Power-oriented resistance training combined with high-intensity interval training in pre-frail and frail older people: comparison between traditional and cluster training set configurations on the force-velocity relationship, physical function and frailty

Baltasar-Fernandez I, Alcazar J, Martín-Braojos S, Ara I, Alegre LM, García-García FJ, Alfaro-Acha A, Losa-Reyna J

Question

Does combining power-oriented resistance training with treadmill HIIT improve force-velocity characteristics, physical function, and frailty in pre-frail and frail older people, and do cluster-set and traditional resistance configurations differ?

Summary

In pre-frail and frail older adults, a supervised program that paired lower-body power-oriented resistance training with treadmill high-intensity intervals improved leg power, walking speed, SPPB physical function scores, and frailty status over about 6-8 weeks. Both traditional and cluster-set resistance formats were feasible with high attendance, but the study was not randomized and the control group was formed from people who declined or could not attend exercise.

Methodology

Pre-frail and frail adults aged 75 years or older from a hospital frailty unit.
43 participants.
Leg press and plantar-flexion resistance training followed by treadmill high-intensity intervals based on gait speed.
Work intervals: After an initial continuous conditioning phase, treadmill HIIT progressed from 6-10 bouts with work:rest around 1:5 to later bouts around 1:3.
Recovery: After an initial continuous conditioning phase, treadmill HIIT progressed from 6-10 bouts with work:rest around 1:5 to later bouts around 1:3.
Intensity: Resistance training used 30-60% of estimated maximal isometric force with the concentric phase performed as fast as possible. Treadmill intervals progressed toward bouts at 90% maximal gait speed with recovery at 50% usual gait speed.
Sessions lasted about 45 minutes and combined lower-body resistance exercise with treadmill intervals.
2 sessions per week.
Approximately 6-8 weeks.
Quasi-experimental, single-blinded, non-randomized controlled intervention comparing traditional concurrent training, cluster-set concurrent training, and non-training control.
Lower-limb force-velocity and power, Physical function, and Frailty were tracked.

Outcomes

Both training formats improved maximal power

Both training formats improved maximal power: cluster training increased Pmax by about 36.7 +/- 34.2 W and traditional training by about 33.8 +/- 44.6 W.

Improved

Short Physical Performance Battery

SPPB improved in all groups, but gains were larger in the training groups: about +43.5% for traditional training, +31.1% for cluster training, and +13.4% for control.

Improved

Usual gait speed

Usual gait speed improved more in the training groups than control: about +26.8% for traditional training, +31.7% for cluster training, and +9.1% for control.

Improved

Frailty Phenotype criteria

Frailty Phenotype criteria decreased in the training groups, about -1.1 criteria for cluster training and -1.6 criteria for traditional training, while control changed little.

Improved

Force-velocity profile

Cluster training improved V0 significantly, while traditional training significantly improved F0; both formats produced broadly similar functional benefits.

Improved

Insights

For frail older adults, HIIT can be scaled to gait speed rather than running speed or maximal aerobic testing.
Very short treadmill bouts with long active recoveries may be a pragmatic way to introduce higher-intensity work in clinical older adults.
Combining HIIT with power-oriented resistance work may be important when the desired outcomes include mobility, frailty, and lower-limb power rather than aerobic fitness alone.
Cluster sets can maintain a high-velocity resistance-training intent by inserting short intra-set rests.

Limitations

Allocation was not randomized, creating substantial selection bias risk.
The control group did not complete force-velocity testing, limiting between-group interpretation for key neuromuscular outcomes.
Small sample size, especially in the two exercise groups.
Participants were a special clinical older-adult population, limiting generalization to typical fitness users.
The intervention combined resistance training and HIIT, so the independent contribution of HIIT cannot be isolated.

Safety

The authors described the programs as safe in this clinical setting, including for participants with cardiac conditions in the cluster-training block, but detailed adverse-event counts were not extracted from the article text.