Tabata interval training. Not sure how much good they'll do for fell running but they're seriously painful. First of the four 30 second intervals were flat and the 2nd four on a slight / medium hill. Felt physically sick after the 8th one.
Whole session including warm up and warm down completed in less than half an hour. Showered and sat down with a brew and a biscuit 45 minutes after leaving the house.
Excellent training for the lazy who don't like cold weather !