Effects of short-term graded dietary carbohydrate intake on intramuscular and whole body metabolism during moderate-intensity exercise.
Author
Maunder, EdBradley, Helen E
Deane, Colleen S
Hodgson, Adrian B
Jones, Michael
Joanisse, Sophie
Turner, Alice M
Breen, Leigh
Philp, Andrew
Wallis, Gareth A
Publication date
2021-05-27Subject
Sports medicine
Metadata
Show full item recordAbstract
Altering dietary carbohydrate (CHO) intake modulates fuel utilization during exercise. However, there has been no systematic evaluation of metabolic responses to graded changes in short-term (< 1 wk) dietary CHO intake. Thirteen active men performed interval running exercise combined with isocaloric diets over 3 days before evaluation of metabolic responses to 60-min running at 65% V̇O2max on three occasions. Diets contained lower [LOW, 2.40 ± 0.66 g CHO·kg-1·day-1, 21.3 ± 0.5% of energy intake (EI)], moderate (MOD, 4.98 ± 1.31 g CHO·kg-1·day-1, 46.3 ± 0.7% EI), or higher (HIGH, 6.48 ± 1.56 g CHO·kg-1·day-1, 60.5 ± 1.6% EI) CHO. Preexercise muscle glycogen content was lower in LOW [54.3 ± 26.4 mmol·kg-1 wet weight (ww)] compared with MOD (82.6 ± 18.8 mmol·kg -1 ww) and HIGH (80.4 ± 26.0 mmol·kg-1 ww, P < 0.001; MOD vs. HIGH, P = 0.85). Whole body substrate oxidation, systemic responses, and muscle substrate utilization during exercise indicated increased fat and decreased CHO metabolism in LOW [respiratory exchange ratio (RER): 0.81 ± 0.01] compared with MOD (RER 0.86 ± 0.01, P = 0.0005) and HIGH (RER: 0.88 ± 0.01, P < 0.0001; MOD vs. HIGH, P = 0.14). Higher basal muscle expression of genes encoding proteins implicated in fat utilization was observed in LOW. In conclusion, muscle glycogen availability and subsequent metabolic responses to exercise were resistant to increases in dietary CHO intake from ∼5.0 to ∼6.5 g CHO·kg-1·day-1 (46% to 61% EI), while muscle glycogen, gene expression, and metabolic responses were sensitive to more marked reductions in CHO intake (∼2.4 g CHO·kg-1·day-1, ∼21% EI).NEW & NOTEWORTHY The data presented here suggest that metabolic responses to steady-state aerobic exercise are somewhat resistant to short-term changes in dietary carbohydrate (CHO) intake within the 5-6.5 g CHO·kg-1·day-1 [46-61% energy intake (EI)] range. In contrast, reduction in short-term dietary CHO intake to ∼2.4 g CHO·kg-1·day-1 (21% EI) evoked clear changes indicative of increased fat and decreased CHO metabolism during exercise.Citation
Maunder E, Bradley HE, Deane CS, Hodgson AB, Jones M, Joanisse S, Turner AM, Breen L, Philp A, Wallis GA. Effects of short-term graded dietary carbohydrate intake on intramuscular and whole body metabolism during moderate-intensity exercise. J Appl Physiol (1985). 2021 Jul 1;131(1):376-387. doi: 10.1152/japplphysiol.00811.2020. Epub 2021 May 27Type
ArticleOther
Additional Links
https://journals.physiology.org/journal/japplPMID
34043470Journal
Journal of Applied PhysiologyPublisher
American Physiological Societyae974a485f413a2113503eed53cd6c53
10.1152/japplphysiol.00811.2020