This workout is designed to be done at solid effort, but not all out. Notice the 100y times in the main set get slightly faster (these times are for a 25 yard pool). As a point of reference, my 100 meter swim pace at USAT Nationals was 1:23, which roughly translates to 1:15 per 100 yards. The goal of this workout is to hold yourself back a bit in the beginning so you are able to make the harder intervals toward the end, when you are tired. This will help you negative-split the swim on race day. 200-ish yard warm up Warm up set (3x through): 150 free on 2:15 50 on :45 Transition set (twice through): 100 on 1:30 75 on 1:00 50 on :50 Main set: 300 on 4:30 4x 100 on 1:25 2x 50 on :50 300 on 4:30 3x 100 on 1:20 2x 50 on :50 300 on 4:30 2x 1oo on 1:15 2x 50 on :50 200-ish yard cooldown Total yardage: 3550 in about 1 hour If you have time and are feeling super motivated, you can continue the main set pattern so that you have a 100 at an all-out pace right at the end.