Favourite intervals from some of the best endurance athletes in the world:

• 10 x 30 seconds on and 30 seconds off 1-3 sets (zone 4)

• 6-10 x 40 seconds on and 20 seconds off (zone 4)

• 4 x 4 minutes with equal rest VO2 max intervals (zone 4)

• 8 x 2 minutes with equal rest (zone 4)

• 1,2,3,4,3,2,1 minutes on with equal rest (zone 4 - one of Kikkan Randall’s favourites)

• 4-6 x 8 minutes (zone 3 /controlled intensity)