Summary
Research article - Report
See the full content of this document
Extract
Cell damage, antioxidant status, and cortisol levels related to nutrition in ski mountaineering during a two-day race.
Introduction
Strenuous exercise, particularly eccentric exercise (in which muscles contract and lengthen), causes muscle cell damage, the so-called exercise-induced muscle damage (EIMD). Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities have been used as markers of muscle cell damage because they are released into blood when a disruption occurs in the sarcomere. High blood levels of these enzymes have been observed in many sports. The highest levels have been found in marathon (Kobayashi et al., 2005), ultramarathon (Fallon et al., 1999), ironman (Neubauer et al., 2008), and cross-country skiing (Ronsen et al., 2004). Although exercise-induced muscle damage is necessary for training progress, excess damage may impair performance. Thus, the damaging effect of eccentric muscle contractions, though necessary for adaptive remodelling, can effect subsequent exercise sessions due to residual muscle pain, restriction of movement, and a reduced capacity to exercise at a beneficial intensity. In fact, muscle-damaging exercise may lead to an impaired muscle function, mainly occurring as a loss of torque and range of motion (Paschalis et al., 2007; Radak et al., 1999). Cells are continuously producing reactive oxygen species (ROS) due to their metabolic processes (Urso and Clarkson, 2003). ROS may damage DNA, cytosolic molecules, and cell membranes (lipoperoxidation), causing cell damage and also death. Strenuous exercise has been shown to be able to accelerate ROS production (Nikolaidis et al., 2008). The effects of ROS are opposed by a complex of antioxidant molecules. These antioxidants may be enzymatic (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase) and nonenzymatic [vitamins A, E, and C, glutathione, ubiquinone, flavonoids, trace elements (selenium, copper, zinc, manganese), uric acid, albumin, ferritin, bilirubin]. The term "oxidative stress" refers to an imbalance between ROS production and the antioxidant defence. Oxidative stress may therefore result from an increased production of ROS (e.g. after strenuous exercise) and...See the full content of this document
Sponsored links
