I. Energy Expenditure:
By preceding almost any cardiovascular or strength workout with a suitable period of hyperthermic exposure (i.e., 15 to 60 minutes), the energy expenditure of the workout can be tripled as shown in the study referenced below (1). The 1990 study explored the effect of exercise and thermal stress on energy expen-diture in obese and lean subjects. The group of obese subjects comprised 20 women with body weight 81-159 kg. A control group included 12 lean women weighing 51-58 kg. Energy expenditure was assessed by the method of indirect calorimetry with a Spirolyt II apparatus. Heart rate, systolic blood pressure and diastolic blood pressure were measured. The tested subjects were subjected to a 60 W (60 J/s) exercise on a cycle ergometer for 10 minutes. Immediately after the aerobic workout the subjects were exposed to hot air in a chamber at about 60 degrees C. for 30 min. On the following day this sequence was reversed, with exercise following heat exposure. In the obese women the energy expenditure at rest was 93.4 +/- 17.5 W, and during exposure to heat after exercise it was 124.0 +/- 21.3 W. During exercise preceded by heat exposure, the energy expenditure was 436.3 +/- 51.6 W. In lean subjects the corresponding values were lower: 77.5 +/- 6.5 W, 104.0 +/- 14.8 W, 376.8 +/- 36.1 W.
The exposure to physical exercise before thermal stress increased the energy expenditure in relation to that caused by each of these exposures separately (in the obese women the energy expenditure increased from 93.4 W. to 124 W.). The exposure to physical exercise after 30 minutes of thermal stress, however, more than tripled the energy expenditure in relation to that caused by each of these exposures separately from 93.4 W. to 436.3 W.!
(1.) Katedry i Kliniki Gastroenterologii Sl. AM w Katowicach, Effect of physical exercise and heat on energy expenditure in obesity].Polskie archiwum medycyny wewnȩtrznej (Impact Factor: 2.12). 04/1990; 83(3):120-6. Source: PubMed
II. Human Growth Hormone (HGH):
Studies have documented that hyperthermic conditioning can significantly induce the release of human growth hormone (HGH). Studies shown a doubling of HGH levels with only two 20-minute heat sessions at 176 degrees F., and that HGH levels can be increased fivefold with only two 15-minute heat-conditioning sessions. The study referenced below (2) showed that two one hour heat sessions each day at 176 degrees F. for one week increased HGH levels by sixteen times on the third day.
(2.) Ten healthy male and seven female volunteers were exposed to dry heat (in a Finnish sauna at 80 degrees C) 1 h twice a day for 7 days. Serum GH in males exhibited a 16-fold (1600%) increase! In females serum prolactin rose over four-fold (P less than 0.01). Acta Physiol Scand. 1986 Nov;128(3):467-70.Leppäluoto J, Huttunen P, Hirvonen J, Väänänen A, Tuominen M, Vuori J., Endocrine effects of repeated sauna bathing, Acta Physiol Scand. 1986 Nov;128(3):467-70.
APL (American Performance Labs) is a research group dedicated to the collection, analysis, and dissemination of published research and articles on the science of hyperthermia and the various applications, technologies and protocols for the use of hyperthermic conditioning.