Beta-receptor desensitization evoked by a multistage ultralong distance exercise in the desert?

Background Few studies addressed to the evolution of cardiac function during a multistage ultra-long duration exercise (MULDE). Methods Serial echocardiographic assessment of cardiac function was performed in male healthy subjects during the 2014 Marathon des Sables before the race (T1), at the second (T2) and fifth (T3) arrival (236 km) then after 48 h recovery. Analysis were performed by 2 sonographers blind for the results of the other and the time of measure. Statistical analysis was performed using ANOVA-RM to compare the evolution of the different parameters. Results Among the 20 athletes, 18 completed the study (mean age 42.4, median 42). RR intervals and (Left ventricular End Diasto…