Leg pain and weakness can be caused by injury or the presence of certain diseases. According to the Mayo Clinic, some of the known diseases that cause leg pain and weakness include fibromyalgia and peripheral arterial disease. If you are unable to put weight on your leg or have unexplained weakness or pain in your legs, contact your physician immediately.
Injury
An injury to the leg area can cause slight to severe pain and significant weakness. According to information found in the American Council on Exercises "Personal Trainers Manual," sudden impacts or awkward movement that causes the leg to bend in an unnatural way can tear or stretch the ligaments and tendons in the joint area, causing pain. If the leg muscle has been injured, you may not be able to put pressure on it. If a leg has been broken, it may require immobilization typically in the form of a cast. A broken or fractured bone is painful and can take anywhere from six to eight weeks--sometimes longer--to heal. When the cast is removed, the muscles in the affected leg will be weak from not being used.
Fibromyalgia
Fibromyalgia is a condition that causes widespread pain in your muscles, ligaments and joints. Often, the muscles and other tissue in your legs can be affected. According to the Mayo Clinic, people with fibromyalgia may have a lower threshold for pain. Muscles that would not normally feel sore or tender through day-to-day activity may be overly sensitive to pain in someone with fibromyalgia. For some people, fibromyalgia may make activities such as, walking, running and weight training difficult. This can leave the leg muscles weaker because of inactivity. Although there is no cure for fibromyalgia, treatment focuses on improving muscle use while minimizing pain. This can be done through medication and physical therapy.
Peripheral Arterial Disease
According to Medline Plus, peripheral arterial disease occurs when there is a narrowing of the arteries outside the heart. Usually this narrowing occurs because of a buildup of plaque that attaches itself to the arterial walls that supply blood to the legs. Symptoms of PAD can cause numbness or pain in the legs leaving the weakened. PAD is a serious disease. If this condition is left untreated, your foot or leg may need to be amputated. Treatment focuses on managing symptoms and reducing pain the legs. Surgical procedures may be an option for those who require it.
References
- "American Council on Exercise Personal Trainers Manual"; Cedric X. Bryant; 2003
- Mayo Clinic: Leg Pain
- Mayo Clinic: Fibromyalgia
