If you run, you’ve probably heard about HIT or «intervals.» In this blog, I want to explain where the term HIT comes from, what it is, and how it can help you run faster.

Let’s get started!

What is HIT?

HIT stands for “High-Intensity Training.” These are training intensities above VT2 (see the blog on VT2), where the main goal is to increase VO2max (see the blog on VO2max), although improvements can also occur in lower training zones (such as VT1 and VT2). Depending on the percentage of VO2max at which we train (90%, 100%, 110%, etc.), we can accumulate more training time and focus on different capacities.

The literature suggests that you need to reach at least 90% of VO2max to induce changes in this physiological parameter because high stress on oxygen transport and utilization is required to stimulate VO2max. This type of training is characterized by alternating work and recovery periods, which helps accumulate more time at these intensities by the end of the training session.

In colloquial terms used in endurance sports, HIT refers to most of the “interval” workouts performed. Depending on the duration and intensity of the intervals, we can focus more on VO2max, the ability to sustain VO2max intensity, VT2 while stimulating VO2max, and so on. Not all “interval” workouts improve the same capacity; we must tailor them to the needs of each athlete at different times of the season.

Types of HIT or Intervals

Within HIT, depending on the intensity used, we find different types:

• HIT with long intervals: These are performed at intensities between 90% and 100% of vVO2max. They last between 2 and 8 minutes, and the recovery time is usually close to the work time. These would be intervals between 600 and 2000-3000 meters.

• HIT with short intervals: These are performed at intensities between 100% and 120% of vVO2max. They last between 10 and 60 seconds. As with the previous type of HIT, the pause times are usually close to the work time. These would be intervals between 100 and 400 meters.

• RST (Repeated Sprint Training): This involves repeated sprints where the speed reaches between 120% and 160% of vVO2max. These sprints last 10 seconds or less, combined with recovery periods of less than 60 seconds. This method is widely used in team sports, where the specificity of the sport requires the ability to repeat maximum sprints.

• SIT (Sprint Interval Training): These are workouts performed at the maximum speed/power that can be generated, even exceeding 180% of vVO2max. The intervals last 10 to 30 seconds and are separated by long pauses that allow for almost complete recovery (2 to 5 minutes). Although it has been shown to be effective, this method is rarely used and studied in runners. However, in cycling, there are many studies showing how 4 to 7 repetitions of 30 seconds can lead to significant changes in endurance events (such as a 40km time trial).

I hope this blog has helped you better understand what this type of training is for. 

Best regards, and happy running!