Introduction: Intestinal fatty acid binding protein two (I-FABP2) is a small 15 KDa cytosolic protein expressed in epithelial cells of the mucosal layer of the small and large intestines [1]. When damage occurs, I-FABP2 is released, and plasma concentrations increase [2]. Notably, I-FABP2 is not expressed in any other tissues. Therefore, I-FABP2 is used to evaluate gut wall integrity and intestinal injury, contributing to gastrointestinal complications and delayed nutrient delivery [1-4]. However, in trained participants, mucosal damage increases in response to exercise > 70% V̇O2Max for durations of ~60 minutes [2, 4, 5]. Therefore, this study aimed to investigate the effect of high-intensity continuous exercise at two different durations, 30 and 60 minutes, on I-FABP2 responses in healthy male participants. Method:Fourteen healthy males (Mean ± SD; age 27 ± 6 years; height 179 ± 9 cm; body mass 79 ± 10 kg; body fat 18.5 ± 4.1 %; BMI 24.9 ± 2 kg/m2; V̇O2peak 42 ± 9 ml/kg/min). Completed two ~4-h trials in a randomised order. Diet was standardised 24-h before experimental trials. Participants arrived at the laboratory following an overnight fast before completing a 60-min continuous cycle (EX-60) or a split 30-min morning and 30-min afternoon cycle (EX-30) at the same intended intensity of ~70% V̇O2Max. Participants then received breakfast at 75-min (Semi-skimmed milk), which amounted to 30% of the estimated trial energy expenditure (ETEE), with the total volume standardised to 500ml with water. Participants then recovered for 2-h (90-210 min) followed by the second 30-min exercise bout from 210-240-min (EX-30 second bout). Heart rate (HR) was recorded every 5-min, and REP every 10-min during all exercise periods. I-FABP2 was measured at baseline (0), Pre-breakfast (75-min), and Post-second EX (270-min). Results: There were no differences in Pre-trial energy intake between EX-60 and EX-30 (2571 ± 1173 Kcal Vs 2547 ± 1311 Kcal; p = 0.779). There was no main effect for I-FABP2 AUC for EX-60 vs EX-30, respectively (p = 0.400). No main effect for trial (p =0.252) nor trial x time interaction (p =0.780) was observed. However, an effect for time (p <0.001) was identified for I-FABP2. Post-hoc tests revealed I-FABP2 increased from baseline to Post-EX (75-min) respectively EX-60 (485 ± 301 vs 1334 ± 626 pg.ml-1; p <0.001) and EX-30 (572 ± 325 vs 1454 ± 792 pg.ml-1) and baseline to post-second EX (270 min) highly significant in both trials (p <0.001). REP was significantly different across all measurements during exercise (p <0.001). There were no differences in HR averaged over 60-min EX-60 and EX-30 (156 ± 14 vs 154 ± 14 bpm; p = 0.534). Conclusion: The results of this study demonstrate that 30 min of high-intensity exercise was sufficient to cause an increased intestinal cellular injury, which caused cell membrane integrity to be compromised following strenuous exercise to the same extent as 60 min when a health population is used. Therefore, the effect of I-FABP2 may depend upon training status, and an individualised approach should be warranted.
Physiology in Focus 2024 (Northumbria University, UK) (2024) Proc Physiol Soc 59, C39
Oral Communications: High-intensity continuous exercise elevates I-FABP2 levels equally across 30 and 60-minute durations in healthy males.
Lewis R Mattin1, Victoria J McIver1, Adora MW Yau1, Gethin H Evans1,
1School of Life Sciences, University of Westminster, London, UK London United Kingdom, 2Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK Newcastle United Kingdom, 3Department of Life Sciences, Manchester Metropolitan University, Manchester, UK Manchester United Kingdom,
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Where applicable, experiments conform with Society ethical requirements.