Heart Rate During an Exercise Test and Acute High-intensity Interval Training in Type 2 Diabetes

To describe and compare the acute heart rate changes during an incremental exercise test and high-intensity interval training (HIIT) in subjects of different glucose control. Seventy-five adults were allocated into three groups: Normoglycaemic (NG, n=32), Pre- (PreT2D, n=30) and Type 2 diabetic (T2D, n=13) subjects. Subjects performed an incremental cycling test to determine cardiorespiratory fitness (VO₂max), maximum heart rate (HRmax) and HR recovery post maximal effort, as well as a HIIT cycling session. HR variations are reported as HR pre (HR-pre_INT), and post interval (HR-post_INT), percentage of maximum HR (%HRmax), delta of HR increased (∆HR_INT), and delta HR recovery after each interval (∆HRR). By groups, there was a significant difference for the %HRmax in 1^st and 2^nd, but not in intervals 3^rd to 10^th between Pre-T2D and T2D groups. There were significant differences for the %HRmax in 1^st to 2^nd intervals between Pre-T2D and T2D groups. Significant (P<0.05) differences at some intervals were found for ΔHR_INT, and ΔHRR. These findings suggest that the HR during an incremental exercise test, and from a typical 10-intervals based HIIT protocol could be used as an intensity marker for individuals independent of their glycaemic control.