Transient Reduction of FMD-Response and L-Arginine Accompanied by Increased Levels of E-Selectin, VCAM, and ICAM after Prolonged Strenuous Exercise.

Christoffer Nyborg,Martin Bonnevie-Svendsen,Helene Støle Melsom,Jonny Hisdal,Ingebjørg Seljeflot,Jørgen Melau

doi:10.3390/sports9060086

Christoffer Nyborg, Martin Bonnevie-Svendsen + Show 4 more

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https://doi.org/10.3390/sports9060086

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Abstract

We assessed endothelial function by flow-mediated dilatation (FMD), levels of the NO-precursor L-arginine, and markers of endothelial inflammation before, at the finish line, and one week after the Norseman Xtreme triathlon. The race is an Ironman distance triathlon with a total elevation of 5200 m. Nine male participants were included. They completed the race in 14.5 (13.4–15.3) h. FMD was significantly reduced to 3.1 (2.1–5.0)% dilatation compared to 8.7 (8.2–9.3)% dilatation before the race (p < 0.05) and was normalized one week after the race. L-arginine showed significantly reduced levels at the finish line (p < 0.05) but was normalized one week after the race. Markers of endothelial inflammation E-Selectin, VCAM-1, and ICAM-1 all showed a pattern with increased values at the finish line compared to before the race (all p < 0.05), with normalization one week after the race. In conclusion, we found acutely reduced FMD with reduced L-arginine levels and increased E-Selectin, VCAM-1, and ICAM-1 immediately after the Norseman Xtreme triathlon. Our findings indicate a transient reduced endothelial function, measured by the FMD-response, after prolonged strenuous exercise that could be explained by reduced NO-precursor L-arginine levels and increased endothelial inflammation.

Highlights

There are few studies of how prolonged exercise affects the flow-mediated dilatation (FMD)-response [6,16,17] and as far as we are aware there are no studies of FMD after any Ironman distance triathlon
Nine male participants of the Norseman Xtreme Triathlon were included in this study
We found increased levels of the endothelial adhesion molecules E-selectin, ICAM-1, and VCAM-1 after the Ironman distance triathlon, along with reduced FMD

Summary

Introduction

Flow-mediated dilatation (FMD) refers to the non-invasive assessment of endothelial function by studying the brachial artery’s dilatation in response to increased blood flow [1]. The dilatation is endothelial-dependent [2] as increased shear forces from the blood activate mechanoreceptors in the endothelium [3], causing a predominantly NO-mediated relaxation of the arterial smooth muscles [4]. A biphasic response has been proposed with an initial reduction in FMD after exercise with normalization within 24–48 h [17]. There are few studies of how prolonged exercise affects the FMD-response [6,16,17] and as far as we are aware there are no studies of FMD after any Ironman distance triathlon

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