Abstract
We examined the capacity of high-intensity intermittent training (HI-IT) to facilitate the delivery of lipids to enzymes responsible for oxidation, a task performed by the carnitine palmitoyl transferase (CPT) system in the rat gastrocnemius muscle. Male adult Wistar rats (160-250 g) were randomly distributed into 3 groups: sedentary (Sed, N = 5), HI-IT (N = 10), and moderate-intensity continuous training (MI-CT, N = 10). The trained groups were exercised for 8 weeks with a 10% (HI-IT) and a 5% (MI-CT) overload. The HI-IT group presented 11.8% decreased weight gain compared to the Sed group. The maximal activities of CPT-I, CPT-II, and citrate synthase were all increased in the HI-IT group compared to the Sed group (P < 0.01), as also was gene expression, measured by RT-PCR, of fatty acid binding protein (FABP; P < 0.01) and lipoprotein lipase (LPL; P < 0.05). Lactate dehydrogenase also presented a higher maximal activity (nmol·min−1·mg protein−1) in HI-IT (around 83%). We suggest that 8 weeks of HI-IT enhance mitochondrial lipid transport capacity thus facilitating the oxidation process in the gastrocnemius muscle. This adaptation may also be associated with the decrease in weight gain observed in the animals and was concomitant to a higher gene expression of both FABP and LPL in HI-IT, suggesting that intermittent exercise is a “time-efficient” strategy inducing metabolic adaptation.
Highlights
High-intensity intermittent training (HI-IT) is characterized by repeated bouts of brief near-maximal or maximal intensity work, interspersed with periods of recovery [1] and is known to be a potent stimulus leading to metabolic adaptation in skeletal muscle [2]
Experimental design Weight gain, muscle lipid content, plasma lactate, and the activity of the proteins related to mitochondrial longchain fatty acids transport (CPT-I and -II), oxidation and glycolysis, as well as the mRNA expression of carnitine palmitoyl transferase (CPT)-I, CPT-II, fatty acid binding protein (FABP), lipoprotein lipase (LPL), peroxisome proliferator-activated receptor α and β (PPARα), PPARβ, and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1-α) were assessed in the gastrocnemius of trained rats submitted to HI-IT
Citrate synthase activity was significantly higher in both HI-IT and moderate-intensity continuous training (MI-CT) compared to Sed and in MI-CT compared to HI-IT
Summary
High-intensity intermittent training (HI-IT) is characterized by repeated bouts of brief near-maximal or maximal intensity work, interspersed with periods of recovery (rest or low-intensity work) [1] and is known to be a potent stimulus leading to metabolic adaptation in skeletal muscle [2]. A wide range of adaptations has been described for carbohydrate metabolism in response to HI-IT, including increased glycogen content [3], and increased lactate transport capacity [4]. HI-IT is generally thought to be less effective on the capacity of muscle to deliver lipids to mitochondria [3]. Intermittent physical activity is associated with a reduced risk of morbidity and mortality from cardiovascular diseases, and cumulative short bouts of repetitive exercise are thought to mimic the effects of longer bouts of exercise [5]. Since fat metabolism disorders are closely associated with the development of cardiovascular diseases, it becomes imperative to better understand the metabolic response to HI-IT
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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