Effects of Controlled Supramaximal High-Intensity Interval Training on Cardiorespiratory Fitness and Global Cognitive Function in Older Adults: The Umea HIT Study-A Randomized Controlled Trial
Question
Does watt-controlled supramaximal HIT adapted for older adults improve cardiorespiratory fitness and global cognition more than moderate-intensity training, and what are its effects on cardiovascular, muscular, cognitive, quality-of-life, adherence, and safety outcomes?
Summary
This randomized trial compared a controlled supramaximal cycling HIT protocol with moderate-intensity interval cycling in nonexercising older adults. Both groups improved VO2peak similarly and lowered blood pressure, while global cognition did not improve. HIT had advantages for working memory and knee extensor strength, used half the session time, had high attendance, and reported no serious adverse events.
Methodology
- Nonexercising older adults aged 66-79 years.
- 68 participants.
- Stationary cycling.
- Work intervals: 10 x 6 seconds.
- Recovery: 54 seconds between intervals: 24 seconds passive and 30 seconds active recovery.
- Intensity: Started at 60% of estimated MPO6; progressed in 4% MPO6 steps; by intervention end mean target was 428 W, 110% MPO6 and 316% MAP.
- 20 minutes.
- 2 sessions/week.
- 3 months.
- Randomized controlled superiority trial with parallel allocation to supramaximal HIT or MIT.
- Cardiorespiratory fitness, Global and domain-specific cognition, Blood pressure, and Muscular function were tracked.
Outcomes
VO2peak
VO2peak improved significantly overall with no between-group difference between HIT and MIT.
Overall mean increase 1.38 mL/kg/min, 95% CI 0.77 to 1.98; between-group difference 0.05 mL/kg/min, 95% CI -1.17 to 1.25.
Global cognition
Global cognitive function did not improve and did not differ between groups.
Overall change 0.02, 95% CI -0.05 to 0.09; between-group difference 0.11, 95% CI -0.03 to 0.24.
Working memory and knee extensor strength
Working memory and maximal isometric knee extensor strength showed between-group advantages for HIT.
Working memory MD 0.32, 95% CI 0.01 to 0.64; knee strength MD 0.07 N*m/kg, 95% CI 0.003 to 0.137.
Blood pressure
Systolic and diastolic blood pressure decreased overall irrespective of group.
SBP -2.09 mmHg, 95% CI -3.54 to -0.64; DBP -1.27 mmHg, 95% CI -2.31 to -0.25.
Safety/adherence
Attendance was high and no serious adverse events occurred, but discomfort/adverse-event reports were recorded in 9.7% of attended-session contexts when combining since-previous and current-training reports.
146 reports across 1,497 attended sessions; 52 in HIT and 94 in MIT; 70% musculoskeletal; no serious AE.
Insights
- For older adults, short supramaximal intervals can be tolerable when intensity is externally controlled, supervised, and adjusted conservatively.
- Do not claim global cognitive benefits; the signal was limited to working memory and should be interpreted cautiously.
- Very short intervals with long recovery may reduce discomfort risk compared with longer all-out sprints.
Limitations
- Active MIT comparator reduced ability to detect between-group differences.
- Some participants may have been more active than intended at baseline.
- VO2peak rather than criteria-based VO2max was used.
- Large interindividual variability.
- Findings apply to medically screened, relatively healthy adults aged 66-79, not frailer or more diseased populations.
- Exact warm-up/cooldown durations were in supplementary material rather than fully reported in main text.
Safety
- No adverse event was considered serious.
- Participants reported discomfort since prior training in 83 sessions and during current training in 63 sessions.
- Most reported events were musculoskeletal pain/soreness/numbness.
- Medical screening excluded several higher-risk conditions.