PMID 35275239

Research
All papers

High-intensity interval training for 12 weeks improves cardiovascular autonomic function but not somatosensory nerve function and structure in overweight men with type 2 diabetes

Bönhof GJ, Strom A, Apostolopoulou M, Karusheva Y, Sarabhai T, Pesta D, Roden M, Ziegler D

Question

Does 12 weeks of supervised cycling HIIT improve cardiovascular autonomic and somatosensory nerve function in overweight men with type 2 diabetes compared with normal-glucose-tolerant men?

Summary

In overweight sedentary men, 12 weeks of supervised cycling HIIT improved aerobic fitness. Men with type 2 diabetes also showed improvements in cardiovascular autonomic measures, but peripheral/somatosensory nerve function and intraepidermal nerve fiber density did not change.

Methodology

  • Overweight sedentary men with type 2 diabetes and overweight normal-glucose-tolerant men.
  • 43 participants.
  • Cycle ergometer.
  • Work intervals: 4 min.
  • Recovery: 3 min.
  • Intensity: 90% HRmax work, 70% HRmax recovery.
  • 35 min.
  • 3 sessions/week.
  • 12 weeks.
  • Controlled before-after exercise intervention
  • Autonomic function, Somatosensory nerve function, Aerobic fitness, and Glycemic markers were tracked.

Outcomes

VO2max

VO2max increased in both normal-glucose-tolerant and type 2 diabetes groups.

NGT 25.5 to 29.6 ml/kg/min; T2D 23.1 to 27.0 ml/kg/min.

Improved

Baroreflex

Men with type 2 diabetes improved baroreflex sensitivity indices.

BRS-allSeq 8.82 to 14.6, BRS+ 7.19 to 15.4, and BRS- 12.8 to 14.6 ms2/mmHg; all p<0.05.

Improved

Resting HR

Resting heart rate decreased in both groups.

NGT 65.1 to 60.2 bpm; T2D 68.8 to 63.4 bpm.

Improved

Nerve measures

Somatosensory nerve function, clinical neuropathy scores, nerve conduction, QST, and IENFD did not change.

No significant change reported across these nerve outcomes.

No clear change

HbA1c

HbA1c did not change despite improved insulin sensitivity in type 2 diabetes.

HbA1c unaltered; M value increased in T2D.

No clear change

Insights

  • A supervised 4 x 4-min cycling format can improve aerobic fitness in overweight men with and without type 2 diabetes.
  • Autonomic benefits should not be translated into claims of peripheral nerve repair.
  • Clinical users need screening before high-intensity HR-targeted training.

Limitations

  • Moderate sample size
  • Men only
  • Nonrandomized clinical group comparison
  • Most participants did not have impaired peripheral or autonomic nerve function at baseline
  • Weight-loss and glycemic-change effects were intentionally limited

Safety

  • No explicit adverse-event results were reported.
  • Participants underwent extensive medical exclusion screening.
  • All sessions were fully supervised.