M189. A PILOT RANDOMISED CONTROLLED TRIAL TO ASSESS THE FEASIBILITY AND ACCEPTABILITY OF HIGH INTENSITY INTERVAL TRAINING (HIIT) AMONG INPATIENTS WITH SEVERE MENTAL ILLNESS (SMI)

Background High intensity interval training (HIIT) is a type of exercise involving alternating short bursts of high intensity exercise with recovery periods of rest or light exercise. HIIT has been shown to improve physical and mental health in healthy individuals and those with physical illnesses, such as cardiovascular and cardiometabolic diseases. Initial work has shown that HIIT may have similar benefits in people experiencing mental illnesses. The primary aim for the trial is to investigate whether HIIT is acceptable and feasible amongst inpatients with severe mental illnesses (SMI), including schizophrenia. The secondary aim is to investigate the impact of the HIIT intervention on potential outcome measures for a definitive multi-centre RCT, including mental health symptoms, cognition, psychiatric symptoms and cardio-metabolic risk factors. Methods A randomised, non-blinded controlled design of HIIT compared to treatment as usual (TAU) in inpatients with SMI will be undertaken. The RCT will act as a feasibility trial and a pilot study. Up to forty 18-60-year olds with a diagnosis of SMI will be recruited and randomly allocated to either 12 weeks of HIIT or 12 weeks of TAU in a 1:1 ratio. Those in the HIIT group will take part in two one-to-one sessions of HIIT each week for 12 weeks on a stationary bike. Each session will comprise: a 4-minute warm-up, followed by 5X 60 second intervals with 85–95% of maximum heart rate (HRmax), with active pauses of 90 seconds cycling at approximately 60–70% of HRmax, followed by a 4-minute cool-down, although this will be adapted for those with lower fitness. In comparison, participants allocated to TAU will be provided with details of their local hospital gym availability and instructed to maintain their usual dietary habits. Acceptability and feasibility will be measured using multiple primary endpoints including the proportion of wards that agree to hosting the project, the proportion of people who consent to take part, adherence and attendance rates, and the proportion of participants who experience any adverse events. Multiple secondary endpoints will be assessed including, mental health markers (psychiatric symptoms, cognition, global functioning, sleep quality, depression, anxiety and stress), self-esteem, cardiometabolic markers (BMI, weight, waist circumference, systolic and diastolic blood pressure), daily activity levels, and cigarette usage. Results Primary endpoints will be reported post-trial completion and summarised by treatment arm over the course of the study. Secondary endpoints will be reported as pre-post intervention change, and overall group differences will be reported. For these secondary endpoints, a statistical analysis will be conducted based on the intention-to-treat sample. Additionally, a subgroup analysis will be conducted whereby we will measure secondary outcome effects in a sub-sample of participants with ‘high’ attendance (>64%). Discussion Following the pilot study, if HIIT is considered to be feasible and acceptable amongst inpatients with SMI, including schizophrenia, a further large-scale multi-centre study can be developed and undertaken to assesses the effectiveness of HIIT in ameliorating mental and physical health parameters, and time to discharge, in this population group.