Modular Control Of Walking And Physical Activity During Pregnancy And Early Postpartum: A Case Study

During pregnancy, changes in weight and weight distribution can affect balance and gait patterns and may require changes in the neuromuscular control of walking. Neuromuscular control can be characterized by modular control, groups of muscles activated together based on changes in organization (which muscles are grouped together) and complexity (the number of modules). PURPOSE: This case study aimed to determine the impact of pregnancy and early postpartum on the modular control of walking. We hypothesized that modular control would 1) become more complex and change in organization as pregnancy progressed to compensate for changes in weight and balance and 2) return to early pregnancy complexity and organization as weight began to normalize postpartum (PP). METHODS: One active pregnant female (31.9 y) walked at preferred speed while motion capture data was collected and electromyography (EMG) was recorded from 9 muscles at 8, 14, 20, 26, 32, and 38 weeks (w) of pregnancy and 6w PP. Physical activity data (daily steps, weekly running mileage) were also collected. Modules were identified from EMG by non-negative matrix factorization. RESULTS: From 8w-26w, modular control complexity and organization was consistent (Fig. 1). At 32w and 38w, complexity increased with the addition of an independent hamstring (H) module. Complexity returned to early pregnancy levels PP, but a new modular organization was observed. The late pregnancy H module was retained while the plantar flexor (PF) and tibialis anterior (TA) modules merged into a single PFTA module. Late pregnancy changes in modular control correlated with increased weight gain and decreased activity. CONCLUSIONS: Modular control organization and complexity was impacted in the last trimester of pregnancy and PP, potentially due to greater changes in weight and decreased physical activity. We are currently investigating if dynamic balance (whole-body angular momentum) changed with modular control during pregnancy.