Well, thank you for this question, and to answer your question quickly, there are a couple of reasons.
First, Whole Body CyroTherapy helps your body produce collagen. As we age our collagen levels do go down, so increasing this level is a good idea. Collagen is the protein that keeps our skin looking young.
Secondly, when you are in a CyroTherapy sauna, the blood vessels near the surface contract from the cold. When you get out, your blood rushes back in order to heat your body back up, this exercises near surface blood vessels allowing your body to deliver nutrients. As these blood vessels strengthen they are there to help your skin stay in a nutrient rich flow.
Does Whole Body Cryo Help With Hair and Nails Too?
Yes, it certainly does. And rightfully, you've deduced that since the protein collagen is responsible for healthy hair and nails too, Whole Body Cryo (WBC) therefore revitalizes here also. WBC inhibits anti-collagen (collagenases) enzymes that break down the peptide bonds in collagen.
Since Collagen is found in bones, tendons, cartilage, joints, blood vessels, and digestive system, you can understand why it's so important in our bodies. With the skin, it replaced dead skin cells, and strengthens skin elasticity.
Now, I'd like to turn you on to some real research on this topic, one very interesting research study I found on Research Gate titled; “Thermography study of skin response due to whole-body cryotherapy,” which was published in Skin Research and Technology (18 (2): 180-7 · April 2011) or DOI: 10.1111 / j.1600-0846.2011.00550.x – by Armand Cholewka, Agata stanek, Alexander Sieron, and Zofia Drazazga – this paper is very much worth your time to peruse.
Would CryoTherapy work better than Collagen Supplements? Perhaps because it's hard to say if your body will uptake swallowed tablets, especially as one ages, which is when something like this would really be important to you. What about Collagen Injections to the specific areas that need attention? Sure, that would probably be just as good or better, still, that does require a doctor's visit or visit to skin specialist, whereas cryotherapy does not.
Yes, some skin specialists are now using localized cryotherapy for such things in addition to Collagen Injections, so, you get the best of both worlds, still, Whole Body CryoTherapy is great for many things, and now you can add to that list; Skin Care and condition. Please consider all this and think on it.