# The efficacy of unsupervised home-based exercise regimens in comparison to supervised laboratory-based exercise training upon cardio-respiratory health facets

PMID: 28912129
Journal: Physiological reports
Published: 2017 Sep
Authors: Blackwell J, Atherton PJ, Smith K, Doleman B, Williams JP, Lund JN, Phillips BE

## Question

Can unsupervised home-based HIIT improve cardiorespiratory fitness as effectively as supervised laboratory HIIT in sedentary middle-aged adults?

## Summary

This small trial compared supervised lab cycling HIIT, unsupervised home bodyweight HIIT, and home isometric hand-grip training in sedentary middle-aged adults. Both HIIT approaches improved cardiorespiratory fitness in only 4 weeks, while hand-grip training improved blood pressure but not fitness. The home HIIT protocol was equipment-free and used five one-minute hard bouts with 90 seconds walking recovery. The study is especially useful because it shows that very short, unsupervised, bodyweight-style HIIT can improve VO2max and anaerobic threshold, but the sample was tiny and home intensity was self-reported.

## Population

- Sedentary middle-aged adults not formally exercising more than twice per week.
- Sample size: 18
- Age: 52 +/- 5 years overall.
- Sex: 13 female, 5 male.
- Fitness level: Sedentary; baseline VO2max roughly 24-28 mL/kg/min.
- Health status: No CPET contraindications or musculoskeletal limitations reported.

## Methodology

- Small randomized parallel-group intervention study comparing three exercise regimens.
- 4 weeks, 3 sessions per week.
- Laboratory-supervised cycling for L-HIIT; unsupervised home training for H-HIIT and H-IHGT.
- Randomized and controlled study design.

## Protocol

- Home HIIT.
- Modality: Equipment-free bodyweight/cardio exercises.
- Work intervals: 1 minute maximum repetitions with good form.
- Recovery: 90 seconds walking.
- Sets or repetitions: 5 intervals using star jumps, squat thrusts, and static sprints.
- Intensity: Max repetitions possible with good form; repetition matching across repeated exercises.
- Session duration: About 12 minutes.
- Frequency: 3 sessions per week.
- Program length: 4 weeks.
- Progression: No formal progression; maintain effort and repetition targets.
- Laboratory HIIT and home isometric hand-grip training.
- Modality: Cycling HIIT or hand-grip isometrics.
- Work intervals: L-HIIT: 1 minute at 95-110% maximal CPET load; H-IHGT: 2-minute hold at 30% MVC.
- Recovery: L-HIIT: 90 seconds unloaded cycling; H-IHGT: 2 minutes rest.
- Sets or repetitions: L-HIIT: 5 intervals; H-IHGT: 4 holds.
- Intensity: L-HIIT targeted HR >85% predicted max and had 10% mid-program intensity increase; H-IHGT 30% MVC.
- Session duration: L-HIIT about 12 minutes; H-IHGT about 14 minutes.
- Frequency: 3 sessions per week.
- Program length: 4 weeks.
- Progression: L-HIIT 10% intensity increase after session 6; H-IHGT not reported.

## Outcomes

### VO2max and anaerobic threshold
Status: improved
Both supervised lab HIIT and unsupervised home HIIT significantly improved CRF.

L-HIIT AT 15.28 to 18.23 mL/kg/min p < 0.01; VO2max 26.50 to 31.00 p < 0.001. H-HIIT AT 13.93 to 15.35 p < 0.05; VO2max 27.77 to 29.98 p < 0.05.

### Blood pressure
Status: mixed
Only hand-grip training significantly reduced SBP and DBP; HIIT groups did not.

H-IHGT SBP 139 to 123 mmHg p < 0.01; DBP 93 to 82 mmHg p < 0.05.

### Safety and completion
Status: improved
No adverse events occurred and all subjects completed all testing and sessions.

## Practical Insights

- Home HIIT does not require equipment to improve CRF over four weeks.
- Five 1-minute hard intervals with 90-second recovery is a practical, evidence-backed structure.
- Blood-pressure claims should be separated from fitness claims in this study.
- Self-reported home intensity is a weakness; an app can improve guidance and tracking.

## Limitations

- Only 18 total participants.
- Only 6 participants per group.
- Home compliance and intensity self-reported.
- Short 4-week duration.
- Potential type II error for blood pressure outcomes.

## Safety And Adherence

- No adverse events during the study.
- All subjects completed all testing and training sessions.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/28912129/) (pubmed)
- [DOI](https://doi.org/10.14814/phy2.13390) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5599857/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.