Effect of training on treadmill performance, aerobic capacity, and body responses to acute cold exposure

Abstract

An attempt was made to test the hypothesis that regular physical activity at the anaerobic thresh old can stimulate an increase in the amount of brown or beige body fat, which can manifest itself in increased lactate utilization during exercise and increased reactivity in response to acute regional cooling. The methods used in the study included the ramp test; regional acute cold exposure; measurement of gas exchange; lactate and glucose in the blood; heart rate; heart rate, blood pressure, and respiration variability at rest and during standard functional tests; infrared thermal imaging; and statistical methods of analysis of results. Training of ten physically active volunteers (7 males and 3 females) on a treadmill at a speed corresponding to 75-80% of personal maximum oxygen consumption ( ) for 30 min 3 times per week at a fixed ambient temper ature of 21-22°C for 6 weeks resulted in a significant (from 19 to 39%) increase in exercise duration in the ramp test, whereas changed, on average, only slightly. The increase in the anaerobic threshold power was associated with a sharp slowdown in the accumulation of lactate during the ramp test. The lactate utili zation rate during the recovery period, on the contrary, increased. In general, work efficiency during test load significantly increased. Noticeable changes in the condition and responses to the standard functional tests of the autonomic system were not found, as judged by the heart rate variability, blood pressure, and respiration variability at rest and during orthostatic tests and imposed breathing rhythm. The functional response of the body to acute cold exposure (1 min cooling of the feet in ice water) did not change after a cycle of training, both in terms of metabolism (oxygen consumption, etc.) and the skin temperature dynamics in the areas of most probable location of brown adipose tissue (BAT). These data do not confirm our previous hypothesis (2010) about the function of BAT as a universal homeostatic instrument in the body. Probably, if the forma tion of the beige adipose tissue is stimulated by physical activity and hormone irisin, produced by muscles, this tissue is involved in lactate utilization but is not involved in the thermoregulatory responses.

Infrared Thermography for Estimating Supraclavicular Skin Temperature and BAT Activity in Humans: A Systematic Review

“…The first study to use IRT to estimate SST was performed in 2011 . Ten studies were then published between 2011 and 2016 , six in 2017 , six in 2018 , and one until April 2019 .…”

“…Most, but not all, of the identified studies ( n = 18; 75%) included cooling protocols, although the duration, temperature, and the way of inducing cooling differed between studies (Figure ). Nine out of these eighteen studies used hands/feet immersion in cold water (temperature 10.8°C ± 8.7°C, duration: 6.1 ± 6.8 minutes) . Seven of these nine studies used a cold exposure of < 5 minutes.…”

“…The first study to use IRT to estimate SST was performed in 2011 (24). Ten studies were then published between 2011 and 2016 (25)(26)(27)(28)(29)(30)(31)(32)(33)(34), six in 2017 (35)(36)(37)(38)(39)(40), six in 2018 (16,(41)(42)(43)(44), and one until April 2019 (45).…”

“…Some 56% of these individuals were from four studies (n = 164, n = 102, n = 88, n = 86) (24,31,43,44) (Table 1). Twelve of the selected twenty-four studies included both sexes (24,26,28,29,31,32,37,(41)(42)(43)45,46), three involved only females (27,33,44), and nine involved only males (16,25,30,(34)(35)(36)(38)(39)(40). One study took into account the phases of the menstrual cycle (32).…”

“…A total of 25 cohorts were represented across the 24 studies, 21 composed of adults, 2 of adolescents (25,27), and 2 of children (25,43). Three of the studies did not report BMI (24,29,38).…”