Elsevier

Appetite

Volume 89, 1 June 2015, Pages 237-245
Appetite

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

https://doi.org/10.1016/j.appet.2015.02.019Get rights and content

Highlights

  • Effects of exercise modalities and hypoxia on appetite are explored.

  • Short exposure to hypoxia causes appetite suppressions.

  • Appetite responses to exercise are not dependant on exercise modality.

  • Suppressed appetite may be explained by decreased circulating acylated ghrelin.

Abstract

This study investigated the effects of continuous moderate-intensity exercise (MIE) and high-intensity interval exercise (HIIE) in combination with short exposure to hypoxia on appetite and plasma concentrations of acylated ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Twelve healthy males completed four, 2.6 h trials in a random order: (1) MIE-normoxia, (2) MIE-hypoxia, (3) HIIE-normoxia, and (4) HIIE-hypoxia. Exercise took place in an environmental chamber. During MIE, participants ran for 50 min at 70% of altitude-specific maximal oxygen uptake (V˙O2max) and during HIIE performed 6 × 3 min running at 90% V˙O2max interspersed with 6 × 3 min active recovery at 50% V˙O2max with a 7 min warm-up and cool-down at 70% V˙O2max (50 min total). In hypoxic trials, exercise was performed at a simulated altitude of 2980 m (14.5% O2). Exercise was completed after a standardised breakfast. A second meal standardised to 30% of participants' daily energy requirements was provided 45 min after exercise. Appetite was suppressed more in hypoxia than normoxia during exercise, post-exercise, and for the full 2.6 h trial period (linear mixed modelling, p <0.05). Plasma acylated ghrelin concentrations were lower in hypoxia than normoxia post-exercise and for the full 2.6 h trial period (p <0.05). PYY concentrations were higher in HIIE than MIE under hypoxic conditions during exercise (p = 0.042). No differences in GLP-1 were observed between conditions (p > 0.05). These findings demonstrate that short exposure to hypoxia causes suppressions in appetite and plasma acylated ghrelin concentrations. Furthermore, appetite responses to exercise do not appear to be influenced by exercise modality.

Introduction

The current obesity epidemic is a major concern since excess weight is associated with morbidity and premature mortality (Bigaard et al, 2004, Canoy et al, 2007). Exercise can play an important role in weight management as it may improve the comorbidities of obesity (Ross et al., 2000) and contribute to a negative energy balance by increasing energy expenditure (Catenacci & Wyatt, 2007). Individuals do not tend to compensate for the energy expended during exercise in the immediate hours after by altering food intake and such energy deficits could be important for weight management if repeated over long periods of time (Schubert, Sabapathy, Leveritt, & Desbrow, 2014). Increasing exercise intensity may increase energy expenditure and evidence suggests high-intensity exercise produces greater short term reductions in appetite compared to moderate-intensity exercise (Deighton et al, 2013, King et al, 1994).

One form of exercise training that is receiving more attention in health-enhancing research is high-intensity interval exercise (HIIE), which may reduce cardiometabolic disease risk (Kessler, Sisson, & Short, 2012) and promote similar or even superior physiological adaptations compared to traditional endurance-based training (Gibala, Little, Macdonald, & Hawley, 2012). All-out sprint interval exercise may acutely suppress appetite more than continuous moderate-intensity exercise (MIE) (Deighton et al., 2013), but this form of supramaximal exercise may not be safe, tolerable, or practical for many individuals (Deighton et al, 2013, Gibala et al, 2012). Submaximal HIIE may thus be preferred and recent evidence suggests this form of interval exercise may also acutely suppress appetite and increase the satiating gut hormone, peptide YY (PYY), more than an energy-matched continuous bout of MIE (Deighton, Karra, Batterham, & Stensel, 2013). Bartlett et al. (2011). observed higher levels of enjoyment during a high-volume HIIE protocol that involved 3 min intervals at 90% of maximum oxygen uptake (V˙O2max) compared to a continuous MIE session matched for average intensity (70% V˙O2max). It would be of interest to explore whether this interval exercise protocol suppresses appetite and affects gut hormone concentrations more than continuous MIE.

A loss of appetite, termed “high altitude anorexia”, is often apparent when individuals are exposed to high altitude (>2500 m) (Kayser & Verges, 2013). Reduced energy intake and weight loss are observed in both normobaric and hypobaric hypoxia and studies using hypobaric chambers suggest it is hypoxia, per se, that causes this altitude-related loss of appetite (Westerterp-Plantenga et al., 1999). 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 et al, 2014, Kelly et al, 2010, Snyder et al, 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). The response of the satiating gut hormone, glucagon-like peptide-1 (GLP-1), to hypoxia has only been investigated in one previous study that showed a trend towards increased concentrations following overnight hypoxic exposure (Snyder et al., 2008). The effect of short exposure to hypoxia (i.e. ≤1 h) on appetite and appetite-related hormones has not been studied, nor has the effect of different exercise modalities performed in hypoxia.

This study therefore investigated the effects of continuous MIE versus HIIE in combination with short exposure to hypoxia on appetite and plasma concentrations of acylated ghrelin, PYY, and GLP-1.

Section snippets

Participants

Following approval from the University of Bedfordshire Ethics Review Board, 12 physically active (≥150 min/wk of moderate-to-vigorous physical activity) and apparently healthy normal-weight men (mean ± SD; age, 21.6 ± 2.0 years; body mass index, 23.5 ± 2.0 kg/m-2) gave written informed consent to participate in the study following a verbal and written explanation of the nature and risks involved. Participants were non-smokers, normotensive, not taking any medications, and had no known history

Appetite perceptions

There were no significant differences in any fasting appetite perception between trials (p > 0.05). Table 1 shows AUC values for each appetite perception for the combined hypoxia and normoxia trials, and for the combined HIIE and MIE trials. Compared with normoxia, hunger AUC was significantly lower during exercise (0 to 0.8 h; p <0.001), post-exercise (0.8 to 2.6 h; p = 0.003), and for the total 2.6 h trial period (0 to 2.6 h; p <0.001) in hypoxia. Satisfaction AUC was significantly higher

Discussion

This study investigated the effects of HIIE versus continuous MIE exercise combined with short exposure to hypoxia on appetite and gut hormone concentrations. Our novel data suggest that appetite perceptions and plasma acylated ghrelin may be suppressed in response to as little as 50 min normobaric hypoxic exposure whilst performing exercise. Acute suppressions in the active form of ghrelin were observed previously during 7 h exposure to a simulated altitude of 4000 m (Wasse et al., 2012) and

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    Funding: University of Bedfordshire Research Investment Programme. This research was supported by the National Institute for Health Research (NIHR) Diet, Lifestyle & Physical Activity Biomedical Research Unit based at University Hospitals of Leicester and Loughborough University. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. The funding body had no involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. Conflict of interest: None.

    1

    Present address: Department of Life Sciences, College of Life and Natural Science, University of Derby, Kedleston Road, Derby, DE22 1 GB.

    2

    Present address: School of Sport, Leeds Beckett University, Headingley Campus, Leeds, LS6 3QS, UK.

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