3 x 20min 5 min sections
1st 20 2 min arm only - 3 min rate 16 as hard as you can
2nd 20 2 min arm and body - 3 min rate 18 as hard as you can
3rd 20 2 min 1 stroke arms 1stroke body 1 full stroke repeated throughout the 2 min - 3 min rate 20 as hard as you can