The High/Low Training System, also known as Hot/Cool training, is a structured approach to training that I first learned about 12 years ago while researching how to optimise high-speed training for the athletes I coached. The system was developed by sprint coach Charlie Francis, who is known for coaching the famous Canadian sprinter Ben Johnson, one of the fastest sprinters in the world at the time, alongside Carl Lewis. The resources I used to learn about the system included Speed Trap, Charlie Francis Training System, Key Concepts, and Structure of Training for Speed.

The system involves alternating between high-intensity (hot) and low-intensity (cool) training sessions in a wave-like pattern that demands different levels of the central nervous system. Hot sessions are separated by 48 hours and are used to develop movements, activities, or qualities that require very high intensity, while cool sessions are used to build more capacity at lower intensity and aid in recovery. The reason why high-intensity days are not done consecutively is that it doesn't allow for adequate recovery, which can cause athletes to overreach and underperform.

You can think of this system as having a battery, with the high-intensity days draining the battery and the low-intensity days allowing time for it to recharge. This battery is referred to as the central nervous system (CNS).

Unfortunately, many people adopt a bodybuilding-style approach to training, focusing solely on hypertrophy and dedicating each day of the week to a specific body part. For instance, Monday might be chest day, Tuesday back day, Wednesday biceps and triceps day, and so on.

However, this approach may not be the best for athletes since it doesn't account for  balancing the physiological demands of training and the sports itself (sport specificity. In contrast, the High/Low Training System is designed to alternate and integrate both the sports technical demands, and the  physiological demands.

Although the bodybuilding approach may help in developing muscle mass and size, it may not be the best for athletes seeking to optimise their sports performance. The High/Low Training System is a more effective and balanced approach to training, tailored to meet the specific needs of athletes.

In the below images are examples of High intensity Training sessions and Low intensity training sessions.