Effects of high intensity interval training among overweight individuals with psychotic disorders: A randomized controlled trial

Physical activity has been suggested to reduce the high prevalence of metabolic complications in individuals with psychosis. Although high intensity interval training (HIIT) is efficacious in other populations, it remains poorly studied in psychosis. Methods: Randomized controlled study comparing the effects of 6 months HIIT supervised program (30-minute treadmill sessions twice a week) to usual-care waiting-list control group. Anthropometric (primary outcome: waist circumference), body composition, blood profile, blood pressure, psychiatric symptoms and global functioning were measured at baseline and 6 months. Results: Sixty-six individuals with psychosis (62% men; 30.7 ± 7.2 years old; mean BMI: 32.7 ± 5.7 kg/m²) were randomly assigned to either HIIT (n = 38) or control group (n = 28). Mean attendance rate to HIIT sessions was 64%, although 50% dropped-out the intervention before the end. Few minor adverse events were reported. The intent to treat analysis showed no impact of HIIT on waist circumference (p = 0.25). However, in a post-hoc analysis among the compliant participants (>64% of prescribed sessions), significant improvements in waist circumference (−2.94, SE = 1.41, p = 0.04), negative symptoms (PANSS negative −3.7, SE = 1.39; p = 0.01), social (SOFAS +6.16, SE = 1.76, p = 0.001) and global functioning (GAF +5.38, SE = 2.28, p = 0.02) were observed. Discussion: HIIT seems to be safe and well accepted in overweight individuals with psychosis. Exercise compliance to HIIT is associated with improvements in waist circumference as well as negative symptoms and functioning. Interventions improving attendance are needed.