Physical Activity and Sedentary Behaviour in Children With Haemophilia

ABSTRACT Introduction Physical activity (PA) is vital in child development, while inactivity remains a leading contributor to global mortality. Therapeutic advances have enabled greater PA in boys with haemophilia (BwH), yet robust UK data on objectively measured PA and sedentary behaviour (SB) across severities are limited. Aim To investigate PA and SB in BwH and assess adherence to World Health Organization (WHO) guidelines for moderate‐to‐vigorous physical activity (MVPA). Methods Sub‐analysis of a prospective cohort at a UK haemophilia centre (2018). Participants ( n = 36; 6–16 years; all severities including inhibitors) wore hip mounted ActiGraph GT3X accelerometers for 7 days. Valid data required ≥ 9 h/day for ≥ 4 days. MVPA and SB were analysed using Evenson thresholds. Mixed‐effects models with random intercepts examined demographic/clinical correlates of MVPA and SB and the odds of achieving >60 min/day of MVPA. Results Across 216 valid days median daily MVPA was 52.5 min/day (IQR: 30.9–80.2), with no significant differences by disease severity. Age was the only significant predictor of MVPA and SB: each additional year was associated with 7.6 fewer minutes of MVPA and 27.6 more minutes of SB per day ( p < 0.01). Only 39.8% of valid days met the WHO MVPA guidelines. The probability of meeting this target declined from 79% at age 6to 8% at age 14. Conclusions Most BwH did not meet WHO MVPA guidelines, though activity levels were encouraging. Age‐related declines in MVPA and increases in SB mirror those seen in the general population, underscoring the need for early, tailored interventions to support lifelong activity in haemophilia.