there are many biological factors that are important for muscular hypertrophy like hormone levels, age, sex, muscle fiber type, diet, among others. These factors have been recognized as extremely important for the hypertrophic adaption to strength training. Many of these factors, however, are known to vary throughout the day. Can the daily differences in the above factors like hormone levels, affect the adaptive response to strength training? What time of day is the best time to train?

A study published in the Journal of Strength and Conditioning Research set out to examine the effects of time-of-day-specific strength training on muscle hypertrophy maximal strength in men. The training group underwent a 10 week preparatory training regimen. Afterwards, the subjects were randomized to either a morning training group or an afternoon training group. The groups trained for another 10 weeks with training times between 07:00 and 09:00 hours and 17:00 and 19:00 hours in the morning group and the afternoon group respectively. Cross-sectional areas and volume of the quadriceps femoris were obtained by magnetic resonance imaging at weeks 0, 10, and 20. Maximum voluntary isometric strength during unilateral knee extensions and the half squat one repetition maximum were tested at weeks 0, 10, and 20.

The entire 20-week training period resulted in significant increases in maximum voluntary contraction and 1RM in both training groups. In this study, the magnitude of muscular hypertrophy and strength did not statistically differ between the morning or afternoon group. However, this study was of short duration and like most research concerning physical improvement through exercise, there needs to be more subjects over longer periods of time.
(J Strength Cond Res 23(9):2451-2457)

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

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. 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 may be doing too much.

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 in going to the gym if you’re not going to make progress. In every workout, if you have fully recovered, and you come ready to work, you should make progress, which is gauged by your strength.

How can anyone get stronger every workout? One can only bench press so much. Eventually, you have to hit a plateau. This is true. If one stays with the same exercises, the same number of reps and the same number of sets, progress may eventually stop. If the proper changes aren’t made at the right time, eventually the body adapts to the stimulus. And this is where the “art” of program design comes to play.

It’s easy to follow a workout. The real challenge is assuring the stimulus is sufficient and more importantly, you recovery from workout to workout so that progress continues over a long period of time. Sometimes this entails having the discipline to deviate from something that is not working. If you’re not making progrss, and you’re training with all out intensity, try taking an extra day off.

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.