Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In



Day 26: Abacus Swim Set

This is a fun and challenging swim session that requires speed, pacing—and a lot of concentration.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

This swim session from former Ironman world champion and coach Karen Smyers involves plenty of changing speed and pace, and is nicknamed the Abacus Swim Set because you might need one to keep track of the changing intervals. You’ve been warned! Bring your brains and your brawn to this workout and expect your heart rate to remain high for much of the main set.

Smyers says: “Challenge yourself to make the fastest interval times that you can. It’s fine to attempt—but just miss—the 50 at the start and end of the set in order to make the rest of the workout challenging enough.”

Abacus Swim Set


300 to 500 easy choice swim

4 x 25 kick with 15 seconds rest, descend 1-4 (get faster each one)

4 x 25 swim with 10 seconds rest, descend 1-4

Main Set

10 x (1 x 50, 1 x 100)

The 50s start with a fast challenging interval and gradually get slower from 1 through 5, while the 100s do the opposite, i.e. you’ll start off on a comfortable interval for the 100s and then get faster/progress effort in those from 1 through 5. 

On rounds six through 10, you’ll see the pattern reverses, so your interval for the 50s will get faster and your interval for the 100s will get slower. 

You should select an interval for these based on the pace per 100 that you can swim 10 x 100 and get ~10 seconds rest. As an example, if you can do 10 x 100 on 2 minutes (with 10 seconds rest), you would aim to use that as your starting interval for the 100s and half of that (1 minute) for the 50s. Here are some example of how this would work, using 1:30 and 2 minutes as base intervals: 

Smyers has some final advice for you, adding: “You will have two very fast 100s to challenge you in the middle of the set (but with 50s on a slow interval time to recover). The pacing is tricky in that you need to start out concentrating on making the 50 intervals and recovering on the 100s, but gradually change your focus to making the 100 interval times and recovering on the 50s mid-set. Your recovery pace needs to be slow enough to recover, but fast enough to still get some rest to set up for the next hard interval. Then you transition back the other way, which means you need to have a little left in the tank to sprint a 50 at the end as well. Maybe now you’ll see why we call this the Abacus Swim Set!”


100 easy choice

Meet Your Coach

Ironman World Champion Karen Freaking Smyers. Need we say more? (OK we have a lot more to say. Read all about the woman, the legend here.)

Video: 4X World Champion Mirinda Carfrae Makes Her Picks for 70.3 Chattanooga

Carfrae and former pro Patrick Mckeon break down the iconic course in Chattanooga, who looks good for the pro women's race, and their predictions for how the day will play out.