PMID 41743231

Research
All papers

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

Chaudhry BA, Morrell JS, Cook SB, Goodwin NJ, Brian MS

Question

Does one bout of REHIT performed after a mixed breakfast improve 3-hour post-prandial and 24-hour continuous-glucose-monitor outcomes compared with non-exercise rest in physically active middle-aged men?

Summary

In healthy physically active middle-aged men, a single 10-minute REHIT cycling bout after breakfast caused a faster drop from post-meal glucose peak to nadir and briefly lower glucose at 65-70 minutes, but did not reduce average 3-hour post-breakfast glucose, 3-hour AUC, 24-hour mean glucose, or 24-hour glucose variability compared with a quiet-rest control day. This is an acute crossover study, not a training study, and its practical glycemic benefit appears limited in this already healthy active group.

Methodology

  • Healthy physically active middle-aged men.
  • 20 participants.
  • Cycling.
  • Work intervals: Two 20-s all-out sprints.
  • Recovery: Unloaded cycling within a 10-min session.
  • Intensity: All-out against 5% body weight; >120% max wattage criterion met.
  • 10 min.
  • Single acute bout.
  • Single visit.
  • Randomized counterbalanced crossover acute intervention study.
  • 3-hour post-prandial glucose, 24-hour glucose control, and Sprint performance/fidelity were tracked.

Outcomes

3-hour mean glucose

REHIT did not reduce average 3-hour post-breakfast glucose or AUC compared with non-exercise.

113 +/- 22 vs 114 +/- 19 mg/dL, p=0.809; AUC p=0.856.

No clear change

Post-prandial glucose timing

REHIT shortened glucose peak-to-nadir time and briefly lowered glucose at 65 and 70 min.

Peak-to-nadir 41.8 +/- 29.3 vs 67.3 +/- 30.1 min, p=0.014; condition x time p<0.001.

Improved

24-hour glucose

REHIT did not lower 24-hour mean glucose or variability metrics.

24h mean glucose 119 +/- 14 vs 117 +/- 13 mg/dL, p=0.453; SD p=0.173; MAGE p=0.474; CV p=0.746.

No clear change

REHIT sprint fidelity

All participants met or exceeded sprint intensity criteria.

Average sprint intensities 155.2 +/- 15.7% and 159.6 +/- 17.7% of peak workload.

Improved

Insights

  • A very short REHIT bout should not be sold as meaningfully improving daily glucose in already active healthy men.
  • Transient glucose-curve effects may not translate into clinically meaningful glycemic exposure changes.
  • REHIT evidence for metabolic benefit is more relevant to repeated training or higher-risk populations than this acute healthy sample.

Limitations

  • Acute single-bout design.
  • Men only.
  • Healthy physically active sample.
  • Physical activity data missing for 7 participants.
  • Caffeine intake differed between conditions.

Safety

  • Participants obtained physician clearance for maximal exercise.
  • No adverse events were described in the reviewed sections.
  • All-out sprint protocol may require screening and familiarization.