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 (VO ₂max), 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 (ΔHR _INT), and delta HR recovery after each interval (ΔHRR). By groups, there was a significant difference for the %HRmax in 1 ^stand 2 ^nd, but not in intervals 3 ^rdto 10 ^thbetween Pre-T2D and T2D groups. There were significant differences for the %HRmax in 1 ^stto 2 ^ndintervals 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.