Abstract
Digitized M mode echocardiography was used to evaluate the effect of a competitive
24-h run on the left ventricular diastolic function in 12 well-trained marathon runners
who completed 146-227 km during the race. Mitral valve opening was delayed, early
diastolic filling was decreased and prolonged, and posterior wall thinning was reduced,
particularly among those athletes completing close to 200 km or more. Since the alterations
were in part the opposite in those running 160 km or less, only the reductions in
the peak rate of dimension increase (P < 0.05) and posterior wall thinning (P < 0.01) were significant in the group as a whole. The delay in mitral valve opening
(r = 0.76), the decrease in the peak rate of dimension increase (r = -0.68), and the prolongation of the early diastolic filling period (r = 0.60) were correlated with the distance completed. The reductions in left ventricular
end-diastolic dimension and fractional shortening were not in proportion to the distance
run, however (r = 0.23 and 0.46, respectively). Measurements made on six athletes 2-3 days after
the race showed reversal of the indices of left ventricular diastolic function.
Extremely exhaustive prolonged exercise thus appears to result in a marked reversible
impairment in left ventricular relaxation and filling. Since the effect of these abnormalities
in cardiac filling during exercise is probably more important due to the shorter diastole,
the prevention of hypohydration, which could otherwise further compromise left ventricular
filling, becomes crucial.
Key words
echocardiography - exercise - cardiac performance
