How does Bikram Yoga affect heart rate and core temperature?
To be completely honest neither Catherine nor I are fans of Bikram yoga or hot yoga in general. Nonetheless, we did our best to discuss Bikram yoga and this study as objectively as possible. In this episode we reviewed an ACE (American Council on Exercise) study, which examines the effect of Bikram yoga on core temperature, heart rate and rate of perceived exertion of 20 Bikram practitioners.
About Bikram Yoga
Bikram yoga consists of 26 poses, two breathing exercises and is practiced in a 105 degree heated room with 40% humidity for 90 minutes. “For many Bikram enthusiasts, having the mental strength and focus to overcome this type of challenge is a big part of the draw.”
Data from the ACE study:
- The average highest core temp was 103.2 for men and 102 for women.
- One male had a core temp of 104 by the end of the 90 minute class.
- The average heart rate was 80% max for men and 72% max for women.
- The highest recorded was 92% for men and 85% for female.
Whether or not to hydrate is part of the Bikram yoga controversy, as there may only be one water break per class. In contrast, some teachers encourage students to hydrate as needed throughout the class. For some Bikram enthusiasts, minimizing water intake during class is thought to enhance the mindful aspects of the practice. The thinking is that fewer water breaks can reduce mental distractions. Most exercise scientists could not disagree more.
It’s essential that Bikram teachers have a basic understanding of thermoregulation and know the signs and symptoms of heat related illness. Teachers should be trained to respond in the event of an emergency to keep the participant’s safety a priority. Because participants experienced dangerous elevated core temperatures 60 minutes into class, shortening the class to 60 minutes or less might minimize potential for heat intolerance.
Based on these findings, researcher Emily Quandt offers three key recommendations: shorten the class, lower the room temperature and focus on hydration.
- Subjects had the option to drink water but were not instructed to do so. As a side note, those who did not drink water during the class had higher core temps.
- There was a steady increase in core temp. At 60 minutes the average of the total reached above 100 and then kept going up during the last 30 minutes.
- Heart rates were high considering this kind of low impact exercise, but their HR averages were at 92% max for the guys and 85% for women. This is high.
- What was interesting is that the people who had elevated core temps did not have symptoms of heat related illness. Perhaps this is due to acclimatization.
- Sweat is great for cooling us down if the sweat evaporates which it does not in the high humidity of a Bikram class. The evaporation of sweat is the key for cooling. Sweating is not detoxification!
- The study concludes that because of the elevated core temps, elevated heart rate, and RPE (8/10) a 90 minute Bikram yoga class poses a risk of heat related illness.
Links and Mentions:
Dr. Brian Tracy eviscerated this study. It’s important to note that he practices Bikram yoga and his studies were sponsored by the Bikram Yoga College of India. You can see his comments about this ACE study here.
This is a must see: Real Sports with Bryant Gumbel – Bikram interview
“Anti catastrophizers”: Greg Lehman
and Adam Meakins
Catherine Cowey: www.fitwizesf.com/
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