As painful as our high-intensity interval training (HIIT) sessions are, they do work, as supported by a study in PLOS One.

The researchers took 50 moderately trained male cyclists who were tested before and after a four-week supervised training period.

Subjects were randomly assigned to repeated sprint training in normoxia (sea level) or hypoxia (3000m/ 14.6 per cent oxygen), as well as a control group (who only completed the pre- and post- tests).

Each participant underwent a 10-minute warm-up at 120W, followed by three sets of five; ten-second sprints with five-minute recovery in between, with a ten minute cool down at 120W.

Those who trained in hypoxia had a significant increase in the amount of sprints prior to exhaustion compared to those who trained in normoxia.

The average power output of hypoxic cyclists improved until the ninth sprint, compared to those who trained at sea level, where power output only stayed consistent for seven sprints.

The study found significant improvements in the average power output in the tenth and eleventh sprints post-test, compared to the ninth sprint in the pre-test.

What does this mean for those of you enduring The Sufferfest and our HIIT classes? Training at altitude delays the decrease in power output and therefore increases the number of sprints performed. It also means that those training in hypoxia show larger gains in repeated sprint performance due to significant molecular adaptations and greater variations in blood perfusion (passage of blood through vessels and tissue) in active muscles.

Richard simmonds racing