Effects of controlled supramaximal high-intensity interval training on muscle capacities and physical functions for older adults: analysis of secondary outcomes from the Umea HIT study-a randomised controlled trial
Question
Does group-based controlled supramaximal high-intensity interval training improve muscle capacities and physical function more than moderate-intensity interval training in older adults not engaged in regular exercise?
Summary
In older adults aged 66-79 years who were not regularly exercising, twice-weekly controlled supramaximal cycling intervals for three months produced larger gains in anaerobic cycling performance than a longer moderate-intensity interval program. Muscle capacity and physical function outcomes generally improved within groups, but between-group differences other than anaerobic cycling were not statistically significant.
Methodology
- Older adults aged 66-79 years, not regularly exercising, recruited by newspaper advertising and medically screened.
- 68 participants.
- Stationary cycling.
- Work intervals: 10 x 6 seconds.
- Recovery: 54 seconds between intervals.
- Intensity: Started at 60% of estimated maximum 6-second mean power output; individualized watt-controlled progression in 4 percentage-point steps.
- 20 minutes including warm-up and cool-down.
- Twice weekly.
- Approximately 3 months; 25 sessions.
- Preplanned secondary outcome analysis from the Umea HIT randomized controlled trial.
- Anaerobic cycling performance, Leg power, Hand grip strength, and Static balance were tracked.
Outcomes
Anaerobic cycling performance
Supramaximal HIT improved more than MIT; within-group changes were 31.3 W for HIT and 12.0 W for MIT.
Between-group difference 19.3 W, 95% CI 3.1 to 35.3; ES 0.60.
Leg power
Both groups improved modestly, but the between-group difference was not significant.
Between-group difference 2.4 W, 95% CI -7.9 to 12.5; ES 0.12.
Hand grip strength
Small improvements were similar between groups.
Between-group difference 0.01 N/kg, 95% CI -0.17 to 0.2; ES 0.04.
Static balance
Both groups improved, with no significant between-group difference.
Between-group difference 1.6 seconds, 95% CI -10.4 to 13.7; ES 0.07.
Dynamic balance
Both groups improved, with no significant between-group difference.
Between-group difference -0.8 steps, 95% CI -2.5 to 1.0; ES -0.22.
Chair stand
Chair stand improved within groups but not significantly more with HIT than MIT.
Between-group difference 0.8 repetitions, 95% CI -0.6 to 2.1; ES 0.28.
Insights
- A medically screened, supervised older-adult cycling protocol can use only 60 seconds of hard work inside a 20-minute session.
- Short controlled supramaximal intervals may be especially relevant when the target outcome is anaerobic capacity for brief demanding tasks.
- For broad physical function outcomes, this protocol should be presented as comparable to MIT rather than clearly superior.
- Exact translation to app workouts needs adaptation because the protocol relies on stationary-bike power control and in-person supervision.
Limitations
- Volunteer selection bias is possible.
- Sample size was powered for parent-trial primary outcomes, not these secondary outcomes.
- No inactive or usual-care control group.
- Limited power to detect small between-group differences.
- Anaerobic cycling results may be influenced by similarity between training and test modality.
Safety
- Exercise session attendance was 88.0% for HIT and 88.1% for MIT.
- Across 1497 attended participant-sessions, discomfort was reported 52 times in HIT and 94 times in MIT, mostly musculoskeletal.
- None of the discomfort reports were considered serious adverse events by external reviewers.
- One exercise discontinuation at participant request was considered related to the intervention due to back pain after handling equipment.