On site assessment of cardiac function and neural regulation in amateur half marathon runners

Abstract

Objective: Strenuous exercise variably modifies cardiovascular function. Only few data are available on intermediate levels of effort. We therefore planned a study in order to address the hypothesis that a half marathon distance would result in transient changes of cardiac mechanics, neural regulation and biochemical profile suggestive of a complex, integrated adaptation.

Methods: We enrolled 35 amateur athletes (42±7 years). Supine and standing heart rate variability and a complete echocardiographic evaluation were assessed on site after the completion of a half marathon (postrace) and about 1 month after (baseline). Biochemical tests were also measured postrace.

Results: Compared to baseline, the postrace left ventricular end-diastolic volume was smaller, peak velocity of E wave was lower, peak velocity of A wave higher, and accordingly the E/A ratio lower. The postrace heart and respiratory rate were higher and variance of RR interval lower, together with a clear shift towards a sympathetic predominance in supine position and a preserved response to orthostasis. At baseline, athletes were characterised by a lower, although still predominant, sympathetic drive with a preserved physiological response to standing.

Conclusions: Immediately after a half marathon there are clear marks that an elevated sympathetic cardiac drive outlasts the performance, together with decreased left ventricular diastolic volumes and slight modifications of the left ventricular filling pattern without additional signs of diastolic dysfunction or indices of transient left or right ventricular systolic abnormalities. Furthermore, no biochemical indices of any permanent cardiac damage were found.

Figure 1

An exemplar scan from tissue-Doppler assessment of regional wall strain in the apical four-chamber view measured at the basal and at the mid-wall level of the septum and lateral wall obtained in an amateur athlete immediately after the completion of the half marathon (postrace, left panel) and 1 month after (baseline, right panel).

Figure 2

Examples of power spectrum analyses of RR and RESP in an amateur athlete (same participant as in figure 1) few minutes after the completion of the half marathon (postrace, left panels) and 1 month after (baseline, right panels) at rest (top panels) and during standing (bottom panels). Baseline autonomic profile is characterised by sympathetic predominance at rest both postrace (left top panel) and at baseline (right top panel). In both conditions the physiological excitatory response to orthostasis is preserved (bottom panels). a.u., arbitrary units; PSD, power spectrum density; RESP, respiratory activity; RR, R–R interval.