This workout is for more advanced swimmers. It challenges your cardio capacity through the negative split work, followed quickly by the IM work. Push through and attack each lap.
8x25s kick with board @:10 seconds rest
4x100s negative split (rest for :10seconds @ the 50, then rest for :30seconds after the 100)
3x75s (odd: Fly, Back, Breast | even: Back, Breast, Free) @:15seconds
2x50s sprint kick @:10seconds rest
200 Sprint Freestyle or IM