We all recover from exercise at different rates. Many people who recover quickly have reached a high level of success performing a high number of sets. Many who recover slowly have also been very successful performing low numbers of sets. Because everybody is unique in their ability to adapt and recover from different programs, the number of sets needs to be individualized.

A very important component of a training program that should be given consideration is training frequency. How often can, or more importantly, should I train per week? Optimum recovery time between training sessions is essential if one is going to continue to make progress. Training frequency, which is determined by ones recovery ability, is often a forgotten part of most training protocols.

Don’t be so concerned with how many training sessions you can handle per week. Be more concerned about the optimal amount. More is not always better. In fact, when somebody comes to me for advice because they’ve stopped making progress, usually I either reduce the workout volume or add days off. There is no reason to go to the gym if you’re not going to make progress.

Does it make sense to keep doing the same routine if gains are not being made? Isn’t the definition of “crazy”, doing the same thing over and over expecting different results. If your current program is not working, change it. The number one complaint people have is they’re not making progress or their progress has come to a halt. In both cases, the answer is more recovery time. Understanding the fact our bodies have a finite amount of recovery ability should help explain this concept.

The following is Mike Mentzer’s explanation of overtraining and recovery. I’m sure you’ll find it interesting.

In bodybuilding, the idea is to impose a training stress onto the body that will serve to induce the biochemical changes which result in muscular hypertrophy. Applying any more of the training stress (high-intensity) than is required by nature will result in the equivalent of over-dosing on a medicine; or, as we say typically in bodybuilding – overtraining.
A person exposed to the sun’s ultraviolet rays at the equator in summer would not have the slightest concern whether the intensity of the sunlight stress is high enough to disturb the physiology sufficiently to induce an adaptive response, i.e., the buildup of a suntan. His only concern, his overriding consideration, would be to properly regulate the volume (or duration) and frequency of exposure time so as not to overdose on the stress/stimulus; and, thereby, incur a sunburn or, in extreme cases, death. A person seeking to develop a suntan at the equator, or wherever the intensity of the sunlight is high has no concern that he will develop a suntan; but only if he doesn’t overexpose. (Note that bodybuilding science is largely based on the medical discipline of stress physiology. Also, that the end result of the healing of a sunburn is not a suntan, just as the end result of the healing of overtraining is not greater strength or added muscle.)
As the stresses grow progressively greater, they will eventually reach a critical point such that they constitute overtraining. The first symptom will be a slow down in progress; and if the individual continues with the same volume and frequency protocol, the stresses will continue to increase until there is a complete cessation of progress, typically referred to as a “sticking point.” One need not ever experience a slow down in progress, let alone a sticking point, if he bears in mind all the while that as the weights grow progressively greater so do the stresses; and he must do certain specific things to compensate for them.

MikeMentzer.com

In the case of weight training, the duration of exercise is the volume or number of sets performed. Intensity and duration have an inverse relationship. Meaning, the harder you train, the less time can be spent training. This is because we have a finite amount of fuel available to carry that level of stress. This is not a choice or an opinion; it?s fact.

This brings us to the most common way people train too much; too many sets. Although training hard is the best way to move forward, some people are under the impression that doing more is training harder. Performing anything more than what is optimum, will hinder your progress. Yet, most perform more sets with reduced weight or reduced intensity because of the more is better mentality. Do not get caught in this no win cycle.

Training all out, poses extreme demands on the body’s resources, which are governed by genetics and in limited supply. Because of this finite supply, the body will not allow you to train ?too hard? for too long, and gives clues you are reaching your limits. Once you reach failure performing a set, or run out of gas during a workout, you?re simply not able to train any harder. And because training intensity is the number one stimulus for building srength and muscle does it make sense to do more with less.

How often can, or much more importantly, should I train per week? Optimum recovery time between training sessions is essential if one is going to continue to make progress. Training frequency, which is determined by ones recovery ability, is often a forgotten part of most training protocols. It never ceases to amaze me, how many people train for months and years experiencing little or no success, and never consider the fact they maybe doing too much.

You can never train too hard, but you can train too much. Training ?too much? can actually be described in two ways. The first and probably the most common way, is training too often. If you are training with 100% intensity, you should not be able to train a body part any more frequently than once every 6-8 days. Everyone should realize that if you are still feeling it from the previous workout of the same body part, then it is best to take a few more days of rest. I have actually heard people say that they train even if they are sore because it is harder on the muscles. True, it is harder on the muscles, but not in a positive way. Ask yourself, ?Where is the logic in training a muscle before it is recovered?? The muscle hasn?t had a chance to adapt to a previous training session and you tear it down with another. Training may stimulate your muscles to grow, but they don’t grow during training. Proper nutrition and enough rest between sessions is what facilitates recovery and allows the muscles to grow. If you train before the muscle is recovered, you not only slow or put a halt to your progress, you increase your risk of injury.