Inflammatory response induced by resistance exercise

In the body human, there are around 640 skeletal muscles which together account for ~38% of total body mass for men and 30% for women.1 Skeletal muscle is crucial in precise movement and your functional unit cell (muscle fibre) has a vigorous regenerative capacity, with rapid reestablishment (by 3 weeks) of full power occurring even after severe damage that causes widespread myofibre necrosis.2 Exercise-induced muscle damage (EIMD) in humans frequently occurs after unaccustomed exercise, particularly if the exercise involves a large amount of eccentric contractions. There are three types of muscle actions: concentric, eccentric and isometric. The eccentric actions occur during the lowering phase of any weightlifting exercise and are defined as muscle actions at the places where the muscle lengthens because the contraction force is less than the resistive force.3 Initial resistance exercise stress affects muscle homeostasis promoting changes in muscle morphology, loss of sarcomeric structural proteins (e.g. desmin and dystrophin), muscle fibre segmental necrosis, alterations in connective tissue, in T-tubules and sarcoplasmic reticulum.4,5 Muscle damage is commonly defined by disruption of the extracellular matrix, basal lamina, and sarcolemma as well as damage within the muscle fiber to the contractile and cytoskeletal proteins. Sarcolemma disruption is confirmed by an increase in blood-borne levels of intramuscular proteins such as creatine kinase (CK), which in turn has been linked to production of an inflammatory response.6 The severity of the inflammation depends on the type, duration and intensity of exercise. Moreover, exercise with eccentric contractions will cause more damage and inflammation than concentric exercise of equal intensity and duration.7 In addition, regular exercise is beneficial to up regulating defense mechanisms against oxidative stress and to increased resistance against infection and a lower risk of appearance of disease. The aim in this review was to focus attention in inflammatory process caused by muscle damage after resistance exercises and, in addition, show the benefits of regular intensity exercise against oxidative stress, infections and some diseases.