| Summary |
Background: Many adults who are at risk or suffer from obesity and diabetes, show to have low energy expenditure or basal metabolic rates, which have then led to an increased use of carbs and less fats. This same pattern of obesity and diabetes has been shown in African American (AA) adults. Furthermore, it has been studied that AA children have an increased risk for developing obesity compared to Caucasian (C) children. Nonetheless, we do not know if these metabolic differences in AA and Caucasian children are present and detectable in infancy. Infants from women with obesity or diabetes have lower energy expenditure, or basal energy expenditure with increased use of carbs and less fat. This same pattern of obesity and diabetes has been shown in African American (AA) adults. Also, it has been shown that one to three-month-old infants of women with either obesity or diabetes during pregnancy have poor metabolic phenotype and lower resting energy expenditure. Conversely, non-gravid adults who are exercised trained have a healthy metabolic phenotype and increased resting energy expenditure with decreased carbohydrate and increased fat oxidation. However, we do not know if one to three-month-old infants exposed to exercise in utero have a similar metabolic phenotype, increased resting energy expenditure.Objective: This study was therefore designed to determine if there are differences in resting infant energy expenditure based on race (AA vs Caucasian), and to determine if there are differences in resting infant energy expenditure based on exercise exposure during pregnancy.Methods: To address these questions, we recruited 15 women with healthy infants between the ages of one to three months old. A maternal questionnaire was given prior to the start of the test to record the maternal descriptors from mother (BMI, maternal age, gestational age). While infants were sleeping, resting energy expenditure was measured for up to 30 minutes with an indirect calorimetry system. The system used a hooded canopy placed over infants to enable gas collection of CO2 and O2. This system provided infant resting energy expenditure (REE), percent fat oxidation (%FAT) and percent carbohydrate oxidation (%CHO) at rest. Results: A total of 15 full- term, healthy infants were recruited. AA and Caucasian women were similar in pre-pregnancy BMI, length of gestation, and age. Although infant REE was similar between AA and Caucasian infants, AA infants had a trend for lower percent fat oxidation in comparison to Caucasian infants (p=.77, Cohen's d=2.39). Exercisers and non-exercising women were similar in pre-pregnancy BMI, length of gestation, and age. Infants from women in the exercise group had a trend for higher REE (p=.39, Cohen's d=0.91) and %FAT (p=.12, Cohen's D=1.58) in comparison to infants from control women. Conclusion: Overall, these findings suggest AA infants have a different metabolic pattern already in infancy. This may suggest more research needs to be done with a larger sample size to determine if there are inherent metabolic differences between races from infancy. Further, these findings suggest that infants exposed to exercise in utero have an increased metabolism. Again, further research is needed to determine if these patterns persist in larger samples. |
