Physical activity and exercise ‘snacks’: a small step towards big gains in severe mental illness

A recent meta-analysis by Rodríguez et al published in the British Journal of Sports Medicine makes an important contribution to the understanding of ‘exercise snacks’—defined as brief, structured bouts of exercise for ≤5 min in duration, performed multiple times per day at moderate or vigorous intensity (eg, bodyweight exercises). It showed that exercise snacks in people with low levels of physical activity can improve cardiorespiratory fitness, which is one of the strongest predictors of premature mortality. Importantly, very high adherence and compliance rates for exercise snacks, far exceeding traditional exercise clinical trials, were reported. Results concurred with a previous meta-analysis of exercise snacks, which reported significant improvements in maximal oxygen uptake and peak power output, as well as significant reductions in total and low-density lipoprotein cholesterol. However, the quality of this evidence ranged from moderate to very low. Of note, none of the included trials across both reviews included populations with mental health conditions. The objective of this editorial is to present the potential value and feasibility of exercise and physical activity snacks in persons with severe mental illness (SMI).