# A flow resistive inspiratory muscle training mask worn during high-intensity interval training does not improve 5 km running time-trial performance

PMID: 33001229
Journal: European journal of applied physiology
Published: 2021 Jan
Authors: Faghy MA, Brown PI, Davis NM, Mayes JP, Maden-Wilkinson TM

## Question

Does wearing a flow-resistive breathing mask during HIIT improve 5 km running time-trial performance, respiratory muscle strength, and diaphragm thickness compared with pressure-threshold IMT or HIIT alone?

## Summary

Wearing a flow-resistive mask during 6 weeks of treadmill HIIT did not improve 5 km performance more than HIIT alone. Separate pressure-threshold inspiratory muscle training did produce greater improvements.

## Population

- Healthy, non-smoking recreationally trained runners.
- Sample size: 23
- Age: 36.5 +/- 9.6 years pooled
- Sex: 13 males, 10 females
- Fitness level: recreationally trained runners; mean indoor 5 km PB 26.15 +/- 3.19 min
- Health status: healthy non-smokers

## Methodology

- randomized three-group training intervention
- 6 weeks
- laboratory treadmill HIIT and home/daily IMT diary monitoring
- Randomized and controlled study design.

## Protocol

- HIIT with flow-resistive mask.
- Modality: treadmill running.
- Work intervals: 2 min.
- Recovery: 2 min static rest.
- Sets or repetitions: 6 reps in weeks 1, 2, and 6; 8 reps in weeks 3 and 4; 10 reps in week 5.
- Intensity: speed equivalent to 95% VO2peak.
- Session duration: 24-40 min interval block plus testing/session setup.
- Frequency: 3 sessions/week.
- Program length: 6 weeks.
- Progression: repetition number increased then tapered: 6, 6, 8, 8, 10, 6.
- HIIT plus pressure-threshold IMT or HIIT only.
- Modality: treadmill running plus optional inspiratory muscle training.
- Work intervals: same 2 min intervals.
- Recovery: same 2 min static rest.
- Sets or repetitions: same HIIT repetition progression.
- Intensity: same 95% VO2peak running; IMT at 50% PImax.
- Session duration: same HIIT; IMT group did 30 breaths twice daily.
- Frequency: HIIT 3 sessions/week; IMT twice daily.
- Program length: 6 weeks.
- Progression: PImax reassessed biweekly to adjust IMT load.

## Outcomes

### 5 km time
Status: improved
All groups improved 5 km time, but IMT improved more than mask and HIIT-only.

MASK 3.13 +/- 1.7%, p=0.034; IMT 5.7 +/- 1.5%, p=0.007; CON 2.64 +/- 1.0%, p=0.043; group x time p=0.015

### Mask benefit
Status: no clear change
The flow-resistive mask did not add benefit beyond HIIT alone.

MASK and CON performance changes were similar, p>0.05

### PImax and Tdi
Status: improved
Pressure-threshold IMT improved inspiratory strength and diaphragm thickness; mask and control did not.

IMT PImax +32 +/- 16%, p=0.008; Tdi +9.5 +/- 3.4%, p=0.032

## Practical Insights

- HIIT itself improved 5 km time, but the mask did not provide extra ergogenic value.
- Dedicated pressure-threshold IMT was more effective than wearing a mask during intervals.
- Consumer breathing-mask claims should be treated cautiously.

## Limitations

- Small sample.
- No placebo/sham IMT group.
- Mask resistance was not individualized to PImax.
- Actual inspiratory load and work of breathing during masked exercise were not quantified.

## Safety And Adherence

- No trial adverse events were explicitly reported; the article noted that other mask work had reported reduced alertness/focus during resistance exercise.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/33001229/) (pubmed)
- [DOI](https://doi.org/10.1007/s00421-020-04505-3) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815609/) (full text)

## Agent Guidance

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