Purpose: This study aimed to characterize the immediate and extended effect of acute exercise on hunger, energy intake, and circulating acylated ghrelin concentrations using a large data set of homogenous experimental trials and to describe the variation in responses between individuals.
Methods: Data from 17 of our group's experimental crossover trials were aggregated yielding a total sample of 192 young, healthy males. In these studies, single bouts of moderate to high-intensity aerobic exercise (69% ± 5% V˙O2 peak; mean ± SD) were completed with detailed participant assessments occurring during and for several hours postexercise. Mean hunger ratings were determined during (n = 178) and after (n = 118) exercise from visual analog scales completed at 30-min intervals, whereas ad libitum energy intake was measured within the first hour after exercise (n = 60) and at multiple meals (n = 128) during the remainder of trials. Venous concentrations of acylated ghrelin were determined at strategic time points during (n = 118) and after (n = 89) exercise.
Results: At group level, exercise transiently suppressed hunger (P < 0.010, Cohen's d = 0.77) but did not affect energy intake. Acylated ghrelin was suppressed during exercise (P < 0.001, Cohen's d = 0.10) and remained significantly lower than control (no exercise) afterward (P < 0.024, Cohen's d = 0.61). Between participants, there were notable differences in responses; however, a large proportion of this spread lay within the boundaries of normal variation associated with biological and technical assessment error.
Conclusion: In young men, acute exercise suppresses hunger and circulating acylated ghrelin concentrations with notable diversity between individuals. Care must be taken to distinguish true interindividual variation from random differences within normal limits.
1School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UNITED KINGDOM; 2NIHR Leicester–Loughborough, Diet, Lifestyle and Physical Activity Biomedical Research Unit, Loughborough University, Loughborough, UNITED KINGDOM; 3Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UNITED KINGDOM; 4Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield, UNITED KINGDOM; 5Faculty of Medical and Human Sciences, University of Manchester, Manchester, UNITED KINGDOM; 6Department of Physical Education and Sport Science, National Institute of Education, Nanyang Technological University, SINGAPORE; 7Department of Medicine, University College London, London, UNITED KINGDOM; 8NIHR University College London Hospitals Biomedical Research Centre, London, UNITED KINGDOM; and 9College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UNITED KINGDOM
Address for correspondence: James King, B.Sc., Ph.D., Lecturer in Exercise Physiology, School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire LE11 3TU, United Kingdom; E-mail: J.A.King@lboro.ac.uk.
Submitted for publication September 2016.
Accepted for publication January 2017.
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