PMID 31175708

Research
All papers

No changes in corticospinal excitability, biochemical markers, and working memory after six weeks of high-intensity interval training in sedentary males

Nicolini C, Toepp S, Harasym D, Michalski B, Fahnestock M, Gibala MJ, Nelson AJ

Question

Does a 6-week 5-by-1-minute cycling HIIT program improve cardiorespiratory fitness and produce parallel changes in corticospinal excitability, intracortical circuits, serum BDNF/IGF-1/cathepsin B, or working memory in sedentary young men?

Summary

In healthy sedentary young men, six weeks of supervised low-volume cycling HIIT improved VO2peak by about 12%, but did not improve working memory or most measured neurophysiology and blood biomarkers.

Methodology

  • Healthy sedentary young men.
  • 18 participants.
  • Cycle ergometer.
  • Work intervals: 1 min at about 105-135% Wpeak.
  • Recovery: 1.5 min active recovery at 30% Wpeak.
  • Intensity: Individualized Wpeak-derived workload.
  • 17.5 min.
  • 3 sessions/week.
  • 6 weeks.
  • Single-arm pre-post exercise intervention
  • VO2peak, Corticospinal excitability, Serum biomarkers, and Working memory were tracked.

Outcomes

VO2peak

VO2peak increased by about 12%, with all participants improving.

Significant increase; individual gains about 3% to 29%.

Improved

Neural measures

ICF decreased, but corticospinal excitability and SICI did not change.

ICF significant; MEP AUCs and SICI not significant.

Mixed

Biomarkers

BDNF, IGF-1, total CTSB, and pro-CTSB did not significantly change.

No significant pre-post changes.

No clear change

Working memory

Operation span performance was unaltered.

No significant pre-post change.

No clear change

Insights

  • A 17.5 min cycling HIIT protocol can improve aerobic fitness in sedentary young men over 6 weeks.
  • Do not translate this study into claims about working memory or BDNF improvement.
  • Completion-based intensity adjustment is a practical way to individualize hard intervals.

Limitations

  • No control group
  • Small male-only sample
  • Young healthy participants only
  • No long-term follow-up
  • Biomarker and TMS outcomes are mechanistic rather than direct health outcomes

Safety

  • No adverse events were reported.
  • All HIIT sessions were supervised and the protocol allowed workload reductions if participants could not complete an interval.
  • All participants successfully completed the experiment; detailed attendance percentages were not reported.