Exercise Training during Normobaric Hypoxic Confinement Does Not Alter Hormonal Appetite Regulation

Abstract

BackgroundBoth exposure to hypoxia and exercise training have the potential to modulate appetite and induce beneficial metabolic adaptations. The purpose of this study was to determine whether daily moderate exercise training performed during a 10-day exposure to normobaric hypoxia alters hormonal appetite regulation and augments metabolic health.MethodsFourteen healthy, male participants underwent a 10-day hypoxic confinement at ∼4000 m simulated altitude (FIO2 = 0.139±0.003%) either combined with daily moderate intensity exercise (Exercise group; N = 8, Age = 25.8±2.4 yrs, BMI = 22.9±1.2 kg·m−2) or without any exercise (Sedentary group; N = 6 Age = 24.8±3.1 yrs, BMI = 22.3±2.5 kg·m−2). A meal tolerance test was performed before (Pre) and after the confinement (Post) to quantify fasting and postprandial concentrations of selected appetite-related hormones and metabolic risk markers. 13C-Glucose was dissolved in the test meal and 13CO2 determined in breath samples. Perceived appetite ratings were obtained throughout the meal tolerance tests.ResultsWhile body mass decreased in both groups (−1.4 kg; p = 0.01) following the confinement, whole body fat mass was only reduced in the Exercise group (−1.5 kg; p = 0.01). At Post, postprandial serum insulin was reduced in the Sedentary group (−49%; p = 0.01) and postprandial plasma glucose in the Exercise group (−19%; p = 0.03). Fasting serum total cholesterol levels were reduced (−12%; p = 0.01) at Post in the Exercise group only, secondary to low-density lipoprotein cholesterol reduction (−16%; p = 0.01). No differences between groups or testing periods were noted in fasting and/or postprandial concentrations of total ghrelin, peptide YY, and glucagon-like peptide-1, leptin, adiponectin, expired 13CO2 as well as perceived appetite ratings (p>0.05).ConclusionThese findings suggest that performing daily moderate intensity exercise training during continuous hypoxic exposure does not alter hormonal appetite regulation but can improve the lipid profile in healthy young males.

Appetite and gut hormone responses to moderate-intensity continuous exercise versus high-intensity interval exercise, in normoxic and hypoxic conditions

“…The role of appetite-regulating hormones in high-altitude anorexia is unclear. The acute and chronic effect of hypoxia on leptin, a hormone released from white adipose tissue that reduces food intake and modulates adiposity, is controversial (Debevec, Simpson, Macdonald, Eiken, & Mekjavic, 2014;Kelly et al, 2010;Snyder, Carr, Deacon, & Johnson, 2008). Acute suppression of appetite and acylated ghrelin (the post-translationally modified form of this gut peptide essential for its appetite-stimulatory effects) was observed during 7 h exposure to normobaric hypoxia, whilst PYY tended to be higher than in normoxic conditions (Wasse, Sunderland, King, Batterham, & Stensel, 2012).…”

Hypoxic Living and Exercise Training Alter Adipose Tissue Leptin/Leptin Receptor in Rats

“…This may suggest a potential stabilization of the effects after 3 months (Gatterer et al, 2015). The majority of studies have showed a decrease in plasma leptin levels with (Bailey et al, 2004) and without (Woolcott et al, 2002) significant weight reduction at high altitude, whereas other studies reported unchanged plasma leptin levels with (Debevec et al, 2014) and without (Barnholt et al, 2006) a change in body weight or adiposity. In animal studies, hypoxia exposure lowered body weight and also increased leptin expression in adipose tissue (Simler et al, 2006).…”

“…Interestingly, daily moderate exercise training during 10-day continuous hypoxic exposure improved lipid profile, but did not alter hormonal appetite regulation, including fasting levels of leptin, in healthy young men (Debevec et al, 2014). However, fasting leptin levels were reduced following daily moderate exercise training during 16-day continuous hypoxic exposure with no changes observed following bed rest in normoxia and bad rest in hypoxia (Debevec et al, 2016).…”

Response of Appetite and Appetite Regulating Hormones to Acute Hypoxia

“…A Composite Satiety Score (CSS) was also used to assess appetite. The CSS was calculated as follows: CSS 5 (fullness + (100 2 desire) + (100 2 hunger) + (100 2 perceived food consumption (PFC)))/4 (Debevec et al, 2014).…”

“…During short-term exposures to hypoxia, ghrelin and acylated ghrelin levels appear to decrease after 48 hours of free-living conditions (Shukla et al, 2005) and after 7 hours of controlled environmental chamber conditions (Shukla et al, 2005;Wasse, Sunderland, King, Batterham, & Stensel, 2012). During extended exposures to altitude, leptin concentrations may decrease, increase, or remain unchanged during acute and chronic exposures to altitude (Barnholt et al, 2006;Debevec, Simpson, Macdonald, Eiken, & Mekjavic, 2014;Shukla et al, 2005;Tschop et al, 2000;Zaccaria et al, 2004). Few studies have investigated adiponectin's acute response to altitude; however, there appears to be no change in adiponectin levels after chronic exposure to free-living altitude (4300 m) conditions (Barnholt et al, 2006).…”