Acute oxidative stress and antioxidant status responses following an American football match.

AIM: Intense physical activity is known to induce oxidative stress. Though regular physical training enhances the antioxidant defence system, the effects of diminished training periods are unclear. American football is one of the recently popular sports in Türkiye and is defined as a mixed activity. The aim of the research was to examine some markers of oxidative stress and antioxidant status in occasionally competitive American football players following a match, and relations with aerobic power and playing position. METHODS: Twenty two male players volunteered for the study. To determine oxidative stress and antioxidant status from blood samples collected before and immediately following a match, plasma malondialdehyde (MDA) and nitric oxide (NO) levels, erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and total antioxidant status (TAS) were assessed, using spectrophotometric methods. Wilcoxon's signed rank test was used to determine the match effect, and Mann-Whitney U test was used to compare playing position and VO2max effects. RESULTS: Plasma MDA (P<0.001) and NO (P<0.05) levels increased significantly following the match. Antioxidant parameters were unchanged following the match when compared with the resting level, except for a VO2max related effect (P<0.05) on TAS. CONCLUSION: Collected data revealed that an American football match caused excessive production of free radicals and oxidative stress. The training loads players underwent were not high enough to cause positive effects on the antioxidant status. To enhance training-induced antioxidant status adaptation, higher amounts of physical activity may be required.

African runners exhibit greater fatigue resistance, lower lactate accumulation, and higher oxidative enzyme activity.

Nine African and eight Caucasian 10-km runners resident at sea level volunteered. Maximal O2 consumption and peak treadmill velocity (PTV) were measured by using a progressive test, and fatigue resistance [time to fatigue (TTF)] was measured by using a newly developed high-intensity running test: 5 min at 72, 80, and 88% of individual PTV followed by 92% PTV to exhaustion. Skeletal muscle enzyme activities were determined in 12 runners and 12 sedentary control subjects. In a comparison of African and Caucasian runners, mean 10-km race time, maximal O2 consumption, and PTV were similar. In African runners, TTF was 21% longer (P < 0.01), plasma lactate accumulation after 5 min at 88% PTV was 38% lower (P < 0.05), and citrate synthase activity was 50% higher (27.9 +/- 7.5 vs. 18.6 +/- 2.1 micromol. g wet wt-1. min-1, P = 0.02). Africans accumulated lactate at a slower rate with increasing exercise intensity (P < 0.05). Among the entire group of runners, a higher citrate synthase activity was associated with a longer TTF (r = 0.70, P < 0.05), a lower plasma lactate accumulation (r = -0.73, P = 0.01), and a lower respiratory exchange ratio (r = -0.63, P < 0.05). We conclude that the African and Caucasian runners in the present study differed with respect to oxidative enzyme activity, rate of lactate accumulation, and their ability to sustain high-intensity endurance exercise.

Time course of the effects of a high-fat diet and voluntary exercise on muscle enzyme activity in Long-Evans rats.

This study examined the time course of the effects of a high-fat diet and voluntary running exercise on rat skeletal muscle carnitine acyltransferase (CAT), beta-hydroxy-acyl-CoA dehydrogenase (HAD), and citrate synthase (CS) activities. Sixty male Long-Evans rats were randomly allocated to receive either a standard (12% fat by energy) laboratory chow diet (CHOW) or a high-fat (76% by energy) diet (HFD) and placed in running wheels for up to 6 weeks. Energy intakes and weekly voluntary running distances were similar in the CHOW and HFD rats. In both groups, weekly training distance more than doubled from week 4 to week 6. However, increased training had little influence on soleus (s) CAT(s), HAD(s), and CS(s) activities. CAT(s) and HAD(s) activities were higher in the HFD rats than in the CHOW rats from 2 weeks onward (p < 0.005), and CS(s) activities were not different between groups and remained constant over time. In contrast, increased training distance after 4 weeks in the CHOW rats resulted in an increase in deep vastus (v) CAT(v) activities to values similar to those in HFD rats prior to increases in training volume (p < 0.005) but had no effect on their HAD(v) and CS(v) activities. Increases in HAD(v) and CS(v) activities with increased training volume were only seen in the HFD rats (p < 0.005). HAD(v) activities and HAD/CS(v) activity ratios correlated with training distance in the HFD rats only (p < 0.001 and p < 0.01, respectively). These results suggest that a high-fat diet improves the beta-oxidation capacity of rat predominantly slow-twitch soleus muscle and enhances the effects of modest levels of training on the mitochondrial density and beta-oxidation capacity of rat deep vastus mixed fast- and slow-twitch muscles.