(P25-026-20) Association of Fitness Level Early in Pregnancy with Compliance Toward an Exercise Intervention Throughout Gestation in Obese Women

Objectives: Low participant compliance with prenatal exercise trials can result in loss of power to detect intervention effects. The objective of this study was to assess the association of aerobic capacity at enrollment with compliance with an exercise intervention throughout gestation.

Methods: Fifty-nine sedentary women with obesity who participated in the exercise arm of a randomized controlled trial were assessed at gestation week 12, and compliance was monitored throughout gestation. Fat-free mass index (FFMI, kg/m²) was obtained by DXA and measured height. Submaximal VO₂ (Borg score of 15) was measured using an incremental treadmill protocol.  VO₂ was normalized to FFMI (ml·min^-1· FFMI^-1).  A VO₂ cutoff of ≥112.7 (Q3 to highest data point) or ≤69.4 (Q1 to smallest data point) was used to classify women as “High” (n=17) or “Low” (n=17) fitness. Compliance (%) was estimated using the date of first exercise and delivery date, assuming a goal of 3 exercise sessions per week. Education level and birth weight were self-reported, whereas gestational weight gain (GWG), and gestational age (GA) were calculated.

Results: Groups were similar in BMI and LBMI at enrollment. The proportion of women with a college degree differed between groups (High=100% vs. Low=29%, p< .0001), and there was interaction between baseline fitness level (VO2) and education level (p=0.004) in predicting compliance to the exercise intervention. For women with a college degree, there was no difference in compliance between high and low fitness groups (72±5% vs. 60±10%, p=NS). However, compliance was lower in women in the Low group with high school degree than in women in the High group (52±6%vs.72±5%, p=0.0244). There were no impact of education on compliance for the low fitness group. GWG, GA and birth-weight were similar between groups (p=NS).

Conclusions: In these preliminary analyses, there was an interaction between fitness and education level on compliance with a prenatal exercise intervention. Compliance was about 20 percentage points lower in women with lower fitness and lower education when compared to women with higher fitness and higher education at enrollment.

Funding Sources: USDA-ARS Project 6026-51000-012-06S