A good deal has been said in Theosophical literature about the danger of pursuing Yoga practice, such as regulating the breathing, assuming certain postures of the body, etc., and several persons, not satisfied with simple declarations by such writers as H. P. B. that these practices are prejudicial, have frequently asked for reasons. Many of the reasons given in the PATH and elsewhere have been merely further declarations. I have instituted some experiments for the purpose of showing what is the effect, if any, upon the physical system of a certain sort of breathing used in Hatha Yoga practices, and desire to record one for the benefit of inquirers.
The persons present were myself, a well-known physician whose name I can give, and the practitioner. The physician first took the person’s pulse for three minutes and found it to be running at 96 beats per minute, and then the experiment began with the practice with the following result:

First minute. Pulse fell to 91 beats.
Second minute. Pulse fell to 81 beats.
Third minute. Pulse remained at 81 beats.

A delay of five minutes then occurred, when the practice was begun again for six minutes, with the following result:

First minute. Pulse running at 91 beats a minute.
Second minute. Pulse fell to 86 beats.
Third minute. Pulse remained at 86.
Fourth minute. Pulse fell to 76.
Fifth minute. Remained at 76.
Sixth minute. Remained at 76.

This shows a reduction in the pulse action of 20 beats in 14 minutes. It also shows that after the first three minutes the intermission of five minutes was not enough to enable the pulse to go back to 96 beats, at which it started. The first three minutes showed a fall of five beats in the first minute and ten in the next minute, making fifteen beats reduction for the three minutes.

It therefore appears that one of the accompaniments of this practice is a distinct effect upon the action of the heart, and as all the Hindu books invariably state that great caution should be used and that there are dangers, we can see here a very great danger found in an effect upon the heart’s action, resulting in a reduction of pulse beats of twenty beats in fourteen minutes. The Hindu books to which I have referred, and which are the only works through which inquirers have heard about these practices, also say that a guide who is fully acquainted with the subject is necessary for each student, and that everyone of these practices requires an antidote for its effects through other regulations tending to neutralize the bad physical effects. Students have been too anxious to try these experiments without paying any attention to the cautions given out, and I know of some cases in which, while well remembering that the cautions had been uttered, persons have pursued these practices by themselves without assistance. I hope that the above record will not only justify the cautionary remarks which have been so often made by sincere Theosophical writers, but will also serve to warn off Theosophical students from this dangerous ground.