Variable Time 4x 6min continuous (3m/2m/1m) rest 3m to 6m between sets Rep 1&3 = rates 20/22/24 Rep 2&4 = rates 22/24/26 These are 4x 6min continuous sets with rate increases along the way. R20 reps start at 2k + 17-18 sec. R22 reps start at 2k + 15-16 sec. Increase pace at least -2 sec (+3-4%) from previous for each rate increase.