4-Second Exercise Test: Reference Values for Ages 18-81 Years

Abstract

BackgroundPhysiological reflexes modulated primarily by the vagus nerve allow the heart to decelerate and accelerate rapidly after a deep inspiration followed by rapid movement of the limbs. This is the physiological and pharmacologically validated basis for the 4-s exercise test (4sET) used to assess the vagal modulation of cardiac chronotropism.ObjectiveTo present reference data for 4sET in healthy adults.MethodsAfter applying strict clinical inclusion/exclusion criteria, 1,605 healthy adults (61% men) aged between 18 and 81 years subjected to 4sET were evaluated between 1994 and 2014. Using 4sET, the cardiac vagal index (CVI) was obtained by calculating the ratio between the duration of two RR intervals in the electrocardiogram: 1) after a 4-s rapid and deep breath and immediately before pedaling and 2) at the end of a rapid and resistance-free 4-s pedaling exercise.ResultsCVI varied inversely with age (r = -0.33, p < 0.01), and the intercepts and slopes of the linear regressions between CVI and age were similar for men and women (p > 0.05). Considering the heteroscedasticity and the asymmetry of the distribution of the CVI values according to age, we chose to express the reference values in percentiles for eight age groups (years): 18–30, 31–40, 41–45, 46–50, 51–55, 56–60, 61–65, and 66+, obtaining progressively lower median CVI values ranging from 1.63 to 1.24.ConclusionThe availability of CVI percentiles for different age groups should promote the clinical use of 4sET, which is a simple and safe procedure for the evaluation of vagal modulation of cardiac chronotropism.

Cardiac vagal index varies according to field position in male elite football players

“…39 Apart from being shown to be reliable, 25 the 4sET protocol has been shown to be safe and simple to perform and to produce quantifiable results. 22 Even more relevant, it remarkably resembles typical conditions occurring in during a football match, in which intermittent and sudden efforts are often seen. 4,9 Interpreting the study findings.…”

“…A control sample was obtained from 303 age-matched male healthy non-athlete subjects (HS) evaluated at the same Medical Centre for routine check-ups and/or exercise prescription advice. 22 Data collection was carried out by five sports & exercise medicine's physicians along the 10-year period of the study.…”

“…[26][27][28][29] The 4sET protocol has fully been described elsewhere. 22,30,31 In brief, the duration of two specific RR intervals were identified and measured at 10 ms resolution in digital ECG tracings (Elite PC, Micromed, Brazil): (a) the longest RR interval (either the interval obtained immediately before the onset of exercise or the first one after the onset) and (b) the shortest RR interval during exercise (generally, the last one). A cardiac vagal index (CVI) is, per definition, the ratio between these two RR intervals.…”

Heart and Skeletal Muscles: Linked by Autonomic Nervous System

“…Based on their current study by Fonseca et al, 5 we can speculate that if they have used other assessment methods, like the 4-second exercise test, 6,7 - a very specific one for assessing cardiac vagal activity - and handgrip strength relative to body weight or maximal muscle power 8 or even a simple functional test like the sitting-rising test, 9 all of them, more specific to assess dynapenia, a likely clinically more relevant issue than sarcopenia, 10,11 they could have found additional discriminative values.…”

Mortality during the COVID-19 pandemic: findings from the CLINIMEX exercise cohort in the year of 2020

“…cardiac vagal tone evaluation: the ratio between two RR-interval durations measured in the electrocardiogram, the first one immediately before and the second one at the end of a 4-second fast and unloaded cycling test that is carried out in a full and maximal inspiratory apnea;(37, 38)…”