This study systematically reviewed and quantified the effects of running a long-distance 23 race (LDR) on heart rate variability (HRV) and arterial stiffness (AS). All types of races 24 of a distance equal to or greater than a marathon (≥42.2 km) were included. A total of 25 2,220 articles were identified, 52 were included in the qualitative analysis, and 48 were 26 meta-analysed. The standardised mean difference pre-post-race of various time-domain 27 and frequency-domain indices of HRV, mean arterial blood pressure (MAP), systolic 28 blood pressure (SBP), diastolic blood pressure (DBP), and carotid-femoral pulse wave 29 velocity (cfPWV) was calculated. Regarding HRV, there was a significant decrease in 30 most of the variables considered as markers of parasympathetic activity, indicating a shift 31 of autonomic balance toward a reduced vagal tone. Regarding vascular variables, there 32 was a significant drop in blood pressure and reduced AS. In conclusion, running an LDR 33 seems to have a considerable acute effect on the autonomic nervous system, 34 haemodynamics, and vascular properties. The observed effects could be categorised 35 within the expected acute responses to long-lasting, strenuous exercise.