PMID 33137993

Research
All papers

High-Intensity Interval Training Improves Cognitive Flexibility in Older Adults

Mekari S, Neyedli HF, Fraser S, O'Brien MW, Martins R, Evans K, Earle M, Aucoin R, Chiekwe J, Hollohan Q, Kimmerly DS, Dupuy O

Question

Does six weeks of high-intensity interval training improve executive-function components in healthy older adults compared with moderate-intensity continuous training or resistance training?

Summary

A 6-week supervised cycling HIIT program improved aerobic fitness and produced a selective improvement in cognitive flexibility in healthy older adults. Moderate continuous cycling and resistance training also improved aerobic fitness, but only HIIT improved the Stroop task switching condition.

Methodology

  • Healthy, cognitively intact older adults recruited from Acadia Active Aging.
  • 69 participants.
  • Cycle ergometer.
  • Work intervals: 15 seconds at 100% peak power output.
  • Recovery: 15 seconds passive recovery at 0% peak power output, with 5 minutes passive recovery between the two sets.
  • Intensity: 100% peak power output during work intervals, with a 15 W increase in the final 2 weeks.
  • 5-minute warm-up at 25% peak power output plus 40-45 minutes of intervals and recovery; final two sessions tapered to 35 minutes.
  • 3 sessions per week.
  • 6 weeks; 18 planned sessions with at least 80% attendance required for post-testing.
  • Randomized controlled trial with three parallel supervised exercise groups: HIIT, moderate-intensity continuous training, and resistance training.
  • Aerobic fitness, Cognitive flexibility, Other Stroop executive-function components, and Safety monitoring were tracked.

Outcomes

VO2max

All groups improved aerobic fitness, with the largest within-group effect in HIIT.

Group-by-time interaction p = 0.001; HIIT t(23) = 9.10, p < 0.001, d = 1.86.

Improved

Stroop switching response time

Only HIIT significantly improved the switching condition, interpreted as improved cognitive flexibility.

Group-by-time interaction F(2,65) = 11.0, p < 0.001, partial eta squared = 0.25; HIIT t(23) = 6.89, p < 0.001, d = 1.06.

Improved

Stroop naming and interference

Naming and interference showed time effects but no clear group-specific advantage, and accuracy analyses did not suggest a speed-accuracy tradeoff.

Speed-accuracy tradeoff checks p > 0.30.

Mixed

Insights

  • Short-interval cycling HIIT can be delivered to screened older adults under supervision using peak-power-output targets.
  • For cognitive-flexibility goals, the article supports repeated brief work/rest cycling intervals rather than assuming all exercise modes have equivalent executive-function effects.
  • The protocol is equipment-based and relatively long for HIIT, so a bodyweight game adaptation would need lower-impact movements, conservative progression, and careful monitoring.

Limitations

  • Participants were healthy, cognitively intact, and already physically active, limiting generalization to sedentary or frail older adults.
  • The intervention lasted only 6 weeks.
  • Executive function was assessed with selected Stroop task components rather than a broad cognitive battery.
  • The study did not include mechanistic measures explaining the cognitive effect.
  • Resistance-training exposure may have been too short to produce cognitive changes.

Safety

  • Participants were screened for cardiovascular, neurological, cognitive, and musculoskeletal risks.
  • Maximal exercise tests were ECG monitored.
  • No adverse-event outcomes were reported in the extracted article text.