Swimming Interval Workouts

Swimming offers a challenging cardio workout.
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Swimming is a low-impact cardiovascular sport that can be done at nearly any age or level of ability. Workouts can be customized to your own personal goals by changing up the intensity and duration. A complete swim workout includes a warmup, drills and intervals, and a cool down. Swimming interval workouts help you build speed and endurance.


An interval is the time it takes you to swim a specific distance. For example, you may aim to swim 50 meters freestyle in a one-minute interval. A rest interval is the amount of time you rest after swimming a specific distance and before starting to swim again. If you are swimming four 200-meter intervals, you could give yourself a rest interval of 15 seconds between each 200-meter swim. This means that immediately after touching the wall following your 200-meter swim, look at the clock and begin your next 200-meter swim exactly 15 seconds later.

Base Interval

The term base interval is commonly used when swimming 100-meter freestyle intervals for a prolonged distance of 1,000 to 2,000 meters. While swimming at your base interval speed, you would be able to swim 15 100-meter freestyle intervals at an aerobic pace that is 70 to 80 percent of your maximum heart rate. The base interval pace is the speed that you could sustain during a prolonged period of time. It is not the fastest pace you can swim but it is a pace that challenges you. As your fitness level improves, so does your base interval.

Send-off Intervals

A send-off interval set can be completed in any stroke, at any pace. In this workout, you establish a set time that includes both the swim portion and the rest portion as one interval. If you aim to swim 50 meters in 45 seconds followed by 15 seconds of rest, your send-off interval would be one minute. When doing send-off intervals, it is important to use a pace clock. To help establish your send-off time, you could swim the first interval and then add a predetermined amount of rest time. For example, if you swam the first interval in 1:15, you would continue the send-off intervals at 1:25 for 10 seconds of rest.

Cruise Intervals

A cruise interval is the time it takes you to comfortably swim a given distance plus recovery time. For example, if you swam a 100-meter freestyle at a comfortable pace in two minutes, your cruise interval for the 100-meter would be 2:07 to 2:10 to reflect seven to 10 seconds of rest. One example of an interval workout built around cruise intervals could be eight 100-meter intervals in which you switch every other interval between your cruise interval pace and your cruise interval pace minus five seconds.

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