High-intensity interval training (HIIT) has become an unstoppable trend in fitness, and for good reason—it delivers impressive results in a short amount of time. But here's where it gets interesting: how often should runners incorporate these powerful sessions into their weekly routine to truly boost their cardiovascular health? The answer might surprise you.
Recent research conducted on German runners sheds some light on this question. In this study, 26 participants were divided into three groups, each performing different weekly frequencies of HIIT—once, twice, or three times a week—while continuing their usual endurance training. This setup allowed researchers to compare how varying the number of sessions impacted their aerobic conditioning.
The HIIT protocol used in this study followed a classic Norwegian workout style, involving four repetitions of four-minute intervals at approximately 5K race pace. Between each interval, runners took a three-minute jog to recover. This well-known format is celebrated for its efficiency and effectiveness in improving aerobic capacity.
What did the results reveal? All groups experienced improvements in their VO2 max and their ability to sustain effort before exhaustion. However, the most significant gains were seen in the group that performed the sessions twice a week.
Specifically, VO2 max increased by only 0.6% with just one session per week, but jumped by an impressive 7.7% when done twice weekly. The group with three sessions saw a 5.6% increase—less than the twice-weekly group, indicating diminishing returns with higher frequency. Furthermore, the two-times-a-week group demonstrated the largest improvement in endurance, with their time-to-exhaustion climbing by 11%.
So, what does this mean for those looking to optimize their training? The takeaway is clear: striking the right balance is crucial. Two HIIT sessions per week appear to hit the 'Goldilocks' zone—optimal for enhancing both VO2 max and endurance. Doing just one session might bring some benefits but likely won't lead to significant improvements, while exceeding two sessions could be overdoing it and potentially causing unnecessary fatigue.
If you're eager to incorporate HIIT into your routine, here are a couple of effective sessions to consider aside from the classic 4x4s used in the study.
Speed Focused HIIT
- Warm up thoroughly.
- Run a series of repeats as fast as you can without losing control: 3 x 100 meters, 3 x 150 meters, and 3 x 100 meters.
- Rest for 2 to 3 minutes after each repeat, either standing or walking, to allow partial recovery.
Endurance Focused HIIT
- Begin with 15 minutes of light jogging to warm up.
- Then perform 10 repetitions of 800 meters at your threshold pace—a pace that’s challenging but sustainable.
- Rest for an amount of time equal to the duration it took to complete each 800-meter run, whether walking or jogging; for instance, if a rep takes 3 minutes and 30 seconds, rest the same amount of time before starting the next.
Are you convinced that two sessions a week are enough, or do you believe more could be better? The real question is—how do you find the balance between pushing yourself and avoiding overtraining? Share your thoughts and experiences in the comments below! And remember, whether you’re a seasoned runner or just starting out, customizing your training to fit your goals and limits is always the smart move.
