Interval training is a highly effective way to improve your athlete’s performance, enabling to train at intensities that are too high to sustain for a long time. To create an effective interval training program, you need to consider the duration and intensity of both the interval and the recovery. In this step-by-step guide, we’ll show you how to create highly individual interval training that actually works.

By Loek Vossen

How to Create Highly Effective Interval Training

What is interval training?

Interval training is a training method that involves alternating periods of high-intensity exercise with periods of lower-intensity exercise or rest. It is designed to improve cardiovascular fitness, and increase muscle strength and endurance. It can be customized to fit a variety of athletes’ levels and goals, making it a versatile and effective workout option. By adjusting the duration and intensity of the intervals, you can create a workout that is challenging yet manageable.

Interval training can be beneficial for sports coaches,  labs, and athletes as it can help improve athletic performance, increase metabolic rate, reduce the risk of injury, and enhance overall health. It’s a time-efficient way to exercise, making it a great option for those with busy schedules. By incorporating high-intensity intervals into your workout routine, you can achieve the same benefits as longer, steady-state workouts in less time.

Interval training is a proven way to increase speed and endurance. By pushing yourself to work harder during the high-intensity intervals, you can challenge your body to adapt and become stronger. Interval training can be used to improve performance in a variety of sports, including running, cycling, and swimming.

What are 4 steps to creating an individualized interval training program?

The 4 steps to create individualized interval training are:

  1. Determine interval intensity based on training goals
  2. Determine interval duration
  3. Determine recovery intensity
  4. Determine recovery duration

Now that you know what interval training is and its benefits, let’s move on to the first step. 

Step 1: Determine Interval Intensity

The first step is to determine the intensity of your intervals. Interval intensity should be based on the specific training goal. Do you want to increase VO2max? Or increase anaerobic power? Or…

Whatever your goal is, make sure to base your interval intensity on that goal. If you want to increase VO2max, for example, it makes no sense to determine the interval intensity based on %FTP or %AT (anaerobic threshold). Instead, you should base interval intensity on %VO2max or aerobic energy contribution.

How to determine interval training intensity?

You can determine the appropriate intensity levels by using heart rate monitors, perceived exertion scales, or power meters.

Although this guide is relevant to all possible goals, we’re going to focus on interval training that boosts anaerobic power (VLamax).

To increase anaerobic power, we need an interval intensity at a high percentage of VLamax (requiring a high anaerobic power and a high anaerobic energy contribution). You can use the INSCYD Training Zone Builder to determine a corresponding intensity. In the example below, we’re looking for an intensity at 40% of VLamax.

The INSCYD Training Zone Builder (TZB) in action:Determine Interval Intensity
Image 1: The INSCYD Training Zone Builder (TZB) in action. We set the intensity to 40% of VLamax. The TZB shows us that this equals a running power of 535 watt and a running speed of 6.38 m/s. At this intensity, lactate will accumulate 13 mmol/l per minute.

The Training Zone Builder shows that our example athlete needs to run 6.38 m/s (or 535 watt running power) to use 40% of VLamax. We could pick a higher percentage of VLamax, but since we want to do several interval repetitions, we stick to 40% for this example.

(Instead of determining intensity based on 40% of VLamax, you could also use the Training Zone Builder to determine it based on e.g. 70% anaerobic energy contribution, or a lactate concentration of 6 mmol/l.)

Step 2: Determine Interval Duration

Determine Interval Duration

An interval is defined by its intensity and duration. Once you’ve determined the intensity of your intervals, the next step is to determine their duration. 

How long should intervals be?

Coaches and labs can determine the optimal duration of interval training sessions for their athletes by considering the athlete’s goal and recovery capacity. 

We determined the intensity based on our goal (%VLamax).

We can again use the Training Zone Builder to learn more about the effect of different interval durations. Here’s an example of what happens when the interval duration is 10, 20 or 60 seconds:

The INSCYD Training Zone Builder (TZB) in action: Determine Interval Intensity
Image 2: The INSCYD Training Zone Builder (TZB) in action. With the intensity set to 40% of VLamax, we can now start playing around with the duration. This example shows what happens when the duration equals 10, 20 or 60 seconds. You can see the lactate concentration and energy contribution of the aerobic vs anaerobic system.

Apparently, the longer the duration, the lower the energy contribution from the anaerobic system. Watch our free webinar to learn why.

On the other hand, if the interval duration is too short, there’s not that much anaerobic energy spent at all. That’s why we continue with a 20s interval duration.

As a sports coach or lab, you know that interval training is crucial for improving athletic performance. This is why we encourage you to Schedule a Free Consultation in your own language with the INSCYD experts to help you determine the perfect interval intensity based on training goals, whether it’s increasing VO2max, boosting anaerobic power, or another. Don’t miss out on this opportunity to take your athletes’ performance to the next level. And athletes you can find an INSCYD coach or lab via this link.

Step 3: determine recovery intensity

Determine Recovery Intensity

The recovery phase of interval training is just as important as the on-phase. In fact, recovery determines the training effect of our interval training.

Incomplete recovery (e.g. too short or at a too high intensity) results in a decrease of anaerobic energy contribution over time. We don’t want that for our example interval training that aims to increase VLamax – anaerobic power.

Learn more about these physiological details in our free webinar: Physiology based interval training: create individual interval programs that actually work.

So the goal of our recovery is to recover “fully” between intervals. What intensity helps to recover fully? The INSCYD Lactate recovery & accumulation graph will tell!

The INSCYD Lactate recovery & accumulation graph: Determine Interval Intensity
Image 3: The INSCYD Lactate recovery & accumulation graph shows how fast an athlete recovers from a lactate accumulation (grey) and how fast an athlete accumulates lactate (purple), depending on the exercise intensity.

Lactate is a good indicator of how well our example athlete is recovered from a previous interval. The lactate recovery & accumulation graph shows that our example athlete “clears” lactate (grey line) fastest at a running speed between 1.3 and 1.6 m/s (130 -145 watt). This will be the recovery intensity. Coaches and labs can use this graph to design interval training programs that optimize lactate clearance and improve athletes’ performance.

That is a slow pace, but note that going too slow (<1.3 m/s) has a negative effect on lactate recovery. That’s kind of intuitive: if you lay in the grass after a hard interval, you don’t feel recovered when standing up.

More experienced runners will find that they actually need to maintain a decent running speed to recover fastest. This emphasizes the need to do individual metabolic testing instead of relying on general interval training instructions. Metabolic testing can provide valuable information about your physiology and help you create a more personalized training program.

Summary interval webinar. Watch the full webinar here 

Recovery is important in interval training because it allows the body to recover from the high-intensity exercise and prepare for the next interval. You can optimize recovery time by engaging in active recovery, passive recovery, or a combination of both.

Step 4: determine recovery duration

Determine Recovery Duration

The final step in creating your interval training is to determine the recovery duration. The recovery duration will depend on the intensity and duration of your intervals and your recovery intensity. 

This last step is super straight forward. Both the Training Zone Builder (image 1) and the lactate accumulation & recovery graph (image 3) show that our example athlete will accumulate 13 mmol/l lactate per minute during the interval. That equals a lactate accumulation of 4.3 mmol/l in our 20s interval.

The lactate accumulation & recovery graph also shows that our example athlete will only recover 0.36 mmol/l lactate per minute, at the recovery intensity that we picked.

To fully recover from our 20-second interval at 40% of VLamax, our athlete needs to recover for 12 minutes at a slow pace of 1.3-1.6 m/s (130-145 watts).

 4.3 ÷ 0.36 = 12

These long recovery durations are common in interval sessions that aim to increase anaerobic power (VLamax). Ben Tilus, National and State Champion coach in track and field and XC, shared some interval workouts to increase VLamax in runners that had similar recovery durations.

Note that if you would recover much shorter, you would have a typical HIIT interval training to increase VO2max (instead of VLamax). That’s why recovery can determine the training effect.

Interval training and HIIT (High-Intensity Interval Training) are similar but not exactly the same. Both involve alternating high-intensity exercise with low-intensity exercise or rest, but HIIT typically involves shorter, more intense intervals and a higher overall intensity level than traditional.

So the length of the recovery period will depend on the intensity and duration of your intervals and your recovery intensity. To ensure optimal recovery, you should allow enough time for lactate to clear and for your body to fully recover before the next interval.

Wrap-up: how to create interval training

By following these 4 steps, you can create a highly individualized interval training program that is tailored to your athlete’s goals and physiology: 

  1. Determine interval intensity: Base interval intensity on the training goal, whether it’s increasing VO2max, anaerobic power, or something else. In this example, we focused on increasing anaerobic power (VLamax).
  2. Determine interval duration: After setting the intensity, choose the duration of your intervals based on your goal and recovery capacity. In our example, we selected a 20-second interval duration.
  3. Determine recovery intensity: Recovery is crucial for optimal interval training. Analyze your lactate recovery and accumulation to find the ideal recovery intensity. In this example, we chose a slow pace of 1.3-1.6 m/s (130-145 watts).
  4. Determine recovery duration: Lastly, calculate the recovery duration needed for complete recovery before the next interval. In our example, the athlete required 12 minutes of recovery at the chosen recovery intensity.

Although we focused on increasing anaerobic power (VLamax), the same steps are important when:

To help you optimize interval training sessions and better understand your athletes’ needs, INSCYD offers a free consultation for sports coaches and labs. Don’t miss this opportunity to explore how our tools, like the Training Zone Builder and lactate accumulation & recovery graphs, can enhance your coaching strategies and improve your athletes’ performance.  You can also download our infographic on how to create effective interval training by clinking the button bellow.

The Top Questions About Interval Training, Answered

What is the most effective interval training?

The most effective interval training program is one that is tailored to the athlete’s level and goals, and includes a variety of exercises and intensity levels. It’s important to start slowly and gradually increase the intensity and duration of your intervals as you build strength and endurance. A mix of cardio and strength exercises can help you achieve optimal results.

Are intervals better than running?

Interval training can be a more effective form of exercise than running alone, as it combines periods of high-intensity exercise with rest periods or low-intensity exercise, allowing you to push yourself harder and burn more calories in less time.

How long should intervals be?

The length of intervals can vary depending on the athlete’s level and goals.

What are the different types of interval training and which one should I choose?

There are various types of interval training, including high-intensity interval training (HIIT), sprint interval training, and endurance interval training. The type of interval training you choose will depend on your training goals and the specific needs of the athlete.

Remember, every athlete is unique, and it’s essential to customize your interval training program based on your goals, fitness level, and recovery capacity. Using tools like the INSCYD Training Zone Builder and metabolic testing can help you create a more personalized and effective interval training program.

Last but not least, watch our free interval training webinar, in which Sebastian Weber talks about creating physiology based interval training:


Human Movement Scientist | Content Marketing and Education