breakdown, and endurance of muscles (Bird, Smith, James). All of these factors combine with increased lung capacity for an overall healthy body. A non-athlete however has atrophied muscles, decreased metabolic enzymes and a diminished lung capacity."(UK Essay,2013) For me to be able to experiment the difference in lung capacities between non-athletes and athletes I need to understand how the lungs work first. Breathing is the most crucial function in the body making our lungs contract and expand ,therefore