So you are slugging it out in the gym every day without fail and not seeing the results you want! You don't feel like you are getting any stronger, in fact you might even be feeling weaker! This is such a common problem amongst keen gym goers like yourselves reading this.
The dictionary definition states, "Overtraining is a common problem in weight training, but it can also be experienced by runners and other athletes. It occurs when the volume and intensity of the exercise exceeds an individual's recovery capacity. They cease making progress, and can even begin to lose strength and fitness."
So it's really quite simple. By training you are creating a stimulus for your body to adapt and grow, However it's in your rest and recovery (particularly your sleep) where the body actually repairs and grows. So if you are not allowing your body enough rest and recovery time then you are not allowing your body to grow and get stronger. This mean that sometimes by doing less you are actually doing more!
So lets say you are in the gym 5 days a week. There would be absolutely no benefit from doing a full body routine 5 days a week.
Splits are a great way of allowing your body to recover from the stress you place on the muscles during a training session. Some common examples of these would be:
Monday - Upper
Tuesday - Lower
Thursday - Upper
Friday - Lower
This is a simple beginners workout - this split would be fairly low in volume and intensity.
Monday - Chest/Triceps
Tuesday - Back /Biceps
Thursday - Legs
Friday - Shoulders/Abs
This is a more Advanced - You will notice that you only hit each muscle group once in a week. This is because it would be much higher in volume and intensity than the previous. This will mean your body needs more time to recover.
These are just examples of different training splits. Your favourite bodybuilders may hit the same muscle groups every other day and you think 'If they can then why can't I?' Well the truth is these people are genetic freaks when it comes to gaining muscle, and pair this with performance enhancing drugs (which help speed recovery) then you have a recipe to become the incredible hulk!