Appropriate timing of lifestyle interventions may facilitate healthy rhythmicity in metabolism and optimize the effectiveness of such interventions in improving metabolic health. In this context, exercise is well-known to improve (skeletal muscle) energy metabolism and is an established intervention to improve muscle insulin sensitivity and to counter the development of type 2 diabetes (T2D). In addition, exercise may also have beneficial effects on the immune response that is known to impact on insulin sensitivity and overall metabolic health. In this study it is hypothesized that exercise performed at different times of the day exerts a differential effect on 24h metabolism in people at risk for developing T2D. To test this, a randomized controlled cross-over study is conducted in which participants are subjected to either an exercise in the morning or late afternoon while staying in the respiration chamber. Main outcome is substrate utilization during the night as measured with the respiration chamber, but 24-hrs blood draws will also be performed to examine effect of exercise on circulating metabolites.
The primary objective of this randomized controlled cross-over study is to investigate if an acute, glycogen lowering exercise bout performed either in the morning or late afternoon differentially affects the respiratory exchange ratio at night in men and women with prediabetes. For this purpose, participants will stay in a respiration chamber and will be subjected to either an exercise bout in the morning or late afternoon.