PMID 28874821

Research
All papers

Sprint interval training decreases left-ventricular glucose uptake compared to moderate-intensity continuous training in subjects with type 2 diabetes or prediabetes

Heiskanen MA, Sjöros TJ, Heinonen IHA, Löyttyniemi E, Koivumäki M, Motiani KK, Eskelinen JJ, Virtanen KA, Knuuti J, Hannukainen JC, Kalliokoski KK

Question

Are two weeks of sprint interval training more effective than moderate-intensity continuous training for improving left- and right-ventricular glucose and fatty-acid metabolism, cardiac structure, and function in adults with type 2 diabetes or prediabetes?

Summary

This small randomized trial compared two weeks of supervised all-out sprint interval training with moderate continuous cycling in adults with type 2 diabetes or prediabetes. Sprint training improved VO2peak, while both training styles improved whole-body insulin-stimulated glucose uptake and some hemodynamic measures. Contrary to the authors' hypothesis, sprint training decreased left-ventricular insulin-stimulated glucose uptake compared with moderate training, raising uncertainty about whether very intense all-out intervals are metabolically ideal for the diabetic heart. The study was short, small, and focused on cardiac imaging endpoints rather than consumer-facing performance outcomes.

Methodology

  • Untrained adults aged 40-55 with type 2 diabetes or prediabetes.
  • 26 participants.
  • Cycle ergometer.
  • Work intervals: 30 seconds all-out.
  • Recovery: 4 minutes.
  • Intensity: All-out with load equal to 10% fat-free mass after 5-second acceleration.
  • Not explicitly stated; interval/recovery structure implies roughly 14-23 min excluding unreported warmup/cooldown.
  • 6 sessions in 2 weeks.
  • 2 weeks.
  • Parallel-group randomized controlled trial.
  • Left-ventricular glucose uptake, Free-fatty-acid uptake, VO2peak, and Whole-body insulin-stimulated glucose uptake were tracked.

Outcomes

Left-ventricular glucose uptake

SIT decreased insulin-stimulated LV glucose uptake compared with MICT.

Reported as significant group difference; exact p value not extracted.

Safety concern

VO2peak

Only SIT significantly improved VO2peak.

Group*time p=0.0495; SIT time effect p=0.013.

Improved

Whole-body insulin-stimulated glucose uptake

Both SIT and MICT improved whole-body insulin-stimulated glucose uptake.

p=0.001 time effect.

Improved

Free-fatty-acid uptake

Fasted fatty-acid uptake in both ventricles remained unchanged by training.

No clear change

Completion/tolerability

Most participants completed, but one SIT participant discontinued due to migraine during the first SIT session.

SIT completers 11/13; MICT completers 10/13.

Mixed

Insights

  • All-out 30-second SIT can improve VO2peak quickly, but in diabetes/prediabetes it may not be uniformly better than moderate training.
  • For users with type 2 diabetes or cardiac risk, prescribed-intensity HIIT may be a safer default than maximal all-out sprinting.
  • Long recoveries and low total hard-work time are not enough to remove the need for screening in clinical populations.

Limitations

  • Small sample size.
  • Only two weeks of training.
  • Cardiac metabolic endpoints do not directly translate to symptoms or long-term outcomes.
  • Medication use during scans/trial could not be fully controlled.
  • Longer studies are needed to determine whether decreased glucose uptake after SIT is acute or persistent.

Safety

  • One SIT participant dropped out due to migraine during the first SIT session.
  • Candidates were screened by medical examination, ECG, and OGTT.
  • The study raises caution about diabetic cardiac substrate metabolism after all-out SIT.