Standard CPR is performed with the person in supine position. Prone CPR or reverse CPR is CPR performed on a person lying on their chest, by turning the head to the side and compressing the back.
Non-spinal structural causes of weak legs may include sacroiliac joint pain syndromes and piriformis syndrome. Non-sciatica related sources of weakness in the legs may include diabetes, peripheral neuropathy and various circulatory and neurological conditions.
Weakness means there is less strength in the muscles than there should be. Some people mistake fatigue as weakness, but technically in the medical world, they aren't the same. People with the flu or cancer, for example, may say they feel weak when they're referring to sluggishness. Weakness in the legs is a symptom of injuries, neuromuscular diseases, toxins and metabolic diseases.