High‐Intensity Interval Training With or Without Post‐Exercise Milk Consumption Improves Cardiovascular Function in Patients with Type 2 Diabetes
Authors: Francois Monique Emily , Durrer Cody , Little Jonathan 
Published: November 2023

High‐intensity interval training (HIIT) can improve several aspects of cardiometabolic health that are important for older adults with type 2 diabetes (T2D), including cardiorespiratory fitness, body composition and endothelial function. Previous studies have suggested that adaptations to exercise training can be augmented with post‐exercise milk or protein consumption but whether this nutritional strategy can impact cardiovascular adaptations to HIIT in T2D is unknown.

Purpose

To examine if cardiovascular adaptations to HIIT can be enhanced by post‐exercise milk supplementation in patients with T2D.

Methods

A proof‐of‐concept double‐blind controlled trial randomized 50 adults with physician‐diagnosed T2D (58 ± 9 y, A1c: 7.1 ± 0.8%, BMI: 35 ± 7 kg/m2) to one of three nutritional beverages (500 mL skim milk, milk‐protein isolate or flavored water placebo, n=16–17 per group) consumed after exercise training (2× cardio‐ and 1× resistance‐based HIIT per week for 12 weeks). HIIT progressed from four (week 1) to 10 (weeks 6–12) 1‐min intervals of vigorous effort (eliciting ~85–90% maximal heart rate [HRmax]) interspersed with 1‐min rest/recovery. Resting HR, blood pressure (MAP), brachial artery flow‐mediated dilation (%FMD) and carotid‐femoral pulse‐wave velocity (PWV) were measured before and 72 h after the intervention. Cardiorespiratory fitness (V̇O2 peak) and HRmax were measured via incremental cycling test to exhaustion with expired gas analyses before and after training. Data were analyzed using general linear mixed models (SPSS) with magnitude‐based inferences for clinically meaningful changes assessed using the spreadsheet available at http://www.newstats.org/.

Results

There were main effects of time (p<0.05) but no group × time interactions (all p>0.31). All results are therefore presented as main effects of time with nutritional beverage groups collapsed. HIIT lowered resting HR by −2.6 bpm (95% CI: −4.5 to −0.8 bpm), MAP by −5.7 mmHg (CI: −7.8 to −3.6 mmHg) and PWV by −1.3 m/s (0 to 2.6 m/s); the reduction in PWV was possibly and reduction in MAP was most likely clinically beneficial. HIIT increased %FMD by 1.5% (CI: 0.9 to 2.0%) and V̇O2 peak by 2.5 mL/kg/min (CI: 1.8 to 3.2 mL/kg/min); the increase in %FMD was very likely and the increase in V̇O2 peak most likely clinically beneficial. Body mass (CI: −1.8 to 0.2 kg) and HRmax (CI: −2.0 to 3.3 bpm) were not significantly changed.

Conclusion

Twelve weeks of HIIT significantly improves important indices of cardiovascular health in patients with T2D. Clinically meaningful improvements in blood pressure, endothelial function and cardiorespiratory fitness were evident after just 12 weeks of progressive interval training (totaling 48 – 78 minutes of exercise per week). The addition of post‐exercise milk or milk protein supplementation did not influence any of the cardiometabolic health markers assessed.

Support or Funding Information

Dairy Farmers of Canada.