Alterations in inspiratory and leg muscle force and recovery pattern after a marathon

We measured lung mechanics and metabolic parameters, first in a series of 15 marathon (M) and 12 half-marathon (H) runners, before and 2.5 h after the race, in order to assess the running effect on respiratory muscles. Maximal static inspiratory (Pi) and expiratory (Pe) pressures, maximal voluntary ventilation (MVV), blood lactate (LAC), arterialized blood gases (ABG), plasma glucose (GLU), and, with a visual analog scale, subjective tiredness were assessed. Pi decreased in M and H without change in Pe, MVV, or lung mechanics; it was still abnormal 2.5 h after the race and did not correlate with LAC, ABG, training parameters, running times, or subjective tiredness. A second study of six other M compared Pi, Pe, adductor pollicis longus (Ppol), and triceps surae (Ptri) forces, aiming to: 1) assess the reproducibility of the prolonged Pi decrease without Pe change, 2) prove that such a decrease corresponded to a real reduction in inspiratory muscle force and was not due to a poor collaboration of the subjects, 3) correlate Pi decrease with the force loss of a potentially tired leg muscle: the triceps surae. We observed a significant and similar decrease in Pi and Ptri, but no change in Ppol and Pe. Moreover, the high correlation between Pi and Ptri diminutions suggested a similar recovery pattern for inspiratory and leg muscles. In conclusion, the prolonged decrease in Pi after such races is compatible with inspiratory muscle fatigue, which, as well as its recovery, is similar to leg muscle tiredness.(ABSTRACT TRUNCATED AT 250 WORDS)