# Effects of Sprint Interval Training at Different Altitudes on Cycling Performance at Sea-Level

PMID: 33217937
Journal: Sports (Basel, Switzerland)
Published: 2020 Nov 18
Authors: Warnier G, Benoit N, Naslain D, Lambrecht S, Francaux M, Deldicque L

## Question

Does performing the same 6-week cycling sprint interval training program at simulated sea level, 2000 m, 3000 m, or 4000 m differentially improve sea-level aerobic, anaerobic, and time-trial performance in well-trained endurance athletes?

## Summary

Six weeks of twice-weekly cycling sprint interval training improved peak incremental cycling power and Wingate mean power in well-trained male endurance athletes. Simulated altitude did not clearly add sea-level performance benefits compared with sea-level sprint interval training, and hematological markers were largely unchanged.

## Population

- Thirty male well-trained endurance athletes completed the study after one dropout from a fall during personal training. Participants were cyclists or triathletes aged 18-35 years, training 4-10 h/week, and without recent altitude exposure, smoking, or health risks for hypoxic exercise.
- Sample size: 30
- Age: 18-35 years
- Sex: Male
- Fitness level: Well-trained endurance cyclists/triathletes
- Health status: Healthy, screened for smoking, recent altitude exposure, and hypoxic-exercise risk

## Methodology

- Single-blinded semi-randomized pre/post training study with four altitude conditions
- 6 weeks training plus pre/post testing
- Supervised laboratory cycling and simulated-hypoxia setting
- Controlled study design.

## Protocol

- Cycling SIT in simulated altitude.
- Modality: Cycle ergometer on personal bicycle in normoxia or simulated hypoxia.
- Work intervals: 30 s all-out-style sprints; first and last sprint used Wingate load, other sprints at 80% Wingate load.
- Recovery: 4 min 30 s active recovery at about 75 W.
- Sets or repetitions: 4 sprints in week 1 progressing to 9 sprints in week 6.
- Intensity: Maximal sprint intent; hypoxic groups used FiO2 equivalent to 2000 m, 3000 m, or 4000 m.
- Session duration: 10 min warm-up plus about 18-45 min interval block depending on week.
- Frequency: 2 sessions/week.
- Program length: 6 weeks.
- Progression: Number of 30 s sprints increased from 4 to 9 across the program.
- Sea-level cycling SIT.
- Modality: Cycle ergometer on personal bicycle at sea-level oxygen fraction.
- Work intervals: 30 s sprints.
- Recovery: 4 min 30 s active recovery.
- Sets or repetitions: 4 to 9 sprints.
- Intensity: Maximal sprint intent in normoxia.
- Session duration: 10 min warm-up plus interval block.
- Frequency: 2 sessions/week.
- Program length: 6 weeks.
- Progression: Same sprint progression as hypoxic groups.

## Outcomes

### Peak aerobic power
Status: improved
Peak power output increased by about 16-22 W in each group, roughly 6%, with no clear altitude dose advantage.

### Wingate mean power
Status: improved
Mean Wingate power increased overall; sea level, 2000 m, and 4000 m showed significant within-group gains, while 3000 m did not.

### Time trial
Status: unclear
The 600 kJ time trial only tended to improve and no group showed a significant individual pre/post change.

### Blood markers
Status: mixed
Hemoglobin mass, hemoglobin concentration, hematocrit, and plasma volume did not materially change; ferritin declined in the sea-level and 4000 m groups.

## Practical Insights

- Twice-weekly 30 s cycling sprint intervals can improve cycling power in trained endurance athletes even with low total sprint volume.
- Adding simulated altitude to this sprint protocol did not provide a clear sea-level performance advantage.
- Long recovery periods around a 1:9 work-to-rest ratio were used to preserve sprint quality.

## Limitations

- Small group sizes after division into four altitude conditions.
- Allocation was semi-randomized and single-blinded rather than fully randomized and double-blinded.
- Nutrition was not tightly controlled.
- VO2max data were not available because of technical issues.
- Repeated-sprint performance was not tested despite the sprint-training emphasis.

## Safety And Adherence

- No intervention adverse events were reported. One enrolled participant dropped out because of a fall during personal training rather than the study intervention.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/33217937/) (pubmed)
- [DOI](https://doi.org/10.3390/sports8110148) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698804/) (full text)

## Agent Guidance

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