Hemodynamic Responses during Enduro-Motorcycling Performance

Abstract

Much of the information available in the literature on physiological responses during Enduro motorcycling is related to heart rate (HR) and blood lactate (BLa). The aim of this work was to investigate the hemodynamic changes that occur during a 10-min session of Enduro motorcycling. Fifteen skilled riders were enrolled on the study and all participants underwent an Enduro-motorcycling session on a standard track. Hemodynamics were assessed using a miniaturized impedance cardiograph. Results show that HR significantly increased from 96.5 ± 12.8 bpm at rest to 153.1 ± 17.7 bpm during riding, while stroke volume (SV) increased from 53.5 ± 14.1 to 72.2 ± 22.1 ml and cardiac output (CO) from 5.0 ± 1.1 to 10.9 ± 3.0 L·min^-1. Moreover, ventricular emptying rate (VER) increased from 192.9 ± 43.0 to 324.1 ± 83.6 ml·s¹ and ventricular filling rate (VFR) from 141.1 ± 160.5 to 849 ± 309 ml·s^-1. Taken together, these data suggest that Enduro motorcycling induces substantial cardiovascular activation, not only in terms of chronotropism but also in terms of cardiac performance and pre-load, thereby increasing SV and CO. Finally, it is likely that sympathetic-mediated venous constriction occurred. This in turn improved VFR and recruited the Frank-Starling mechanism and inotropic reserve. It was concluded that Enduro motorcycling is a challenging activity for the cardiovascular apparatus.

Keywords: blood lactate; blood pressure; exercise pressor reflex; heart rate; stroke volume.

Figure 1

An example of a subject wearing the New Core device. (a) Shows the application of pairs of neck and thoracic electrodes. (b,c) Show the subject after wearing all the Enduro equipment. (d) Is an aerial picture of the Enduro track. (e) Shows the subjects while riding. Finally, (f) Is an example of analog electrocardiogram traces (ECG), thoracic impedance (Z0), and its first derivative (dZ/dt) recorded during the riding session. (g) Is a schematic representation of electrodes placement.

Figure 2

An example of heart rate (HR), stroke volume (SV), and cardiac output time course throughout an Enduro session in one subject.

Figure 3

Group heart rate values (HR, A), stroke volume (SV, B), and cardiac output (CO, C) during the various periods of the Enduro session. Variables at rest were considered those of the last minute of rest preceding the motorcycle session, variables during riding were the average of the 10 min Enduro session, while variables at recovery were considered those of the third minute of recovery. Values are mean ± SD (n = 15). ^*p < 0.05 vs. pre-exercise; ^†p < 0.05 vs. recovery.

Figure 4

Group ventricular emptying rate (VER, A), ventricular filling rate (VFR, B), pre-ejection period (PEP, C), ventricular ejection time (VET, D), and diastolic time (DT, E) during the various periods of the Enduro session. Values are mean ± SD (n = 15). ^*p < 0.05 vs. pre-exercise; ^†p < 0.05 vs. recovery.

Figure 5

Group mean arterial pressure (MAP, A), systemic vascular resistance (SVR, B), and blood lactate (BLa, C) during the pre-exercise and recovery from the Enduro session. Values are mean ± SD (n = 15). ^*p < 0.05 vs. pre-exercise.