The Hot Yoga Balancing Act: Heat and Humidity

Yes, it's hot in the hot yoga room - so it's cool to read how your hot little body cools down to keep you safe and strong in your 90 minute hot box called hot yoga class.

Cool to the Core

Your body maintains its core temperature at 98.6º F (37º C) by balancing the rate of internal heat production with heat loss to the environment. This little balancing act is called thermoregulation.

Thermoregulation is challenging in any heated environment, especially if the air temperature is greater than the skin temperature. During moderate exercise, core body temperature rises and the additional heat must be moved from the core to the skin.

Heat is removed from the body to the environment in four ways: radiation, conduction, convection, and evaporation. The first three occur in environments where air temperature is cooler than skin temperature or where cooler air blows over the skin. The hot yoga room is typically heated to 105º F which exceeds skin temperature, and possibly above core temperature when you're practicing.

Sweat Your Heat 

Evaporation is the body’s primary protection against overheating. Through this process, the body transfers heat from your core by evaporating sweat from the skin and respiratory passages. Sweat alone does not cool the body. To produce a cooling effect, the sweat must be evaporated to lower the skin temperature. By blowing cooler air over the skin - note the fan in our hot yoga room -  sweat vaporizes and heat is released. We may even open our doors a bit to the cooler exterior rooms. 

No Wiping, No Griping

In hot yoga, humidity is ideally 40-45%.  Depending on the heat source, the room ventilation, and the number of students, humidity may fluctuate in the room.  Do NOT wipe sweat from the body with your  towel.  If the sweat is removed from the skin, evaporation will not occur, and heat will be retained. Sweating will subsequently increase, leading to a greater loss of water and increased risk of dehydration.

Go With the Hydration Flow

As the sweat rate increases and body water loss increases, the need for replacement fluids increases. Without adequate fluid replacement, the body’s ability to dissipate heat can be compromised.

Hydrate very well BEFORE you come to hot yoga! If you're properly hydrated, the effectiveness of fluid replacement while practicing hot yoga is increased.

If dehydration occurs, the body’s ability to lose heat is compromised. As little as a 2% loss of body mass from fluid loss will impair your practice. This means a 150-pound person who loses 3 pounds during a hot yoga class from increased sweating will experience increased heart rate and decreased blood volume, causing a loss of endurance.

Sidestepping Heat Illness

Heat cramps are a somewhat mild form of heat illness, defined as muscle spasms that occur during or after intense physical activity. Imbalanced body fluids and/or electrolytes are the believed cause of heat cramps. In most cases, the cramps occur in the abdomen and extremities.

Heat exhaustion can occur when blood plasma volume is reduced and the heart is unable to maintain cardiac output. The symptoms of heat exhaustion include a weak, rapid pulse, dizziness, headache, general weakness, and low blood pressure when upright. Body temperature is not severely elevated and sweating may be moderately reduced.

If at any time you need to treat heat exhaustion, move to a cooler area and rehydrate by taking fluids. A 0.1% NaCl electrolyte solution can replace lost sodium (or try our Coconut Water). If blood sodium becomes depleted, symptoms of heat exhaustion can include vomiting and muscle cramping, combined with progressive weakness.

Heat stroke is when core body temperature increases to 103–104º F (39–40º C) and the body’s heat-dissipating efforts have failed, usually due to central nervous system impairment. At this point, sweating ceases, skin becomes hot and dry, and core temperature continues to increase. Individuals experiencing heat stroke will be disoriented and confused, their mental acuity impaired, and they may lose consciousness. Immediate medical intervention is required.

 Acclimate Yourself

Acclimatization trains the body to tolerate any particular environment. In hot yoga, acclimating to the temperature of the room will help reduce risk and improve performance. Heat acclimatization involves the body adapting to heat by stimulating the physiological changes  needed to gain heat tolerance: changes in cardiovascular function and autonomic nervous system adaptations. Ideally, the body should be exposed to heat stress gradually, over a period of 10–14 days. Take it easy in hot yoga for the initial 2 weeks of your practice -  lie down and take poses off any time you feel the need. Drink water BEFORE you're thirsty. The duration and intensity of your hot yoga practice can be systematically increased.

Taking Caring Of Yourself in Hot Yoga

Follow these recommendations for hydration before, during, and after hot yoga:

1. Daily intake of 8–10 glasses of water (8 oz. per glass) for normal activity, not including exercise.
2. At least 2 hours prior to class, drink 16 oz. of water or fluid without caffeine.
3. If possible, determine body weight while hydrated, prior to class.
4. During class, sip water before you are actually thirsty. Your goal is to replenish fluids at the same rate you are sweating. 
5. After hot yoga, evaluate change in body weight. Consume fluids to return to body weight prior to exercise.

Avoid caffeinated beverages such as coffee, many teas, and sodas as these  will increase fluid loss by increasing urinary output. Wine, beer, and other alcoholic beverages cause fluid loss as well.