Pharmacological antioxidant vitamins have previously been investigated for a prophylactic effect against exercise-induced oxidative stress. However, large doses are often required and may lead to a state of pro-oxidation and oxidative damage. Watercress contains an array of nutritional compounds such as β-carotene and α-tocopherol which may increase protection against exercise-induced oxidative stress. The present randomised controlled investigation was designed to test the hypothesis that acute (consumption 2 h before exercise) and chronic (8 weeks consumption) watercress supplementation can attenuate exercise-induced oxidative stress. A total of ten apparently healthy male subjects (age 23 (sd 4) years, stature 179 (sd 10) cm and body mass 74 (sd 15) kg) were recruited to complete the 8-week chronic watercress intervention period (and then 8 weeks of control, with no ingestion) of the experiment before crossing over in order to compete the single-dose acute phase (with control, no ingestion). Blood samples were taken at baseline (pre-supplementation), at rest (pre-exercise) and following exercise. Each subject completed an incremental exercise test to volitional exhaustion following chronic and acute watercress supplementation or control. The main findings show an exercise-induced increase in DNA damage and lipid peroxidation over both acute and chronic control supplementation phases (P< 0·05 v. supplementation), while acute and chronic watercress attenuated DNA damage and lipid peroxidation and decreased H2O2 accumulation following exhaustive exercise (P< 0·05 v. control). A marked increase in the main lipid-soluble antioxidants (α-tocopherol, γ-tocopherol and xanthophyll) was observed following watercress supplementation (P< 0·05 v. control) in both experimental phases. These findings suggest that short- and long-term watercress ingestion has potential antioxidant effects against exercise-induced DNA damage and lipid peroxidation.

Antioxidants have shown beneficial effects in several biological systems, in which they were able to prevent oxidative stress-associated damage. Vitamins C and E are key antioxidants in man. Dietary intake cannot accurately reflect plasma vitamin levels. However, the plasma levels of antioxidant vitamins could also reflect the acute assimilation of these vitamins. It has been pointed out that antioxidant vitamin blood contents reach a saturation level by intake of dietary supplements. Antioxidant vitamin plasma levels are the parameter most used to determine antioxidant status. However, the vitamin plasma levels may not reflect the nutritional status of vitamins. It has been pointed out that the vitamin E in adipose tissue can be used as a measure of vitamin E status. To determinate antioxidant vitamin contents in lymphocytes and neutrophils after exercise is a useful tool to assess the functional status of antioxidant vitamins.

The present study was to investigate the effects of l-arginine (l-Arg) supplementation on cardiac oxidative stress and the inflammatory response in rats following acute exhaustive exercise on a treadmill. Rats were randomly divided into four groups: sedentary control (SC); SC with l-Arg treatment (SC+Arg); exhaustive exercise (E); exhaustive exercise with l-Arg treatment (E+Arg). Rats in groups SC+Arg and E+Arg received a 2% l-Arg diet. Rats in groups E and E+Arg performed an exhaustive running test on a treadmill at a final speed of 30m/min, 10% grade, at approximately 70–75% VO2max. The results showed a significant increase in cardiac xanthine oxidase (XO) and myeloperoxidase activities and membrane lipid peroxidation endproduct (malondialdehyde; MDA) levels of exercised rats compared with SC rats. The increased cardiac XO activity and MDA levels in exercised rats were significantly decreased in exercised rats supplemented with l-Arg. Myocardial GSSG content increased whereas the GSH:GSSG ratio was depressed in exercised rats compared with SC rats. Cardiac GSSG levels significantly decreased, whereas total glutathione, GSH and the GSH:GSSG ratio increased in exercised rats supplemented with l-Arg compared with exercised rats. The activities of creatinine kinase (CK) and lactate dehydrogenase (LDH), and lactate, uric acid, and nitrite and nitrate levels in the plasma significantly increased in exercised rats compared with SC rats. The activities of plasma CK and LDH were significantly decreased in l-Arg-supplemented plus exercised rats compared with exercised rats. These findings suggest that l-Arg supplementation reduces the oxidative damage and inflammatory response on the myocardium caused by exhaustive exercise in rats.

Strenuous exercise is known to induce oxidative stress leading to the generation of free radicals. The purpose of the present study was to investigate the effects of lycopene, an antioxidant nutrient, at a relatively low dose (2·6 mg/kg per d) and a relatively high dose (7·8 mg/kg per d) on the antioxidant status of blood and skeletal muscle tissues in rats after exhaustive exercise. Rats were divided into six groups: sedentary control (C); sedentary control with low-dose lycopene (CLL); sedentary control with high-dose lycopene (CHL); exhaustive exercise (E); exhaustive exercise with low-dose lycopene (ELL); exhaustive exercise with high-dose lycopene (EHL). After 30 d, the rats in the three C groups were killed without exercise, but the rats in the three E groups were killed immediately after an exhaustive running test on a motorised treadmill. The results showed that xanthine oxidase (XO) activities of plasma and muscle, and muscular myeloperoxidase (MPO) activity in group E were significantly increased compared with group C. Compared with group E, the elevations of XO and MPO activities of muscle were significantly decreased in group EHL. The malondialdehyde concentrations of plasma and tissues in group E were significantly increased by 72 and 114 %, respectively, compared with those in group C. However, this phenomenon was prevented in rats of the ELL and EHL groups. There was no significant difference in the GSH concentrations of erythrocytes in each group; however, exhaustive exercise resulted in a significant decrease in the GSH content of muscle. In conclusion, these results suggested that lycopene protected muscle tissue from oxidative stress after exhaustive exercise.