The Effect of Frequency in Volume Matched Exercise Training on Aerobic Capacity, Heart Rate Variability, and Glucose Variability in Type 2 Diabetes

BACKGROUND: It is estimated that by 2045 close to 700 million people worldwide will be suffering from Type 2 Diabetes (T2D). Exercise is important in the treatment and prevention of T2D. The frequency of exercise required for optimal effect is still to be explored. OBJECTIVES: To compare two volume and intensity matched exercise protocols with different frequencies in individuals with T2D and to investigate the effects of these protocols on cardiorespiratory fitness, cardiovascular health and glycemic control. METHODS: Subjects with T2D were recruited and randomly assigned either a high frequency high intensity interval training protocol (HF) or a low frequency high intensity interval training protocol (LF). Both groups were matched for volume and intensity and the study participants exercised for 120 minutes a week for 12 weeks. Changes in aerobic capacity (VO2peak), glycosylated hemoglobin (HbA1c), heart rate variability, glucose variability, blood lipids and body composition were measured. RESULTS: Both the HF and LF group significantly improved aerobic capacity by 9% and 10% respectively, with no significant difference between groups. HbA1c improved significantly only in the LF group by 5%. Heart rate variability improved only in the LF group. No significant improvements in glucose variability were seen in either groups. CONCLUSION: Both HF and LF exercise protocols can be used as effective programs for improving aerobic capacity and reducing cardiovascular risk factors. Longer, less frequent exercise training seems to be more effective in improving heart rate variability and glycemic control provided this is at a frequency of at least four times a week