Just as important as knowing how to exercise for maximum benefit is knowing when to stop to prevent injury or CNS fatigue. There is a strong link between exercise duration and health. A common question from intense athletes involves how should be HIIT duration, how often HIIT can be performed in the course of a week and if it can be done with other workout sessions.

Let’s just look at some basic facts and you can begin to see the answer clearly for yourself.

1. HIIT workouts should be so intense that you are completely exhausted.

2. HIIT recovery intervals and cool down are absolutely necessary and cannot be avoided.
Even if you are too tired to cool down, you don’t want to risk blood pooling in your

3. Heart rate should drop to 70% of max during recovery.

4. Fatigue or soreness means that your body is demanding rest – it has been depleted and needs to recover.

5. For beginners, the work to rest interval should be roughly 1/4 – it takes that long for the body to adjust itself to the demands.

6. Progressive overload – increasing the volume, intensity and frequency of training – is progressive based on the body’s reaction to the demands, not according to the calendar or a schedule.

Overtraining Syndrome

Have you ever reached a plateau in your training or wondered why you are losing ground instead of making improvements? The reason this occurs is usually what is called ‘Overtraining Syndrome’. What this means is that a higher volume, intensity or frequency in training, if not handled properly with appropriate lower intensity intervals and rest periods, can result in Central Nervous System (CNS) Fatigue.

Overtraining Syndrome

Let’s just mention that overtraining means not being able to handle the workout load you usually can and feeling tired, dissatisfied and in discomfort. It’s about regression – losing the gains you have made.

HIIT workouts are all about intensity and timing and the general recommendation is to perform them only 3 times per week. The other days can be used for cardio training that strictly target aerobic fitness or anaerobic strength training.

There are ways, however, to incorporate HIIT activities on a more frequently basis without hitting the proverbial wall. The key is to choose activities that are as different as possible – using different muscle groups – and keeping the overall reps to a minimum for a shorter workout time. For example, if you cycle one day, row the next, swim another and do calisthenics the next.