I've just completed run 2 in week 4, running for 4 minutes, walking for 1 minute x 4. I struggle every week due to painful thigh muscles which I think is just because I haven't used these muscles very much for a long long time. We finished with a 5 minute run which I couldn't complete due to the pain. I probably stopped around the 4 minute point. How long will it take before I can run for 5 minutes without pain? I'm sure there's no definitive answer but it is starting to hold me back. I'm 57, about 5ft 2 and I weigh 10 stone. A fair amount of weight on a small frame. Would be interested to hear whether others have had these problems and how best to deal with it.