Abstract
High-intensity interval training (HIIT) markedly activates muscle anaerobic glycolysis and increases blood lactate. As the liver is a major organ for lactate clearance from the bloodstream, it might improve gluconeogenesis from lactate (NEO-lac) after a period of resistance HIIT. NEO-lac was evaluated by <i>in situ</i> liver perfusion in mice subjected to a resistance HIIT for 4 (T4) or 8 (T8) weeks, or not trained (T0). Perfusion was carried out immediately after an incremental exercise session to test the acute NEO-lac. Muscle strength (expressed as relative maximum load) and blood lactate were higher in T4 than in T0, but NEO-lac did not differ, possibly because of energy discharge of the liver and substrate overload. After 8 weeks of HIIT (T8), both muscle strength and liver NEO-lac increased, but blood lactate did not. The resistance HIIT for 8 weeks modulated liver gluconeogenic efficiency and capacity, which are important mechanisms for the improved clearance of blood lactate.
Highlights
When there is an intense use of glucose as energy source, such as in high-intensity exercise, muscle pyruvate tends to build up because of saturation of the cyclic acid cycle
Blood lactate is used for the assessment of aerobic capacity because it is a residual product of glycolysis that is measured and has a high correlation with exercise performance [5,6,7,8]
These data on performance assure that the resistance High-Intensity Interval Training (HIIT) was suitable to assess the major goal of this study: to evaluate if liver gluconeogenesis from lactate (NEO-lac) responds positively to a resistance high-intensity interval training or, in other words, whether this metabolic pathway can be modulated by this model of HIIT
Summary
When there is an intense use of glucose as energy source, such as in high-intensity exercise, muscle pyruvate tends to build up because of saturation of the cyclic acid cycle. Under these circumstances, it is reduced to lactate, a reaction catalyzed by cytosolic enzyme lactate dehydrogenase (LDH). Blood lactate concentration depends on its turnover, its rates of addition to and removal from the bloodstream. These can vary according to the physiological circumstances, among which exercise [3]. Blood lactate is used for the assessment of aerobic capacity because it is a residual product of glycolysis that is measured and has a high correlation with exercise performance [5,6,7,8]
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