Large breasts present a challenge for runners, but ways exist to stop the pain associated with bouncing, chafing and muscle tension. The same rules of physiology -- or how your body functions within its environment -- apply to all women, but since you carry around extra mass and weight, side effects like pain are more likely to occur. Try a few simple ideas to lessen pain and focus on your workout.
The simplest source of pain when you run is your breasts' weight. If you wear a D cup, your breasts may weigh between 15 and 23 pounds, which strains your chest, back and shoulder muscles. The more complex pain source is force. Newton's second law of motion is that force equals mass times acceleration. According to biomechanist and bra engineer Julie Steele, the mass of your breasts and the acceleration from running creates a force that can be very painful.
Large breasts usually cause pain two ways. Repetitive stress injures the upper and middle back, and many women with large breasts develop poor posture, which causes spinal pain. Strengthening your back muscles can help mitigate this pain. Perform about 15 minutes of daily back exercise, including knee-to-chest and rotational stretches, the bridge pose and shoulder blade squeezes, to prevent or heal back injury.
A high-quality sports bra may be your greatest running buddy. Look for one with a high level of compression; that often means you can't stretch it over your head. The material of the cups, sides or wings and back should not stretch either. Test the fabric for resistance with your hands before trying the bra on. Reinforced fabric is even better. The silhouette should include wide bands and full-coverage cups to support your breasts adequately.
Chafing, or irritation from friction between your bra and your nipples or skin, presents a potential pain for all runners. Large-breasted women may be more prone to it because of the area of skin in contact with fabric and the potential for fit issues with clothes or bras. A good sports bra should solve a chafing problem, but sometimes it does not. Fitness coach Levi Bloom recommends nipple guards. He uses medical tape, but bandages over the nipples work too.