Altered substrate utilization during sequential short‐term under‐ and over‐feeding
Abstract
Cycles of under‐ (UF) and overfeeding (OF) experienced during training and competition may result in alterations in energy expenditure (EE) and substrate utilization (SU) that impact body composition and physical performance. The time‐course and persistence of energy imbalance influences on EE and SU however, are not well‐defined. This study aimed to determine if a short period of UF affects resting EE (REE) and SU during rest and exercise during a subsequent period of OF. Volunteers (10M, 4F) underwent consecutive 4 day periods of energy balance (EB), UF (60% of EB) and OF (150% of EB); dietary macronutrient composition and total energy expenditure were constant. SU and EE were measured by indirect‐calorimetry on day 4 of each phase. REE was stable between conditions. During OF, resting fat oxidation was decreased (p<0.001) compared to EB and UF (0.32±0.29 vs. 0.93±0.51, 1.06±0.42, mg/kg‐FFM/min) and carbohydrate oxidation increased (3.30±1.02 vs. 2.00±1.43, 1.24±0.74 mg/kg‐FFM/min). Fat oxidation during exercise was higher during UF (2.39±1.29) and lower during OF (0.79±0.58) compared to EB (1.90±1.03 mg/kg‐FFM/min, p<0.001). Concomitantly, CHO oxidation during exercise was lower during UF (25.00±5.07) and higher during OF (29.69±5.98) compared to EB (27.11±5.27 mg/kg‐FFM/min, p<0.001). These data suggest that 4 days of energy imbalance is sufficient to alter SU during rest and exercise. Funded by MRMC.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 01, 2010
- Source ID
- 10.1096/fasebj.24.1_supplement.805.1
Entities
People
- Andrew J Young
- David W. DeGroot
- J Philip Karl
- Matthew R. Ely
Organizations
- United States Army Medical Research and Development Command
- United States Army Research Institute of Environmental Medicine