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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
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.