Acta Psychiatrica Scandinavica | 2019
High‐intensity interval training: an adjunctive treatment for schizophrenia spectrum disorders?
Abstract
Schizophrenia is associated with a premature mortality gap of 15–20 years compared with that in the general population (1). The majority of years of life lost in schizophrenia results from poor physical health, specifically cardiovascular and cardiometabolic diseases (2). The rates of cardiovascular disease (CVD), coronary heart disease (CHD), type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) are at least two-fold higher in people with schizophrenia compared with the general population (2, 3). The increased incidence and deleterious impact of cardiovascular and cardiometabolic disease in schizophrenia are multifactorial including genetic predisposition, the illness itself, side-effects of antipsychotic medication, social determinants and lifestyle behaviours (3). Despite a growing interest in the mental and physical interface and advances in health care, the unfortunate reality is that the number of years of life lost due to physical health conditions is increasing in this population group (4). Recently, there is growing interest in lifestyle interventions such as physical activity as a method of protecting physical health and wellbeing among people with schizophrenia (3). This is for good reason since outside of mental health services, there is robust evidence that physical activity is equally as effective as common pharmacological treatments to prevent and manage cardiovascular disease and mortality (5). Despite this, people with schizophrenia spend on average 476.0 min per day being sedentary and engage in substantially less physical activity than matched controls (6). People with schizophrenia experience many barriers to engagement in physical activity, including sedative effects of psychotropic medication, complications from poor physical health, lack of support and avolition (7). A pressing focus of current research (and implementation in clinical practice) is to increase the reach of exercise-based interventions amongst people with schizophrenia and establish optimal programmes for individuals (8). The positive effects of physical activity and exercise interventions for people with schizophrenia have been researched in an abundance of randomised controlled trials (RCTs), systematic reviews and meta-analyses. A recent meta-review of 20 systematic reviews and meta-analyses displayed a therapeutic benefit of physical activity in people with severe mental illnesses, including schizophrenia (8). Specifically, physical activity and exercise interventions improved psychiatric symptoms, body weight, body mass index (BMI), waist circumference (WC), body fat percentage, cardiorespiratory fitness and cognitive domains amongst people with schizophrenia, although evidence was hampered by a small number of RCTs for each outcome, and small sample size (8). Additional to these benefits, physical activity and exercise interventions may improve sleep quality (9) and help people quit smoking and reduce cravings (10). Thus, physical activity may be a modifiable lifestyle factor that can revise cardiovascular and cardiometabolic ill health and improve wellbeing. Hence, the recent EPA guidance recommends utilising physical activity as an adjunctive treatment for schizophrenia spectrum disorders (8). Whilst promising evidence now exists about the benefits of physical activity in schizophrenia, most trials have focussed on the benefits of continuous aerobic exercise over longer periods of time on health outcomes, for instance, completing three sessions of at least 30 min of moderate exercise which can seem unachievable for some. Additionally, a small number of trials have considered the therapeutic benefits of resistance training (8). Recently, there has been growing interest in high-intensity interval training (HIIT). HIIT has been proposed as a time efficient form of exercise that may overcome some of the motivational barriers associated with traditional forms of continuous longer duration exercise. HIIT is a type of exercise involving alternating short bursts (typically 30 s to 4 min) of exercise at ≥ 85% peak heart rate (HRpeak), followed by similar length periods of light exercise or