# Acute Effects of Work Rest Interval Duration of 3 HIIT Protocols on Cycling Power in Trained Young Adults

PMID: 33923545
Journal: International journal of environmental research and public health
Published: 2021 Apr 16
Authors: García-De Frutos JM, Orquín-Castrillón FJ, Marcos-Pardo PJ, Rubio-Arias JÁ, Martínez-Rodríguez A

## Question

How do 30-, 60-, and 90-second work-rest intervals affect acute cycling power, heart rate, lactate, and jump performance when total work is matched?

## Summary

Twenty-two young trained men completed three acute all-out cycling HIIT protocols with 30-, 60-, or 90-second work intervals. Shorter intervals allowed higher power output while lactate and jump performance responses were not meaningfully different; all participants completed sessions without incidents.

## Population

- Twenty-two active young men experienced with HIIT
- Sample size: 22
- Age: 21 +/- 2 years
- Sex: Male
- Fitness level: Active and HIIT-experienced
- Health status: Healthy

## Methodology

- Counterbalanced crossover acute exercise study
- Three HIIT sessions, one per week for three weeks
- Exercise laboratory at San Antonio Catholic University of Murcia
- Randomized and controlled study design.

## Protocol

- 30-second all-out cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 30 seconds.
- Recovery: 30 seconds passive rest.
- Sets or repetitions: 10 intervals.
- Intensity: All-out self-selected workload.
- Session duration: 10-minute interval block after warm-up.
- Frequency: One acute session.
- Program length: Crossover over three weeks.
- Progression: None.
- 60- and 90-second all-out cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 60 or 90 seconds.
- Recovery: 60 or 90 seconds passive rest.
- Sets or repetitions: 5 x 60 s or 3 x 90 s.
- Intensity: All-out self-selected workload.
- Session duration: 10-minute interval block after warm-up.
- Frequency: One session per protocol.
- Program length: Crossover over three weeks.
- Progression: None.

## Outcomes

### Power
Status: improved
30-second intervals produced higher maximal and mean cycling power than longer intervals.

Pmax and Pmean p<0.001.

### HR
Status: mixed
Mean HR was higher in the 30-second protocol than the 90-second protocol.

HRmean p<0.001.

### Lactate
Status: no clear change
Blood lactate did not differ significantly across interval durations.

p about 0.337-0.373.

### CMJ
Status: no clear change
Jump height and jump power did not differ significantly by protocol.

CMJ height p=0.682; CMJ power p=0.832.

## Practical Insights

- For power-focused workouts, shorter all-out intervals may preserve output better than longer all-out intervals.
- A 1:1 work-rest density can be implemented with different interval lengths, but physiological and performance outputs differ.
- All-out interval prescriptions should be reserved for experienced users.

## Limitations

- Small all-male sample.
- Participants were trained young adults, limiting beginner applicability.
- Acute-only protocol with no adaptation outcomes.
- No non-exercise control group.

## Safety And Adherence

- All 22 participants completed the three HIIT sessions without incidents.
- Participants were active, HIIT-experienced young men screened for medications and compliance with pre-session guidelines.
- Sessions were supervised by professional sport scientists with heart-rate and lactate monitoring.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/33923545/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph18084225) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8073758/) (full text)

## Agent Guidance

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