A term not always liked by athletes but as essential as training. In order to be able to keep running, cycling, weight training and so on, the body and central nervous system must be allowed to rest and recover. This is doubly the case when increasing distance, weight or level of training as the muscles and bones will change with extra stresses placed on them. Without rest the muscles become fatigued and weaker which can lead to muscle strain, overuse syndrome, reduced performance and in more serious cases stress fractures and ligament sprain.
How does rest help? Well, we need to look at what happens to the body when we train to answer this effectively. The muscles are made up of many separate fibres and these will be both long and weak and short and strong. When stress is placed on the muscles through resistive or increased training the weaker muscle fibres will tear and divide. This tearing causes post exercise ache in the muscles and it is after this that the body must be given time to recover. During the recovery stage the damaged fibres will shorten and become strong. Over time this process of fibre division and shortening will cause the muscles to bulk out and become stronger. As a result performance increases and training can progress. If the muscle becomes over worked during through lack of rest injury risk increases as form fails; meaning that the overworked muscle fails to contract fully resulting in reduced ability to correctly perform an action. An example of this may be seen when a squat is performed, when the Quadricep muscles are fatigued; prior to that days training; they will not be able to correctly support the down phase of a squat. Form fails and the knees tend to rotate inward which places increased stress on the joint and with it increased risk of injury to ligaments and surrounding muscles. This also places extra work on to other muscles attached to the knee.