Swimming Workouts to Build Running Endurance

Swimming is a tremendously effective form of cross-training for runners. And yet, if you ask a room full of them how many swim as part of their training, you’re not likely to see a large show of hands.

Why is that? Well, the runners I know seem to have two major concerns when it comes to swimming for fitness. They tend to either think it’s boring, or they find it too hard. As a certified U.S. Masters Swim (USMS) Adult-Learn-to-Swim instructor, I believe they’re just doing the wrong workouts.

Before we dive into specific workout tips, it’s important to note that you do not need to be an experienced swimmer to glean the benefits of knocking out a few laps. You will, however, need at least some level of comfort in the water. If you do have fear or discomfort in the water, consider scheduling a few sessions with an instructor or group designed to help adult beginner swimmers. (Here’s more information on swimming as an adult as well as resources to help you find someone to get you started.)

Now, if you’re comfortable in the water and can go down and back the length of the pool a few times, you’re ready to get started. Here’s what you need to know.

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Time vs. Distance

Just as in running, you can base your swimming workouts on either time or distance; but Patrick Billingsley, a coach for Palm Beach Masters in Florida who holds USMS Level 3 and USA Triathlon Level 1 certifications, always bases his workouts on time. And he stresses the importance of remembering that, just because you can run for four hours, it doesn’t mean you’ll have great endurance in the pool—at least, not right away.

“The number one issue I see with runners who are just starting to swim is that they get in the pool and are immediately gassed,” says Billingsley. “It’s just an entirely different type of exercise.” All too often, that leads to the athletes becoming discouraged and not continuing on with their work in the pool, but he recommends athletes simply start out where they are and focus on building rather than getting discouraged about becoming fatigued.

The number two issue he sees? Lack of ankle flexibility, which can throw off the way runners kick and can even lead to cramping. “To see where they’re starting, I’ll have a runner get in the pool and do a simple swim workout, maybe repeating 100s, until they are just done—with zero judgment on how long that takes,” he says. That might only be 15 minutes to start, and that’s just fine. With consistent training, they’ll improve and build endurance very quickly.

Tools to Use

One of the great things about swimming is that, if you have goggles and a swimsuit (and possibly a swim cap), you only need water in order to do your workout. However, investing in a few tools can come in handy, and can help keep things interesting.

Many pools offer kickboards and pull buoys, but if you want to use a snorkel (which can be a helpful as it builds lung capacity and teaches you how to breath in a pattern), fins (there are many different kinds out there, each with slightly different functions), or hand paddles, you’ll likely need to bring your own. These aren’t considered crutches; you’ll find elite swimmers utilizing these tools as well as novices.

There are also a number of multi-sport watches and other swimming gadgets designed to help you keep track of your distance when swimming laps, and you can even find underwater headphones that let you listen to music. However, once you’ve learned to build some workouts you love, you might not find such technological assistance necessary.

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Building Your Workout

“Have a purpose for your workout, whatever it is you plan to do,” says Billingsley. You can certainly show up at the pool and simply plan to swim back and forth for 20 minutes, not worrying about pace or distance. That’s along the lines of going for a run strictly to get more miles on your legs, and we all know there’s a time and place for that in many of our training cycles.

However, if 20 minutes of down and back doesn’t exactly have you quivering with excitement, there are plenty of ways to mix up your workout (similar to the difference between a track workout or tempo run versus a long, slow run). Most workouts include a warm-up—such as a 300 easy swim, 200 with the pull buoy, or 100 kicking with kickboard—a pre-set (where you can incorporate some drills, or perhaps short bursts of speed to prep your body for sprints), a main set (examples listed below), and a warm down (100-300 easy swimming).

Feel free to adjust any of the following times or distances to better match your current skill level and goals.

Odds/Evens: Choose something to focus on for laps falling on an odd number, then either make the even laps an easy recovery lap, a different distance, or a different stroke (if that’s in your skillset).

Example: 10 x 100m, odds at 75% maximum effort, evens at easy recovery pace

Ladder (or Mountain): Start at 100, then build up from there, doing a different stroke, incorporating a different tool, working on a new skill, or simply altering your breathing pattern with each bigger interval. Make it a mountain by going back down the ladder after reaching your longest distance.

Example Ladder:      100m kick

                                    200m build to 80% effort

                                    300m breast stroke, easy effort        

                                    400m pull buoy, steady 50% effort

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Time Reduction: Select a distance to repeat, and begin with an interval that gives you loads of time to rest (so, if it takes you 1:45 to swim 100m, start at an interval like 3:30). Repeat anywhere from 2-4 times on that interval before resting one minute, then dropping 15-30 seconds and doing the same thing on that new interval. Go until you miss your interval. (This is a great one for seeing improvement over time.)

Example:                  2x100m on 3:30; rest 1 min.

                                    2x100m on 3:00; rest 1 min.

                                    2x100m on 2:30; rest 1 min.

                                    2x100m on 2:00; rest 1 min.

                                    2x100m on 1:30; rest 1 min., etc.

Increased Effort/Decreased Distance: As your effort (which you can gauge in whatever way makes the most sense to you—RPE, percentage of max effort, easy/medium/hard, etc.) increases, the distance you’re swimming goes down.

Example:                     200m 50% max effort; rest 10s

                                    150m 70% max effort; rest 20s

                                    100m 80% max effort; rest 30s

                                    50m 90% max effort; rest 30s

                                    25m ALL OUT; short rest to catch breath before going into 25 easy Recovery

                                    Rest 2 min, repeat from top

Repeating Distance With Altered 25s: If you’re working on endurance and want to get in some longer, steady efforts, keep things interesting by doing something different on the last 25 of every 100. (This can help you keep track of your distance, too.) You can add in different strokes, varied breathing patterns, a drill or just a change of your level of effort—anything that makes that 25 meters stand out will do the trick.

Example:       3x300m as follows:

                        First 300: last 25 of every 100m is backstroke

                        Second 300: last 25 of every 100m is breaststroke

                        Third 300: last 25 of every 100m is a build in speed to 90% max effort