Improving swimming stamina, or endurance, relates to your capacity to perform continuous repetitions, while resisting the need to stop. Without stamina, arms and legs easily become fatigued, resulting in inability to maintain proper technique, a major cause of water drag and ultimately poor swimming results, according to the author of "The Triathletes Triathlon Bible," Joe Friel. In order to improve stamina, decrease rest periods during your training session while still performing back-to-back sets of moderate distance.
Swim Workout to Improve Stamina
Warm up by swimming for 200 to 400 meters at a slow pace, resting as often as needed and varying your stroke every 100 meters.
Swim a total of 300 meters, breaking it up into 3 sets of 100. Swim each set at a moderate pace, using the stroke of your preference. Using your stopwatch, time yourself and rest for 10 to 15 seconds in between each set and the next step.
Swim a second set of 300 meters. Break it up by swimming two segments of 150 meters. Swim the first segment at a moderate pace followed by a 20 second rest. Swim the second 150 at a gradually increasing pace, increasing pace every 50 meters up to 90 percent of your maximum effort followed by 30 seconds of rest.
Swim a final set of 300 meters at a moderate pace. Avoid resting until the 300 meters is completed. If rest becomes necessary, rest for 5 to 10 seconds and then continue.
Cool down by swimming 200 meters at a slow pace. Use fins if you would like.