Metabolic flexibility to lipid during exercise is not associated with metabolic health outcomes in individuals without obesity
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Date
2024
Journal Title
Journal ISSN
Volume Title
Publisher
Nature Research
Abstract
A low metabolic flexibility to lipid (MetF-lip) in skeletal muscle may promote ectopic lipid accumulation, thus inducing metabolic disturbances. We aimed to determine the association between MetF-lip in skeletal muscle and metabolic health outcomes in individuals without obesity. We also explored the association between MetF-lip and the inflammatory signaling pathway in skeletal muscle. This was a cross-sectional study in 17 individuals aged (median [IQR]) 55.4 [48.6, 58.5] years, with a BMI of 24.4 [22.6, 26.0] kg/m(2). MetF-lip was assessed as the increase in relative lipid oxidation during a single exercise session (similar to 50% VO(2)max, 2 hours), quantified as the drop in whole-body respiratory exchange ratio (Delta RER = RER at 2 hours - maximum RER attained). HOMA-IR, metabolic syndrome z-score, fat percentage, trunk-to-appendicular fat, and VO(2)max were included as metabolic health outcomes. The abundance of proteins of the inflammatory pathway was analyzed in resting muscle. Acute exercise progressively increased relative lipid oxidation (Delta RER = -0.04 [-0.08, -0.02]). MetF-lip was not associated with any metabolic health outcome but correlated inversely with p-p38(Thr180/Tyr182) in muscle. A low MetF-lip in skeletal muscle does not seem a major determinant of metabolic disturbances but associates with a partial activation of the inflammatory signaling in individuals without obesity.
Description
Keywords
Mitogen-activated protein kinases, Cardiorespiratory Fitness, Body composition, Insulin resistance