PMID 33401694

Research
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A Comparison of the Gluco-Regulatory Responses to High-Intensity Interval Exercise and Resistance Exercise

Gordon BA, Taylor CJ, Church JE, Cousins SD

Question

Do acute gluco-regulatory and hormonal responses differ between duration-matched high-intensity interval cycling and resistance exercise?

Summary

In healthy recreationally active adults, one fasted cycling HIIT session caused a larger short-term glucose, cortisol, heart-rate, and lactate response than a duration-matched lower-body resistance session, while insulin and perceived exertion were similar.

Methodology

  • Healthy recreationally active adults accustomed to both high-intensity interval and resistance exercise
  • 16 participants.
  • Cycle ergometer.
  • Work intervals: 30 seconds at 80% predicted peak power.
  • Recovery: 90 seconds very light active recovery.
  • Intensity: 80% predicted peak power; mean 84 +/- 7.4% HRmax.
  • 24-minute interval block.
  • Single session.
  • Acute study.
  • Randomized cross-over trial
  • Glucose, Insulin, Cortisol, and Exercise load were tracked.

Outcomes

Glucose

Glucose was higher after cycling HIIT than resistance exercise during early recovery.

Condition x time interaction p=0.026, eta squared=0.23; mean glucose 0.7 mmol/L higher with HIE; higher immediately, 30 minutes, and 90 minutes.

Mixed

Insulin

Insulin responses did not differ between exercise modes.

No significant condition difference, p=0.275.

No clear change

Cortisol

Cortisol was higher after cycling HIIT than resistance exercise.

Mean cortisol 71 ng/mL higher with HIE, 95% CI 16 to 126, p=0.015; higher from 30 to 120 minutes.

Mixed

Heart rate

HIIT produced a higher heart-rate response than resistance exercise, while RPE was similar.

%HRmax 84 +/- 7.4 for HIE vs 71 +/- 7.5 for RE, p<0.001; RPE 16 +/- 2.8 vs 16 +/- 1.3, p=0.605.

Mixed

Insights

  • Acute fasted cycling HIIT can produce larger glucose and cortisol perturbations than lower-body resistance exercise.
  • Similar RPE does not imply similar cardiometabolic stress across modalities.
  • Fasted high-intensity work may provoke nausea or presyncope in some participants.

Limitations

  • Acute study only.
  • Young healthy active sample.
  • Fasted laboratory condition may not reflect typical training.
  • Diet was replicated but not tightly controlled.
  • Oxygen consumption was not measured during the trials.
  • Menstrual phase was not controlled.

Safety

  • Several participants experienced nausea or presyncope in both fasted exercise conditions; one participant stopped HIE after 8 of 12 intervals.