Long-term Moderate Intensity Aerobic Exercise And Changes In Macronutrient Energy Intake: Midwest Exercise Trial Ii (met Ii): 1340: Board #76 June 1 11:00 AM - 12:30 PM

Honas, Jeffery J.; Lambourne, Kate; Betts, Jessica L.; Sullivan, Debra K.; Donnelly, Joseph E. FACSM

Medicine & Science in Sports & Exercise:
doi: 10.1249/01.MSS.0000400740.07517.d5
A-34 Free Communication/Poster - Energy Expenditure: JUNE 1, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
Author Information

University of Kansas, Lawrence, KS.

Email: jhonas@ku.edu

(No relationships reported)

INTRODUCTION: Studies on the effects of aerobic exercise (Ex) on macronutrient energy intake profile (EIP) have primarily utilized acute Ex interventions or cross-sectional design and have been limited by the use of self-reported energy intake (EI) and Ex. The few long-term studies have produced conflicting results which may be explained by differences in EI and Ex assessments.

PURPOSE: To determine if participation in a progressive, 10 month moderate intensity supervised Ex program influenced EIP when compared to a sedentary control condition. Also, to examine the effects of sex and exercise energy expenditure (ExEE) level on EIP.

METHODS: 67 sedentary, overweight and obese (BMI 25 to < 40) young adults (age 18-30 years, 54% female) were randomly assigned to an Ex (n=52) or control group (n=15). The Ex groups expended 400 kcal (n=27) or 600 kcal (n=25) per session, 5 days/week under direct supervision of research staff. Ex intensity was prescribed by target heart rate range and verified by downloadable heart rate monitor. ExEE was assessed monthly via indirect calorimeter and minutes of Ex were adjusted to meet the ExEE targets. Participants were instructed to maintain their baseline EI patterns during the trial. During the EI assessment, participants consumed an ad libitum diet in a university cafeteria and all EI consumed outside the cafeteria was assessed using standardized dietary recall procedures. EI was assessed via digital picture plate waste over 7 consecutive days at baseline, 3.5, 7, and 10 months.

RESULTS: General linear mixed modeling was used to evaluate changes in macronutrient proportions across time for the Ex groups. The Ex and control groups did not differ in the percentage of fat (F2, 62 = 0.32, p = 0.73), carbohydrate (F2, 62 = 1.06, p = 0.35), or protein (F2, 62 = 1.76, p = 0.18) consumption after controlling for participants' age, gender, and baseline value. There was no significant sex difference in the EIP at baseline or any of the three follow-up assessment periods.

CONCLUSION: Participation in 10 months of supervised moderate intensity Ex did not change macronutrient profile in a group of sedentary young adults. This finding is in opposition to the commonly held belief that diet composition changes when people become physical active.

Supported by NIH Grant RO1 DK49181.

© 2011 American College of Sports Medicine