Q: I have been asked before regarding the difference/advantages/disadvantages to hot yoga; and I found your explanation very informative. Could you pass along some of the info from a factual/kinesiology standpoint to me to in turn pass along when asked?
A: I just had this conversation with someone in the gym, so here is my science-based perspective on WHY PEOPLE SHOULD BE CAUTIOUS AND INFORMED WHEN DOING HOT YOGA:
*ELASTIC EDGE – our muscles and connective have a finite elastic edge where, once you pass that edge, the tissues simply break (ie tears) … we have sensory mechanisms that help us feel when we are reaching this elastic edge to prevent injury … in hot yoga, the excessive heat can readily dampen these sensory mechanisms allowing us to pass our elastic edge and fall into acute injuries
*DETOXIFICATION – the claims that sweating detoxifies the body is an exaggeration … the liver, lymphatic system and kidneys are our dominant detoxifying mechanisms … the skin accounts for a very MINOR amount of potential detoxification … by dehydrating the body in hot yoga, we actually diminish the function of the major detoxification mechanisms leading to the next point
*DEHYDRATION – rapid dehydration (especially without correct preloading) depletes cells of intracellular water … all (I repeat, ALL) chemical reactions in the body function in a water state … dehydration via hot yoga can lead to reduced energy, constipation, adverse effects on metabolism, and other unwanted physiology effects like increased heart rate (next point)
*SYMPATHETIC NERVOUS REACTION – when we exercise (yoga), our body requires an increase in oxygen which is delivered via our heart and blood vessels … our CARDIAC OUTPUT (volume of blood x beats/min) increases to meet oxygen demands … however, by rapidly dehydrating the body (sweating), we pull water from the blood … blood volume goes down, so in order to maintain cardiac output, the heart has no choice but to increase beats/min … for me, the primary benefit of yoga is to tap into the parasympathetic nervous system as much as possible to heal, purge stress, and to restore … an increase in heart beat is brought forward by the sympathetic nervous system (our ‘fight or flight’ system) … given that people are already chronically stressed and sitting in constant states of sympathetic activity, this seems counterproductive
… staying on the sympathetic nervous reaction thought, I hear so often that people are encouraged to stay and sit through feelings of nausea – literally fighting the emergency response that the body is calling out to them … again, this is counterproductive to the healing nature we are trying to achieve in yoga … if you feel dizzy, nausea, faint, you are in a fight or flight state (near maximal levels) and could be causing damage to systems of the body
My take home message – know what you are getting yourself into – be mindful of biased claims by hot yoga studios and teachers – be bold in asking questions on those claims including ‘where is the science behind your claims’ – most of all, HOT YOGA IS NOT FOR BEGINNERS, it is an advanced form of practice and if a studio/teacher suggests it is ok for beginners, they are not looking out for the students’ best interest (ie just trying to make $) and/or are highly misinform