News & Views from the Editor-in-Chief - L. Bruce Gladden
Three papers are highlighted in this month's journal, two of which relate to blood glucose control with changes in physical activity/training. First, it is known that prolonged periods of physical inactivity can result in poor glycemic control, insulin resistance, and can swing the energy balance equilibrium towards positive. Winn et al. hypothesized that reducing energy intake during a period of physical inactivity would prevent insulin resistance. Their results reported for the first time that independent of diet composition, controlled dietary feeding, causing a mild energy deficit preserves metabolic function during a period of physical inactivity in young healthy individuals. They also combined physical inactivity with excess energy intake and showed that this combination leads to hyperglycemia and hyperinsulinemia. Importantly, the translational impact of these findings is that "restricting energy intake may buffer adverse metabolic perturbations during short-term periods of physical inactivity" thus contributing to the maintenance of metabolic health.
On the same topic, Fisher et al. sought to compare the chronic effects of aerobic exercise training (i.e., no acute exercise prior to testing; NE) with the acute effects of a single bout of moderate-intensity continuous aerobic exercise (MIC) or high-intensity interval exercise (HII) for improving insulin sensitivity while controlling for energy balance. A unique aspect of their study was the use of a 23-h whole room calorimetry visit to control for energy balance prior to assessment of insulin sensitivity. They found that HII exercise improved insulin sensitivity 22 h following exercise under energy-balanced conditions; however, there were no significant improvements following the NE or MIC conditions. This study suggests that the widely reported improvements in insulin sensitivity in response to exercise training may be at least partially mediated by shifts in energy balance, and that HII has the potential to improve insulin sensitivity even in the context of energy balance.
On a different topic, it is well known that the progression of Chronic Obstructive Pulmonary Disease (COPD) is variable and affects several disease domains. Demeyer et al. demonstrated that a higher physical activity level is associated with an attenuated lung function decline and a slower decline of questionnaire-assessed health status in patients with moderate-to-very severe COPD. This is the first study to investigate longitudinally the effect of objectively measured physical activity on multidimensional disease progression in COPD. The results bring an important clinical message. By suggesting that physical activity attenuates lung function decline irrespective of smoking habits and other associated covariates, on top of pharmacological treatment, this study clearly indicates that regular physical activity has to be considered an essential component of COPD treatment.
L. Bruce Gladden
School of Kinesiology