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

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.

Methodology

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.
30 participants.
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.
Intensity: Maximal sprint intent; hypoxic groups used FiO2 equivalent to 2000 m, 3000 m, or 4000 m.
10 min warm-up plus about 18-45 min interval block depending on week.
2 sessions/week.
6 weeks.
Single-blinded semi-randomized pre/post training study with four altitude conditions
Peak power output during incremental cycling, Power at Dmax lactate threshold, Wingate peak and mean power, and 600 kJ cycling time trial were tracked.

Outcomes

Peak aerobic power

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

Improved

Wingate mean power

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

Improved

Time trial

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

Unclear

Blood markers

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

Mixed

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

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