Trench foot
Trench foot can be prevented by keeping the feet clean, warm, and dry. It was also discovered in World War I that a key preventive measure was regular foot inspections; soldiers would be paired and each made responsible for the feet of the other, and they would generally apply whale oil to prevent trench foot. If left to their own devices, soldiers might neglect to take off their own boots and socks to dry their feet each day, but if it were the responsibility of another, this became less likely. Later on in the war, instances of trench foot began to decrease, probably as a result of the introduction of the aforementioned measures; of wooden duckboards to cover the muddy, wet, cold ground of the trenches; and of the increased practice of troop rotation, which kept soldiers from prolonged time at the front.
Subungual hematoma
Runner's toe is a common condition seen in runners caused by downward pressure or horizontal separation of nail plate from the nail bed. This repetitive traumatic injury leads to bleeding and pooling of blood underneath the nail plate. Clinically, it is characterized by reddish-black discoloration of the toe nail. The nail plate may also become thicker and more brittle as a result of the injury (onychochauxis). The deformed nail plate will gradually grow out and be replaced by new, normal-appearing nail plate in several months time. Infrequently, the toe may become painful and require surgical drainage.