alternatively, there are many charities transprting clothes and shoes that still have some wear left in them to the third world. they may not be fit for your training, but they might keep somebody's feet out of direct contact with the ground. check out your local salvation army, charity shops, ar wait a while and you might get a bag through the letterbox to fill with unwanted items of clothing.
or send them to a jumble sale, but that seems a bit more heartless.
Pamela x