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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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SUBSTRATE UTILIZATION IS INFLUENCED BY ACUTE DIETARY CARBOHYDRATE INTAKE IN ACTIVE, HEALTHY FEMALES |
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Sara Gregory  ,
Richard Wood, Tracey Matthews, Deborah VanLangen, Jason Sawyer and Samuel
Headley |
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Department of Exercise Science and Sports Studies, Springfield College, Springfield, MA, USA |
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© Journal of Sports Science and Medicine (2011) 10, 59 - 65 |
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| ABSTRACT | |||
| The present study compared the metabolic responses between a single
low-carbohydrate (LC) and low-fat (LF) meal followed by an aerobic exercise
bout in females. Subjects included 8 active, premenopausal females. Subjects
completed a LC and LF testing session. Respiratory gas exchange (RER) measurements
were taken for 20 min fasted, for 55 min postprandial (PP), and during 30
min of exercise. Blood was collected for assessment of glucose (G), insulin
(IN), triglycerides (TG), and free fatty acids (FFA) during the final 10
min of each time period. The LF meal provided 396 kcal (78% carbohydrate,
7% fat, and 15% protein). The LC meal provided 392 kcal (15% carbohydrate,
68% fat, and 18% protein). No significant differences existed between test
meals for fasting blood measurements. PP IN (µU·mL-1) levels were significantly
lower following LC compared to LF [10.7 (6.1) vs. 26.0 (21.0)]. Postexercise
(PE) FFA (mEq·L-1) levels were significantly greater following LC [1.1 (0.3)
vs. 0.5 (0.3)]. PE TG (mg·dL-1) levels were significantly greater following
LC [152.0 (53.1) vs. 114.4 (40.9)]. RER was significantly lower at all time
points following LC compared to LF. In moderately active adult females,
ingestion of a single LC meal resulted in greater lipid oxidation at rest
and during exercise as compared to a single LF meal. Although macronutrient
distribution appears to have dictated substrate utilization in the present
study, more research is needed regarding the long-term effects of macronutrient
redistribution with and without exercise on substrate utilization.
Key words: Macronutrient distribution, exercise, low-carbohydrate. |
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