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A few years ago, a friend invited me to a hot yoga studio. They were running a special: $20 for a 10 class intro package. I said, "sure," and plopped my happy little naive booty into a studio heated to 105 degrees Fahrenheit, 40% humidity. I had done yoga before, but never consistently and never in a hot room. I loved it and hated it. I struggled and sweat. I vowed to never go back, then promptly used all 10 classes and bought more. All winter, I went to hot yoga twice a week, gradually getting better at each pose and not really thinking about whether or not it was good for me. Because I'm an avid runner, the yoga helped keep my muscles loose and limber, or so I thought. That spring, I rain a trail marathon in Big Bear, CA, which sits around 7,000 feet. I was apprehensive about the elevation because it had always bothered me in the past but for some reason, this time around, I felt almost nothing. No familiar chest constriction. No gasping for air, even when running up steep inclines. I was pleasantly surprised, but also confused. The only thing I had changed in my training was the hot yoga, and it seemed to really help.
Everyone knows that a lot of serious (and not so serious) athletes train at altitude (usually 7,000-8,000 feet above sea level) to improve oxygen efficiency. Less oxygen availability means a higher energy expenditure, and the body generates more red blood cells to carry more oxygen to muscles. When athletes return to sea level they experience a boost in performance due to higher oxygen availability and efficiency.
The underlying premise of altitude training is that increased blood volume and more oxygen available to the muscles enhances performance. It's an age-old trick that has been shown to improve elite performance by about two percent. Since most people can't just pick up and train or live at altitude, heat is a viable and more accessible way to increase performance.
While altitude training encourages the body to generate a higher number of red blood cells, heat training increases red blood plasma volume, offering more blood to carry oxygen to the muscles. Increased blood volume doesn’t automatically guarantee increased red blood cells (and more oxygen), however, some studies have found a relevant connection between heat training and performance, finding an improved performance in time trials and VO2 Max amidst cyclists who were subjected to hotter conditions as compared to the control group.
Researchers have been looking at the effects of heat on athletic performance for decades, and their results have been consistently surprising. Studies have found that, in addition to an increased rate of perspiration, training in the heat can increase an athlete’s blood plasma volume (which leads to better cardiovascular fitness), reduce overall core temperature, reduce blood lactate, increase skeletal muscle force, and, counterintuitively, make a person train better in cold temperatures. Santiago Lorenzo, a professor of physiology at Lake Erie College of Osteopathic Medicine and a former decathlete at the University of Oregon states that, “Heat acclimation provides more substantial environmental specific improvements in aerobic performance than altitude acclimation,” he says. And in contrast to the live low, train high philosophy, we more quickly adapt to heat stress than we do to hypoxia. In other words, heat training not only does a better job at increasing V02 max than altitude, but it also takes less time to adjust to.
To reap the benefits of heat training:
1. Workout in the heat of the day instead of avoiding it. Many of us wake up early or run in the evening to beat the heat, which isn't always feasible. Reap the benefits of heat training by working out in the afternoon, just be sure to hydrate after.
2. Head to a dry sauna immediately before or after your run for 20-25 minutes, and avoid drinking water during this time. This won't deplete you in the same way that working out in the heat does, and the benefits are similar. You'll notice that you'll be able to build a tolerance to the heat over time and can increase the length of your sauna sessions.
3. Do what I did and adopt a hot yoga practice. Be sure to find a true hot yoga class, not a "heated," or "warm" class to reap maximum benefits. Hot yoga is great because you'll benefit from heat training while minimizing the impact on training, both physically and logistically.
4. If you do choose to heat train, keep your effort on the lower end of the spectrum because heat adds a layer of stress. Be sure to hydrate with electrolytes after, and don't heat train every day. Studies show benefits from 1-3 days of heat training a week.