When you swim, you aren’t just training your muscles. You’re training your lungs, too! That’s the core concept behind hypoxic training, which challenges your body to adapt to lower levels of oxygen. Essentially, you’re working on breath control. 

Hypoxic swim sets have been used for decades to help swimmers reduce excessive breathing and simulate the challenge of maintaining a breathing pattern during a tough race.

It’s important to note that hypoxic training is best for intermediate or advanced swimmers who are very comfortable in the water and have an understanding of basic stroke mechanics. 

Related: How to Improve Breath Control for Swimming

Hypoxic Training is NOT Breath Holding

Hypoxic training is often mistaken for prolonged breath holding, when in fact, it is perfectly ok — and encouraged — to exhale. If you hold your breath for a long period of time or try to swim long distances underwater, carbon dioxide builds up in your system, which can cause headaches, blackouts and drowning. Avoid prolonged breath holding or long underwater swims. 

During a hypoxic set, slowly exhale out of your nose while your head is in the water before taking another breath. Doing so allows you to continue working on breath control without concerns about carbon dioxide poisoning. The same concept applies when you are swimming with your usual breathing pattern. 

Related: How to Breathe When Swimming Freestyle

Why You Should Incorporate Hypoxic Training

While researchers have yet to agree that hypoxic training improves swimmers’ aerobic capacity, incorporating hypoxic sets into your swimming has other benefits:

  • Fix stroke issues: Hypoxic training can help you address stroke issues that occur when you breathe, such as your catch. When you take fewer breaths, your body has more time to work on correct movement patterns. 
  • Better control in open water: If you swim in rough open water, it can be tough to maintain a breathing pattern. Hypoxic training can give you peace of mind that you’ll be able to manage a few extra strokes before breathing if you encounter a particularly choppy section of your swim.
  • Boosts heart rate: A short hypoxic set can help get your heart rate up in a swim meet warm up without pushing yourself too hard.

Related: How to Improve Your Catch (EVF) – Fist Drill Workout

Examples of Hypoxic Swim Training

Customize your hypoxic training based on your skill level, and don’t try a hypoxic set if there isn’t a lifeguard watching. We don’t recommend taking more than 15 seconds between breaths. 


  • Add to your breathing pattern: 4×50, adding one stroke to your typical breathing pattern (If you breathe every two strokes, try breathing every three strokes, etc.).
  • Focus on walls: 2×100, taking no breaths in the last five meters before the wall.
  • Kick: 4×50, kick for 10 seconds and breathe (or, 10 kicks/one breath)


  • Breathing by stroke count: 4×200 pull, breathing every 3/5/3/5 strokes by 50.
  • Descending breath count: 4×50 swim, four breaths for the first 50, three breaths for the second, two breaths for the third, and one breath for the fourth. Choose a starting breath count and decrease by one each rep!
  • Underwater kick: 8×25 underwater dolphin kick (with or without fins).

Be sure to give yourself adequate rest on hypoxic swim sets. We recommend at least 20 seconds of rest for a 25, but take as much rest as you need!

Related: How to Improve Your Underwater Dolphin Kick – 45-Minute Workout

Wrong Ways to Practice Hypoxic Training

Avoid these mistakes when swimming a hypoxic set:

  • Breath holding: Holding your breath for extended periods of time and not exhaling causes carbon dioxide to build up in your lungs, which can lead to blackouts.
  • Long underwater swims: Do not try to swim more than a 25 underwater at one time. Going too long without breathing can cause blackouts and drowning. 
  • Taking fast, deep breaths: This can result in hyperventilation, which causes your body’s oxygen and carbon dioxide stores to go out of balance and reduces your body’s natural signals to breathe. Instead, take one deep breath before pushing off the wall. 

Listen to Your Body

If you’re new to hypoxic training, take it easy. The suggestions above are just that — suggestions. Adjust your breath count, distance and rest periods to fit with your current skills and comfort level.

If you ever feel lightheaded, stop on the wall and take slow, deep breaths. With consistent practice, your breath control will improve over time. For extra peace of mind, always swim when there is a lifeguard on deck.

Have you tried hypoxic training? Let us know in the comments! 

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  1. Sometimes, while streamline dolphin kicking a 25 yd underwater, when I stop at the wall, I get a heavy sensation in my legs. It feels like a heavy weight flowing down my core and down my legs. It is not a painful or anxiety causing feeling. Any ideas what is causing that sensation?

  2. yoo advanced swimmer here, my hypoxic training typically focuses on sprints, meaning 5×50, 8×50 freestyle swims are best for lung control and breath control, limiting your breaths is recommended (for me atleast) to 3-10 breaths each 50, so that your body pushes itself to go faster. underwater 25s are my favorite workouts especially with fins though pushing yourself to not breathe can be dangerous (as pointed out above) so be sure to take a breath or two when you need it!!

  3. Mark Carroll on

    As I’m getting older (51) I’m finding breath/lung capacity becoming a bigger and bigger issue. I find it more challenging to do breastroke pullouts – particularly in a race – and underwater kicks off the wall. I’ve modified my free from bilateral breathing, to 3 strokes each side. I’m doing the IMX pro challenge plan (leading to 400IM) at the moment and trying to work on breathing and lung capacity as part of that – but finding it hard to make improvements.

    Would welcome tips and comments from others!

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