Runner's World suggests focusing on deep breathing from the belly to reduce fatigue levels in respiratory and leg muscles. Deeper breaths use more air sacs in the lungs, allowing the body to take in more oxygen to feed the muscles. Strengthening the diaphragm, which is essential for deep breathing, improves endurance and minimizes fatigue. Because of this, Runner's World considers training these muscles as essential as training hamstrings and calves.
To switch from the more typical chest breathing to belly breathing, Runner's World first advocates for runners to focus on deep breathing while not running, easing the transition. Some runners praise Pilates, which, in addition to improving breathing, increases strength and flexibility by stretching the intercostal muscles and lengthening the spine. Runner's World recommends three particular exercises to help improve breathing: the Hundred, the Swan and the Standing Chest Expansion. These exercises combine to teach breath control, open the chest up to increase lung capacity and balance breathing between both lungs.
To engage the diaphragm, open the mouth. Because it is larger than the nostrils, it is more effective at inhaling oxygen. Keeping the mouth open helps the face stay relaxed. Coordinate breathing patterns with footfalls, which also helps develop and strengthen diaphragmatic muscles.