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

      Bailey, Daniel Paul; Smith, Lindsey Rachel; Chrismas, Bryna C.; Taylor, Lee; Stensel, David J.; Deighton, Kevin; Douglas, Jessica A.; Kerr, Catherine J.; University of Bedfordshire; Oxford Brookes University; et al. (Elsevier, 2015-06)
      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 (View the MathML sourceV˙O2max) and during HIIE performed 6 × 3 min running at 90% View the MathML sourceV˙O2max interspersed with 6 × 3 min active recovery at 50% View the MathML sourceV˙O2max with a 7 min warm-up and cool-down at 70% View the MathML sourceV˙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.
    • Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults

      Bailey, Daniel Paul; Broom, David R.; Chrismas, Bryna C.; Taylor, Lee; Flynn, Edward; Hough, John (NRC Research Press, 2015-12-14)
      Background: Breaking up periods of prolonged sitting can negate harmful metabolic effects but the influence on appetite and gut hormones is not understood and is investigated in this study. Methods: Thirteen sedentary (7 female) participants undertook three, 5 h trials in random order: 1) uninterrupted sitting (SIT), 2) seated with 2 min bouts of light-intensity walking every 20 min (SIT+LA), and 3) seated with 2 min bouts of moderate-intensity walking every 20 min (SIT+MA). A standardised test drink was provided at the start and an ad libitum pasta test meal provided at the end of each trial. Subjective appetite ratings and plasma acylated ghrelin, peptide YY, insulin, and glucose were measured at regular intervals. Area under the curve (AUC) was calculated for each variable. Results: AUC values for appetite and gut hormone concentrations were unaffected in the activity breaks conditions compared to uninterrupted sitting (linear mixed modelling: p>0.05). Glucose AUC was lower in SIT+MA than SIT+LA (p=0.004) and SIT (p=0.055). There was no difference in absolute ad libitum energy intake between conditions (p>0.05), however, relative energy intake was lower in SIT+LA (39%; p=0.011) and SIT+MA (120%; p<0.001) than SIT. Conclusion: Breaking up prolonged sitting does not alter appetite and gut hormone responses to a meal over a 5 h period. Increased energy expenditure from activity breaks could promote an energy deficit that is not compensated for in a subsequent meal.