Physical activity associations with physical fitness in anorexia nervosa at baseline and after recovery

Anorexia nervosa (AN) patients often perform high levels of physical activity (PA), which does not necessarily diminish after a successful therapy (Kostrzewa, 2013), and have lower physical fitness (PF) than normal weight peers both at baseline and after weight restoration (Alberti, 2013). PURPOSE: This study examined the individual variation in PA in AN patients before and after treatment and explored if they are related to PF outcome. METHODS: 33 females receiving inpatient treatment for AN participated in this study (age, 23.2±8.8yr; weight, 38±5.2kg; height, 1.61±0.6m). PA was assessed with an activity monitor that combined heart rate and movement signals by measuring minutes of moderate PA (MPA), vigorous PA (VPA), and the sum of the minutes spent in moderate and vigorous PA (MVPA). PF was assessed with an adapted version of the Eurofit Physical Fitness Test Battery (EPFTB) including aerobic fitness, musculoskeletal fitness, flexibility and motor fitness (Alberti, 2013). All measurements took place during the first week and at the end of treatment. The treatment lasted 20 wk, and included 13 wk of inpatient therapy followed by 7 wk of day-hospital (Dalle Grave, 2008). RESULTS: The treatment was associated with a significant increase in body mass index (p<0.0001). Significant associations, adjusted for BMI, were found between MVPA and PF for Sit-Up Test (R2, .351; β, .244; p, <.001) at baseline. PA levels were positively associated with an increase in PF performance outcome (Handgrip Test: R2, .276; β, .439 p, <.01; Six-Minutes Walk Test: R2, .149; β, .307; p, <.05) at discharge, with a greater contribution of MPA. Each 10-min of MPA was associated with an increase of 0.4 kg of handgrip strength and with a gain of 2.88 m in the Six-Minutes Walk Test. CONCLUSION: Weight was restored after therapy. Aerobic and musculoskeletal fitness were positively affected by moderate physical activity levels. Future studies should investigate when an individualized health-enhancing physical activity program might be implemented during the weight restoration phase.