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Substrate Oxidation Changes During Exercise In Children: Recommended VS. Low Dairy Intake: 2465Board #48 May 31 8:00 AM - 9:30 AM

Smith, Bryan K.1; Goetz, Jeannine R.2; Cook-Wiens, Galen3; Sullivan, Debra K.2; Donnelly, Joseph E. FACSM1

Medicine & Science in Sports & Exercise: May 2008 - Volume 40 - Issue 5 - p S466
doi: 10.1249/01.mss.0000322978.43241.8c
G-14 Free Communication/Poster - Children and Adolescents 2: MAY 31, 2008 7:30 AM - 11:00 AM ROOM: Hall B

1University of Kansas, Lawrence, KS. 2University of Kansas Medical Center, Kansas City, KS. 3University of Kansas School of Medicine, Kansas City, KS.


(No relationships reported)

PURPOSE: To determine if increased dairy product consumption will result in increased fat oxidation in children during an exercise induced energy deficit.

METHODS: Twenty-four sedentary and overweight (90.9±4.4 BMI%tile), adolescent (14.2±0.8 y) boys (n=14) and girls (n=10) who consumed less than 1 dairy serving per day (0.42±0.44 servings/d) were randomized to a 7 day iso-caloric diet consisting of a recommended dairy diet (REC; 3-4 servings/d) or a low dairy diet (LOW; <1 serving/day). All meals and snacks were provided during each dietary treatment. 24-h substrate oxidation was measured in a whole room indirect calorimeter on day 7 of each dietary treatment. An energy deficit of 300 kcal was induced through cycle ergometer. Following a 2 wk washout period during which participants consumed less than one dairy serving per day, they crossed over to the opposite treatment and repeated all procedures.

RESULTS: Calcium intakes were 1325.1±191 and 497.2±51.4 mg/day for the REC and LOW treatments respectively. The average exercise energy deficit was 254±134 and 261±165 kcal for the REC and LOW treatments respectively. When comparing the REC and LOW treatments, there were no significant differences between treatments for 24-hr fat oxidation rates (113.7±16.2 vs. 113.8±22.5 g/day, respectively) or exercise respiratory quotient (0.91±0.03 vs. 0.91±0.02, respectively). The 24-hr protein oxidation rates were significantly lower (p=0.011) in the REC treatment (29.1±5.9 g/d) compared to the LOW treatment (34.6±6.0 g/day).

CONCLUSION: Increased consumption of dairy products did not increase mean 24-h fat oxidation or mean fat oxidation during exercise in overweight adolescent children in this study. Increased dairy consumption did decrease mean protein oxidation. There is evidence in the literature to suggest that this decrease in protein oxidation may be due to an increase in muscle protein synthesis. If this is in fact true, increased dairy consumption may have the potential to preserve or increase muscle mass, which in turn could play a favorable role in long term weight management. This association between increased dairy consumption and decreased protein oxidation and its role in long term weight management requires further investigation. Supported by National Dairy Council.

©2008The American College of Sports Medicine