People who engage in vigorous physical activity are often used to muscle soreness after a hard workout. However, sometimes pain develops even after a moderate workout or that seems unrelated to exercise. While most cases of left side pain are not a cause for serious medical concern, sudden, debilitating pain or pain that worsens requires prompt medical evaluation.
People with pain in the left side might notice additional symptoms such as difficulty breathing during physical activity or exercise, coughing with expectoration of mucus, numbness, squeezing pain or pressure in the chest or pain that spreads into the lower back, abdomen, left arm or left side of the jaw. The pain might worsen with exercise or when lying on your back or left side.
Pain in the left side that feels like muscle soreness that develops after running often results from a strained muscle in the rib cage. A slip and fall, sudden twist or turn during exercise, running, throwing a ball or lifting a heavier weight than the upper body can manage can cause a strain to a muscle or ligament, according to the Mayo Clinic website. In addition, repetitive movements of the upper body, such as swimming strokes, throwing or lifting weights, on a regular basis can cause overuse injuries to muscles in the left side of the body. Asthma attacks and infections such as pneumonia, flu and bronchitis might also cause left side pain, especially when exercising or coughing. Stress and anxiety can also cause tightness, numbness and pain in the left side of the body.
Pain on the left side of the chest, especially when it is accompanied by additional symptoms such as sweating, nausea, dizziness, shortness of breath or feelings of panic or anxiety could indicate a heart attack. This is a life-threatening emergency. Anyone with these symptoms should immediately call 9-1-1 or another emergency number for urgent medical evaluation.
Most muscle strains are treatable at home with compression, rest, ice and elevation of the affected area. Doctors might recommend using an over-the-counter pain reliever such as ibuprofen to reduce discomfort, especially before or after exercise. Left side pain resulting from an asthma attack often requires prescription medications to restore normal breathing functions and relax upper-body muscles. Emergency medical situations such as heart attack require immediate medical treatment at a hospital.
Alternating forms of physical activity, such as playing baseball or swimming one day and walking the next can help prevent left side pain resulting from repetitive activities. Following a prescribed treatment program for conditions such as asthma can help prevent asthma attacks that cause left side pain. Following a healthy diet and maintaining a healthy body weight, along with quitting smoking can help reduce the risk of left side of the body pain resulting from a heart attack.