Overload Principle

The overload principle states that any new training gain requires an appropriate training stimulus that is greater than the amount of training stress to which the body is currently adapted. Just as the name of the principle implies, you must “overload” the system to bring about a response and adaptation. Keep in mind that the training stimulus must still be appropriate, however. It needs to be an appropriate stress to ratchet up your fitness level incrementally, rather than a stress that completely overwhelms the system and leads to overtraining or injury.

Fitness professionals use the acronym FIT as a mnemonic for the key elements that comprise a training load: frequency, intensity, and time. Frequency refers to the number of training sessions done per week. Intensity refers to the effort level put forth during a training session. Time, or what is also commonly termed duration, refers to how long a training session lasts.

When taken together, these three elements—frequency, duration, and intensity—comprise your overall training load. Frequency and duration combine to give you training volume. Training volume contrasts with training intensity. In this way, your training load consists of volume plus intensity, or the sum total of training stress you throw at your body in its various forms.

Training Load = Volume + Intensity

Since training volume refers to the total amount of training you do, to quantify training volume you need to take into account the frequency of your training (i.e., how many times per week you train) plus the duration of each of those sessions. Many competitive athletes are accustomed to thinking in mileage or yardage instead of hours trained. In that case, training volume is quantified as distance rather than duration.

Training intensity refers to the exertion level put forth during your training sessions. Whereas volume refers to the quantity of your training, intensity deals with the qualitative nature of your training.

In sum, the overload principle states that you need to provide an appropriate training stress to achieve a fitness gain. Not enough stress and the body will fail to achieve a fitness gain. Too much stress and the body will fail to positively adapt, resulting in overtraining or injury. In other words, you need to deliver a training stimulus appropriate to your current fitness level to move you forward toward your performance goals.