Summary
Researcher Michael Rosenblat presents findings from his meta-analysis comparing high-intensity interval training (HIIT) versus sprint interval training (SIT) on time trial performance in endurance athletes. The analysis pooled six randomized studies with over 110 participants (cyclists, rowers, runners, triathletes) to determine which interval type produces better performance outcomes. Key findings: there was no statistically significant difference between HIT and SIT for VO2 max improvements. However, HIT showed approximately 1% greater improvement in time trial performance and 2.5% greater improvement in max aerobic power (MAP) compared to SIT. Rosenblat defines HIT as longer intervals in the severe intensity domain (sustainable for minutes), while SIT consists of all-out 30-second efforts in the extreme domain. A 2016 study by Granata found SIT produced greater VO2 max and mitochondrial improvements, but only HIT improved time trial performance.
Key Points
- Meta-analysis of 6 studies (110+ participants) comparing HIT vs SIT on endurance performance
- HIT: longer intervals in the severe intensity domain; SIT: all-out 30-second efforts in the extreme domain
- No significant difference between HIT and SIT for VO2 max improvements
- HIT showed ~1% greater time trial improvement and ~2.5% greater max aerobic power improvement vs SIT
- Granata (2016) found SIT improved VO2 max and mitochondrial respiration more, but only HIT improved time trial performance
- SIT produces a significant neuromuscular response similar between 5-second and 30-second bouts
- Both HIT and SIT improve endurance performance; neither should be dismissed
- For triathlon, HIT on the bike and SIT for running (to improve leg speed) is one practical approach
Key Moments
Defining HIT vs SIT for endurance athletes
Researcher Michael Rosenblat defines HIT as longer-duration intervals in the severe intensity domain (sustainable for a few minutes up to 20), while SIT consists of all-out 30-second efforts in the extreme domain.
"Sure. Actually, I think that's a great way to start because there's always a little bit of confusion based on interval training. And sometimes people call certain things hit when it might not actually be hit. And so there's different types. There's hit or high-intensity interval training and sprint interval training. So high-intensity interval training would be..."
Meta-analysis results — HIT vs SIT on performance
Pooling 6 studies with 110+ participants: no significant difference between HIT and SIT for VO2 max, but HIT showed ~1% better time trial and ~2.5% better max aerobic power improvements.
"Looking at the difference between hit and sit just as it is without doing a subgroup analysis, it showed that there wasn't a statistically significant difference between hit and sit."
Granata study — SIT improves mitochondria but not time trials
A 2016 study by Granata found SIT produced greater improvements in VO2 max and mitochondrial respiration compared to HIT, but only HIT improved time trial performance — suggesting different adaptations from each protocol.
"the results were very interesting. It showed that the SIT group showed a greater improvement in VO2 max and in mitochondrial biogenesis, or let's say respiration, compared to HIT. But only the HIT group showed an improvement in time trial performance."
