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_Nowadays, systematic exercise is an integral component of current guidelines for health promotion and improvement of quality of life. Exercise is traditionally categorized in two main types, endurance exercise and resistance exercise. Despite their differences in performing these two types of physical activity, both affect beneficially human health. Indeed, there is strong evidence that people who participate regularly in either endurance or resistance exercise are less likely to develop obesity, abnormal lipid profiles, coronary artery disease, type 2 diabetes, and sarcopenia. Most resistance exercise programs include dynamic repetitions with both concentric and eccentric muscle actions. A concentric muscle action primarily occurs when the muscle shortens to lift a load (e.g., ascending stairs or the upward movement of a bicep curl), whereas an eccentric muscle action occurs when the muscle lengthens to lower a load (e.g., descending stairs or the downward movement of a bicep curl). It is worth noting that an acute bout of eccentric exercise usually disturbs muscle function up to a week. Research from our group have shown that most of the changes in resting energy expenditure, substrate oxidation, and blood lipid profile appear and disappear during a week after an acute eccentric exercise session. Moreover, it is known that eccentric exercise can increase oxidative stress/damage in blood and skeletal muscle of rats and humans. In a study of our group it was found that alterations in redox biomarkers may persist for and/or appear several days after muscle-damaging exercise which is in direct contrast to the rapid return of redox biomarkers to the resting values within a few hours after an acute non-muscle-damaging exercise. Our research is focusing on the effects of eccentric exercise on human health status, on muscle oxygenation and on redox biology.