In patients with COPD, muscle carnosine concentration is positively correlated with quadriceps endurance (rs=0.427), peak oxygen uptake (V̇o2peak; rs=0.334), and moderate-to-vigorous physical activity (rs=0.379), indicating that lower carnosine levels are associated with reduced exercise capacity and physical function.

In people with COPD, toxic chemicals build up in the leg muscles from ongoing stress, and carnosine absorbs these chemicals to protect the muscle tissue. This use up carnosine faster than the body can replace it, leaving less available to manage acid buildup during exercise. With less carnosine, the muscles tire faster and cannot sustain activity as long, reducing overall physical capacity.