HIIT stands for High Intensity Interval Training. It is a training method that involves performing exercises at a very high intensity, alternating phases of intense effort with recovery periods. In HIIT, training takes place in the aerobic power zone, beyond the threshold but below the Maximum Aerobic Power (MAP), with the goal of completing a large number of repetitions.
Article published in Trimax-magazine – December 2021, written by Jean-Baptiste Wiroth.
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The Benefits of HIIT Training
- Improvement of VO2max.
- Better tolerance to muscle acidosis.
- Increase in muscle power.
- Improvement in muscle strength. This improvement is the least significant but still present, especially in beginners.
- Time efficiency: High-intensity training leads to adaptations similar to aerobic work but in less training time. According to some studies, HIIT provides the same benefits as a longer endurance workout, making it ideal for those with a busy schedule or low motivation.
- The “Boomerang Effect”: HIIT boosts calorie expenditure not only during exercise but also afterward. This effect can last up to 48 hours after the session!
- Mental toughness: Triathlon, duathlon, or ultracycling require strong mental endurance and concentration, especially in transitions where efficiency and speed are key. High-intensity training is physically and mentally demanding, but completing a session can be very rewarding. Training hard builds a champion mindset.
How to Structure a HIIT Session?
This type of training is relatively simple to execute: high-intensity phases are short, generally ranging from 10 to 30 seconds. These phases require strong concentration.
“Active recovery” phases are longer, between 2’30” and 3’30”, at a moderate intensity (maximum power zone 3). This results in 3-minute blocks that must be repeated multiple times.
Three Examples of Sessions
- Swimming: 2 sets of 8 x 25m freestyle at fast pace with power, followed by 75m focusing on maximum glide.
- Cycling: 15 x 15 seconds of rapid acceleration, starting with a high gear (e.g., 50X14), followed by 2’45” of active recovery in low Z3.
- Running: 12 x 30 seconds of staircase or hill acceleration, followed by 2’30” of active recovery by walking or light jogging.
How to Keep It Simple?
Intensity phases of 10 or 15 seconds demand a very intense effort. In these cases, monitoring performance metrics (power, speed) during exercise is quite difficult and even unnecessary. It is better to check the values achieved post-exercise.
For longer intensity phases (30” and more), the proposed protocol allows efficient management of these durations. For these longer phases, it is essential to avoid starting too strong and slowing down significantly at the end of the 30” period. A decrease of more than 20% (in power or speed) from the peak level reached is not satisfactory.
From a cardiac perspective, you should ensure that you never reach your maximum heart rate before completing the planned number of repetitions. If this happens, the exercise is too difficult for you, and the number of repetitions should be reduced.
To assess the levels achieved in cycling, using a power meter is the best solution. For those without one, a speedometer can be used. Although the speed parameter is less precise, it is sufficient to verify the values achieved during an exercise and monitor progress over multiple sessions.
What Intensity for Recovery Phases?
- If using a power meter, stay in zone 2 (base endurance).
- Otherwise, focus on your sensations: the effort should be low but not minimal.
- Monitor your HR; it should not drop by more than 20-25 bpm after each effort.
This method is less precise but allows a proper session execution.
How Many HIIT Sessions per Week?
One session per week is a good starting point. Adding more depends on your experience with interval training and the season’s training phase.
Warm-up Before a HIIT Session
HIIT sessions are very intense, so to perform them under optimal conditions, it is essential to take the time to warm up properly.
Warm-up Guidelines:
- Before a HIIT swimming session: muscle and joint mobilization, followed by 15-20′ of low-intensity swimming.
- Before an indoor cycling session: 20′ of low-intensity pedaling (zone 1-2).
- Before an outdoor HIIT cycling session: 30′ of low-intensity pedaling (zone 1-2).
- Before a running HIIT session: muscle and joint mobilization, followed by 20-30′ of low-intensity jogging (zone 1-2) with drills (high knees, butt kicks, etc.).
