Exercise FITT-V during pregnancy: dose-dependent reduction in infant cellular lipid content and whole body fat

Modifiable health behaviors such as exercise regulate adiposity in adults, but the effects of exercise during pregnancy on infant adiposity remain understudied. This report analyzed the relationship between prenatal exercise frequency, intensity, time, type, and volume (FITT-V) and infant adiposity, to better guide prenatal exercise prescription. Female participants [body mass index = 29.0 kg/m², 30.5 yr of age, with gravida = 1 and parity = 0, peak oxygen consumption (V̇o_2peak) = 21.9 mL/kg/min, and pregnant for 39.6 wk] were randomized to supervised exercise (aerobic, resistance, combination) or attention control for ∼24 wk during pregnancy. FITT-V metrics were analyzed from session records. Infant mesenchymal stem cells (MSCs), a model of infant adiposity, were collected from umbilical cord at delivery, adipogenically differentiated, and stained for lipids. Infant body fat percentage was estimated from skinfolds measured at 1 mo of age. Higher weekly exercise volume correlated with lower infant body fat (<i>R</i>² = 0.12, <i>P</i> = 0.03) and MSC lipids (<i>R</i>² = 0.13, <i>P</i> = 0.01). Weekly exercise frequency (<i>R</i>² = 0.06, <i>P</i> = 0.10) and total volume (<i>R</i>² = 0.19, <i>P</i> = 0.002) influenced adiposity. Subscapular skinfolds were notably affected by exercise (<i>R</i>² = 0.27, <i>P</i> < 0.001). We conclude that in utero exposure to exercise beyond minimum recommendations is associated with reduced infant adiposity. Specifically, our findings suggest that exercising below 450 metabolic equivalent (MET)·min/wk, e.g., exercising at an average of 3 METs for 150 min/wk or 5 METs for 90 min/wk, excludes individuals from these offspring health benefits.<b>NEW & NOTEWORTHY</b> This study was the first to test how specific prenatal exercise dose, i.e., the FITT-V (frequency, intensity, time, type, volume) metrics, could influence the storage of triglycerides in infant adipogenic mesenchymal stem cells (MSCs). Prenatal exercise led to a reduction in infant whole body fat percentage (BF%), which was reflected by lower lipid storage in infant MSCs. Changes in lipid content were observed in offspring born to participants exercising beyond the minimum recommended weekly volume, 450 metabolic equivalent (MET)·min/wk.