Abstract
PurposeAlthough superoxide dismutase (SOD) and malondialdehyde (MDA) affect Delayed Onset Muscle Soreness (DOMS), their effects are unclear in rectus femoris muscles (RFM) of rats with different eccentric exercise programs and time points. The purpose of this study is to investigate the effects of the various eccentric exercise programs at different time points on the SOD mRNA expression and MDA using rat as the animal model.Methods248 male rats were randomly divided into 4 groups: control group (CTL, n = 8), once-only exercise group (OEG, n = 80), continuous exercise group (CEG, n = 80), and intermittent exercise group (IEG, n = 80). Each exercise group was divided into 10 subgroups that exercised 0.5 h, 6 h, 12 h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h, or 168 h. Rats were sacrificed and their SOD mRNA expression, and MDA concentrations of skeletal muscle tissue were measured.ResultsThe specimen in all eccentric exercise programs showed increased RFM SOD1 mRNA expression levels at 0.5 h (P<0.05), and decreased RFM SOD3 mRNA expression at 0.5 h (P<0.05). The continuous eccentric exercise (CE) significantly enhanced muscle SOD2 mRNA level at 0.5 h (P<0.05). After once-only eccentric exercise (OE), SOD1, SOD2, and SOD3 mRNA expression significantly increased at 96 h, whereas MDA concentrations decreased at 96 h. After CE, the correlation coefficients of SOD1, SOD2, SOD3 mRNA expression levels and MDA concentrations were −0.814, −0.763, −0.845 (all P<0.05) at 12 h.ConclusionRegular eccentric exercise, especially CE could enhance SOD1 and SOD2 mRNA expression in acute stage and the SOD2 mRNA expression correlates to MDA concentration in vivo, which may improve the oxidative adaption ability of skeletal muscles.
Highlights
Delayed-onset muscle soreness (DOMS) is the local pain and discomfort that develops 12–48 h after intensive and/or unusual eccentric exercise muscle action [1,2]
The mechanism of DOMS is unclear, but the etiology of DOMS is usually attributed to the establishment of an acute-phase inflammatory response that results from metabolic, mechanical, and oxidative stress, eccentric exercise is the main exercise mode that results in DOMS [4,5,6,7]
There were significant effects of time in SOD1, SOD2, and SOD3 mRNA levels and MDA concentrations were found at the same eccentric exercise programs
Summary
Delayed-onset muscle soreness (DOMS) is the local pain and discomfort that develops 12–48 h after intensive and/or unusual eccentric exercise muscle action [1,2]. Physical exercise can increase systemic oxygen consumption, causing generation of excessive reactive oxygen species (ROS) that elicit oxidative stress reactions in turn. Muscular oxidative stress induced by exercise training is the most obvious of these reactions and can cause muscular oxidative damage [8]. Superoxide dismutase (SOD) is the first enzymatic line of antioxidant and is an important enzyme in the antioxidant system, it could convert O22 to hydrogen peroxide (H2O2), thereby SOD were regarded as which could protect muscular oxidative stress from exercise effectively [9]. SOD exists in three isoforms, two of which are intracellular: SOD1, which accounts for approximately 90% of total SOD and exists in the cytoplasm and combines with copper or zinc to form a dimer; and SOD2, an inducible mitochondrial enzyme that combines with manganese to form a tetramer. Malondialdehyde (MDA) is a peroxidation product of lipids, and indirectly reflects the degree of ROS on membrane lipid peroxidation [14]
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