Why you should take rest days from lifting and/or exercising.

Many "gym rats" go into the gym with one goal in mind, lift as much weight as possible until I can lift anymore. That is a great way to recieve an amazing strength response. Pushing the nervous system and the muscular system to the max is the best way to push your muscle strength and endurance levels through the roof. However, if this is done day after day week after week, your body will burn out. Unless you are on performance enhancing drugs, the stress and lack of recovery will catch up with you.

The nervous system needs anywhere from 48 to 72 hours to recover from an extremely intense stressful situation such as maximal weightlifting. If you go pound out sets of benchpress day after day, there is no room for recovery and you chances of burnout and many times serious injury skyrocket.

The muscular system is a little more tricky. Some muscle energy stores can be replenished in seconds, some need more time. Either way nutrients is the key here. The muscles get there energy from carbohydrate calories, and they rebuild muscle proteins by using, you guessed it, protein. So often your training will depend on the amount of necessary nutrients you are taking in. Simply, if your training is intese, take in more carbohyrdates so you have the energy to train; and take in more protein to rebuild broken down muscle protein. Soreness can have an affect on mental state too. If you are really sore from and intense bout of exercise, it is difficult to fight through the pain to get in a good workout. Light body weight movements have been shown to flush muscle waste products at the end of a workout, as well as help maintain flexibility and nutrient transport in the following days.

My cheesy rule of thumb. If your muscles ache, take a break!