Abstract
BackgroundBranched-chain amino acids (BCAA) i.e., leucine (Leu), isoleucine (Ile) and valine (Val) are important amino acids, which metabolism play a role in maintaining system energy homeostasis at rest and during exercise. As recently shown lowering of circulating BCAA level improves insulin sensitivity and cardiac metabolic health. However, little is known concerning the impact of a single bout of incremental exercise and physical training on the changes in blood BCAA. The present study aimed to determine the impact of a gradually increasing exercise intensity—up to maximal oxygen uptake (VO2max) on the changes of the plasma BCAA [∑BCAA]pl, before and after 5-weeks of moderate-intensity endurance training (ET).MethodsTen healthy young, untrained men performed an incremental cycling exercise test up to exhaustion to reach VO2max, before and after ET.ResultsWe have found that exercise of low-to-moderate intensity (up to ∼50% of VO2max lasting about 12 min) had no significant effect on the [∑BCAA]pl, however the exercise of higher intensity (above 70% of VO2max lasting about 10 min) resulted in a pronounced decrease (p < 0.05) in [∑BCAA]pl. The lowering of plasma BCAA when performing exercise of higher intensity was preceded by a significant increase in plasma lactate concentration, showing that a significant attenuation of BCAA during incremental exercise coincides with exercise-induced acceleration of glycogen utilization. In addition, endurance training, which significantly increased power generating capabilities at VO2max (p = 0.004) had no significant impact on the changes of [∑BCAA]pl during this incremental exercise.ConclusionWe have concluded that an exercise of moderate intensity of relatively short duration generally has no effect on the [∑BCAA]pl in young, healthy men, whereas significant decrease in [∑BCAA]pl occurs when performing exercise in heavy-intensity domain. The impact of exercise intensity on the plasma BCAA concentration seems to be especially important for patients with cardiometabolic risk undertaken cardiac rehabilitation or recreational activity.
Highlights
Amino acids in human body are present mainly in the form of proteins, most of which are contained in skeletal muscles (40–45% of total body protein pool), whereas the pool of free amino acids constitutes less than 2% of total body amino acids
The 5-week endurance training resulted in a significant increase (∼8%) in power output reached at VO2max, which was accompanied by the significant increase in time to exhaustion (Table 1)
The main finding of this study is that low-to-moderate intensity exercise performed in young healthy men had essentially no significant impact on the plasma branched-chain amino acids concentration in relation to their levels at rest, when cycling in heavy-intensity domain a significant decrease in plasma Branched-chain amino acids (BCAA) concentration have been found
Summary
Amino acids in human body are present mainly in the form of proteins, most of which are contained in skeletal muscles (40–45% of total body protein pool), whereas the pool of free amino acids constitutes less than 2% of total body amino acids. Among the essential amino acids (which cannot be synthesized from other metabolites in human body), the branched-chain amino acids (BCAA) i.e., leucine (Leu), isoleucine (Ile) and valine (Val), are the most relevant amino acids metabolized during exercise (Wagenmakers et al, 1989). Restriction of dietary BCAA by lowering of circulating BCAA levels improves whole-body and skeletal muscle insulin sensitivity in obese rats (White et al, 2016) and lowers lipid accumulation in their hearts, which has positive impact on cardiometabolic health (McGarrah et al, 2020). The present study aimed to determine the impact of a gradually increasing exercise intensity—up to maximal oxygen uptake (VO2max) on the changes of the plasma BCAA [ BCAA]pl, before and after 5-weeks of moderate-intensity endurance training (ET). The impact of exercise intensity on the plasma BCAA concentration seems to be especially important for patients with cardiometabolic risk undertaken cardiac rehabilitation or recreational activity
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