Pins and needles, defined as a tingling or prickling sensation, is medically known as paraesthesia. Temporary paraesthesia can result from a brief, harmless constriction of circulation -- for instance, from kneeling or assuming an uncomfortable position -- and goes away when you change position. Prolonged paraesthesia with no apparent cause, such as pins and needles in the arms while exercising, can be a sign of an underlying medical condition and should be diagnosed by a doctor.
Pinched Nerve Features
A pinched nerve in your arm or shoulder, which occurs when a nerve becomes inflamed by pressure from the surrounding bones, cartilage, muscles or tendons, can cause a pins-and-needles sensation in your arms as well as pain radiating away from the nerve. Other symptoms include numbness and muscle weakness. The National Institute of Neurological Disorders and Stroke notes that "tennis elbow" is a type of pinched nerve, and recommends early treatment to avoid further injury.
Pinched Nerve Diagnosis and Treatment
Your doctor might use a nerve conduction study, electromyography, or MRI, to diagnose your pinched nerve. Treatments for a pinched nerve include rest, anti-inflammatory medications and physical therapy; sometimes, your doctor will recommend a splint or brace. A doctor may also prescribe analgesics to help with pain. In severe cases, surgery may be needed.
Chronic Exertional Compartment Syndrome Features
Pins and needles in your arms during exercise can be a symptom of chronic exertional compartment syndrome, or CECS. This condition, caused by a buildup of pressure in a compartmentalized section of muscle, primarily affects active people and athletes. CECS usually appears in the lower legs, but also can strike hands, feet and arms. According to Sports Injury Bulletin, CECS causes pins and needles in the affected area, as well as muscle pain; symptoms occur with strenuous exercise and decrease with rest. You also might experience swelling in your arm during and immediately after exercise, as well as weakness and a pronounced feeling of fullness. CECS of the arm can occur in weightlifters, sports climbers and cyclists, and usually affects the forearm. The cause of CECS is unknown, and although CECS is not a medical emergency, Kerlan-Jobe Surgery Center says you should see your doctor if you have symptoms.
Chronic Exertional Compartment Syndrome Diagnosis and Treatment
Along with taking careful note of your reported symptoms and history, your doctor can diagnose CECS by measuring the affected muscle during exercise with a pressure probe. According to Kerlan-Jobe Surgery Center, your doctor also might use a slit catheter or a tonometer. CECS can require a type of surgery called a fasciotomy, in which the surgeon makes an incision in muscle tissue to reduce pressure. The website adds that 70 percent to 85 percent of patients are symptom-free after surgery and able to return to their normal activity levels.
Other Pins and Needles Causes
There are other conditions that can cause pins and needles in your arms while exercising. According to the National Multiple Sclerosis Society, an unexplained tingling sensation in your arms can be one of the many symptoms that accompany MS, a disease that causes damage to the protective sheath that covers the nerves. The National Diabetes Information Clearinghouse says that pins and needles also can be a symptom of the neuropathy, or nerve damage, that accompanies diabetes. See a doctor if you have unexplained sensations of pins and needles.