Biking (spin class) 55:00
At the gym at work.
Got on the spin bike early for about 10 minutes of extra warm up spinning.
Then warmed up with 3 x 2 min @ 90+ rpm, 1 min easy.
60, 50, 40, 30, 20 s with 1 min rest between each, pushing as hard of a gear as you could sprint with for that duration.
Then the same but in reverse: 20, 30, 40, 50, 60s with 1 min rest between each.