When we exercise and ask our muscles to do more work than they are used to, the microscopic fibers inside them tear apart. This “Microtrauma” is perfectly natural and is what enables us to grow stronger. When the muscle fibers are repaired by the body, they are built bigger and stronger so as not to tear again. This is why we are able to get fitter through a structured training program that utilizes this natural breakdown and rebuilding.
Rest days allow your muscles, nerves, bones and connective tissue time to repair and strengthen. Therefore, it is important to take time off from hard exercising often enough for the body to recover and perform it’s rebuilding function. You will also need a healthy diet and plenty of sleep as muscles are torn in the gym, fed in the kitchen and built in bed!!
What constitutes a rest day will depend on your activity level. If you are doing high intensity workouts through running, cycling or in the gym, a full inactive rest day will probably be needed to recover properly. If your workouts are on the light to moderate side then an active rest day involving some walking, gentle swimming or yoga will probably suffice.
Massage therapy, foam rolling and stretching are good things to schedule on a rest day as they help with the repairing process.
If you do not rest enough between exercise sessions you may experience problems with muscle fatigue leading to decreased performance and be more prone to injury. Other issues can include poor sleeping habits, loss of appetite and hormone imbalances.