Autonomic Indices Research Articles

Left ventricular hypertrophy in world class elite athletes is associated with signs of improved cardiac autonomic regulation.

In this study we sought to assess whether in elite athletes the physiological increase in cardiac mass attending severe long-term training leading to athlete's heart is accompanied by an improvement of autonomic performance, as assessed by post exercise vagal indices and a novel unitary Autonomic Nervous System Index for sports (ANSIs). The study involved 500 elite athletes (23.9 ± 6.4 years) participating in a screening organised by the National Italian Olympic Committee. All subjects underwent a complete medical examination, rest and stand autonomic assessment (heart rate variability) as well as bicycle exercise. ANSIs was also derived as radar plot from rest, stand and heart rate recovery individual proxies of autonomic nervous system regulation. All subjects were grouped into those with left ventricular hypertrophy present (LVH(+)), or not (LVH(-)), according to recognised thresholds. We observed that LVH(+) athletes (24.8%) showed a marked increase of post-exercise vagal indices (p < 0.001) and of ANSIs (p < 0.001), while no difference was observed for heart-rate variability indices. These changes were contingent upon sport intensity categories. Elite athletes with physiological cardiac hypertrophy (LVH(+)) present a selective profile of indices of autonomic nervous system performance, characterised by increases of markers of vagal recovery and of the novel unitary autonomic index for sports while RR variance and spectral indices seem to be unmodified. Athlete's heart may be characterised by a specific combination of anatomical and neurocardiac remodeling. This approach might furnish potential warning signs differentiating normal training induced physiology from pathological adaptation.

Correlation of systemic arterial stiffness with changes in retinal and choroidal microvasculature in type 2 diabetes

This study was conducted to assess whether systemic arterial stiffness, indicated by cardio-ankle vascular index (CAVI), is related to changes in the microvasculature of the retina and choroid in diabetes mellitus (DM). This study included 113 patients with a confirmed diagnosis of type-2 DM. Among them, 18 patients did not have diabetic retinopathy (DR), 71 had non-proliferative DR (NPDR), and 24 had proliferative DR (PDR). The mean CAVI was 7.58 ± 1.41 in no DR, 8.72 ± 1.47 in NPDR, and 8.43 ± 1.25 in PDR group. Of the 113 eyes, 42 (37.2%) were classified as abnormal CAVI group (CAVI ≥ 9). This group had significantly higher cardiac autonomic neuropathy risk index score, decreased central choroidal thickness, and decreased choroidal vascularity index (CVI). Deep foveal avascular zone area was higher in the abnormal CAVI group. After adjustment for possible confounding factors, CAVI showed negative correlation with the CVI (r = −0.247, P = 0.013). In conclusion, there was a significant correlation between arteriosclerosis and choroidal vascular changes in DR. We suggest prompt ophthalmic evaluation in patients with systemic arteriosclerosis. If the ophthalmologist notes advanced DR, the patient should be referred to a cardiovascular clinic for detailed evaluation of systemic arteriosclerosis.

Carotid chemoreflex activity restrains post-exercise cardiac autonomic control in healthy humans and in patients with pulmonary arterial hypertension.

Dysfunction of post-exercise cardiac autonomic control is associated with increased mortality risk in healthy adults and in patients with cardiorespiratory diseases. The afferent mechanisms that regulate the post-exercise cardiac autonomic control remain unclear. We found that afferent signals from carotid chemoreceptors restrain the post-exercise cardiac autonomic control in healthy adults and patients with pulmonary arterial hypertension (PAH). Patients with PAH had higher carotid chemoreflex sensitivity, and the magnitude of carotid chemoreceptor restraint of autonomic control was greater in patients with PAH as compared to healthy adults. The results demonstrate that the carotid chemoreceptors contribute to the regulation of post-exercise cardiac autonomic control, and suggest that the carotid chemoreceptors may be a potential target to treat post-exercise cardiac autonomic dysfunction in patients with PAH. Dysfunction of post-exercise cardiac autonomic control predicts mortality, but its underlying mechanisms remain unclear. We tested whether carotid chemoreflex activity restrains post-exercise cardiac autonomic control in healthy adults (HA), and whether such restraint is greater in patients with pulmonary arterial hypertension (PAH) who may have both altered carotid chemoreflex and altered post-exercise cardiac autonomic control. Twenty non-hypoxaemic patients with PAH and 13 age- and sex-matched HA pedalled until 90% of peak work rate observed in a symptom-limited ramp-incremental exercise test. Recovery consisted of unloaded pedalling for 5min followed by seated rest for 6min. During recovery, subjects randomly inhaled either 100% O2 (hyperoxia) to inhibit the carotid chemoreceptor activity, or 21% O2 (normoxia) as control. Post-exercise cardiac autonomic control was examined via heart rate (HR) recovery (HRR; HR change after 30, 60, 120 and 300s of recovery, using linear and non-linear regressions of HR decay) and HR variability (HRV; time and spectral domain analyses). As expected, the PAH group had higher carotid chemosensitivity and worse post-exercise HRR and HRV than HA. Hyperoxia increased HRR at 30, 60 and 120s and absolute spectral power HRV in both groups. Additionally, hyperoxia resulted in an accelerated linear HR decay and increased time domain HRV during active recovery only in the PAH group. In conclusion, the carotid chemoreceptors restrained recovery of cardiac autonomic control from exercise in HA and in patients with PAH, with the restraint greater for some autonomic indexes in patients with PAH.

Music therapy intervention in cardiac autonomic modulation, anxiety, and depression in mothers of preterms: randomized controlled trial

BackgroundMothers of preterm infants often have symptoms of anxiety and depression, recognized as risk factors for the development of cardiovascular diseases and associated with low rates of heart rate variability (HRV). This study aimed to evaluate the influence of music therapy intervention on the autonomic control of heart rate, anxiety, and depression in mothers.MethodsProspective randomized clinical trial including 21 mothers of preterms admitted to the Neonatal Intensive Care Unit of a tertiary hospital, recruited from August 2015 to September 2017, and divided into control group (CG; n = 11) and music therapy group (MTG; n = 10). Participants underwent anxiety and depression evaluation, as well as measurements of the intervals between consecutive heartbeats or RR intervals for the analysis of HRV at the first and the last weeks of hospitalization of their preterms. Music therapy sessions lasting 30–45 min were individually delivered weekly using receptive techniques. The mean and standard deviation of variables were obtained and the normality of data was analyzed using the Kolmogorov-Smirnov test. The paired sample t-test or Wilcoxon test were employed to calculate the differences between variables before and after music therapy intervention. The correlations anxiety versus heart variables and depression versus heart variables were established using Spearman correlation test. Fisher’s exact test was used to verify the differences between categorical variables. A significance level of p < 0.05 was established. Statistical analysis were performed using the Statistical Package for the Social Sciences, version 20.ResultsParticipants in MTG had an average of seven sessions of music therapy, and showed improvement in anxiety and depression scores and autonomic indexes of the time domain (p < 0.05). Significant correlations were found between depression and parasympathetic modulation using linear (r = − 0.687; p = 0.028) and nonlinear analyses (r = − 0.689; p = 0.027) in MTG.ConclusionMusic therapy had a significant and positive impact on anxiety and depression, acting on prevention of cardiovascular diseases, major threats to modern society.Trial registrationBrazilian Registry of Clinical Trials (no. RBR-3x7gz8). Retrospectively registered on November 17, 2017.

Tracking autonomic balance using an open-loop model of the arterial baroreflex.

Blood pressure control is vital for maintaining adequate perfusion of the brain and other organs in the body across varying physiological demands, and the arterial baroreceptor reflex (baroreflex) is the major short-term blood pressure control loop mediated by the autonomic nervous system (ANS). Accurate quantitative models of the baroreflex would provide physiological insight and could allow for real-time tracking of ANS activity in clinical settings. In this work, we formulate a causal, parametric beat-to-beat model, relating systolic blood pressure (input) to heart rate (output). Model structure and parameterization are explicitly based on prior physiological insights of the response dynamics of the sympathetic and parasympathetic branches of the ANS. We analyze the model's ability to track changes in autonomic balance using data from 14 nonsmoking adult males, without any history of cardiopulmonary disease, subject to both pharmacological blockade and postural changes. Our results show that the model parameters faithfully track expected changes in autonomic balance resulting from changing posture ( P < 0.01) and sympathetic blockade ( P < 0.05), and in many cases, the model parameters are more sensitive to changes in autonomic activity and balance than autonomic indices derived from the power spectral density of heart rate variability. Overall, the contributions of this work further the goal of obtaining real-time quantitative assessment of the ANS.

Characterization and reduction of exercise-based motion influence on heart rate variability using accelerator signals and channel decoding in the time–frequency domain

Objective: Heart rate variability (HRV) is defined as the variation of the heart’s beat to beat time intervals. Although HRV has been studied for decades, its response to stress tests and off-rest measurements is still under investigation. In this paper, we studied the influence of motion on HRV throughout different exercise tests, including a maximal running of healthy recreational runners, cycling, and walking tests of healthy subjects. Approach: In our proposed method, we utilized the motion trajectory (which is known to exist partially in HRV) measured by a three-channel accelerator (ACC). We then estimated their shares in HRV using a wearable electrocardiogram (ECG) and an error-correcting problem formulation. In this method, we characterized the motion components of three orthogonal directions induced into the HRV signal, and then we suppressed the estimated motion artefact to construct a motion-attenuated spectrogram. Main results and Significance: Our analysis showed that HRV in the exercise context is susceptible to motion artefacts. Furthermore, the interpretation of autonomic nervous system (ANS) activity and HRV indices throughout exercise has a high margin of error depending on the intensity level, type of exercise, and motion trajectory. Our experiment on 84 healthy subjects throughout mid-intensity cycling and walking tests showed 39% and 32% influence on average, respectively. In addition, our proposed method revealed through a maximal running test with 11 runners that motion can describe on average 20%–40% of the HRV high-frequency (HF) energy at different workloads of running.

Autonomic cardiac regulation after general anesthesia in children.

General anesthesia dramatically decreases the activity of the autonomic nervous system. Most of the hypnotic agents used to induce anesthesia inhibit sympathetic cardiovascular regulation and baroreflex control in a dose-dependent manner, lowering cardiac adaptability during the operation. The consequence of this effect in children during and after surgery has never been studied to date. The aim of this study was to follow the variations in autonomic cardiac indices in children younger than 8years old after general anesthesia (6-24hours) in programmed surgery. A prospective descriptive monocentric study of 44 children under 8years old who underwent scheduled surgery at our hospital center (Saint-Étienne University Hospital, France) was performed between June 1, 2016 and November 1, 2016. Heart rate variability was monitored for 24hours using Holter-ECG devices and the resulting data were interpreted using linear and nonlinear analyses. Compared to baseline thresholds before surgery, all heart rate variability indices decreased dramatically during general anesthesia. After awakening, a slight reduction in sympathetic activity persisted 6hours after surgery, but all measurements of sympathetic and parasympathetic activity had returned to baseline thresholds 12hours after the operation. Twenty-four hours after surgery, some parameters had increased above the corresponding baseline levels. Autonomic nervous function normalizes rapidly (within 12hours) in prepubertal children. This study indicates that general anesthesia does not seem to increase the long-term risk of autonomic dysfunction in these patients.

A16293 Autonomic dysfunction index and its relationship with arterial stiffness and left ventricular mass index

A16293 Autonomic dysfunction index and its relationship with arterial stiffness and left ventricular mass index

Detection of acute periodontal pain from physiological signals

Objective: To investigate the feasibility of the detection of brief orofacial pain sensations from easily recordable physiological signals by means of machine learning techniques. Approach: A total of 47 subjects underwent periodontal probing and indicated each instance of pain perception by means of a push button. Simultaneously, physiological signals were recorded and, subsequently, autonomic indices were computed. By using the autonomic indices as input features of a classifier, a pain indicator based on fusion of the various autonomic mechanisms was achieved. Seven patients were randomly chosen for the test set. The rest of the data were utilized for the validation of several classifiers and feature combinations by applying leave-one-out-cross-validation. Main results: During the validation process the random forest classifier, using frequency spectral bins of the ECG, wavelet level energies of the ECG and PPG, PPG amplitude, and SPI as features, turned out to be the best pain detection algorithm. The final test of this algorithm on the independent test dataset yielded a sensitivity and specificity of 71% and 70%, respectively. Significance: Based on these results, fusion of autonomic indices by applying machine learning techniques is a promising option for the detection of very brief instances of pain perception, that are not covered by the established indicators.

Peter H. Venables (1923–2017)

Peter H. Venables (1923–2017)

Interaction between cardiovascular autonomic control and sex hormones in perimenopausal women under menopausal hormone therapy.

The aim of this study was to assess the dynamical interaction between the cardiovascular autonomic control and sex hormones in perimenopausal women under menopausal hormone therapy (MHT). Seventy women (age: 51.6±2.1 years) were treated with MHT. Standard time and frequency domain measures of heart rate variability (HRV) and index S of synchronization between the slow oscillations in HRV and photoplethysmographic waveform variability were studied during a 6-week treatment with MHT. We assessed also the dynamics of the following sex hormones: estradiol, follicle-stimulating hormone, dehydroepiandrosterone sulfate, and testosterone. MHT increased estradiol and decreased follicle-stimulating hormone. Hot flashes and index S were significantly decreased under MHT (P<0.05). Other autonomic indices were not significantly changed (P>0.05). Changes of index S did not correlate with changes of sex hormones and hot flushes (P>0.05). The obtained results may indicate the independence of heart autonomic control (assessed by HRV measures) from women's hormonal status. However, any changes in sex hormones contribute to changes in the systemic control of circulation, which is assessed by index S.

Towards response success prediction: An integrative approach using high-resolution fMRI and autonomic indices

Brainstem and midbrain nuclei are closely linked to effective cognitive performance and autonomic function. In the present study, we aimed to investigate indices of successful and unsuccessful response inhibition paying particular attention to the interplay between locus coeruleus (LC), ventral tegmental area (VTA)/substantia nigra (SN) and, most importantly, peripheral markers. We aimed to get insight in the predictive value of neural and physiological signals in response inhibition.A total of 35 healthy controls were recruited from the local community and a typical task of behavioral response inhibition (Go/No-Go paradigm) was applied. We used high-resolution fMRI, advanced brainstem analyses and specifically corrected for respiratory signal and cardiac noise.Our main results characterize specific neural activation patterns during successful and unsuccessful response inhibition especially comprising the anterior cingulate as well as the medial and lateral prefrontal cortex. A significant activation of the dopaminergic nuclei (VTA/SN) was found during error processing, but not during response inhibition. Most remarkably, specific neural activation patterns (i.e., dorsal anterior cingulate cortex) as well as accompanying autonomic indices (i.e., skin conductance response (SCR)) were identified to hold predictive information on an individual's performance.In summary, the importance of the VTA/SN during error processing was shown. Furthermore, autonomic indices and specific neural activation patterns may contain valuable information to predict task performance.

A New Sympathovagal Balance Index from Electrodermal Activity and Instantaneous Vagal Dynamics: A Preliminary Cold Pressor Study.

Sympathovagal balance, an autonomic index resulting from the sympathetic and parasympathetic influences on cardiovascular control, has been extensively used in the research practice. The current assessment is based on analyzing Heart Rate Variability (HRV) series in the frequency domain by regarding the ratio between the low and high frequency components (LF/HF). Nevertheless, LF and HF powers are known to be both influenced by vagal activity which strongly bias the accuracy of this method. To this extent, in this study we combine time-varying estimates from electrodermal activity (EDA) and HRV to propose a novel index of sympathovagal balance. Particularly, sympathetic activity is estimated from the EDA power calculated within the 0.045-0.25Hz bandwidth $(EDA_{Symp})$, whereas parasympathetic dynamics is measured instantaneously through a point-process modeling framework devised for heartbeat dynamics $(HF_{pp})$. We test our new index $SV = EDA_{Symp/HF_{pp}}$ on data gathered from 22 healthy subjects (7 females and 15 males) undergoing a 3 minutes gold standard protocol for sympathetic elicitation as the cold-pressor test (CPT). Results show that the activation of the proposed sympathovagal tone is consistent with CPT elicitation and is associated with a significantly higher statistical discriminant power than the standard LF/HF ratio, also revealing different dynamics between female and male subjects.

Role of Free Fatty Acids in the Alteration of Cardiovascular Autonomic Activity and Its Postprandial Changes in Obese Patients with Glucose Intolerance

Rationale: Depressed cardiac vagal activity and elevated sympathetic activity have been reported in prediabetic obese patients. In healthy individuals, insulin was shown to acutely induce such changes, and free fatty acids (FFA) to enhance sympathetic activity. This study aimed to examine the relations between glycemia, insulinemia and plasma FFA with cardio-vascular autonomic activity in obese patients with glucose intolerance. Patients and Methods: We included 24 obese patients (BMI 36.6±5.0 kg/m²) with glucose intolerance, normal blood pressure, and no cardio-vascular events. Cardiac vagal (HFnu-HR) and sympathetic (LFnu-HR) activity, and sympatho-vagal balance (LF/HF-HR) were measured by spectral analysis of heart rate variations during 6 minutes of controlled breathing rate (12 cycles/minute) (Task Force Monitor®). These measurements were performed at fasting and after a standardised breakfast including 75g of carbohydrates. The changes (∆) between fasting and 2 hours after breakfast were calculated. Results: At fasting, age correlated positively with LFnu-HR (p=0.02) and negatively with HFnu-HR (p=0.02). There was no significant correlation between autonomic indexes and glycemia and insulinemia. At fasting, FFA correlated positively with LFnu-HR and LF/HF-HR and negatively with HFnu-HR (p&amp;lt;0.04 and &amp;lt;0.02, respectively); and positively with nitrotyrosine (p=0.02). The correlations of FFA with spectral indexes were not altered after age adjustment, but were no more significant after adjustment for nitrotyrosine. Post-prandially, ∆FFA correlated positively with ∆LFnu-HR and ∆LF/HFnu-HR and negatively with ∆HFnu-HR (p&amp;lt;0.04 to &amp;lt;0.02). Conclusion: In prediabetic obese patients, FFA (lipotoxicity) play an important role both at fasting and post-prandially in sympathetic activation and vagal depression, probably by increasing oxidative stress. These effects could increase the arrhythmogenic risk. Disclosure A. Rezki: None. M. Fysekidis: None. C. Sabrina: None. I. Banu: None. E. Cosson: Consultant; Self; Lilly France. Board Member; Self; Novartis France. Consultant; Self; Roche Diagnostics France. Board Member; Self; Ascensia Diabetes Care. Consultant; Self; Bezins France. Board Member; Self; MSD France. P. Valensi: None.

Analysis of Autonomic Indexes on Drivers' Workload to Assess the Effect of Visual ADAS on User Experience and Driving Performance in Different Driving Conditions

Advanced driver assistance systems (ADASs) allow information provision through visual, auditory, and haptic signals to achieve multidimensional goals of mobility. However, processing information from ADAS requires operating expenses of mental workload that drivers incur from their limited attentional resources. The change in driving condition can modulate drivers' workload and potentially impair drivers' interaction with ADAS. This paper shows how the measure of cardiac activity (heart rate and the indexes of autonomic nervous system (ANS)) could discriminate the influence of different driving conditions on drivers' workload associated with attentional resources engaged while driving with ADAS. Fourteen drivers performed a car-following task with visual ADAS in a simulated driving. Drivers' workload was manipulated in two driving conditions: one in monotonous condition (constant speed) and another in more active condition (variable speed). Results showed that drivers' workload was similarly affected, but the amount of attentional resources allocation was slightly distinct between both conditions. The analysis of main effect of time demonstrated that drivers' workload increased over time without the alterations in autonomic indexes regardless of driving condition. However, the main effect of driving condition produced a higher level of sympathetic activation on variable speed driving compared to driving with constant speed. Variable speed driving requires more adjustment of steering wheel movement (SWM) to maintain lane-keeping performance, which led to higher level of task involvement and increased task engagement. The proposed measures appear promising to help designing new adaptive working modalities for ADAS on the account of variation in driving condition.

1D4-2 Autonomic nervous system indices and subjective mental workload during mirror tracing task

1D4-2 Autonomic nervous system indices and subjective mental workload during mirror tracing task

Task-induced deactivation in diverse brain systems correlates with interindividual differences in distinct autonomic indices

Neuroimaging research has shown that different cognitive tasks induce relatively specific activation patterns, as well as less task-specific deactivation patterns. Here we examined whether individual differences in Autonomic Nervous System (ANS) activity during task performance correlate with the magnitude of task-induced deactivation. In an fMRI study, participants performed a continuous mental arithmetic task in a task/rest block design, while undergoing combined fMRI and heart/respiration rate acquisitions using photoplethysmograph and respiration belt. As expected, task performance increased heart-rate and reduced the RMSSD, a cardiac index related to vagal tone. Across participants, higher heart rate during task was linked to increased activation in fronto-parietal regions, as well as to stronger deactivation in ventromedial prefrontal regions. Respiration frequency during task was associated with similar patterns, but in different regions than those identified for heart-rate. Finally, in a large set of regions, almost exclusively limited to the Default Mode Network, lower RMSSD was associated with greater deactivation, and furthermore, the vast majority of these regions were task-deactivated at the group level. Together, our findings show that inter-individual differences in ANS activity are strongly linked to task-induced deactivation. Importantly, our findings suggest that deactivation is a multifaceted construct potentially linked to ANS control, because distinct ANS measures correlate with deactivation in different regions. We discuss the implications for current theories of cortical control of the ANS and for accounts of deactivation, with particular reference to studies documenting a ”failure to deactivate” in multiple clinical states.

Association between autonomic control indexes and mortality in subjects admitted to intensive care unit

This study checks whether autonomic markers derived from spontaneous fluctuations of heart period (HP) and systolic arterial pressure (SAP) and from their interactions with spontaneous or mechanical respiration (R) are associated with mortality in patients admitted to intensive care unit (ICU). Three-hundred consecutive HP, SAP and R values were recorded during the first day in ICU in 123 patients. Population was divided into survivors (SURVs, n = 83) and non-survivors (NonSURVs, n = 40) according to the outcome. SURVs and NonSURVs were aged- and gender-matched. All subjects underwent modified head-up tilt (MHUT) by tilting the bed back rest segment to 60°. Autonomic control indexes were computed using time-domain, spectral, cross-spectral, complexity, symbolic and causality techniques via univariate, bivariate and conditional approaches. SAP indexes derived from time-domain, model-free complexity and symbolic approaches were associated with the endpoint, while none of HP variability markers was. The association was more powerful during MHUT. Linear cross-spectral and causality indexes were useless to separate SURVs from NonSURVs, while nonlinear bivariate symbolic markers were successful. When indexes were combined with clinical scores, only SAP variance provided complementary information. Cardiovascular control variability indexes, especially when derived after an autonomic challenge such as MHUT, can improve mortality risk stratification in ICU.

Trajectories of frontal brain activity and socio-emotional development in children.

Asymmetric frontal brain activity is thought to reflect individual differences in approach- and avoidance-oriented motivation and emotional experience. Using a prospective longitudinal design, the authors investigated whether trajectories of frontal electroencephalogram (EEG) asymmetry in children (Mage = 6.39 years at enrollment) predicted subjective, behavioral, and autonomic indices of socioemotional processes. Resting frontal EEG activity was measured across four separate repeated assessments spanning approximately 2 years. Children's EEG asymmetry across assessments was best characterized by two trajectories: a stable right frontal asymmetry class (48.65%), and a stable left frontal asymmetry class (51.35%). At visit 4, children in the stable right frontal asymmetry displayed more avoidance-related tendencies and children in the stable left frontal asymmetry class exhibited more approach-related tendencies across social, emotional, and autonomic measures. These findings suggest that developmental patterns of resting frontal brain activity across the early school years may underlie approach- and avoidance-related motivation and predict socio-emotional processes in some children.

Can the use of a single integrated unitary autonomic index provide early clues for eventual eligibility for olympic games?

Optimal autonomic regulation and stress resilience might be considered critical elements of athletic performance. We hypothesize that a novel unitary autonomic index for sports (ANSIs), together with a somatic stress related symptom score (4SQ) might help characterize athletes who were eventually selected for the Rio 2016 Olympic Games Italian team (Rio +). In this retrospective study we examined 778 athletes (age 24.4 ± 6.7 yrs) who underwent a planned yearly pre-participation screening. All athletes underwent clinical, autonomic and exercise ECG evaluation. The combination of vagal and sympathetic indices from RR variability into ANSIs was performed by radar plot and percent ranking of index variables. We assessed (Rio +) versus (Rio -) athletes also after subdivision into three sport intensity groups (low, mid and high intensity). Overall there were no significant differences between (Rio +) and (Rio -) athletes when considering individual spectral derived variables. Conversely, the unitary Index ANSIs was significantly higher in (Rio +) compared to (Rio -) athletes (respectively 54.5 ± 29.5 and 47.9 ± 28.4 p = 0.014). This difference was particularly evident (p = 0.017) in the group of athletes characterized by both high static and dynamic components. 4SQ was smaller in the (Rio +) group, particularly in the groups of athletes characterized by both low-medium static and dynamic components. ANSIs, a proxy of integrated cardiac autonomic regulation and simple assessment of resilience to stress, may differentiate Italian athletes who were eventually selected for participation in the 2016 Rio Olympic Games from those who were not, suggesting the possibility of a "winning functional phenotype".