals. Maximal exercise, eliciting 100% of maximal oxygen consumption (VO2max) resulted in a 26% increase in plasma MDA (P less than 0.005). Short periods of intermittent exercise, the intensity of which was varied, indicated a correlation between lactate and MDA (r2 = 0.51) (p less than 0.001). Blood lactate concentrations increased throughout this exercise regimen. A significant decrease (10.3%) in plasma MDA occurred at 40% VO2max. At 70% VO2max plasma MDA was still below resting values, however the trend to an increase in MDA with exercise intensity was evident. At exhaustion, plasma MDA and lactate were significantly greater than at rest. These results suggest, that exhaustive maximal exercise induces free radical generation while short periods of submaximal exercise (i.e. less than 70% VO2max) may inhibit it and lipid peroxidation.

Aspectos atuais sobre estresse oxidativo, exercícios físicos e suplementação

“…Concomitantly, these adaptations influence in the body preparation for a new stress, increasing the activity of the cellular antioxidant system (19)(20) . In the majority of the cases, it is verified that the greater the exercise intensity (≥ 70% of the maximal oxygen uptake [VO 2máx ]), the higher the ORS synthesis is (11,21) . Individuals who are submitted to intense and prolonged exercises or exhaustive training, or even, who have a very high training frequency may surpass the capacity of the endogenous antioxidant system and, consequently, promote severe muscular injuries, causing a local inflammatory process and oxidative stress.…”

Frequent Hard Physical Activity Lowered Serum .BETA.-Carotene Level in a Population Study of a Rural City of Japan.

“…There is another possibility that hard physical activities inhibit absorption of /3-carotene from digestive tract. Indicators of peroxidation caused by free radicals should be measured (Lovlin et al 1987) to clarify the mechanism which reduces /3-carotene among persons with frequent hard physical activities.…”

Physical exercise as pro-oxidant

“…Brady et alii (1979) & Davies et alii (1982) demonstraram aumento de peroxidação em diversos tecidos de ratos não treinados exercitados até a exaustão. Lovlin et alii (1987) estudaram humanos exercitados a 40, 70 ou 100% do V 0 2max e encontraram significativa correlação entre as concentrações plasm áticas de lactato e TBARs. O exercício até a exaustão resultou no aumento sobre seus valores de repouso.…”