Much research over the past decade has demonstrated the benefits of physical exercise in reducing symptoms of anxiety and depression.
What’s not clear, however, is whether exercise provides a benefit specifically in obese adults, or whether even low levels of physical activity may also be helpful in this population.
Investigators studied 850 patients with severe obesity being evaluated for bariatric (weight-loss) surgery as part of the Longitudinal Assessment of Bariatric Surgery-2 (LABS-2) observational study. All patients received a battery-powered activity monitor, to be worn above the ankle for a period of seven days.
This monitor measured steps and gait speed. Patients also took a battery of instruments to measure depressive symptoms (Beck Depressive Inventory, BDI) and mental health and well-being (SF-36), and reported any current treatment for depression or anxiety symptoms.
Results showed that a low level of physical activity was significantly associated with the presence of depressive symptoms: every reduction of 100 active minutes per day corresponded to an 18% increase in the odds of a BDI score over 10. This correlation was not observed, however, when adjusted for physical symptoms like bodily pain. In other words, pain—not surprisingly—may have limited physical activity and worsened depressive symptoms itself.
On the other hand, there was a significant correlation between the lack of vigorous physical activity and current treatment for depression or anxiety, and this relationship held up even when controlling for role limitations due to physical problems. Vigorous physical activity was measured in “high-cadence minutes,” or minutes during which the patient took more than 80 steps.
Surprisingly, a very low level of vigorous activity, only eight high-cadence minutes per day (corresponding to approximately one hour of moderate- to vigorous-intensity physical activity per week), was sufficient to reduce the likelihood that a patient was seeking treatment for depression or anxiety.
Because this was an observational study, investigators could not explain whether deliberate increases in physical activity over baseline (as in a prescribed exercise regimen) would further reduce symptoms of depression or anxiety. It was also impossible to determine whether people with better mental health are simply more active than others, or whether non-ambulatory exercises (like yoga) are similarly associated with improved mental health.
But the use of an objective measure of physical activity (instead of self-report) strengthens this study’s conclusions and suggests avenues for further research and treatment interventions (King WC et al, J Psychosomatic Res 2013;74(2):161-169).
TCPR’s Take: Nearly 40% of patients undergoing bariatric surgery report recent treatment for depression or anxiety, mostly in the form of psychotropic medication.
This study raises the possibility that alternative modalities, like physical activity, may reduce the need to seek treatment for these conditions. Moreover, it shows that the intensity of physical activity may not need to be very high to have a significant effect.