Bruising under the second toenail from running

Blood under the toenail of the second toe during running is caused by factors such as ill-fitting shoes, incorrect running posture, or coronary heart disease. The specific analysis is as follows:

1. Ill-fitting shoes

Wearing improper footwear while running—such as shoes that are too small or too tight—can compress the toes, leading to subungual hematoma (blood under the nail). If this is the cause, switch to properly fitting shoes to prevent further pressure on the toenails.

2. Incorrect running posture

Poor running form, such as landing too heavily on the feet or using an improper foot-strike pattern, can also put excessive pressure on the toenails, resulting in bruising and bleeding underneath. Applying ice packs or cold compresses to the affected toenail may help reduce pain and swelling.

3. Coronary heart disease

In patients with coronary heart disease, intense physical activity may lead to decreased oxygen and hemoglobin levels in the blood, causing insufficient peripheral circulation and localized vascular congestion. This impaired blood flow can result in toenail bruising after strenuous exercise. In such cases, surgical intervention may be considered under a doctor's guidance.

Additionally, heart failure could also be a contributing factor. If the toenail discoloration is mild, the patient should rest appropriately, reduce running, or temporarily stop running to allow the toes to recover. However, if the bruising is severe or accompanied by other symptoms such as pain or infection, prompt medical attention is necessary to avoid delayed treatment.