GO2 device

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    Dada on #51951


    As I understood, that is a one-off device and has no direct effect on training progress.

    With regards to indirect training progress, I can imagine that you could train harder which should favor adaptions.

    Thomas Summer, MD on #51953

    That’s indeed quite interesting!


    this is the study that is cited on the website. It’s interesting but there are some caveats:
    – very small sample since
    – not really fit subjects
    – no real time trial
    – comparison against another mouthpiece!?!? – maybe that impaired the performance?!?

    anyway, I would like to test it;-)

    russes011 on #51964

    This device doesn’t make physiological sense.

    It increases PEEP (positive end expiratory pressure) by adding resistance to exhalation. PEEP increases blood oxygenation.

    1. Your blood oxygenation, however, is already at 100%, or near 100%, ESPECIALLY during exercise (one exception may be training at very HIGH altitude). Nevertheless, increasing it a few percentage points will not help the average athlete. And no, you can’t make it higher than 100%.

    2. PEEP paradoxically reduces ventilation–the volume of air that passes through your lungs with each breath. This is because the device prevents you from fully exhaling. Furthermore, this failure to fully exhale or “air trapping”, makes a higher percent of the air you breath to never reach the lungs–a higher percentage just ‘ventilates’ your airways not your lungs. (This device PARTLY simulates asthma. Asthma also prevents you from fully exhaling and causes air trapping. If you want to simulate asthma to train harder, however, this may be a good purchase.)

    3. Your lungs oxygenating your blood, in general, is not a rate limiting problem with exercise. Your blood oxygenation stays near 100% during exercise. Even at moderate altitude, where your oxygen saturation may be less than 100%, exercise naturally opens more alveoli in lungs and increases your saturation by a number of percentage points if below 100%. Air hunger during intense exercise is from CO2 build up (and adrenaline), not a low oxygen level in the blood–increasing PEEP can only make this worse. (O2 can also stimulate breathing but this doesn’t occur until the saturation is quite low, like say <90%).

    True rate limiting factors with exercise include your heart during high zone work (hence maxHR), mitochondrial density (and a variety of other enzymatic factors) for low zone work, and MOSTLY your nervous system, which is what they call the ‘governor’–it makes you slow down or stop when things get too hard, heavy, or long, even if your body can keep going.

    PS – how do you add a photo of yourself to your profile?

    Rachel on #51973

    And I thought my BreatheRight strips made me look funny on the trails…

    Steve — you can add a pic using Gravatar, if you click on your profile image.

    russes011 on #51980


    Thomas Summer, MD on #52032

    Thank you very much Steve! You shifted my attention back to sports medicine. The advertisement of the go2 managed to fool me into shifting my focus to intensive care medicine. Luckily that’s not our topic here;-)
    I agree with everything you wrote. Except that your blood oxygen saturation stays at 100% all the time during exercise. There is a phenomenon called “exercise-induced arterial hypoxemia” – EIAH. It’s not totally understood why that occurs. But PEEP will probably increase the hypoxemia and not reduce it. That’s because the constraint of breathing out will lead to air trapping (as you wrote), and increase CO2 and prevent adequate hyperventilation.

    conclusion: Don’t let the advertisement fool you. And never trust your doc;-)

    russes011 on #52037


    Thanks for pointing out my error regarding saturation always being 100% during exercise, or at least my oversimplification. Honestly I noted that after I originally posted but didn’t go back to edit my post. As you know (and EIAH aside) most normal folks have an O2 sat around 95-100% at rest. With the potentially tremendous pulmonary compensation we all have during exercise (in the order of 8-fold) this O2 sat usually increases a few points, say putting most at 97-100% during exercise. As I believe you understand, my point was that the oxygenation of the blood by the lungs, specifically, is not a common rate limiting process during exercise. Therefore devices that purportedly increase the lungs ability to oxygenate (or even ventilate) are probably not useful. For example, breath right strips don’t work, aside from their placebo effect.

    I was not aware of EIAH–thank you for pointing it out to me! Very interesting. It seems that in athletes with stupendous cardiac outputs from extensive aerobic training, their hearts (aka blood flow) may actually outpace their lungs ability to oxygenate their blood when they are close to maximal efforts. (This also can happen in children, who have yet undeveloped lungs compared to their hearts). It would be fascinating to speculate about the cause but that would be way way out of my league. It reminds me of the finish to Ravel’s Bolero, when the frenzied crescendo becomes disjointed and eventually falls apart.

    — Steve

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