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Inspiratory Muscle Training

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7BDiver

Active Member
Sep 5, 2019
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There are numerous posts about Power Lung and Expand-a-Lung but they are largely focused on breath hold time and increasing lung capacity. In large part the consensus is that a more flexible ribcage and upper body achieves better results. After reading an article on the matter https://www.active.com/cycling/articles/how-to-train-your-respiratory-muscles there is a focus on Rating of Perceived Exertion (RPE). With the benefit of stronger respiratory muscles and potentially a reduced oxygen consumption during breath up has anyone felt more relaxed and less fatigued during a long session of diving after incorporating such dedicated strength training. I see a lot of posts about people having trouble with breath holds and the perception that they are overtraining for days after diving or even static practices. It makes me ask if they are not used to the CO2 yet or if their lungs are just fatigued.
 

SDS

Member
Feb 16, 2018
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It is indeed an interesting question to ask whether inspiratory muscle training (IMT) can increase breath hold performance.

Let's first be clear about this :
- IMT will increase the strength and thickness of the diaphragm.
- IMT prior to cardiac or major abdominal surgery reduces postoperative pulmonary complications.
- IMT will reduce symptoms of dyspnea in severe chronic lung disease.
- IMT may improve performance in endurance and intermittent sports. This effect is primarily induced by the metaboreflex: fatiguing inspiratory muscle work demands greater perfusion of these muscles and induces a redistribution of the blood from the contracting peripheral muscles (i.e., the legs) to the inspiratory muscles. Increasing the work capacity of the inspiratory muscles will delay the work intensity at which inspiratory muscles fatigue, and thus delay of the metaboreflex. The peripheral skeletal muscles benefit from greater maximal blood flow --> high-intensity exercise performance enhancement.

Is there a use of IMT for freedivers? Not sure, but I don't think so:
- You want your diaphragm to be as flexible as possible (at least for depth). I wonder whether a thicker and stronger diaphragm would come at the cost of flexibility?
- I wonder whether a stronger diaphragm will increase the intensity of your contractions, seems a reasonable hypothesis to me.
- A breathe up is very gentle and does not require a lot of inspiratory muscle work. Therefore, during your breathe up, there should not be any inspiratory muscle fatigue. Neither will there be during your breathold. I therefore don't think your hypothesis still stands?

The only argument in favour of IMT I can think of, is that it might be easier to inhale to your full lung capacity whenever you experience resistance by a not so flexible wetsuit in addition to some resistance by the water pressure (supine < prone < vertical position in the water).

What do you think?
 
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7BDiver

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Sep 5, 2019
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I think anyone knows there is a very noticeable difference between inhale above water and chest below the surface. The next consideration that comes to mind is which training biased on flexibility/strength side is less prone to injury. Especially when it comes to stretching after inspiration there are a number of people that get hurt that way. Whether a stronger diaphragm will induce stronger contractions is an interesting point, and from Fletcher Techniques https://www.fletchertechniques.com/breath-hold/breath-hold-strong-diaphragm/ the answer may be yes, however somewhere in the mix there is less energy demands. The tradeoff is a little misunderstood for me and may take some practical experience.
 

SDS

Member
Feb 16, 2018
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Thanks for the interesting link! Their hypothesis that IMT could increase breath hold time through reduced fatigablity of the respiratory muscles should still be experimentally confirmed --> but it doesn't take much to do a little experiment on that :).

Regarding your concern for injuries:
- I have never heard or read about any injury occurring during IMT. What happens on depth after training adaptations have taken place (in other words: what happens with flexibility) is a question mark to me.
- Barotrauma during diaphragmatic stretches using empty lungs (either or not with reverse packing and thoracic extension etc.) can occur and should thus be performed with caution. However, increasing the flexibility of the diaphragm will reduce the vulnerability for lung squeeze (and reduce residual volume) and should thus be part of your (depth) training program.
- Mobility/flexibility exercises on full lungs (i.e., full lungs + thoracic rotation) you referred to: the goal here is to increase the expansion capacity of the thorax. This is not a stretch of the diaphragm. I presume the injuries occurring through aggressive mobilisation exercises on full lungs (either or not with packing) are similar to injuries occurring with traditional lung overexpansion (but now with overexpansion in a more regional area of the lung)??

Something to play around with: seal the opening of your snorkel with tape and punch a few little holes in it. Now do some swimming exercises whilst breathing through your snorkel. Notice that you will be breathing against resistance (=a form of IMT) whilst substantially increasing CO2 levels in the blood. Fun thing to do as a warming up for training in the swimming pool :).
 

7BDiver

Active Member
Sep 5, 2019
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I definitely can fill my lungs up with enough air to feel the pressure without any sort of packing but really need to work on flexibility and how to use my diaphragm effectively. Have you ever heard of anyone timing their swimming technique with the diaphragm contractions? Would someone versed in DNF form not kick or stroke at the same time the diaphragm moves, if that would make any difference in ones performance or state of relaxation? Perhaps the opposite.
 

cdavis

Well-Known Member
Jan 21, 2003
4,006
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It is indeed an interesting question to ask whether inspiratory muscle training (IMT) can increase breath hold performance.

Let's first be clear about this :
- IMT will increase the strength and thickness of the diaphragm.
- IMT prior to cardiac or major abdominal surgery reduces postoperative pulmonary complications.
- IMT will reduce symptoms of dyspnea in severe chronic lung disease.
- IMT may improve performance in endurance and intermittent sports. This effect is primarily induced by the metaboreflex: fatiguing inspiratory muscle work demands greater perfusion of these muscles and induces a redistribution of the blood from the contracting peripheral muscles (i.e., the legs) to the inspiratory muscles. Increasing the work capacity of the inspiratory muscles will delay the work intensity at which inspiratory muscles fatigue, and thus delay of the metaboreflex. The peripheral skeletal muscles benefit from greater maximal blood flow --> high-intensity exercise performance enhancement.

Is there a use of IMT for freedivers? Not sure, but I don't think so:
- You want your diaphragm to be as flexible as possible (at least for depth). I wonder whether a thicker and stronger diaphragm would come at the cost of flexibility?
- I wonder whether a stronger diaphragm will increase the intensity of your contractions, seems a reasonable hypothesis to me.
- A breathe up is very gentle and does not require a lot of inspiratory muscle work. Therefore, during your breathe up, there should not be any inspiratory muscle fatigue. Neither will there be during your breathold. I therefore don't think your hypothesis still stands?

The only argument in favour of IMT I can think of, is that it might be easier to inhale to your full lung capacity whenever you experience resistance by a not so flexible wetsuit in addition to some resistance by the water pressure (supine < prone < vertical position in the water).

What do you think?
Comprehensive post SDS, nice job; very interesting to contemplate. The flexibility point I had not thought of.

I think your last point is true and more important than many would expect. Resistance can SUBSTANTIALLY reduce inhale volume. Try a full inhale out of the water vs in the water. Wetsuits also reduce inhale volume, a lot for a thick or poorly fitting suit. If a divers style requires a full inhale, IMT is almost certainly a benefit. As a counter, diving at less that a full lung is often advantageous. I dive half lung and get longer, more comfortable dive times as a result. Probably safer too. My guess is that, for divers used to full lung, doing a lot of IMT will increase volume and produce longer(but not necessarily safer) dives. Greater inhale might also overcome decreased flexibility when doing depth.
 
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7BDiver

Active Member
Sep 5, 2019
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Talk about comprehensive cdavis, just ran across your post from 2015 "Exhale diving, theory and practice, a laymans view". Up until this week I have completely been doing full inhale diving but tried half lung during a DNF session the other day and saw a glimpse of the potential for shallow diving. I worked on IMT for a while and got from feeling unable to fill my lungs fully every time to the feeling of overdoing it and having the excess CO2, mild discomfort and buoyancy as a result. IMT will get the job done filling the lungs, but my point may be that more IMT may not achieve the comfort and performance I am looking for and need to try other techniques.
 

xristos

Well-Known Member
Sep 5, 2013
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Comprehensive post SDS, nice job; very interesting to contemplate. The flexibility point I had not thought of.

I think your last point is true and more important than many would expect. Resistance can SUBSTANTIALLY reduce inhale volume. Try a full inhale out of the water vs in the water. Wetsuits also reduce inhale volume, a lot for a thick or poorly fitting suit. If a divers style requires a full inhale, IMT is almost certainly a benefit. As a counter, diving at less that a full lung is often advantageous. I dive half lung and get longer, more comfortable dive times as a result. Probably safer too. My guess is that, for divers used to full lung, doing a lot of IMT will increase volume and produce longer(but not necessarily safer) dives. Greater inhale might also overcome decreased flexibility when doing depth.
Maybe it is too obvious but isn't it easy to get those extra milliliters of air you can't with a handful of packs?

Intuitively I have made the conclusion that IMT doesn't offer much if anything and still do but there are people like Homar Leuci that swear by it:unsure:.
 

cdavis

Well-Known Member
Jan 21, 2003
4,006
779
218
71
Talk about comprehensive cdavis, just ran across your post from 2015 "Exhale diving, theory and practice, a laymans view". Up until this week I have completely been doing full inhale diving but tried half lung during a DNF session the other day and saw a glimpse of the potential for shallow diving. I worked on IMT for a while and got from feeling unable to fill my lungs fully every time to the feeling of overdoing it and having the excess CO2, mild discomfort and buoyancy as a result. IMT will get the job done filling the lungs, but my point may be that more IMT may not achieve the comfort and performance I am looking for and need to try other techniques.
78diver, Interesting comments from somebody who actually used IMT. I was just guessing.

excess c02? Why?

Thanks for the comment on the exhale diving thread; glad it was helpful. Half lung, aka FRZ or exhale ,diving works astonishingly well in the right circumstances, in my case, serial diving in 40-90 ft. Keep at it, benefits keep getting better as your body adapts. There is another thread out there that describes my progression into exhale. Worth reading if that becomes your thing.
 

7BDiver

Active Member
Sep 5, 2019
104
36
43
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For me IMT just gets a similar result as packing, in the end you just get more air and the feeling of a balloon in the chest. With not being versed in staying relaxed or having great flexibility my heart rate will be higher compared to half filled lungs and the diaphragm response is a little sharper. The principle benefit is getting more air for depth and not feeling week/more mobility for inspiration. I can't say whether the diaphragm reacts stronger and quicker due to more quantity of CO2 or if the stretched chest makes the sensation different. I don't like packing, it is slow, the air doesn't seem as fresh and takes away from the relaxation.
 
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