Those readers interested in strength training have surely come across kettle bell training and the other methods advocated by Pavel Tsatsouline in his many books. Bust as a respiratory physiologist the one method I became interested in was power breathing that Pavel refers to, citing Professor Zatsiorsky as the creator of this breathing method to improve strength.
So I decided to do a bit of searching about to see what scientific basis this method had, and found only 1 paper with evidence to support the claims made (as a side note I have actually tried the power breath method and found it to be very effective).
The study was carried out by Dr Djarova and colleagues in Bulgaria and they compared hyperventilation (breathing too deeply and quickly) only, breath holding only and hyperventilation and breath holding combined. The results demonstrate that the breathing maneuvers employed led to and increase in growth hormone by up to 5-fold and an increase in cortisol of up to 2-fold. They attribute this hormonal response to a generalised stress response caused by extreme breathing maneuvers. Imagine choking and the stress you feel, well this response is similar to that and wouldn’t be recommended for people with cardiovascular disease or blood pressure problems.
More recently preliminary evidence suggests that the same effects can be created by utilising a vibrated breathing training device (youbreathe, Exoscience, UK). 10 powerful breaths through a youbreathe device led to similar hormonal response to that described above except that cortisol was significantly reduced (which is a very good thing as cortisol is a stress hormone and too much cortisol can lead to health problems). Additionally there were increases in strength seen after youbreathe use in the small number of subjects tested.
Initially this seems to be strange as there would appear to be no link between the breathing muscles and the other skeletal muscles, but Turner and colleagues demonstrated that stimulating the breathing muscles with a breathing resistance can alter the recruitment of leg and arm muscles. The mechanism of this action appears to be communication between the breathing nerves and the skeletal nerves in the spinal cord.
If we think more deeply about breathing, we realise it is fundamental to everything else we do, so it is vitally important that breathing is connected at every level of control to all other actions. Maybe we are only at the start of using the breath to increase our performance in everything else we do.