The Role of Resistance Exercise in the Treatment of Co-morbid Insulin Resistance and Depressive Symptoms

Abstract

Insulin resistance (IR) and major depressive disorder (MDD) share common pathophysiology, and when clustered together, increase the risk of type-2 diabetes. Exercise has been shown to effectively manage both IR and MDD separately. However, it is unknown to what extent exercise can simultaneously improve IR and depressive symptoms, with the specific role of resistance training (RT) requiring further investigation. To address this gap, a systematic review of the literature and a randomised controlled trial were performed. First, seven electronic databases were searched, with search terms for IR combined with search terms for exercise. Seven randomised controlled trials reporting the effects of RT on depressive symptoms in individuals with IR were identified. The limited data available suggests RT may be an effective standalone intervention to simultaneously reduce depressive symptoms and glycated haemoglobin (HbA1c). However, the studies were of low quality, with no studies performed in adults with MDD or using a clinician-rated assessment of depression. Next, a 12-week randomised controlled trial of progressive RT in adults with metabolic syndrome and MDD was conducted. Eleven participants were randomised to receive high intensity RT (n=4) or usual care (n=7). Data were analysed with a repeated measures ANOVA. No group x time interaction was observed for the Hamilton Depression Rating Scale. However, a significant (p<0.05) group x time reduction on the Patient Health Questionnaire-9 was observed favouring RT. There were no changes in IR or HbA1c. Overall, the existing literature on the effects of RT on simultaneously improving IR and depressive symptoms was small and of low quality. While our randomised controlled trial attempted to address this gap in the literature, the small sample size meant the study was underpowered. Nevertheless, a significant reduction in self-rated symptoms was observed. Given the small sample size, future studies of RT are warranted.