Chronic Influence of Inspiratory Muscle Training at Different Intensities on the Serum Metabolome

Abstract

This study investigated the chronic effect of inspiratory muscle training (IMT) on the human serum metabolome in healthy male recreational cyclists. Using a randomized, parallel group design, twenty-eight participants were randomized to three IMT groups: low intensity (LI, n = 7); moderate intensity (MI, n = 10); and high intensity (HI, n = 11). The IMT was performed for 11 weeks. Another group of participants under the same conditions, who did not perform the IMT but participated in all procedures, was included as controls (CG, n = 6). Blood samples were collected one week before and after 11 weeks of IMT and analyzed for metabolite shifts using 1H NMR. Statistical analysis included a 4 (group) × 2 (time) repeated measures ANOVA using the general linear model (GLM), and multivariate principal component analysis (PCA). Untargeted metabolomics analysis of serum samples identified 22 metabolites, including amino acids, lipids, and tricarboxylic acid cycle intermediates. Metabolites shifts did not differ between groups, indicating that IMT at three intensity levels did not alter the serum metabolome relative to the control group. These results reveal novel insights into the metabolic effects of the IMT and are consistent with the results from other studies showing negligible chronic alterations in the serum metabolome in response to physical training.

Metabolomics, physical activity, exercise and health: A review of the current evidence

“…The literature to date, with some notable exceptions [22][23][24][25], overwhelmingly concludes that varying degrees of PA or exercise induce, or are associated with, quantifiable changes in the metabolome, as measured by MS and NMR spectroscopy in biological samples [15][16][17]. The metabolomic alterations associated with overall PA/exercise are most commonly characterized by changes in fatty acid metabolism, mobilization and lipolysis, the TCA cycle, glycolysis, amino acid metabolism, carnitine metabolism, purine metabolism, cholesterol metabolism and insulin sensitivity among others (Figure 1).…”

“…Importantly, they were able to validate these findings in an independent population-based cohort. Among the intervention studies, while some studies comparing metabolomic profiles of individuals before and after a long-term or PA/exercise intervention observed a clear distinction in the pre-and post-metabolomics profiles [36,43,66,68], several others have reported no differences [22][23][24][25]69]. Consequently, further work is needed to disentangle whether long-term PA/exercise can shift the metabolome, and by how much.…”

Research advances in the application of metabolomics in exercise science

“…For example, a short period of acute exercise can immediately cause changes in the metabolic pathways of skeletal muscle substrate utilization, and the changes in tricarboxylic acid (TCA) cycle metabolites are obvious after 1 h of exercise (Kelly et al, 2020;Tabone et al, 2021). Amino acids such as leucine, isoleucine, asparagine, methionine, lysine, glutamine, and alanine decreased significantly after 14 h of exercise, reflecting the large magnitude of changes in amino acid levels after acute exercise (Sakaguchi et al, 2019). Changes in plasma fatty acids, ketone bodies, bile acids, and triglycerides also showed changes that can last for several hours after acute exercise, eventually returning to pre-exercise levels (Sakaguchi et al, 2019).…”

“…Amino acids such as leucine, isoleucine, asparagine, methionine, lysine, glutamine, and alanine decreased significantly after 14 h of exercise, reflecting the large magnitude of changes in amino acid levels after acute exercise (Sakaguchi et al, 2019). Changes in plasma fatty acids, ketone bodies, bile acids, and triglycerides also showed changes that can last for several hours after acute exercise, eventually returning to pre-exercise levels (Sakaguchi et al, 2019). For example, weight lifting and dumbbell training, resistance exercises such as pull-ups.…”

“…The main question in exercise science research is to understand how exercise induces physiological adaptations in the body, such as an increase in muscle strength or aerobic metabolic capacity, and how these adaptations affect health. But what are the molecular network mechanisms and metabolic pathways that govern how humans adapt to exercise and gain health benefits (Sakaguchi et al, 2019;Blackburn et al, 2020;Febvey-Combes et al, 2021;Babu et al, 2022)? These questions remain to be fully elucidated, and the study of exercise metabolomics will greatly enrich the understanding of these molecular network mechanisms and metabolic pathways.…”