When taking medicine, we are always looking for the minimal effective dose — or what is the least amount of medicine we can take with the greatest benefit. The same goes for exercise.
Proper exercise is nothing but a stimulus — a signal being sent to our bodies telling them they aren't good enough. When properly applied, the stimulus causes the body to make an adaptation. In other words, get stronger, build muscle, etc. In order to allow your body to make these adaptations, you need to give your body time. If you don't get sufficient rest and recovery, you'll never allow yourself to actually get stronger.
|Mark at www.musclehack.com made this chart to show the importance of recovery when strength training.|
The problem with working out four or five or six times a week, is you never really allow that hole to fill back up. You just keep digging and digging, deeper and deeper, until eventually you burn out and get injured.
So back to the minimal effective dose — when it comes to exercise, how little can we get away with? Surprisingly to some, very little. If you train one set of each exercise to true momentary muscular failure, it can take some people up to 14 days to properly recover from a workout. Granted, these people are the outliers, but on average, a recovery window of 5-10 days can be perfectly reasonable, especially when dealing with the stressors of everyday life.
If you are new to High Intensity Training, you can get away with a shorter recovery window, mostly because you are still learning what momentary muscular failure feels like, and are probably not bringing the intensity to the work out that you will soon be capable of. Once you achieve that skill, extending recovery time will be necessary, since you are fatiguing skeletal muscle much more, and bringing more punishment to yourself than you were at first.
So if you've ever felt burnt out from your New Year's resolution to hit the gym every single day, there's a reason for that. In the past, I've often felt discouraged if I didn't hit the lofty goals I'd set for myself, thinking if I can't go every day, what's the point of going at all? This is a thought process that leads to zero strength training, which is equally as bad — albeit in different ways — as over training.