Increase Repeat Sprint-ability by 10X

As a former professional rugby player myself, you can probably imagine the type of training and conditioning work we did. It was brutal.

I’ll never forget a series of pre-seasons when players would throw up during the anaerobic shuttle training in between sets and carry on. By the end of the session, you’d have a metallic taste in your mouth. We were there to push our limits, to reach higher levels of conditioning and in order to do so have to go to some very dark and uncomfortable places in order to force the body to adapt to higher levels of conditioning.

But how were we breathing?

We didn’t give it a second thought. Breath training wasn’t something anyone considered back in the early 2000’s during my rugby career.

We certainly push or limited and improved our conditioning, but was there a better way? How does our breathing affect our anaerobic conditioning? This is what we’ll discuss in this blog.

Improving Repeat Sprint Ability (RSA)

Some very interested research has been conducted by French scientist and researcher Xavier Woorons around the effect of breath-holding during training and increases in repeat sprint-ability.

When his 2018 study was published in the European Journal of Sports Science, reporting a 10-fold improvement in repeat sprint-ability, in only a 4 weeks trial my ears certainly pricked up! What was creating such a strong adaptation?

They were simply holding their breath when doing their repeat sprint conditioning. Is it that simple?

What is the breath-hold technique?

It’s very simply holding the breath after a normal exhalation. It’s done after a normal exhalation because that way we create a stronger drop in blood oxygen saturation (SpO2). %SpO2 is the percentage of red blood cells that are saturated with oxygen. As oxygen leaves the blood, in the presence of the carbon dioxide build up, the oxygen in the blood is not being replaces as you are holding the breath with relatively empty lungs. This means rather than holding the breath after an inhale, the drop in %SpO2 is stronger and quicker, leading to the anaerobic conditioning that we are trying to adapt to.

The theory is that the technique of holding the breath after an exhale would create a stronger stimulus for anaerobic adaptions during repeat string training compared with simply breathing normally during bouts of repeat sprints. In theory when we are doing repeat sprints with normal breathing, we’re working on anaerobic conditioning. Short recovery periods force adaptations to being able to repeatedly sprint when oxygen levels are low (anaerobic).

The holding of the breath would create a stronger stimulus and therefore greater adaptations. This was the theory, and this study puts it to the test.

What did the study do and show?

In 2018 Woorons and his team took 21 professional rugby player from Ireland and tested their repeat sprint-ability over 40m. They tested repeat sprint-ability at the start and end of a 4 week trial. The test was 40m sprints, departing every 30 seconds and they recorded peak velocity. They counted the number of sprints performed until peak velocity dropped below 85% of their maximum velocity.

The players we then match for ability from the test and separated into 2 groups. During the 4 week trial one group would be allows to breath ‘normally’ (non breath-hold group) and the other group hold their breath after exhalation for each 40m sprint in their training during the 4 week trial.

The 4 week trial comprised of 8 sessions in total, 2 per week separated by at least 48hrs. During the first week they performed 2 sets of 8, 40m sprints, with a departure every 30 seconds. Each week increased by 2 reps, so that by the 4th week they performed 3 sets of 8, 40m sprints, departing every 3 seconds. Each set was separated by 3 minutes of walking recovery.

Study Results

The non breath-hold group went from an average of 9.8 reps to 10.4 reps after the 4 week training period. A relatively small 6% improvement, which you’d expect after 4 weeks of training for the test.

However, the breath-hold group went from an average of 9.1 reps to 14.9 reps. A massive 64% improvement!

The breath-hold group average %SpO2 over an entire training session was 90.1%, whereas the non breath-hold group was only 95.5%. Normoxia is considered anything between 95-99% showing that on average during a whole session the non breath-hold group spent large portions of the session within normal blood oxygen saturation levels. Whereas, the breath-hold group’s average over the entire session was 90.1% anything below 91% considered hypoxia (low oxygen in the blood).

The breath-hold group therefore had a significantly greater exposure to low blood oxygen saturation giving them a great anaerobic stimulus to force greater adaptions over the 4 weeks.

Interestingly, it was also noted that maximal velocity was not different between testing before and after the 4 week trial for both groups, but the mean velocity decreased in the non breath-hold group and remained unchanged in breath-hold group.

What adaptations were causing such a large increase in the results?

“In addition to the hypoxic effect, an elevated carbon dioxide partial pressure (i.e. hypercapnic effect) has been shown to systematically occur during exercise with VHL. The main consequence of this phenomenon is to induce a blood, and probably muscle acidosis. When this kind of exercise is regularly repeated, it may be possible that physiological adaptations, such as improved buffer capacity, occur within blood or muscle tissue, therefore leading to better pH regulation. This would reinforce the potent effects of RSH over both an improvement in buffer capacity and an upregulation of genes involved in pH control. Since the accumulation of hydrogen ions within muscle has been argued to be an important factor leading to fatigue during repeated sprint exercise, one could assume that an improved pH regulation may have played a role in the large performance increase in the RSH-VHL group.” (Woorons, 2018)

What the researchers are saying here from the study is that as well as the hypoxia (low oxygen) effect of the breath-hold, there was also a significant increase in hypercapnia (carbon dioxide levels) in the blood and in the muscle tissues. The increase in acidity (H+ ions) that the low oxygen and high carbon dioxide creates in the blood and in the muscles forces the blood to adapt and improve its ability to buffer H+ ions and regulate pH, which leads to improved performance and delays onset on muscle fatigue. The breath-hold group had significantly low oxygen levels and higher carbon dioxide levels during the training simply because they were holding the breath for each training sprint.

Conclusions from the study

“From a practical point of view, this RSA enhancement can be obtained in specific conditions (running, on grass if needed and without the use of any hypoxic device) and can therefore be easily integrated in a conditioning program.” (Woorons, 2018)
It’s shown to be as simple of holding the breath to create a stronger anaerobic condition for training. It makes me think “wow I wish I knew then what we know now” but in the same breath, I’m passionate and excited to work with and help the current crop of rugby professionals that I work with.

For me therefore, it’s a no brainer for the professional athletes I work with. As simple as holding the breath after a normal exhale during some parts or elements of their training, all the way to a specific training plan specifically designed to their individual needs and the needs of their sport.

Practical Application

I’ve spent some time experimenting on myself with this type of training to produce some guidelines for the practical application of this in the real world and with sports teams and players.

One of the biggest things to appreciate is how hard 30 second departures for a 40m sprint are when you are holding the breath. The first few reps are alright, but it get very intense very quickly for those not well adapted, particularly if they have a poor tolerance to carbon dioxide.

The first and most important thing when looking at the practical application of this breath-holding in conditioning is to make it progressive.

I’ve successfully used a progressive approach to this training with initially working from a departure every 60 seconds then progressively working towards, 50 seconds, 40 seconds and then 30 seconds. You can even do 5 seconds reductions for an even more graduated approach.

You can progress the intervals weekly or even during the session itself. For example, if you are doing say 3 sets of 7 reps, you can start with departures every 60 seconds in set 1, reduce to every 50 seconds in set 2 and then reduce to just 40 seconds in the final set.

Over a series of weeks, you can reduce the departure time down to just 30 seconds as per the study.

Week 1: 2 sets x 6 reps (3 mins between sets)
Set 1 departing every 60 secs
Set 2 departing every 50 secs

Week 2: 3 sets x 6 reps (3 mins between sets)
Set 1 departing every 60 secs
Set 2 departing every 50 secs
Set 3 departing every 40 secs

Week 3: 3 sets x 6 reps (3 mins between sets)
Set 1 departing every 60 secs
Set 2 departing every 50 secs
Set 3 departing every 40 secs

Week 4: 3 sets x 6 reps (3 mins between sets)
Set 1 departing every 50 secs
Set 2 departing every 40 secs
Set 3 departing every 30 secs

So by the 4th week you have one set at 30 second departures and you can progressively work through a number of weeks to increase to doing 2 out of the 3 sets at 30 second departures, and eventually all 3 sets.

You can also increase the number of reps from 6 to 7 and then 8 reps as well as increasing from 1 session per week to 2 if desired, as per the study.

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Additional Applications in Rehab and Injury Prevention

There is something that isn’t mentioned in the discussion, that I’d like to point out and is very much part of the practical application of this study.

I want to point out how beneficial this could be for reducing risk of injury as well as during rehabilitation.

Typically to work on lactate threshold and anaerobic conditioning, as I mentioned at the start of this article, you are ‘red lining’. Pushing your limits to stress the body and force it to adapt. There is a high risk of injury when doing this type of training and conditioning. Hence why it is only used in pre-season typically and not during the season. However with the simple breath-holding techniques that is used in this study they created over just 4 weeks great adaptations by a factor of 10.

One thing this potentially means is that we can work on lactate threshold and anaerobic capacity by using breath-holds techniques whilst working at a much lower intensity. Working at 85% of maximum we have much lower risk of injury, yet while performing the conditioning with breath-holding we are conditioning the muscle tissues and blood to adapt physiologically.

The other potential benefit can be for injured players to both reduce the level of anaerobic de-conditioning they experience whilst out injured as well as better preparing them for higher intensity workload as they return to play.

We can create a anaerobic environment within the muscle tissues by simply walking and holding the breath. Working at very low levels of intensity, in terms of exercise out put, but pushing an athlete in regard to a breath-hold practise lets the muscular and circulatory systems maintain some level of anaerobic conditioning which otherwise they would not get to experience whilst out injured when not able to exercise at that intensity.

Also, as a player starts to return to ‘full fitness’ in terms of injury rehabilitation, they will have become de-conditioning from the high intensity anaerobic work they couldn’t perform due to the injury. If during their rehabilitation, they had been progressively working on their breath-holding they would have a better anaerobic conditioning profile making them more resilient to the higher intensity work they are now able to do and need to do in order to become ‘match fit’.

I hope you’ve found this article to be helpful and it’s made the practical application and understanding of this exciting research paper easier to digest. I’d love to hear from you if you experiment with implementing it into your own training. Or if you are a coach, physiotherapist or strength and conditioning coach working with athletes or teams I’d love to hear from you. My email is info@probreathwork.com.

Thanks again for reading.

Keep it nasal


Woorons et al (2018). European Journal of Sport Science. Repeated sprint training in hypoxia induced by voluntary hypoventilation improves running repeated sprint ability in rugby players. DOI: 10.1080/17461391.2018.1431312


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