I don’t actually think so, but it is definitely putting unnecessary strain on my lower legs. Last weekend I did some quarters (tempo runs 4x 0.25mile distance) which went great, but by Monday my lower legs were aching worse than ever before. It wasn’t until Friday that it actually feels back to normal. I’ve had these kinds of problems since getting past 3 miles distance or so, which makes me think I never really did build up my leg strength properly. I try and take it easy on the training to reduce the risk of making things worse, but that has to be balanced against the need to keep training.