If going to the pool is your favorite form of exercise every day, you may have asked yourself the question “is swimming an aerobic or anaerobic exercise?”
While swimming is generally considered a gentle form of aerobic exercise (opens in a new tab), it is possible to challenge yourself to make pool time more anaerobic. A great low-impact activity, with the right settings, swimming can get your heart rate up and activate the fast-twitch muscles associated with the toughest workouts.
And whether you’re working aerobically or anaerobically, swimming is an effective form of exercise to promote physical health and help prevent cardiovascular disease.
Below, we’ll walk you through everything you need to know when it comes to aerobic vs anaerobic exercise (opens in a new tab) and share our top tips on how you can make swimming training that much more challenging.
What is aerobic and anaerobic exercise?
The American College of Sports Medicine (opens in a new tab) defines aerobic exercise as any activity that uses large muscle groups, can be sustained continuously, and is rhythmic in nature.
“The term aerobic means with oxygen and refers to the use of oxygen to adequately meet energy demands during exercise. The body uses this oxygen to break down energy sources such as glycogen and fats to supply energy,” says the scientist sports Emily Codd.
Emily Codd is a sports scientist and product analyst at INCUS Performance (opens in a new tab). She has a Masters in Exercise Physiology and a Bachelors in Sport and Exercise Science. In her role at INCUS, she works with a variety of recreational and elite athletes to help them learn more about their performance, how to improve technique, and how to reduce injuries.
Aerobic exercise can mean many different things. It can be swimming, rowing, walking or cycling in one of the best exercise bikes (opens in a new tab).
anaerobic exercise (opens in a new tab) is defined by the Journal of the Canadian Chiropractic Association (opens in a new tab) as intense physical activity of very short duration, fueled by the energy sources within the contracting muscles, without the use of oxygen.
Anaerobic exercise involves the use of fast-twitch muscles with examples of this exercise including sprinting, high-intensity interval training (HIIT), and weightlifting.
Aerobic and anaerobic exercise are categories of metabolism and take place in different parts of the muscle cell. Aerobic exercise predominantly relies on fat for fuel and anaerobic exercise predominantly relies on carbohydrate for fuel.
When we swim fast we rely more on anaerobic metabolism and when we swim slower we rely on aerobic metabolism.
“How fast we swim will determine what fuel sources we are using and therefore whether we rely predominantly on aerobic metabolism or predominantly anaerobic metabolism. This, in turn, will change as we slow down and speed up. The word ‘predominantly’ is important here. Metabolism relies on a combination of these different energy pathways being used, we don’t just turn different metabolic pathways on and off,” explains sports and exercise scientist Mitch Lomax.
Dr Mitch Lomax (opens in a new tab) is a reader in pulmonary exercise physiology at the School of Sport, Health and Exercise Sciences (opens in a new tab) in the University of Portsmouth (opens in a new tab). She is a BASES Accredited Sport and Exercise Scientist and a Chartered Scientist. As well as providing scientific support to various individual athletes, she has also provided scientific support to the England pistol shooting team, Swim England and British Swimming.
Is swimming aerobic or anaerobic?
Swimming can be both aerobic and anaerobic depending on the intensity and duration.
“Typically, the longer the exercise duration, the greater the aerobic dominance. Shorter, more explosive swim training, like sprinting, is primarily anaerobic,” says Codd.
The dominance of the energy system depends on how fast you are swimming. Slow swimming uses predominantly aerobic metabolism, while fast swimming uses predominantly anaerobic metabolism.
“Fast is a relative term and is not related to an absolute or fixed swimming speed. What will be considered a slow speed for a fit and skilled swimmer will be considered a fast speed for someone less fit and less skilled. This means that the contributions made by the different metabolic pathways will differ even though the swimming speed is the same,” adds Lomax.
Thus, the more you accelerate, the greater the contribution of the anaerobic pathways and the more you slow down, the greater the contribution of the aerobic metabolism. But the best way to judge this is perceived effort rather than a set speed.
How can you make swimming a more challenging exercise?
Codd recommends adding resistance to your training sessions to make them more challenging. “Using equipment like fins or paddles will increase muscle engagement when you swim,” she says.
You can also add intervals to your training just like you would running. This is a pace that is hard but sustainable for a certain amount of time.
“You will feel more comfortable at the beginning of the session, however, you will start to feel uncomfortable as the session progresses. Train this way with a higher effort and incorporate shorter rest periods between each repetition, instead of swimming with a easy intensity with a long rest, will create a more challenging workout, build your aerobic capacity, and train you to sustain moderately high speeds for longer,” says Codd.
Mixing up your swimming and being creative is only limited by your imagination, says Lomax.
“You could try swimming different strokes. Not all strokes are created equal when it comes to swimming efficiency, you could spend more time on a stroke that you find harder to swim. You could also try to complete more laps in your usual swim time For example, having a part of the swim where you swim faster than normal or reducing your rest periods between laps,” he adds.
Alternatively, reorganize your usual steady state swim into a series of sets that are swum at progressive speeds. Divide 12 laps into one easy length, one moderate length, one fast length, then rest and repeat this four times.
You can also play with progressive distances like 50 meters short rest, 100 meters short rest, 200 meters long rest, repeat three times.
“Instead of always swimming a full stroke, you can also introduce some swimming drills, or swim with just your legs or just your arms – there are swimming aids like kick boards and pull buoys that can help with this. You can also wear a special swim suit over your regular costume to make it more difficult to move through the water,” adds Lomax.
This article is not intended to offer medical advice, and readers should consult their physician or health care professional before adopting any diet or exercise regimen.
