When we exercise and get hot we sweat to help keep us cool… and help maintain our “normal” core temperature – usually between 96 to 99 degrees Fahrenheit. Sweating burns calories! The rate of sweating is increased with both exercise and heat exposure. A study with 12 fit subjects exercising to exhaustion at 95 degrees F. (and 87% relative humidity) published in 1997 showed a 26% increase in sweating rate.(1)
The 1997 study explored acute and repeated exposure for 8–13 consecutive days to exercise in humid heat. Twelve fit subjects exercised at 150 W [45% of maximum O2 uptake (V.O2,max)] in ambient conditions of 35°C and 87% relative humidity which resulted in exhaustion after 45 min. The average core temperature of the subjects reached 39.9 ± 0.1°C, mean skin temperature (T– sk) was 37.9 ± 0.1°C and heart rate (HR) 152 ± 6 beats min–1 at this stage. No effect of the increasing core temperature was seen on cardiac output and leg blood flow (LBF) during acute heat stress.
After acclimation the subjects reached exhaustion after 52 min with a core temperature of 39.9 ± 0.1°C, T– sk 37.7 ± 0.2°C, HR 146 ± 4 beats min–1. Acclimation induced physiological adaptations, as shown by an increased resting plasma volume (3918 ± 168 to 4256 ± 270 ml), the lower exercise heart rate at exhaustion, a 26% increase in sweating rate, lower sweat sodium concentration and a 6% reduction in exercise V.O2. Neither in acute exposure nor after acclimation did the rise of core temperature to near 40°C affect metabolism and substrate utilization. The physiological adaptations were similar to those induced by dry heat acclimation. However, in humid heat the effect of acclimation on performance was small due to physical limitations for evaporative heat loss.
Heat acclimation also increases the size of the eccrine sweat glands — and larger glands produce more sweat. Additional studies have shown that thermal exposure combined with exercise results in greater increases in sweating than passive heat exposure alone. Exercising in heat can cause sweat loss of from 2 to 6 pounds (1 to 3 liters) per hour, and each vaporized liter of sweat extracts 580 calories from the body!
When we heat up—like exercising in the heated Cocoon—our body THERMOREGULATORY system automatically increases our cardiovascular and circulatory system outputs, and sweating cools our body and skin by increasing our circulation. Exercise sweating prevents overheating.
Extra blood is pumped to our skin surface at the same time increased sweating occurs. This process allows the warmer blood from our bodies’ core to be cooled by EVAPORATION. Cocoon body exercise sweating is the key! Each drop of sweat removes calories and heat from our bodies and evaporates it into the air! When we lose one liter of sweat, 580 calories of heat are removed from the body.
Note: A moderate exercise workout over one hour generally produces a sweat loss of from 0.5 liter to 1.0 liters. For an acclimated person, water loss by sweating reaches a peak of about 3.0 liters per hour during intense exercise in the heat. Pp. 651-652, Exercise Physiology (Sixth Edition) McArdle, Katch and Katch). 3 liters of perspiration represents caloric consumption of about 1740 calories!
Studies show a heat-conditioned person can easily sweat from 500 to 1000 grams of perspiration during a high heat Cocoon session (depending on the duration of the session)— resulting in a calorie “burn” of 300 to 600 calories depending on the person and the length of the session! And 300 – 500 calories is like running from 2 to 3 miles! With more Cocoon Fitness sessions, a heat-conditioned person can increase sweat output from 600 to 800 calories while Cocooning – like running 3 to 6 miles! And, we keep burning more calories for up to 24 hours after our Cocoon Fitness Sessions!
- Nielsen B, Strange S, Christensen NJ, Warberg J, Saltin B. Acute and adaptive responses in humans to exercise in a warm, humid environment. Pflugers Arch. 1997 May;434(1):49-56. PubMed PMID: 9094255.