I can't find the exact figure but Captain Ross route was something like four months, 1,800 miles (2,900 kilometers) on foot while also pulling very heavy loads and in some cases with barely any food.
By training I mean physical exercise like I would expect marching, and hiking before the voyage, calisthenics during the voyage and practice marches to take place before any major outing on the ice. But other than casual football games I haven't read much about any regimented/organised exercise sessions.
By training do you mean physical exercise like marching and calisthenics to get in shape for the haul or training in how to move over ice with sledges? Shackleton had been with Scott on the Discovery expedition in 1901-1904 so he had some experience hauling sleds, but I don't think they trained before and expedition to get better at it. According to Roland Huntford's book Scott was almost irrationally averse to practising anything before embarking on a major expedition. If you meant exercise I would need to defer to someone with more knowledge about that.