Infancy Weight Gain And Fat Mass In Youth- Does Physical Activity Modify The Association?

Abstract

Rapid weight gain in infancy has been linked to increased risk of obesity in youth. Hence, an increased knowledge on possible strategies to prevent excessive total fat mass (total FM) and trunk fat mass (trunk FM) is important to avoid development of obesity. One possible strategy could be moderate-to-vigorous physical activity (MVPA) or vigorous physical activity (VPA), since MVPA and VPA has been associated with lower levels of adiposity. However, it is unknown whether physical activity may modify the association between rapid infant weight gain and later adiposity. PURPOSE: To examine whether MVPA and VPA modifies the associations between weight gain the first year of life and total FM and trunk FM in youth. METHODS: We used data from a sub-cohort of the Norwegian Mother and Child Cohort Study (MoBa), including assessment of total FM and trunk FM by dual-energy X-ray absorptiometry (DXA), and MVPA (≥2296 cpm) and VPA (≥4012 cpm) assessed by Actigraph accelerometers. Weight gain was calculated as change in weight z-scores between birth and 1 year. We used multiple regression analyses to examine the association between infancy weight gain and total FM and trunk FM (with adjustments for sex, birth weight, gestational age, height and family income), and included the interaction term weight gain x MVPA and weight gain x VPA to examine the modifying effect of MVPA and VPA (adjustments for monitor wear time included). RESULTS: The mean age (sd) of the 147 participants (45.6% girls) were 11.0 (0.61) years. There was a positive association between infancy weight gain and total FM (B=1.1, 95%CI= 0.40, 1.8) and trunk FM (B=0.5 95%CI= 0.16, 0.89). MVPA did not modify the association between infancy weight gain and total FM (p=0.157) and trunk FM (p=0.116), whereas VPA modified both total FM (B (gain x VPA) = -0.061, p=0.026) and trunk FM (B(gain x VPA)= -0.034, p=0.014). CONCLUSION: These findings indicate that VPA, but not MVPA, modifies the associations between weight gain during the first year of life and total FM and trunk FM in youth. Vigorous intensity PA may be considered as one of many public health strategies to curb childhood obesity, especially in those who are prone to obesity due to rapid infant weight gain.