# Should I Rest or Should I Go Now? A Randomized Cross-Over Trial Comparing Fixed and Self-Selected Rest Durations in High-Intensity Interval Training Cycling Sessions

PMID: 37395902
Journal: Sports medicine - open
Published: 2023-07-03
Authors: Colorni E, Ohayon E, Côté JN, Obolski U, Halperin I

## Question

When total rest duration is matched, do fixed 90-second rests and self-selected rest distribution produce different performance, physiological, or psychological outcomes during HIIT cycling sessions?

## Summary

This crossover study asked whether trained male cyclists perform or feel differently when HIIT rest is fixed versus self-selected, while total rest time is kept the same. Each cyclist completed nine 30-second cycling intervals and had 720 seconds total rest between intervals. In one condition, rest was fixed at 90 seconds between intervals; in the other, cyclists could distribute the same total rest however they wanted. Performance, heart rate, muscle activity, effort, fatigue, and enjoyment were highly similar. Self-selected rest increased perceived autonomy. For programming, this suggests that when total rest is fixed, trained cyclists can choose rest distribution without meaningfully changing the session's physical outcome.

## Population

- Healthy amateur adult male cyclists riding at least 200 km/week.
- Sample size: 24
- Age: Mean 36.6 years (SD 7.2); eligible 18-45 years
- Sex: Male only
- Fitness level: Trained amateur cyclists
- Health status: Healthy

## Methodology

- Randomized counterbalanced crossover trial.
- Acute crossover sessions separated by 3-8 days; one familiarization and two experimental sessions.
- Laboratory cycling sessions on an SRM ergometer.
- Randomized and controlled study design.

## Protocol

- Self-selected rest HIIT cycling.
- Modality: Cycling on SRM ergometer.
- Work intervals: 30 sec.
- Recovery: 720 sec total active recovery at 50 W, self-distributed between intervals.
- Sets or repetitions: 9 intervals.
- Intensity: Maximize accumulated watts across all intervals.
- Session duration: 16.5 min work-plus-rest, excluding warmup/cooldown.
- Frequency: Acute test session.
- Program length: Acute crossover.
- Progression: None.
- Fixed rest HIIT cycling.
- Modality: Cycling on SRM ergometer.
- Work intervals: 30 sec.
- Recovery: 90 sec active recovery at 50 W between intervals.
- Sets or repetitions: 9 intervals.
- Intensity: Maximize accumulated watts across all intervals.
- Session duration: 16.5 min work-plus-rest, excluding warmup/cooldown.
- Frequency: Acute test session.
- Program length: Acute crossover.
- Progression: None.

## Outcomes

### Performance watts
Status: no clear change
Average watts and interval watt patterns were highly similar between fixed and self-selected rest conditions.

Average aggregated difference 0.57 watts, 95% CI -8.94 to 10.09.

### Heart rate
Status: no clear change
Heart-rate responses were highly similar between conditions.

Average aggregated difference -0.85 bpm, 95% CI -2.89 to 1.18.

### RPE
Status: no clear change
Perceived effort increased across intervals but did not differ meaningfully by condition.

Average aggregated difference 0.01 on 0-10 scale, 95% CI -0.29 to 0.30.

### Perceived autonomy
Status: improved
Perceived autonomy was higher in the self-selected rest condition.

Differences across autonomy items roughly 0.5 to 1.5 mean estimate points.

### Enjoyment and fatigue
Status: no clear change
Enjoyment and rating of fatigue were similar between conditions.

## Practical Insights

- For trained users, giving autonomy over rest distribution may improve perceived autonomy without changing acute work output when total rest is fixed.
- A rest-budget interface could let advanced users choose when to restart while preserving total workout structure.
- This evidence is about acute session design, not long-term adaptation.

## Limitations

- All-male trained cyclist sample.
- Small sample.
- Acute crossover design without training adaptation outcomes.
- Cycling-specific ergometer protocol.
- Total rest was fixed, so it does not answer open-ended self-selected rest duration.

## Safety And Adherence

- No adverse events extracted from the paper.
- Findings are limited to healthy trained cyclists in a supervised laboratory session.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/37395902/) (pubmed)
- [DOI](https://doi.org/10.1186/s40798-023-00601-8) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10317935/) (full text)

## Agent Guidance

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