Interval Variable. 1600m warm up 60/50/40/30/20/10 Rest 1:30 10/20/30/40/50/60 60secs work/rest - 50secs work/rest - 40secs work/rest - 30secs work/rest - 20secs work/rest - 10 work/90secs then reverse back up matching interval work with interval rest. Targets over 120%"