Variable Time 2x 7min cont. (2m/2m/2m/1m) @ 57-61% watts start, rates 20/22/24/26 2x 4min cont. (2m/1m/1m) @78-83% watts start, rates 28/30/32 rest 3-6min between sets 2x 7min sets, followed by 2x 4min sets. Start targets = 2k PB pace +16-18 at r20, and +6-8 at r28. Increase pace at least -2 seconds (~3%) from previous with each rate increase.