’s trying to make it around the block four times, as well as the 36-minute 10K runner who’s training for a first marathon with long runs that stretch to 12 miles, then 16, then 20.The gradual-adaptation principle is deeply rooted in human physiology, and has

to all circumstances and all runners – the beginner who’s trying to make it around the block four times, as well as the 36-minute 10K runner who’s training for a first marathon with long runs that stretch to 12 miles, then 16, then 20.The gradual

this first-hand on a 1998 trip to Kenya. One morning, I joined a handful of marathon runners who were being coached by Dr Gabriella Rosa as they tackled the infamous Fluorspar Hill that rises nearly 4000ft in 13 miles.I managed to hang on for only 10 minutes