You have to cut your toenails before a walk. To avoid injuries. It seems silly, but if left long nails of the feet, these shoes strike the steep down hills and can cause injuries to fingers, toenails, etc..
In case of escalation, and for obvious reasons, this applies also to the fingernails. If long-term expeditions, then do not forget to bring at least one nail clippers or pliers, as although the fingernails usually grow poorly if tasks are performed basic camp (fire management, collecting firewood, cooking, washing utensils, etc.). toenails are not so lucky: although heavy foot traffic, usually grow at a normal pace.