Arm muscle soreness can occur for a number of reasons. Whether you can gain muscle while your muscles are still sore is largely dependent on why your muscles are sore. Understanding how your muscles grow is important to making your gym time as effective as possible. If you are unsure why your arm hurts, consult with your primary care physician.
Muscle growth in your arms occurs as a direct result of resistance training or exercise to that particular muscle. The muscle growth process begins with the fibers of the muscle literally tearing from use, according to University of New Mexico's Len Kravitz, Ph.D. When you lift a dumbbell to the point of exhaustion, your muscles break down and tear from the inside out. After your workout is finished, your body sends satellite cells to the site of the tear in an attempt to repair the damage done. These cells fuse to the torn fibers, multiply at a rapid rate and heal back as a larger, stronger muscle.
The muscle growth process is driven by a combination of breaking down the muscle fibers and fueling your body with the proper amount of nutrients — namely protein. If you want to increase muscle size through exercise, you need to eat upwards of 0.8 g of protein for every pound of body weight daily, according to the United States Department of Agriculture. This protein can be gotten from easy-to-cook foods like eggs, tofu and poultry.
Delayed Onset Muscle Soreness
Arm muscle soreness isn't always a sign of muscle injury. In fact, according to Kravitz, it may be a sign that you recently had an intense bout of exercise in which your arm muscles are now suffering from delayed-onset muscle soreness. DOMS usually sets in within 24 hours after exercise to an isolated muscle and can result in muscle soreness, stiffness and swelling. There are currently no known treatments for DOMS; however, you can still build muscle while suffering from it.
Attempting to build muscle through exercise is generally safe. However, if you are suffering from a muscle strain, sprain or tear, exercise to the affected area can increase the severity of the injury. It can also result in injuries to other muscles, according to the American Academy of Orthopaedic Surgeons. The muscles surrounding your injured arm muscle will try to compensate for the weakness to the injured area, potentially putting more stress on these muscles than they can handle. Speak with your doctor or trainer as to whether you are physically able to exercise the injured area before attempting to increase muscle size through training.