Tag Archives: freedive training

Training for freediving with the Moxy muscle oxygen monitor

This post goes with a webinar that I gave on data collected with the Moxy Muscle oxygen monitor. In the webinar I test some specific exercises and try to speculate on myoglobin desaturation and training to increase myoglobin stores.

I want to use this post to give some extra thought to some keypoints, and to make the webinar a bit more understandable. But first, keep these things in mind:

  • The Moxy measures oxygen in the muscles. I put it on my left Vastus Lateralis (quadriceps).
  • The Moxy gives you one number for total SmO2 (muscle oxygen). This number is a weighted average of myoglobin and hemoglobin.
  • Everything I tested only relates to me and my (left) quad. The numbers will be different for you. The squats that work for me may not work for you. The apnea walks that don’t work for me may work for you.
  • On all the graphs in the presentation, the x axis = time in seconds. The left y axis is for heart rate, muscle oxygen and SaO2. The right y axis pertains to Thb and is a measure of blood flow to the muscles.

Ok now you can watch:

I used the Moxy to test a series of exercises. What do these exercises actually do?

Apnea walks

For example, the apnea walks that I described here actually did not train my muscles to perform under hypoxia at all. The body has a fantastic set of feedback mechanisms in place to make sure that oxygen is delivered where it is needed, and without the vasoconstriction and blood shift during a dive that oxygen will go right into your muscles. Apnea walks debunked. Sorry everyone.

It didn’t matter whether I did them on an exhale or inhale.  I think that apnea walks on an inhale probably don’t work for anyone. On an exhale, they may work for some people, but I doubt it.

What about holding your breath until contractions and then starting exercise? Same thing. The muscles actually never get hypoxic. In fact, even doing this with a more strenuous exercise like a wall sit the muscles never dipped below ~35 %.

Doing a wall sit or even one-leg stand with breath did not help either. You can do a wall sit until failure, but there will be plenty of oxygen in your quads. It’s not a lack of oxygen that causes your muscles to fail, it’s the accumulation of waste.

RV squats

The only exercise that I found effective was a set of isometric squats with short recovery intervals, done after a forceful exhale. Using these squats and tinkering with the variables (length of recovery, initial static, and squat) I was able to consistently let SmO2 dip below 10%.

Now before you all start doing a 150 kg squat on breath hold, remember that if you do this with too much resistance you might simply be training for fast twitch muscle. If I focus on slow twitch muscle I try to stick to no higher than 30% of my personal max resistance.

How do you know this works? Are you increasing myoglobin in the muscles?

I don’t know if this works. But here is my rationale. In order to get the body to generate hemoglobin (red blood cells) you need to desaturate the blood of oxygen. This is why being at altitude increases your red blood cell count. The body will automatically create more red blood cells once it realizes it does not have enough of them to efficiently bring oxygen to where it is needed.

Along the same lines of logic, we need to desaturate myoglobin of oxygen in order to tell the body to create more of it. This happens naturally on some deeper or longer dives thanks to vasoconstriction and blood shift, but is hard to achieve when cross training.

I can’t promise you that by lowering SmO2 you will cause more myoglobin to be generated. I do think it is a sound hypothesis. Keep SaO2 high, and decrease SmO2. This is what naturally happens in our bodies during a dive, and one of the things to aim for during cross training.

The in-water method of training for myoglobin is called the Foundational Training and described in Eric Fattah’s book Holistic Freediving.

A practical guide to apnea walking as training for freediving

You have probably heard about apnea walking as a form of training. But how does it really work? What are you actually training? There are a few specific ways to practice apnea walking. Here I will describe the method I use.

As you know from our previous posts on muscle fiber type, and muscle metabolism, different metabolic pathways and muscle fibers are active during different parts of the dive. With apnea walking, you train the ascent phase of your dives. During the ascent phase, your legs are gradually becoming more hypoxic as a result of vasoconstriction and overall oxygen depletion.

If you feel like your legs are always tired when you are coming up, apnea walking is worth a try.

Should I practice apnea walking with full or empty lungs?

Apnea walking is a good way to train the muscles under hypoxic conditions. If you do a static with full lungs, your oxygen saturation only starts to decline after several minutes. It starts to decline within a minute if you do a static with empty lungs. The same thing happens if you are walking. Empty lung apnea walks result in lower oxygen saturation, and will be shorter as a result.

Because I find the dive reflex is hard to initiate on land, I do most of my dry apnea with empty lungs. I always train with an oximeter. If the goal is 85% SaO2 it does not matter whether I get there with full or empty lungs.

For me, training with empty lungs is faster and more comfortable. If you have no problem doing long full lung breath holds on land you can fully inflate your lungs before apnea walks.

apnea walking
A simple oximeter that I use for apnea walking. It is far from perfect, but definitely allows me to track my performance better.

I use an initial static of around 30 seconds to become slightly hypoxic before I start the walk. The reason for this is that my body might maintain blood flow to the muscles if I start walking prior to the onset of the dive reflex (or HR drop). This is an obvious issue if the goal is to train the muscles under hypoxic conditions.

After my 30 seconds empty lung static I walk for approximately a minute while maintaining the breath hold. At the end of my static I try to be at SaO2 80 – 85%. I take about 10 recovery breaths, and note the final SaO2. My total recovery interval is 1:30 between walks. I get a maximum of 5 contractions per breath hold this way and I can easily keep it up for more than 10 repetitions.

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Empty lung apnea walking

Apnea walking in point form:

Get your oximeter and a timer ready. If you do not have an oximeter you can still do the exercise but it will be harder to tweak it to your needs.

  • Warm up with a couple breath holds or simply breathe slowly for a few minutes
  • Do an initial static
  • Walk
  • Take up to 10 recovery breaths (quick breaths) and relax. Your total recovery interval is 1:30
  • While in recovery the numbers on your oximeter may keep dropping. Note the lowest value. If this value is lower than your target, reduce your next static and/or walk
  • Repeat for 12 cycles

I use the ‘runtastic’ timer app for iOS in order to time my training (I am not affiliated with this app in any way).

I use the runtastic timer app for my apnea walks
I use the runtastic timer app for my apnea walks

Tweaking the exercise

Your initial static should be short enough to allow for a decent walk. If you have a strong dive reflex on land you may not even need the static. I suggest starting the static at 30 – 50 % of your onset of contraction time. For example a diver that gets contractions at 1 minute on an empty lung static should start with a static of 20 – 30 seconds. If you have an oximeter with heart rate monitor, stop the static and start the walk when you see your heart rate drop (if you see a heart rate drop at all – I often don’t).

Your oximeter will not show the current oxygen saturation. Rather, it records a moving average. Because of that you will have to keep checking your oximeter during your recovery. The lowest value should show up within 15 seconds after you start breathing. Compare this value to your target value.

Your apnea walks should be of a comfort level that you can keep up for more than 10 repetitions. The reason is that you are simply not going to induce adaptations by only one minute of hypoxic walking per training session.

Before you start training, know the risks. Any exercise involving apnea can lead to loss of consciousness, injury, or even death. Choose a safe site to train. Do not attempt this training with a heart condition. Always train with a buddy/spotter.

How do you train your apnea walks? Leave a comment!



Hypoxia and brain function

In this post we are going to take a closer look at how your judgement changes due to hypoxia. Being hypoxic means having too little oxygen to support your body. Hypoxia manifests itself as fatigue, lightheadedness, tunnel vision, altered colour perception, and most importantly, impaired judgement.

How do we recognize hypoxia?

The body has no receptors that tell us we are hypoxic at all. Instead what you feel when you are holding your breath is the increase in CO2. This leads to a buildup of carbonic acid in the blood, and thus increased acidity. If we do not build up any CO2 and have gas in our lungs (any gas), there will be no alarm bells going off. Most freedivers notice the uncomfortable feeling associated with hypercapnia (elevated CO2 levels), but unfortunately have no idea about hypoxia. For obvious reasons, this can be problematic.

Luckily we can have a peek at what happens at low levels of O2 because of pilots’ altitude training. It is revealing, and really, a bit scary:

What do we learn from this? By the time we reach PaO2 = 60%, our judgment is so impaired that we are unable to make any sensible decisions. This carries the implication that as a freediver you need to be on your way to the surface at this point, and hopefully you can complete your surface protocol by force of habit. During a breathhold the drop of oxygen saturation tends to stall for a bit at PaO2 = 70% before dropping further. At this level you should be experiencing tunnel vision and other funny effects, although this will differ for everyone personally.

Lucky breaks at depth

We do get some lucky breaks at depth, thanks to the pressure. Oxygen reacts at higher rates at depth. Because of that, your oxygen saturation is unlikely to drop very low until you come closer to the surface and the pressure decreases. This is the reason that most blackouts occur at, or close to the surface. Let’s say you are at 40 meters and you have 5% total O2 in your lungs, this will react as if you have 5 x 5% =  25% O2 in your lungs because of the pressure. However, if you now go back up and by doing so you drain the lungs to 3% total oxygen at 20 meters, the result of the pressure at this depth will be that the O2 reacts as if you have 9% in your lungs. Oxygen will move back from the blood into the lungs and you are now in the low O2 zone, where you are prone to blacking out (more info on this can be found in this article on shallow water blackout). The point: once you are on your way back up make sure you go back to the surface fast.

Is identifying hypoxia useful?

Knowing this, is it still helpful to know when we are hypoxic? I think so, but you also need to realize when you are going to notice it. This is probably in the last 10 – 20 m of your ascent (depending on how deep you dive). If you have dipped below 70% or 60% PaO2 you should notice this at the surface as some type of lightheadedness or tunnel vision. The depth and duration of that dive should probably be your maximum for the day unless you are still warming up. It will vary daily and between dives, depend on what you have eaten, rest, hydration, and so forth. Doing a 2 minute dive to 30 meters on one day is no guarantee that you can do a 1 minute dive to 20 meters on another day. Even in one dive session you may not always get the same results, so be careful. You can use an oximeter and exhale statics if you want to know what hypoxia feels like. However, note also that in some cases (if your mind wanders at the wrong time?) you may not sense it at all.


Yoga for Freediving by Sara Campbell

Yoga for Freediving is one of the best ways to train for freediving. Pranayama, meaning breath control in Sanskrit, is a discipline that finds its origin in ancient India. In western culture, yoga is commonly seen as a stretching exercise, but it is much more than that. Yoga increases the awareness of the body and the control of both breath and mind in ways that a stretching exercise can never do on its own. You could argue that freediving is actually a form of yoga.

yoga for freediving
Yoga for Freediving: deep relaxation will be launched on June 21st 2016; International Yoga Day

Sara Campbell is a four times world record holder, with a personal best CWT of 104m. It is the practice of yoga, and the mental and physical benefits of yoga that have allowed her to get there. Sara is releasing her first yoga for Freediving course on the 21st of June, International Yoga Day, and Freedive Wire has had a chance to review it.

 “Freediving, and yoga and meditation are more than inextricably linked, they are one and the same thing. If freedivers want to create the best foundations for their training, and really see their performance improve exponentially, meditation and disciplining the mind is the one place they need to focus their attention.” – Sara

Yoga for Freediving: Deep Relaxation

Deep Relaxation is the first of six of the Yoga for Freediving courses. It is a resource that is beneficial for divers of any level. Deep Relaxation is an online course that works mainly with simple meditations, exercises and lectures. By signing up you are effectively inviting Sara Campbell as your private yoga teacher to guide you through meditations and yoga postures. Within the course you can find 28 lectures that add up to about 6 hours of material (22 of these are core How To materials which appear in every course to ensure you have the basics to hand each time; the unique content to every course is around 2 hours per course).

The most important videos, the guided meditations and lectures, are also downloadable as mp3’s. This is a great addition, because you can download them to your mp3 player and do them in the park if you wish. Nothing like meditating on the beach, just before you get into the water.

The videos are highly geared towards freediving, and all contain Sara’s personal perspective on how it affects performance. An example of a ‘how to’ video is ‘how to get the deepest inhale’. It won’t get much more applicable to freediving than this.

“There is more than enough information available for freedivers on the technical aspects of the sport, i.e. how to dive. But to date there is really no structured approach tailored to freedivers explaining the essentials of spirituality within freediving or teaching how to integrate yoga and meditation into their training. Learning to master the mental and emotional aspects of a dive are the make or break of every experience in the water. I’m excited to finally address this crucial aspect for freedivers of all levels.” -Sara

yoga for freediving
Sara teaching Kundalini Yoga. Photo credit: Embah Safari

Personal experience

When I started freediving, I did daily yoga sessions and often meditated outside of that. These yoga sessions were not geared specifically to freediving, but they had a profound effect on my performance. If I meditated before statics, I would get contractions after 3 ½ minutes (my p.b. then was 4 minutes). If I do not meditate at all, my contractions start at 2 – 2 ½ minutes (my p.b. now: 5:20 minutes.

My most relaxed diving session of this season, was after I had started reviewing yoga for Freediving, and specifically, did a 40 minutes guided meditation by Sara. I believe Yoga for Freediving is a great resource for all freedivers that you can keep referring back to and I think many freedivers will agree with me.

Find out more here.