Ultraendurance exercise increases the production of reactive oxygen species in isolated mitochondria from human skeletal muscle

Abstract

Exercise-induced oxidative stress is important for the muscular adaptation to training but may also cause muscle damage. We hypothesized that prolonged exercise would increase mitochondrial production of reactive oxygen species (ROS) measured in vitro and that this correlates with oxidative damage. Eight male athletes (24-32 yr) performed ultraendurance exercise (kayaking/running/cycling) with an average work intensity of 55% V(O(2peak)) for 24 h. Muscle biopsies were taken from vastus lateralis before exercise, immediately after exercise, and after 28 h of recovery. The production of H(2)O(2) was measured fluorometrically in isolated mitochondria with the Amplex red and peroxidase system. Succinate-supported mitochondrial H(2)O(2) production was significantly increased after exercise (73% higher, P = 0.025) but restored to the initial level at recovery. Plasma level of free fatty acids (FFA) increased fourfold and exceeded 1.2 mmol/l during the last 6 h of exercise. Plasma FFA at the end of exercise was significantly correlated to mitochondrial ROS production (r = 0.74, P < 0.05). Mitochondrial content of 4-hydroxy-nonenal-adducts (a marker of oxidative damage) was increased only after recovery and was not correlated with mitochondrial ROS production. Total thiol group level and glutathione peroxidase activity were elevated after recovery. In conclusion, ultraendurance exercise increases ROS production in isolated mitochondria, but this is reversed after 28 h recovery. Mitochondrial ROS production was not correlated with oxidative damage of mitochondrial proteins, which was increased at recovery but not immediately after exercise.

Exercise modulation of total antioxidant capacity (TAC): towards a molecular signature of healthy aging

“…The influence of physical exercise regularity on TAC concentrations was tested. After consecutive days of exercise training a progressive decreasing on oxidative stress was observed, whereas the TAC remained at higher levels (Sahlin et al 2010). Although ultraendurance exercise had increased ROS production in isolated mitochondria this effect was abolished after 28 h and no mitochondrial protein damage was observed (Shing et al 2007).…”

Mitochondrial Proteomics: From Structure to Function

“…Severe exercise intensities activate a cascade of intracellular sources for reactive oxygen species (ROS) and it is clear that muscle adaptation depends on this process. However, it is important to observe that excessive ROS production can negatively influence exercise performance and can also lead to long-term health consequences (Bailey et al, 2004;Sahlin et al, 2010;Sun et al, 2010). The mechanism of increased ROS production during exercise is not totally clear, but experimental evidence suggests that mitochondria are the main source of ROS production during exercise (Di Meo & Venditti, 2001;Fernstrom et al, 2007).…”

The exercised skeletal muscle: a review

“…The first evidence that exercise induced increases in RONS came from electron spin resonance data [20,48]. Further studies demonstrated that active skeletal muscles released nitric oxide [7], hydroxyl radicals [84], superoxide anions [70] and hydrogen peroxide [71], but only recently it was incontrovertibly demonstrated that mitochondria are the major biological source of ROS production during physical exercise [93]. In fact, there are a number of possible intracellular sources for ROS beside mitochondria, including cytochrome P450, myeloperoxidase, xanthine oxidase, NADH oxidase and peroxisomal oxidative enzymes, all of which may be substantially increased upon exercise.…”