Some say repeated sprints are the devil’s work. During the HypoxicHIIT classes in the chamber, particularly the cycle-specific, or even your own training, you may have come across these. They typically last for 5–10 s with around 20–50 s recovery, with repetitions until you can’t go any further.
However, the volume of work completed when doing repeated sprints alone won’t be overly large – so why do we prescribe them? If completed properly, i.e., maximising the fast-twitch muscle fibers every time, the performance gains to benefit from are huge!
A recent research paper has also confirmed this in a group of team-sport athletes. The authors prescribed 4 sets of 5 s maximal sprints with 25 s recovery, 5 times, with 5 mins recovery between each set. One group carried out 3 sessions per week for 2 weeks in hypoxic conditions, breathing ~14% oxygen (equivalent to ~3200 m), with a control group carrying out the exact same activity in sea level conditions. Naturally, the findings showed a significant increase in heart rate and decrease in blood oxygenation values in the group who did the sprints in hypoxia, compared to sea level. Additionally, sprint performance decreased over time, as expected due to fatigue; however, there were no significant differences in sprint performance between the two groups.
The findings of this research, and the reason that we prescribe repeated sprints during our classes in the chamber, is that you get a significantly greater physiological stimulus whilst still maintaining performance. If one can still produce the same peak speed or power output when their heart rate is higher and blood oxygen lower in a hypoxic environment, the adaptive response will be much greater and lead to improved performance subsequently.
Overall, repeated sprints may appear daunting. However, the increases in performance when these are carried out to a sufficiently high-standard in a hypoxic environment regularly are a lot higher than in sea level conditions. Check out our classes to see when you can next give them a go!
Brocherie et al. (2017). Int J Sports Phys and Perf, 12, 115-123.