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What is "pack stretching" before a dive?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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We must organise to get those pictures posted to the site somewhere :cool:

Sorry to be the bearer of bad news, but . . .

I am curently researching an article for Freediver Magazine on 'lung packing' and so far the results don't look too good. Yes, there may be increases in lung volume of 22-39% but there are also blood pressure shifts of up to 87%!

For the young, fit and healthy this may be tolerable; just the occasional blackout due to reduced cardiac output. For the older and plumper amongst us transient ischaemic attacks, cerebral aneurisms and strokes are potential outcomes.

Performance may also be reduced if one spends too much time packing rather than 'immersing' . . .

As with everything in life -- moderation is the key.



To say that a diver gets 22-39% more air from packing may be true for those who are just learning the technique. Spirometer experiments have shown, for example, the following differences:
Me: No packing (7.89L max, 7.50L avg), with packing (10.52L max, 10.35L avg)
Herbert Nitsch: No packing (7L), with packing (10L)
Hubert Maier: No packing (10L), with packing (14L)

Further, if you do the math on the air packed per second, and substract metabolic O2 consumption, you'll see that you gain, no matter how long you pack for, based solely on the fact that the O2 store increases at a greater rate than O2 consumption, even allowing for the high BP and high HR which occur from the stress during packing.

However, care must be taken. I don't believe you can cause an embolism from packing (some scientist tried to prove it was impossible, and I agree), however the intercostal (and other muscles) are at risk of hyperstretching unless you proceed gradually. I have gradually worked up over the years, but in Florida I showed Karoline Dal Toe how to pack an extra liter by changing her body position. She got the extra liter, and her apnea improved along with it, but she suffered sore chest muscles for several days.

When deep diving in constant weight, I pack through my snorkel, about 70 times, and it takes about 20-30 seconds.

Packing can cause a blackout under certain circumstances. I take great care to ensure my physiology is balanced before attempting a huge pack. The body must be well hydrated, BP must be good or better, all vasodilators must be avoided (i.e. garlic, onions), the electrolytes must be balanced, and the adrenals must be in top shape (i.e. avoid simple sugar, caffeine, alcohol).

Eric Fattah
BC, Canada
packing and blackouts

Eric, you stated that,
Packing can cause a blackout under certain circumstances.
and Peter you mentioned
.....just the occasional blackout due to reduced cardiac output.
Could you folks say more about this. When is the blackout likely to occur and for what reasons? How is this different from SWB? Are there warning signs? Is it more likely to happen for beginners or when one has developed greater capacity, or is a risk factor across the board? How much of a risk factor is it? Have either of you experienced this personally or witnessed it in others? If so what was it like? If a person blackouts from packing what first aid steps are necessary? Thanks, Angus
Packing and Fainting

There appears to be two distinct issues of risk associated with packing -- both of which are uncommon in the literature and neither of which I have personally winessed.

1) Fainting due to blood being driven out of the chest cavity by the stretch/recoil pressures of the intercostal muscles and connective tissues. This leads to a drop in venous return of blood to the heart therefore, lower cardiac output on subsequent heartbeats. Less blood out of heart = less blood to brain = fainting. Interestingly this scenario is usually accopmanied by a drop(!) in blood pressure, both systolic (~27%) and diastolic (~26%.)

2) Fainting due to elevated airway pressure as (safe) Fresnel technique are assisted/bastardised by (unsafe) Valsalva manouvres. Sustained airway pressures of 5.72 kPa have been measured after packing compared to 'normal' airway pressure of 3.06 kPa after 'normal' inspiration to total lung capacity. Transient blood pressure peaks of 226 mm Hg ('normal' 120 mm Hg) have been associated with Valsalva manouvres at these elevated airway pressures. In 'individuals at risk' minor instances of transient ischaemic attack (mini-strokes) may precipitate black-out and other 'inconveniences.'

Again, neither scenario is common so don't panic too much. But, it is best to be aware of possible risks and to progress slowly in your quest for bigger, better packing.

  • Like
Reactions: sanso
sounds dangerous and fun lol but also very reward full ill do it on my bed therefore if i do black out then im ok and................im 14 lol thanks bye
wow it was kool it makes you feel very dizzy and also very agitated but apart frm that it was ace m8 thakns
Hi Carlo,

Packing is something that should only be done by experienced freedivers. It's an advanced technique that only provides benefit after you've exhausted other avenues such as breathing techniques, flexibility and relaxation. I'd strongly advise you to do some searching on the forum about these before looking at packing.

Although packing does provide some increases to performances, it does have to be approached very slowly and carefully as it can bring about very real injuries. In my earlier days of packing i've hurt myself many times, including chest and rib pain, packing blackouts (and consequential head injuries from falling over and cracking my head on the ground), throat pain and i've coughed up blood more times than I care to remember. Even now after 3 years of doing it I still have the occasional pain or injury if I haven't warmed up properly.

You can go a long way without packing - only last week I was talking to a girl at training who has done some pretty deep dives (over 50m), has good dynamic and static and she said she doesn't pack. Umberto Pellizzari, one of the worlds greatest freedivers is also a non-packer.

Have a look around the forums, there's tons to learn here and tons of great freedivers happy to give out advice. It's particularly good at your age because you can learn to avoid all the bad habits we've picked up ;)

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