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The Journal of Sports Medicine and Physical Fitness 2016 Mar 09

lingua: Inglese

Dietary macronutrient distribution influences post-exercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility

Eric T. TREXLER 1, 2, Abbie E. SMITH­RYAN 1, 2, Hailee L. WINGFIELD 1, Malia N. BLUE 1, Erica J. ROELOFS 1, Katie R. HIRSCH 1

1 Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA; 2 Human Movement Science Curriculum, Department of Allied Health Sciences, University of North Carolina, Chapel Hill, NC, USA


BACKGROUND: Metabolic flexibility is the ability to alter substrate utilization in response to substrate availability, which may influence health and performance. The current study evaluated the effects of habitual macronutrient distribution on energy expenditure (EE) and metabolic flexibility in physically active women.
METHODS: Participants (n=20) completed a 3­day food log and a standardized bout of high­ intensity interval training to determine EE and respiratory exchange ratio (RER). EE and RER were measured via indirect calorimetry at rest (PRE) and immediately (IP), 30 minutes (30min), and 60 minutes post­exercise (60min). To evaluate metabolic flexibility, RER changes were calculated from PRE to IP, IP to 30min, and IP to 60min. For each macronutrient, participants were categorized into high­ and low­intake groups using a median split.
RESULTS: No significant correlations were observed between macronutrient distribution and EE when covaried for lean mass (all p≥0.232), and ANCOVAs revealed no significant group × time interactions (all p≥0.241). Fat intake was not associated with ∆RER (all p≥0.477). Correlations between PRO intake and ∆RER approached significance (r=0.373−0.411; p=0.079−0.115), as did inverse associations between CHO and ∆RER (r= ­0.404 − ­0.409; p=0.084−0.087). Lower RER values were observed in the low­CHO group at 30min and 60min (p=0.030) compared to high­CHO. Higher RER values were observed in the high­PRO group at IP (p=0.042) compared to low­PRO. Estradiol was not correlated with RER at any time point, or different between diet groups (all p≥0.401).
CONCLUSIONS: Results suggest that high PRO and low CHO intakes are associated with greater metabolic flexibility in women.

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