When Is Swimming Cardio, and When Is It Not?
Any swim gets your body moving, but not every swim is a cardio workout. What matters is how hard you work, and for how long.
The short answer
Swimming is cardio when it keeps your heart rate and breathing raised for a sustained period, usually at least several minutes at a time and adding up to 20 minutes or more in a session. Splashing around, standing and chatting in the shallow end, or swimming a length and then resting for several minutes is enjoyable, but it is not much of a cardio workout.
When swimming IS cardio
- Continuous swimming at a pace where you can say a few words but not hold a conversation.
- Repeats with short rests, such as 10 x 50 metres with 20 to 30 seconds' rest. Your heart rate stays up during the short breaks.
- Interval sessions that alternate harder and easier lengths without long stops.
- Kick sets with a board, which are surprisingly hard work because the legs are large muscles.
- Water running or aqua aerobics at a brisk pace, which counts as moderate activity.
When swimming is NOT really cardio
- Long rests. If you rest for longer than you swim, your heart rate drops back down.
- Very easy floating and play. Great for relaxation and for children's water confidence, but light in intensity.
- Struggling with technique. If you stop after every few strokes because breathing feels hard, you cannot keep going long enough. Fixing your breathing turns those sessions into proper workouts; see our front crawl tips.
How to tell how hard you are working
Heart rate monitors and watches can help, but many swimmers find their readings differ from what they are used to on land. A simpler guide is the talk test, recommended by the CDC: at moderate intensity you can talk but not sing; at vigorous intensity you can only say a few words before pausing for breath. Check yourself at the wall between lengths.
Three sample cardio sessions
These assume a 25 metre pool and that you can swim at least 50 metres without stopping. Halve the lengths in a 50 metre pool.
Steady session (30 minutes)
Warm-up: 4 lengths easy. Main: 3 x 200 m at a moderate pace, resting 1 minute between. Cool-down: 2 lengths easy.
Interval session (30 minutes)
Warm-up: 4 lengths easy. Main: 12 x 50 m, alternating one moderate and one harder, resting 20 to 30 seconds after each. Cool-down: 2 lengths easy.
Mixed session (25 minutes)
Warm-up: 4 lengths easy. Main: 4 rounds of 50 m front crawl, 50 m kick with a board and 50 m any stroke, resting 30 seconds after each 50 m. Cool-down: 2 lengths easy.
New to structured sessions? Start with our swim workouts for beginners.
How much cardio swimming do you need?
WHO recommends that adults do 150 to 300 minutes of moderate aerobic activity, or 75 to 150 minutes of vigorous activity, every week. Two or three 30-minute swims, plus walking or other activity, gets most people there. Read more in is swimming an aerobic exercise.
Safety
Build up gradually, drink water, and stop if you feel dizzy, chest pain or unusual breathlessness. If you have a heart or lung condition, check with your doctor before starting vigorous exercise. Swim where a lifeguard is on duty and leave the pool when you hear thunder.
Get the technique right first
If you cannot yet swim comfortably for a few minutes, technique is what holds you back, not fitness. A few lessons focused on breathing and body position make cardio swimming possible. See our adult swimming course or private swimming course.
More in health and wellbeing
- Swimming and asthmaWhat research says and how to swim safely with asthma
- Does swimming help you lose weight?An honest answer, and how to get the most from your swims
- 10 swimming workouts for weight lossSteady swims, intervals and kick sets for a weekly plan
- 7 reasons swimming is good for recoveryLow impact, active recovery and rehabilitation
Sources
- CDC, Measuring physical activity intensity. The talk test for judging moderate and vigorous intensity.
- World Health Organization, Physical activity fact sheet. Adults: 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous aerobic activity a week.
Want to swim long enough for a real workout?
Tell us how you swim now and your fitness goals. We will suggest a suitable course, format and pool. Lessons run at public swimming complexes, private venues and condominium pools across Singapore.