Heart Rate Changes In Response Research Articles

The effect of chronotropic incompetence on physiologic responses during progressive exercise in people with Parkinson's disease.

Heart rate (HR) response is likely to vary in people with Parkinson's disease (PD), particularly for those with chronotropic incompetence (CI). This study explores the impact of CI on HR and metabolic responses during cardiopulmonary exercise test (CPET) in people with PD, and its implications for exercise intensity prescription. Twenty-eight participants with mild PD and seventeen healthy controls underwent CPET to identify the presence or absence of CI. HR and metabolic responses were measured at submaximal (first (VT1) and second (VT2) ventilatory thresholds), and at peak exercise. Main outcome measures were HR, oxygen consumption (VO2), and changes in HR responses (HR/WR slope) to an increase in exercise demand. CI was present in 13 (46%) PD participants (PDCI), who during CPET, exhibited blunted HR responses compared to controls and PD non-CI beyond 60% of maximal workload (p ≤ 0.05). PDCI presented a significantly lower HR at VT2, and peak exercise compared to PD non-CI and controls (p ≤ 0.001). VO2 was significantly lower in PDCI than PD non-CI and controls at VT2 (p = 0.003 and p = 0.036, respectively) and at peak exercise (p = 0.001 and p = 0.023, respectively). Although poorly understood, the presence of CI in PD and its effect on HR and metabolic responses during incremental exercise is significant and important to consider when programming aerobic exercises.

Heart Rate Changes In Response To Putting Distance In Collegiate Golfers

Heart Rate Changes In Response To Putting Distance In Collegiate Golfers

Cardiovascular response to anticipatory and reactionary postural perturbations in young adults.

What is the central question of this study? It has been suggested that the cardiovascular responses to a postural perturbation are centrally mediated and reflex mediated. We wanted to know the extent to which the cardiovascular responses to external perturbations could be executed in a feedforward manner, in anticipation of the perturbation. What is the main finding and its importance? We found no anticipatory component driving heart rate and systolic blood pressure responses, suggesting that reflexive mechanisms dominate cardiovascular regulation after a postural perturbation in young adults. Cardiovascular responses to postural perturbations have been reported, but whether the cardiovascular responses to external perturbations could be executed in anticipation of the perturbation is unknown. The purpose of this study was to determine the effect of anticipated and reactionary perturbations on heart rate (HR) and systolic blood pressure (SBP) responses in healthy young adults. A secondary aim was to determine whether perceived state anxiety scores were correlated with the change in HR response during postural perturbation. Twenty healthy young adults stood on a treadmill and experienced two perturbation conditions (anticipatory vs. reactionary), each with two intensity levels (Step vs. No Step). The HR and SBP were collected continuously. Two-way repeated-measures statistical non-parametric mapping tests were used to compare HR and SBP responses to the perturbations over time (from -3 to +8 s). The results indicated that HR was significantly elevated in the higher intensity perturbations [Step vs. No Step, at 0.56-1.32s (P<0.0001) and 1.92-3.44 s (P<0.0001) post-perturbation], while there were no differences in HR between perturbation types (anticipatory vs. reactionary) or in SBP between perturbation types and intensity levels. The perceived state anxiety scores did not differ between perturbation types and intensity levels but were correlated with the change in HR post-perturbation (P=0.013). We suggest that reflexive mechanisms dominate cardiovascular regulation after anticipatory and reactionary perturbations. The data highlight the cardiovascular mechanism(s) associated with perturbations that should be considered when assessing postural stability in populations with poor balance performance.

Low defensive cardiac reactivity as a physiological correlate of psychopathic fearlessness: Gender differences

Affective/interpersonal features of psychopathy have been consistently associated with diverse psychophysiological indicators of low threat sensitivity, suggesting an underlying deficit in the reactivity of the brain’s defensive motivational system. This study examined the Cardiac Defense Response (CDR) —a complex pattern of heart rate changes in response to an aversive, intense, and unexpected stimulus— and its second accelerative component (A2), as a new physiological indicator of the fearlessness trait component of psychopathy. The differential contribution of dispositional fearlessness, externalizing proneness, and coldheartedness to the CDR pattern elicited during a defense psychophysiological test was examined in a mixed-gender sample of 156 undergraduates (62% women) assessed by the Psychopathic Personality Inventory-Revised (PPI-R). Higher PPI-R Fearless Dominance scores were related to lower heart rate changes throughout the CDR in women, but not in men. Further analyses on scales conforming the fearless dominance factor revealed that the hypothesized reduced A2 was specifically related to higher PPI-R Fearlessness scores only in women. Our findings provide initial evidence for the utility of the A2 to better understand the physiological aspects of fearlessness tendencies and its potential distinct manifestations across genders.

Monitoring the effect of water temperature on the heart rate of olive flounder (Paralichthys olivaceus) using a bio-logger

Olive flounder (Paralichthys olivaceus) is a major aquaculture fish species in South Korea and is primarily cultivated in running water culture systems. However, these systems undergo continuous water temperature changes due to environmental variations, and abrupt changes in water temperature can lead to physiological stress. This study was conducted to monitor the health conditions of farmed olive flounder according to water temperature. A bio-logger (DST milli-HRT, Star-Oddi) was inserted near the heart of olive flounder to observe heart rate changes in response to water temperature under two scenarios. In Experiment 1, the water temperature was increased (1 °C/day) from 15 °C to 25 °C. In Experiment 2, the water temperature was constant (28 °C). Control fish were cultivated at 24 °C. All logged heart rate measurements were graded with a data verification quality index (QI) to calibrate the electrocardiogram data. All experiments were conducted in duplicate. In Experiment 1, the average heart rates at 15 °C and 25 °C were 35 ± 8.70 beats min−1 and 59 ± 20.99 beats min−1, respectively, demonstrating a significant (p < 0.05) increase of 69%. No significant changes in heart rates relative to those at 15 °C (baseline) were observed from 15 °C to 22 °C (p > 0.05); however, a significant difference was observed at 23 °C (p < 0.05). In Experiment 2, heart rates fluctuated between 66 and 69 beats min−1 at 28 °C. In the control experiment, heart rates remained relatively constant with an average of 46 ± 1.66 beats min−1. Notably, heart rates were higher in Experiment 2 than in Experiment 1, suggesting that cardiac output may increase with the increased oxygen requirement of olive flounder under certain conditions, especially during growth at high water temperatures. Moreover, the variations in the heart rate of olive flounders according to the diurnal cycle were found to increase from day to night when the fish were kept within an optimal water temperature range (control experiment). Additionally, the heart rate of olive flounders was found to increase during feeding.

Comparison of Mean Arterial Blood Pressure and Heart Rate Changes in Response to Three Different Randomized Isotonic Crystalloid Boluses in Hypotensive Anesthetized Dogs.

Simple SummaryAnecdotal reports of a paradoxical exacerbation of hypotension in response to a bolus of a balanced isotonic crystalloid solution containing acetate buffers in dogs under general anesthesia was studied in a prospective clinical trial. The response to three different balanced isotonic crystalloid solutions administered as an intravenous bolus to dogs experiencing hypotension while anesthetized for elective orthopedic or dental procedures was investigated. None of the subjects experienced a paradoxical hypotensive reaction or an increase in blood pressure in response to a fluid bolus.The aim of this prospective, randomized, nonblinded, controlled clinical trial was to compare mean arterial blood pressure (MAP) and heart rate (HR) during an intravenous bolus of three different balanced isotonic crystalloid solutions in euvolemic, anesthetized dogs with hypotension. Thirty healthy dogs (American Society of Anesthesiologists Physical Status I–II) weighing at least 15 kg that presented for elective orthopedic or dental surgical procedures at the Ryan Veterinary Hospital for Small Animals of the University of Pennsylvania were included in this study. Anesthetized hypotensive patients (defined as a MAP ≤ 65 mmHg), were administered an infusion of Lactated Ringer’s solution (LRS), Plasma-Lyte (PLYTE) or Canadian Plasma-Lyte (PLYTECA), selected at random. The infusion was administered over 15 min via a volumetric fluid pump. Differences in oscillometric MAP and HR between time points and across treatments were evaluated by mANOVA. Intravenous isotonic crystalloid infusions over 15 min did not significantly change MAP or HR in hypotensive dogs under general anesthesia. Neither LRS, PLYTE nor PLYTECA exacerbated hypotension or caused tachycardia.

Special Report: Stress and Distress During Pregnancy—How to Protect Both Mother and Child

Special Report: Stress and Distress During Pregnancy—How to Protect Both Mother and Child

Inappropriate Heart Rate Response to Hypotension in Critically Ill COVID-19-Associated Acute Kidney Injury.

Angiotensin-converting enzyme 2 (ACE2) receptor of severe acute respiratory syndrome coronavirus 2 is involved in baroreflex control mechanisms. We hypothesize that severe coronavirus infectious disease 2019 (COVID-19) patients may show an alteration in baroreflex-mediated heart rate changes in response to arterial hypotension. A pilot study was conducted to assess the response to hypotension in relation to continuous venovenous hemodiafiltration (CVVHDF) in critically ill patients with PCR-confirmed COVID-19 (from February to April 2020) and in critically ill non-COVID-19 patients with sepsis (from February 2018 to February 2020). The endpoint was a change in the heart rate in response to CVVHDF-induced hypotension. The association between COVID-19 status and heart rate change was estimated using linear regression. The study population included 6 COVID-19 patients (67% men; age 58 (53–64) years) and 12 critically ill non-COVID-19 patients (58% men; age 67 (51–71) years). Baseline characteristics, laboratory findings, hemodynamic parameters, and management before CVVHDF-induced hypotension were similar between the two groups, with the exception of a higher positive end-expiratory pressure and doses of propofol and midazolam administered in COVID-19 patients. Changes in the heart rate were significantly lower in COVID-19 patients as compared to critically ill non-COVID-19 patients (−7 (−9; −2) vs. 2 (2;5) bpm, p = 0.003), while the decrease in mean arterial blood pressure was similar between groups. The COVID-19 status was independently associated with a lower change in the heart rate (−11 (−20; −2) bpm; p = 0.03). Our findings suggest an inappropriate heart rate response to hypotension in severe COVID-19 patients compared to critically ill non-COVID-19 patients.

Physiological measurement of emotion from infancy to preschool: A systematic review and meta-analysis.

IntroductionEmotion regulation, the ability to regulate emotional responses to environmental stimuli, develops in the first years of life and plays an important role in the development of personality, social competence, and behavior. Substantial literature suggests a relationship between emotion regulation and cardiac physiology; specifically, heart rate changes in response to positive or negative emotion‐eliciting stimuli.MethodThis systematic review and meta‐analysis provide an in‐depth examination of research that has measured physiological responding during emotional‐evoking tasks in children from birth to 4 years of age.ResultsThe review had three main findings. First, meta‐regressions resulted in an age‐related decrease in baseline and task‐related heart rate (HR) and increases in baseline and task‐related respiratory sinus arrhythmia (RSA). Second, meta‐analyses suggest task‐related increases in HR and decreases in RSA and heart rate variability (HRV), regardless of emotional valence of the task. Third, associations between physiological responding and observed behavioral regulation are not consistently present in children aged 4 and younger. The review also provides a summary of the various methodology used to measure physiological reactions to emotional‐evoking tasks, including number of sensors used and placement, various baseline and emotional‐evoking tasks used, methods for extracting RSA, as well as percentage of loss and reasons for loss for each study.ConclusionCharacterizing the physiological reactivity of typically developing children is important to understanding the role emotional regulation plays in typical and atypical development.

Exercise in the management of postural orthostatic tachycardia syndrome

Postural Orthostatic Tachycardia Syndrome (POTS) is an autonomic dysfunction characterized by orthostatic symptoms including an increase in heart rate of at least 30 beats per minute (bpm) or reaching above 120 bpm soon after a postural change (Busmer, 2011). Symptoms include, but are not limited to, dizziness, nausea, palpitations, sweating, and fatigue. Twenty-five percent of those with POTS are unable to work (Busmer, 2013). One common pharmacologic treatment is beta-blockers (Lai et al 2009). There is little research into non-pharmacologic treatments, including exercise. The purpose of this case study was to determine if physical activity alleviates physical (heart rate) and psychological (depression and anxiety) symptoms of a patient with POTS. Following eight weeks of physical activity, the patient still met the diagnostic criteria of POTS. However, her quality of life improved based on the WHOQOL-100 AND HADS scores, and she reported being able to perform more tasks at home without feeling heart palpitations. The case study showed an improvement in quality of life for the participant with POTS, but minimal changes in heart rate response following standing post-intervention.

Metformin may adversely affect orthostatic blood pressure recovery in patients with type 2 diabetes: substudy from the placebo-controlled Copenhagen Insulin and Metformin Therapy (CIMT) trial

BackgroundMetformin has been shown to have both neuroprotective and neurodegenerative effects. The aim of this study was to investigate the effect of metformin in combination with insulin on cardiovascular autonomic neuropathy (CAN) and distal peripheral neuropathy (DPN) in individuals with type 2 diabetes (T2DM).MethodsThe study is a sub-study of the CIMT trial, a randomized placebo-controlled trial with a 2 × 3 factorial design, where 412 patients with T2DM were randomized to 18 months of metformin or placebo in addition to open-labelled insulin. Outcomes were measures of CAN: Changes in heart rate response to deep breathing (beat-to-beat), orthostatic blood pressure (OBP) and heart rate and vibration detection threshold (VDT) as a marker DPN. Serum levels of vitamin B12 and methyl malonic acid (MMA) were analysed.ResultsAfter 18 months early drop in OBP (30 s after standing) was increased in the metformin group compared to placebo: systolic blood pressure drop increased by 3.4 mmHg (95% CI 0.6; 6.2, p = 0.02) and diastolic blood pressure drop increased by 1.3 mmHg (95% CI 0.3; 2.6, p = 0.045) compared to placebo. Beat-to-beat variation decreased in the metformin group by 1.1 beats per minute (95% CI − 2.4; 0.2, p = 0.10). Metformin treatment did not affect VDT group difference − 0.33 V (95% CI − 1.99; 1.33, p = 0.39) or other outcomes. Changes in B12, MMA and HbA1c did not confound the associations.ConclusionsEighteen months of metformin treatment in combination with insulin compared with insulin alone increased early drop in OBP indicating an adverse effect of metformin on CAN independent of vitamin B12, MMA HbA1c.Trial registration The protocol was approved by the Regional Committee on Biomedical Research Ethics (H–D-2007-112), the Danish Medicines Agency and registered with ClinicalTrials.gov (NCT00657943).

Overground Locomotor Training In Parkinson's Disease: Effects On Walking Economy And Performance Fatigability

Walking economy (WE) is a measure of metabolic energy expenditure relative to walking speed, and, when elevated, may contribute to decreased capacity and performance relative to sustained walking in people with Parkinson’s Disease (PD). Coupled with performance fatigability (PF), these factors may increase disability in this population. Although sustained walking underlies many daily activities and impacts physical activity for many people with PD, responses to walking-specific interventions to develop optimal training methods have not been fully investigated in this population. PURPOSE: Determine changes in WE, PF, and physiologic response during sustained walking following a task-specific, performance-based overground locomotor training program (OLT) in people with mild/moderate PD. METHODS: 7 males and 2 females (68.9 ± 7.1 years old, H&Y scores 1-3) completed a 12-week program of 24 OLT sessions lasting 45 - 60 minutes each. Subjects were coached through multiplanar movement drills based on components of the gait cycle emphasizing power, stability and stepping under aerobically challenging conditions (ClinicalTrials.gov. - NCT03864393). Walking performance was measured during an overground 10-minute walk test (10MWT) by total distance (TD) and PF (Δ speed/total distance). During the final 5 minutes of the 10MWT, average heart rate (HR), oxygen consumption (V̇O2), and carbon dioxide production (V̇CO2) were recorded using a portable metabolic system. These values were divided by the average speed in the final 5 minutes of the 10MWT to assess WE and physiologic response. RESULTS: There were moderate to large, significant effects for TD (925.77 ± 175.67 vs 1018.37 ± 133.83, p=0.019, d=0.59), PFS (1.11 ± 0.19 vs 0.98 ± 0.13, p=0.013, d=0.79) and HR/speed (76.46 ± 7.69 vs 71.49 ± 6.71 bpm/m/s, p=0.05, d=0.69). There were small, non-significant effects for V̇O2/speed (12.14 ± 1.99 vs 11.47 ± 2.89 mL/min/kg/m/s, d=0.34) and V̇CO2/speed (790.56 ± 196.8 vs 778.93 ± 197.94 mL/min/m/s, d=0.06). CONCLUSIONS: OLT improved WE and PFS during sustained walking. Despite a moderate effect, HR changes in response to OLT are difficult to interpret without additional measures of cardiorespiratory function. Larger and more mechanistic studies can provide further insight into this potential adaptation.

Heart Rate Response after Heart Transplantation

Denervation after heart transplantation (HTx) results in attenuated heart rate (HR) control and limited exercise tolerance. The aim of this study was to assess HR response changes to exercise with time in HTx recipients, compared with healthy controls. The HR response to maximal cardiopulmonary exercise was tested in 50 de novo HTx recipients at 11 weeks (range 7-16) after surgery, at 1-year follow-up and in 50 age and gender matched controls. The HR was measured at rest, at 25-, 50-, 75-, and 100% of VO2peak, and 30 sec, 1, 2, and 4 min after peak exercise on a treadmill or bicycle ergometer. We also assessed the HR reserve and the chronotropic response index. 11 weeks after HTx, the HR response to exercise was blunted, but improved significantly during follow-up. The change in HR from rest to peak exercise increased by 32% (46 bpm vs 68 bpm; p&lt0.001) from inclusion to the 12 months' follow-up (Figure). In comparison, the change in HR during exercise in controls was 115 bpm. In HTx recipients, approximately 50 % of the total increase in HR occurred between rest and 25% of VO2peak (figure). In the controls, roughly 40% of the total increase in HR occurred during the initial 25% of VO2peak. The HTx recipients had a significantly higher change in HR between 75- and 100% of VO2peak at inclusion than at 1-year follow-up (p=0.004) and this delayed change in HR was higher than in controls (p = 0.001). The chronotropic response index increased during follow-up (0.48 ± 0.2 vs 0.79 ± 0.2; p&lt0.001) and normalized in 50% of the HTx recipients at 1 year. Finally, the HR declined more rapidly after exercise at follow-up than at inclusion, however, the decline remained slower than in controls (Figure). The increase and decrease in heart rate during exercise are considerably reduced in de novo HTx recipients, but improve during the first year after surgery. Whether this response continues to improve during longer follow-up remains to be determined.

Persistent Impairment in Cardiopulmonary Fitness after Breast Cancer Chemotherapy

Anthracycline chemotherapy (AC) is associated with acute reductions in cardiopulmonary fitness (V˙O2peak). We sought to determine whether changes in V˙O2peak and cardiac function persisted at 12 months post-AC completion, and whether changes in cardiac function explain the heightened long-term heart failure risk. Women with breast cancer scheduled for AC (n = 28) who participated in a nonrandomized trial of exercise training (ET; n = 14) or usual care (UC; n = 14) during AC completed a follow-up evaluation 12 months post-AC completion (16 months from baseline). At baseline, 4 months, and 16 months, participants underwent a resting echocardiogram (left ventricular ejection fraction; global longitudinal strain), a blood sample (troponin; B-type natriuretic peptide), a cardiopulmonary exercise test, and cardiac MRI measures of stroke volume (SV), heart rate, and cardiac output (Qc) at rest and during intense exercise. Seventeen women (UC, n = 8; ET, n = 9) completed evaluation at baseline, 4 months, and 16 months. At 4 months, AC was associated with 18% and 6% reductions in V˙O2peak in the UC and ET groups, respectively, which persisted at 16 months (UC, -16%; ET, -7%) and was not attenuated by ET (interaction, P = 0.10). Exercise Qc was lower at 16 months compared with baseline and 4 months (P < 0.001), which was due to a blunted augmentation of SV during exercise (P = 0.032; a 14% reduction in peak SV), with no changes in heart rate response. There was a small reduction in resting left ventricular ejection fraction (baseline to 4 months) and global longitudinal strain (between 4 and 16 months) and an increase in troponin (baseline to 4 months), but only exercise Qc was associated with V˙O2peak (R = 0.47, P < 0.01). Marked reductions in V˙O2peak persisted 12 months after anthracycline-based chemotherapy, which was associated with impaired exercise cardiac function. ACTRN12616001602415.

Monitoring Players' Readiness Using Predicted Heart-Rate Responses to Soccer Drills.

To examine the ability of multivariate models to predict the heart-rate (HR) responses to some specific training drills from various global positioning system (GPS) variables and to examine the usefulness of the difference in predicted vs actual HR responses as an index of fitness or readiness to perform. All data were collected during 1 season (2016-17) with players' soccer activity recorded using 5-Hz GPS and internal load monitored using HR. GPS and HR data were analyzed during typical small-sided games and a 4-min standardized submaximal run (12km·h-1). A multiple stepwise regression analysis was used to identify which combinations of GPS variables showed the largest correlations with HR responses at the individual level (HRACT, 149 [46]GPS/HR pairs per player) and was further used to predict HR during individual drills (HRPRED). Then, HR predicted was compared with actual HR to compute an index of fitness or readiness to perform (HRΔ, %). The validity of HRΔ was examined while comparing changes in HRΔ with the changes in HR responses to a submaximal run (HRRUN, fitness criterion) and as a function of the different phases of the season (with fitness being expected to increase after the preseason). HRPRED was very largely correlated with HRACT (r = .78 [.04]). Within-player changes in HRΔ were largely correlated with within-player changes in HRRUN (r = .66, .50-.82). HRΔ very likely decreased from July (3.1% [2.0%]) to August (0.8% [2.2%]) and most likely decreased further in September (-1.5% [2.1%]). HRΔ is a valid variable to monitor elite soccer players' fitness and allows fitness monitoring on a daily basis during normal practice, decreasing the need for formal testing.

Processing emotions: Effects of menstrual cycle phase and premenstrual symptoms on the startle reflex, facial EMG and heart rate

Emotional reactivity varies across the menstrual cycle although physiological findings are not entirely consistent. We assessed facial EMG and heart rate (HR) changes in healthy free cycling women (N = 45) with an emotional startle paradigm both during the early follicular and the late luteal phase, verified by repeated salivary 17β-estradiol, progesterone and testosterone assessments. Cycle phase impacted startle responses with larger magnitudes during the luteal phase. Notably, this effect was only present when premenstrual symptoms and sequence of lab sessions were included as co-variates. At rest, participants showed a tendency towards higher HR and reduced high frequency (HF) power during the luteal phase indicating reduced parasympathetic tone. HF power was also negatively associated with startle magnitudes. HR changes in response to emotional images differed between the two cycle phases. Initial HR deceleration was more marked during the follicular phase particularly when viewing negative pictures. However, cycle phase did not significantly impact corrugator and zygomaticus activity in response to emotional pictures. Among the three gonadal steroids, correlation patterns were most consistent for testosterone. During the follicular phase, testosterone was associated with zygomaticus activity while viewing neutral or positive pictures and with less pronounced HR deceleration in response to negative images. During the luteal phase, testosterone was negatively associated with fear potentiated startle. The findings underscore the importance of considering menstrual cycle phase when investigating physiological indicators of emotion. However, the modulating effect of premenstrual symptoms also emphasizes potential inter-individual differences.

Heart Rate Monitoring in Team Sports-A Conceptual Framework for Contextualizing Heart Rate Measures for Training and Recovery Prescription.

A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an athlete's individual responses to training to optimize the scheduling of training and recovery strategies. Resting and exercise-related heart rate measures have received growing interest in recent decades and are considered potentially useful within multivariate response monitoring, as they provide non-invasive and time-efficient insights into the status of the autonomic nervous system (ANS) and aerobic fitness. In team sports, the practical implementation of athlete monitoring systems poses a particular challenge due to the complex and multidimensional structure of game demands and player and team performance, as well as logistic reasons, such as the typically large number of players and busy training and competition schedules. In this regard, exercise-related heart rate measures are likely the most applicable markers, as they can be routinely assessed during warm-ups using short (3–5 min) submaximal exercise protocols for an entire squad with common chest strap-based team monitoring devices. However, a comprehensive and meaningful monitoring of the training process requires the accurate separation of various types of responses, such as strain, recovery, and adaptation, which may all affect heart rate measures. Therefore, additional information on the training context (such as the training phase, training load, and intensity distribution) combined with multivariate analysis, which includes markers of (perceived) wellness and fatigue, should be considered when interpreting changes in heart rate indices. The aim of this article is to outline current limitations of heart rate monitoring, discuss methodological considerations of univariate and multivariate approaches, illustrate the influence of different analytical concepts on assessing meaningful changes in heart rate responses, and provide case examples for contextualizing heart rate measures using simple heuristics. To overcome current knowledge deficits and methodological inconsistencies, future investigations should systematically evaluate the validity and usefulness of the various approaches available to guide and improve the implementation of decision-support systems in (team) sports practice.

New meanings of thin-skinned: The contrasting attentional profiles of typical 12-month-olds who show high, and low, stress reactivity.

Previous research is inconsistent as to whether a more labile (faster-changing) autonomic system confers performance advantages, or disadvantages, in infants and children. To examine this, we presented a stimulus battery consisting of mixed static and dynamic viewing materials to a cohort of 63 typical 12-month-old infants. While viewing the battery, infants' spontaneous visual attention (looks to and away from the screen) was measured. Concurrently, arousal was recorded via heart rate (HR), electrodermal activity, head velocity, and peripheral movement levels. In addition, stress reactivity was assessed using a mild behavioral stressor (watching a video of another infant crying). We found that infants who were generally more attentive showed smaller HR increases to the stressor. However, they also showed greater phasic autonomic changes to attractive, attention-getting stimulus events, a faster rate of change of both look duration and of arousal, and more general oscillatory activity in arousal. Finally, 4 sessions of attention training were applied to a subset of the infants (24 trained, 24 active controls), which had the effect of increasing visual sustained attention. No changes in HR responses to stressor were observed as a result of training, but concomitant increases in arousal lability were observed. Our results point to 2 contrasting autonomic profiles: infants with high autonomic reactivity to stressors show short attention durations, whereas infants with lower autonomic reactivity show longer attention durations and greater arousal lability. (PsycINFO Database Record

Clozapine-Induced Cardiovascular Side Effects and Autonomic Dysfunction: A Systematic Review.

Background: Clozapine is the antipsychotic of choice for treatment-resistant schizophrenia and has minimal risk for extrapyramidal symptoms. Therapeutic benefits, however, are accompanied by a myriad of cardiometabolic side-effects. The specific reasons for clozapine's high propensity to cause adverse cardiometabolic events remain unknown, but it is believed that autonomic dysfunction may play a role in many of these.Objective: This systematic review summarizes the literature on autonomic dysfunction and related cardiovascular side effects associated with clozapine treatment.Method: A search of the EMBASE, MEDLINE, and EBM Cochrane databases was conducted using the search terms antipsychotic agents, antipsychotic drug*, antipsychotic*, schizophrenia, schizophren*, psychos*, psychotic*, mental ill*, mental disorder*, neuroleptic*, cardiovascular*, cardiovascular diseases, clozapine*, clozaril*, autonomic*, sympathetic*, catecholamine*, norepinephrine, noradrenaline, epinephrine, adrenaline.Results: The search yielded 37 studies that were reviewed, of which only 16 studies have used interventions to manage cardiovascular side effects. Side effects reported in the studies include myocarditis, orthostatic hypotension and tachycardia. These were attributed to sympathetic hyperactivity, decreased vagal contribution, blockade of cholinergic and adrenergic receptors, reduced heart rate variability and elevated catecholamines with clozapine use. Autonomic neuropathy was identified by monitoring blood pressure and heart rate changes in response to stimuli and by spectral analysis of heart rate variability. Metoprolol, lorazepam, atenolol, propranolol, amlodipine, vasopressin and norepinephrine infusion were used to treat tachycardia and fluctuations in blood pressure, yet results were limited to case reports.Conclusion: The results indicate there is a lack of clinical studies investigating autonomic dysfunction and a limited use of interventions to manage cardiovascular side effects associated with clozapine. As there is often no alternative treatment for refractory schizophrenia, the current review highlights the need for better designed studies, use of autonomic tests for prevention of cardiovascular disease and development of novel interventions for clozapine-induced side effects.

Heart Rate Changes in Response to Mechanical Pressure Stimulation of Skeletal Muscles Are Mediated by Cardiac Sympathetic Nerve Activity.

Stimulation of mechanoreceptors in skeletal muscles such as contraction and stretch elicits reflexive autonomic nervous system changes which impact cardiovascular control. There are pressure-sensitive mechanoreceptors in skeletal muscles. Mechanical pressure stimulation of skeletal muscles can induce reflex changes in heart rate (HR) and blood pressure, although the neural mechanisms underlying this effect are unclear. We examined the contribution of cardiac autonomic nerves to HR responses induced by mechanical pressure stimulation (30 s, ~10 N/cm2) of calf muscles in isoflurane-anesthetized rats. Animals were artificially ventilated and kept warm using a heating pad and lamp, and respiration and core body temperature were maintained within physiological ranges. Mechanical stimulation was applied using a stimulation probe 6 mm in diameter with a flat surface. Cardiac sympathetic and vagus nerves were blocked to test the contribution of the autonomic nerves. For sympathetic nerve block, bilateral stellate ganglia, and cervical sympathetic nerves were surgically sectioned, and for vagus nerve block, the nerve was bilaterally severed. In addition, mass discharges of cardiac sympathetic efferent nerve were electrophysiologically recorded. Mechanical stimulation increased or decreased HR in autonomic nerve-intact rats (range: −56 to +10 bpm), and the responses were negatively correlated with pre-stimulus HR (r = −0.65, p = 0.001). Stimulation-induced HR responses were markedly attenuated by blocking the cardiac sympathetic nerve (range: −9 to +3 bpm, p < 0.0001) but not the vagus nerve (range: −75 to +30 bpm, p = 0.17). In the experiments with cardiac sympathetic efferent nerve activity recordings, mechanical stimulation increased, or decreased the frequency of sympathetic nerve activity in parallel with HR (r = 0.77, p = 0.0004). Furthermore, the changes in sympathetic nerve activity were negatively correlated with its tonic level (r = −0.62, p = 0.0066). These results suggest that cardiac sympathetic nerve activity regulates HR responses to muscle mechanical pressure stimulation and the direction of HR responses depends on the tonic level of the nerve activity, i.e., bradycardia occurs when the tonic activity is high and tachycardia occurs when the activity is low.