High Intensity Interval Training in Severe Mental Illness

People experiencing severe mental illnesses (SMI), including schizophrenia, psychosis, bipolar disorder and major depressive disorder, are prone to poorer physical health and increased incidences of premature mortality when compared to the general population (De Hert et al., 2009; Hert et al., 2011; Hennekens et al., 2005; Tiihonen et al., 2009 . High-intensity-interval-training (HIIT) is a type of exercise involving alternating short bursts of high intensity exercise with recovery periods of rest/ light exercise (Weston, Wisløff \& Coombes, 2014). HIIT improves physical health, quality of life and cognition in the general population and in those with physical health disorders (Gomes-Neto et al., 2017; Hwang, Wu \& Chou, 2011; Wen et al., 2019). It has been proposed that HIIT may improve symptoms, physical health and time to discharge among inpatients with SMI. The research will involve three stages: 1) Focus groups, 2) A pilot study, 3) Follow-up qualitative interviews and focus groups. Firstly, a series of focus groups with inpatients with SMI, carers of individuals with SMI and clinical staff will be conducted. The focus groups will scope perceptions of attitudes, and practicalities of a pilot RCT. The information gained will be used to inform a pilot HIIT trial which will evaluate whether HIIT is acceptable and feasible amongst this population group. Each focus group will run for ≈2 hours and will involve an open discussion about the benefits and barriers of conducting HIIT exercise sessions in a population with SMI. Secondly, the HIIT pilot study will be trialed. The final protocol will be developed with feedback from the focus group but will involve an RCT where 12 weeks of HIIT will be compared to 12 weeks of treatment-as-usual (TAU). HIIT will be conducted, twice a week, in a supervised environment using a stationary bike. Inpatients with a diagnosis of SMI will be eligible to participate. Thirdly, follow-up qualitative interviews, with pilot study partic