Reduced-exertion high-intensity interval training (REHIT) provides limited improvement in post-prandial and 24-hour glycemia in healthy, physically active men

Introduction Reduced-Exertion High-Intensity Interval Training (REHIT) is a 10-min cycling regimen that has improved glucose tolerance in adults with metabolic dysfunction. However, the ecological relevance of REHIT for application in healthy, middle-aged men as a prevention tool to improve glucose control remains unknown. This study aimed to investigate the effects of a single bout of REHIT following a mixed meal on 3h post-prandial and 24h blood glucose measures in physically active, middle-aged men compared to a non-exercise control condition (Non-EX). Methods Twenty physically active men (Age: 52 ± 8 years; VO 2 max: 44.5 ± 6.0 mL min −1 ·kg −1 ; BMI: 24.3 ± 1.7 kg m −2 ) completed a randomized crossover study comparing REHIT to Non-EX. All participants completed both interventions 30 min after consuming a standardized breakfast. Each study condition was separated by 48 h. Continuous glucose monitors (CGMs) measured interstitial glucose continuously throughout the study. CGM data were analyzed to assess post-prandial, 24h mean glucose, and 24h glucose variability (standard deviation; mean amplitude of glycemic excursions, MAGE; coefficient of variation, CV). Results REHIT led to a significantly shorter glucose peak-to-nadir ( p = 0.014). While a significant condition × time interaction was observed ( p < 0.001), there was no significant effect of condition ( p = 0.725). REHIT vs. Non-EX did not lower 3h post-breakfast glucose responses (113 ± 22 vs. 114 ± 19 mg dL −1 , p = 0.809), 24h mean glucose (119 ± 14 vs. 117 ± 13 mg dL −1 , p = 0.453) or measures of glucose variability including 24h standard deviation of blood glucose (17 ± 5 vs. 18 ± 6 mg dL, p = 0.173), 24h MAGE (2.5 ± 0.9 vs. 2.6 ± 0.9 mmol L −1 , p = 0.474), and 24h CV (14.6 ± 4.0 vs. 14.9 ± 4.6 %, p = 0.746), respectively. Conclusion While REHIT led to transient reductions in post-prandial glucose in active middle-aged men, there was no clinically meaningful reduction in 3h post-prandial or 24h glucose control.