It is important that you have adequate rest days during any training to allow your body to adapt to the new demands being made on it and to recover. When you cross train, it helps with your aerobic fitness and reduces the impact forces that can become a problem from too much running. Best Women Crossfit Shoes It has long been recognised that it is important to have the correct type of running shoes for each individual's running style and foot type. Being fitted with the right shoes is important for avoiding injury so consult an athletic footwear specialist or talk with your local CrossFit Physio for the best advice.