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Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. Judo requires highly technical and tactical skills with physiological response optimization to succeed. Aim of Study. The present study aims to investigate an association between a rating of perceived exertion (RPE), a heart rate (HR), and a blood lactate concentration [La-] along with a grip strength (GS) deterioration in successive judo simulations (randori). Material and Methods. Ten male judokas performed six successive fights (randori), of 5-minute each, with 5-minute rests. The HR, [La-], GS, and grip activation time (GAT) were recorded with a standard procedure at various time points (resting - T0 and after each bout T1-T6). Results. The HR and [La-] showed significant (p < 0.001) differences when compared among T1-T6, including T0, but a variation in the HR (ΔHR) and a variation in the lactate concentration (Δ[La-]) reported no significant difference after a post-simulation data comparison. The GS (for both dominant and non-dominant hand) reported significant differences among post-simulation GS measurements, including T0. The GAT was negatively and significantly (p < 0.01) correlated with GS-right (r = -0.397) and GS-left (r = -0.440). Similarly, the RPE was positively correlated with the ΔHR, Δ[La-], HR, and [La-]. Whereas the GS (for both hands) was negatively (p < 0.05) correlated with the Δ[La-] and [La-]. Finally, the ΔHR was positively (p < 0.01) correlated with the Δ[La-] and [La-]. Conclusions. Judo simulations involve high-intensity exercises, leading to a maximum average frequency RPE of 7-9 with an HR of 192-193 beats·min-1 (90-95% HRmax) and 9.79-15.41 mmol·L-1 of peak [La-]. The RPE was positively (significantly) correlated with the ΔHR, Δ[La-], HR, and [La-]. Whereas the GAT was negatively (significantly) correlated with the GS-right and GS-left. [ABSTRACT FROM AUTHOR]

Rationale: Obstructive sleep apnea (OSA) severity is typically assessed by the apnea–hypopnea index (AHI), a frequency-based metric that allocates equal weight to all respiratory events. However, more severe events may have a greater physiologic impact. Objectives: The purpose of this study was to determine whether the degree of event-related hypoxemia would be associated with the postevent physiologic response. Methods: Patients with OSA (AHI, ⩾5/h) from the multicenter Canadian Sleep and Circadian Network cohort were studied. Using mixed-effect linear regression, we examined associations between event-related hypoxic burden (HBev) assessed by the area under the event-related oxygen saturation recording with heart rate changes (ΔHRev), vasoconstriction (vasoconstriction burden [VCBev] assessed with photoplethysmography), and electroencephalographic responses (power ratio before and after events). Results: Polysomnographic recordings from 658 patients (median [interquartile range] age, 55.00 [45.00, 64.00] yr; AHI, 27.15 [14.90, 64.05] events/h; 42% female) were included in the analyses. HBev was associated with an increase in all physiologic responses after controlling for age, sex, body mass index, sleep stage, total sleep time, and study centers; for example, 1 standard deviation increase in HBev was associated with 0.21 [95% confidence interval, 0.2, 0.22], 0.08 [0.08, 0.09], and 0.22 [0.21, 0.23] standard deviation increases in ΔHRev, VCBev, and β-power ratio, respectively. Conclusions: Increased event-related hypoxic burden was associated with greater responses across a broad range of physiologic signals. Future metrics that incorporate information about the variability of these physiologic responses may have promise in providing a more nuanced assessment of OSA severity. [ABSTRACT FROM AUTHOR]

Physiologically ageing refers to the impaired ability to maintain homeostasis during external as well as internal stresses. This impairment makes the individual vulnerable to these stresses and finally succumbs to one of the diseases. Autonomic nervous system is vital for homeostasis and its potency is gradually reduced with aging, ultimately leading to the development of many cardiovascular diseases. The sympathetic system predominates during emergency "fight-or-flight" reactions and during exercise. The overall effect of the sympathetic system is to prepare the body for strenuous physical activity. This study was carried out in 150 healthy male subjects in the age group of 20yrs - 70 yrs of Guwahati city and to assess the effect of age on the cardiovascular Parasympathetic function. The standard bedside non-invasive Sympathet ic Function tests (Blood Pressure response to Sustained Handgrip and Blood Pressure responsetoStanding) was performed in each subject. The tests of Sympathetic Nervous System showed agradual and significant decreasein function with increasing age of the subjects. There were however no significant differences in the parameters after 50 years of age of subjects. [ABSTRACT FROM AUTHOR]

Autonomic nervous system is vital for homeostasis and its potency is gradually reduced with aging. Aging may affect cardiac autonomic nerve functions, disrupting the complex interactions with several physiologic mechanisms that maintain the heart rate and blood pressure within normal limits. This may ultimately lead to the development of many cardiovascular diseases. This study was carried out in 150 healthy male subjects in the age group of 20yrs - 70 yrs. of Guwahati city and to assess the effect of age on the Parasympathetic Balance. The standard bedside noninvasive Parasympathetic Function tests (Valsalva maneuver, Heart rate variation during deep breathing, and Heart rate response to standing) was performed in each subject. This study thus demonstrated that ageing is associated with a decrease in the function of the autonomic nervous system in apparently healthy individuals. Therefore, it can be said that in the diagnosis and treatment of autonomic-related diseases, physiological differences in the cardiovascular autonomic functions due to age should be considered. [ABSTRACT FROM AUTHOR]

Introduction: Myocardial perfusion imaging (MPI) with pharmacologic stress is a useful technique for evaluation of suspected coronary artery disease (CAD). Heart rate responses (HRR) to vasodilators such as dipyridamole mirror autonomic activity and may provide important prognostic information in CAD patients. In this study, the impact of baseline characteristics of patients including age and gender on the expected HRR has been assessed. Methods: This retrospective study included database of 2584 patients (1575 female, 1009 male) who were referred to the nuclear medicine department for pharmacologic MPI. The HRR to dipyridamole was calculated as ratio of maximal heart rate (HR) during or shortly after dipyridamole infusion to baseline HR. The association of HRR with age, gender, presence of other known CAD risk factors and perfusion findings was evaluated. Results: Significant correlation was found between HRR and sex, age, diabetes mellitus (DM), hypertension (HTN), and chronic kidney disease (CKD) (P < 0.001) in both univariate and multivariate analysis. The mean HRR was also significantly higher in patients with normal perfusion on SPECT MPI as compared to patients with abnormal findings, however, multivariate regression analysis showed no significant correlation. In the subgroup of patients with no CAD risk factors, HRR was significantly higher in women under age 55 years. Conclusion: The HRR during dipyridamole infusion depends on age and gender, irrespective of presence of other CAD risk factors and should be considered in the interpretation of. Besides, DM, HTN and CKD are also correlated with lower HRR to dipyridamole stress. [ABSTRACT FROM AUTHOR]

Several predator–prey systems are in flux as an indirect result of climate change. In the Arctic, earlier sea-ice loss is driving polar bears (Ursus maritimus) onto land when many colonial nesting seabirds are breeding. The result is a higher threat of nest predation for birds with potential limited ability to respond. We quantified heart rate change in a large common eider (Somateria mollissima) breeding colony in the Canadian Arctic to explore their adaptive capacity to keep pace with the increasing risk of egg predation by polar bears. Eiders displayed on average higher heart rates from baseline when polar bears were within their field of view. Moreover, eiders were insensitive to variation in the distance bears were to their nests, but exhibited mild bradycardia (lowered heart rate) the longer the eider was exposed to the bear given the hen's visibility. Results indicate that a limited ability to assess the risks posed by polar bears may result in long-term fitness consequences for eiders from the increasing frequency in interactions with this predator.

With climate change, humans are at a greater risk for heat-related morbidity and mortality, often secondary to increased cardiovascular strain associated with an elevated core temperature (Tc). Critical environmental limits (i.e., the upper limits of compensable heat stress) have been established based on Tc responses for healthy, young individuals. However, specific environmental limits for the maintenance of cardiovascular homeostasis have not been investigated in the context of thermal strain during light activity. Therefore, the purposes of this study were to 1) identify the specific environmental conditions (combinations of ambient temperature and water vapor pressure) at which cardiovascular drift [i.e., a continuous rise in heart rate (HR)] began to occur and 2) compare those environments to the environmental limits for the maintenance of heat balance. Fifty-one subjects (27 F; 23 ± 4 yr) were exposed to progressive heat stress across a wide range of environmental conditions in an environmental chamber at two low metabolic rates reflecting minimal activity (MinAct; 159 ± 34 W) or light ambulation (LightAmb; 260 ± 55 W). Whether systematically increasing ambient temperature or humidity, the onset of cardiovascular drift occurred at lower environmental conditions compared with Tc inflection points at both intensities (P < 0.05). Furthermore, the time at which cardiovascular drift began preceded the time of Tc inflection (MinAct P ¼ 0.01; LightAmb P ¼ 0.0002), and the difference in time between HR and Tc inflection points did not differ (MinAct P ¼ 0.08; LightAmb P ¼ 0.06) across environmental conditions for either exercise intensity. These data suggest that even in young adults, increases in cardiovascular strain precede the point at which heat stress becomes uncompensable during light activity. NEW & NOTEWORTHY To our knowledge, this study is the first to 1) identify the specific combinations of temperature and humidity at which an increase in cardiovascular strain (cardiovascular drift) occurs and 2) compare those environments to the critical environmental limits for the maintenance of heat balance. We additionally examined the difference in time between the onset of increased cardiovascular strain and uncompensable heat stress. We show that an increase in cardiovascular strain systematically precedes sustained heat storage in young adults. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: The contribution of chronotropic incompetence to reduced exercise tolerance after a heart transplant is well known, but its role as a prognostic marker of post-transplant mortality is unclear. The aim of this study is to examine the relationship between post-transplant heart rate response (HRR) and survival. Methods: We performed a retrospective analysis of all adult heart transplant recipients at the University of Pennsylvania between the years 2000 and 2011 who underwent a cardiopulmonary exercise test (CPET) within a year of transplant. Follow-up time and survival status were observed through October 2019, using data merged from the Penn Transplant Institute. HRR was calculated by subtracting the resting HR from the peak exercise HR. The association between HRR and mortality was analyzed using Cox proportional hazard models and Kaplan–Meier analysis. The optimal cut-off point for HRR was generated by Harrell's C statistic. Patients with submaximal exercise tests were excluded, defined by a respiratory exchange ratio (RER) cut-off of 1.05. Results: Of 277 patients with CPETs performed within a year post-transplant, 67 were excluded for submaximal exercise. In the 210 included patients, the mean follow-up time was 10.9 years (Interquartile range (IQR) 7.8–14). Resting HR and peak HR did not significantly impact mortality after adjusting for covariates. In a multivariable linear regression analysis, each 10-beat increase in heart rate response was associated with a 1.3 mL/kg/min increase in peak VO2 and a 48 s increase in the total exercise time. Each beat/min increase in HRR was associated with a 3% reduction in the hazard of mortality (HR 0.97; 95% CI 0.96–0.99, p = 0.002). Using the optimal cut-off point generated by Harrell's C statistic, survival was significantly higher in patients with an HRR > 35 beats/min compared to those with an HRR < 35 beats/min (log rank p = 0.0012). Conclusion: In heart transplant patients, a low HRR is associated with increased all-cause mortality and decreased exercise capacity. Additional studies are needed to validate whether targeting HRR in cardiac rehabilitation may improve outcomes. [ABSTRACT FROM AUTHOR]

The agricultural industry of many Southeast Asian countries, including Indonesia, is highly reliant on human labor, with minimal use of modern equipment. Preliminary studies on the paddy planting activity revealed a significant occurrence of musculoskeletal disorders (MSDs) and structure malalignments in the lower extremities. This is because these farmers usually execute paddy planting activities on heavy and muddy terrain with bare feet using more significant lower extremity muscle. The exhaustive activity of muscles leads to an increase in the heart rate response as the muscle demand for energy is higher. This condition causes a decline in muscle performance. Therefore, this research examines the effect of muddy terrain on the lower extremity of 30 experienced rice farmers through simulated rice planting activities in terms of heart rate response and perceived pain. The Suunto wristband and the modified Standardized Nordic Questionnaire (SNQ)-visual analog scales (VAS) for perceived pain questionnaire were used to collect the data of heart rate response and pain perception on the lower extremity, which were compared between muddy (mud force) and flat rigid (no mud force) terrain, respectively. The Repeated Measure ANOVA test revealed that muddy work terrain had a significant effect on heart rate (100.11 ± 1.71 beat per minute) compared to flat rigid terrain (94.13 ± 1.16 beat per minute). Meanwhile, the paired T-test results showed that muddy work terrain had a significant effect on the increase in pain in the farmer's lower extremity when performing rice planting activities compared to flat hard terrain. The results of this study can be used for modifying the work-break interval arrange and as a basis for the development of an assistive device capable of preventing injuries to the lower extremity caused by muddy work surface conditions.

The purpose of this study was to show the reference values of suitable performance for amputee soccer outfield players based on amputation level and playing position through field test and match analysis. Fifteen players with disabilities greater than unilateral femoral amputation (high-level amputation group) and 15 players with disabilities such as unilateral lower leg amputation (low-level amputation group) participated in the study. Both groups consisted of 5 defenders, 5 midfielders, and 5 forwards, respectively. The 20m sprint test and 20m W agility test were used to measure physical fitness. As match analysis, total distance covered, distance covered by speed category, and frequency of acceleration and deceleration were measured using global positioning systems technology, and heart rate response was measured using a short-range radio telemetry device. In the sprint test, the low-level amputation group was significantly faster than the high-level amputation group, but there was no difference in the agility test. The low-level amputation group had significantly higher total distance covered and sprinting values than the high-level amputation group. In both groups, distance covered tended to be significantly higher in the order of defender, midfielder, and forward. In the high-level amputation group, the second half of both acceleration and deceleration tended to be significantly less frequent than the first half. The percentage of duration of ≥95% HRmax was significantly higher in the high-level amputation group than in the low-level amputation group for all positions. The reference values presented could be used to develop an optimal play model as a suitable performance criterion.

Rationale: Randomized controlled trials of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA) have not demonstrated protection against adverse cardiovascular outcomes. Recently, observational studies revealed that OSA-related cardiovascular risk is concentrated in patients with an elevated pulse rate response to respiratory events (ΔHR). Objectives: Here, in this post hoc analysis of a prospective clinical trial, we test the hypothesis that a greater pretreatment ΔHR is associated with greater CPAP-related protection against adverse cardiovascular outcomes. Methods: ΔHR was measured from baseline polysomnography of the RICCADSA (Randomized Intervention with CPAP in CAD and OSA) randomized controlled trial (patients with coronary artery disease [CAD] and OSA [apnea-hypopnea index ⩾ 15 events/h] with Epworth Sleepiness Scale score < 10; nCPAP:ncontrol = 113:113; male, 85%; age, 66 ± 8 [mean ± SD] yr). The primary outcome was a composite of repeat revascularization, myocardial infarction, stroke, and cardiovascular mortality. Multivariable Cox regression assessed whether the effect of CPAP was moderated by ΔHR (treatment-by-ΔHR interaction). Measurements and Main Results: The CPAP-related reduction in risk increased progressively with increasing pretreatment ΔHR (interaction hazard ratio [95% confidence interval], 0.49 [0.27 to 0.90] per SD increase in ΔHR; P < 0.05). This means that in patients with a ΔHR of 1 SD above the mean (i.e., 10 beats/min), CPAP was estimated to reduce cardiovascular risk by 59% (6% to 82%) (P < 0.05), but no significant risk reduction was estimated in patients with a mean ΔHR (6 beats/min; CPAP risk reduction, 16% [-53% to 54%]; P = 0.6). Conclusions: The protective effect of CPAP in patients with CAD and OSA without excessive sleepiness was modified by the ΔHR. Specifically, patients with higher ΔHR exhibit greater cardiovascular benefit from CPAP therapy. [ABSTRACT FROM AUTHOR]

Patients with Anderson-Fabry disease (AFD) have an elevated incidence of resting arrhythmias and ischemic heart disease, but their exercise arrhythmia burden and ischemic changes are not well understood. In addition, little research has been done on heart rate recovery in these patients. We retrospectively reviewed charts of patients with AFD who underwent maximal effort cardiopulmonary exercise testing (CPET) (n=44; 38.2 ± 13.8 yr; 23 men) from 2012 through 2018. Electrocardiographic, Holter monitoring, echocardiographic, cardiac magnetic resonance imaging, and patient demographic data were collected. No patient had adverse events that necessitated CPET termination, whereas 25 (57%) had ectopy during CPET, including 3 (7%) with frequent premature atrial contractions and 5 (11%) with frequent premature ventricular contractions. The ectopic burden was higher during resting electrocardiographic monitoring before exercise. In addition, 7 patients (16%) had pathologic ST-segment or T-wave changes on CPET, defined as ST-segment changes ≥2 mm. Among the patients who had concurrent cardiac magnetic resonance findings with their CPET (n=27), ST-segment or T-wave changes were associated with left ventricular myocardial mass (r=0.43, P=0.02). Chronotropic incompetence was seen during CPET in 28 patients (64%); however, only 2 patients (4%) had abnormal heart rate recovery at 1 minute. This study shows that patients with AFD can safely undergo exercise testing but have a high incidence of exercise-induced arrhythmias and ischemic changes. Ischemic electrocardiographic changes during exercise testing are associated with myocardial mass. Despite the chronotropic incompetence associated with AFD, heart rate recovery appears to be generally preserved in these patients. [ABSTRACT FROM AUTHOR]

The HF syndrome is characterized by an autonomic unbalance with sympathetic hyperactivity which contributes to increased myocardial oxygen demand, oxidative stress, peripheral vasoconstriction, afterload mismatch with a progressive desensitization and down-regulation of cardiac β1-receptors. These changes, together with a few other structural and peripheral changes, lead to chronotropic incompetence (CI), such as the inability to increase heart rate (HR) consistently with activity or demand. CI, regardless of the method and cut-off adopted to define it, is associated with reduced exercise capacity and a worse prognosis. Furthermore, different pharmacological classes might interfere with the physiologic exercise-induced HR response, thus generating some confusion. In particular, the β-blockers, albeit lowering peak HR, are known to improve prognosis and left ventricular inotropic reserve so that their withdrawal should be avoided at least in HF with reduced and mildly reduced ejection fraction. Similarly, a still debated strategy to counterbalance a blunted exercise-induced HR response, is represented by rate-adapting pacing. The present review, besides supplying an overview on possible CI definitions, discusses the clinical impact of CI and potential pharmacological and non-pharmacological therapeutic strategies., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Although heart rate response (HRR) to regadenoson stress has been shown to be a strong predictor of outcome, it has not been investigated in a large all-comers cohort. The prognostic utility of systolic blood pressure response (SBPR) has not been investigated in comparison with HRR., Methods and Results: In a retrospective cohort of 10,227 patients undergoing regadenoson stress single-photon emission computed tomography myocardial perfusion imaging (MPI), HRR, and SBPR were calculated as 100×(peak hyperemia value-baseline value)/baseline value. During 35±21 months follow-up, 921 (8.8%) deaths were observed. The median HRR was 35% (interquartile range [IQR], 21% to 51%). The median SBPR was -9% (IQR, -17% to -2%). HRR and SBPR were independently associated with all-cause mortality with adjusted hazard ratio [HR] of .980 per 1% increment in HRR (CI, .977-.984) and .994 per 1% increment in SBPR (CI, .988-.999). Mortality rates increased with decreasing HRR quartile and SBPR tertile. HRR provided incremental prognostic value for all-cause mortality beyond clinical and imaging parameters (area under the curve [AUC] increase, .03; P<.001) and SBPR data (AUC increase, .11; P<0001). SBPR did not provide significant incremental prognostic value beyond clinical and imaging parameters or HRR data. We derived and validated HRR of <20% as a cut-off that can improve risk stratification beyond clinical and MPI findings., Conclusion: Among patients undergoing stress MPI, impaired HRR to regadenoson provided independent and incremental prognostic value for all-cause mortality beyond clinical, imaging, and SBPR data. SBPR positively correlates with HRR, but it does not provide incremental prognostic utility. HRR, but not SBPR, should be routinely reported and considered in assessing patients' overall risk. An abnormal HRR threshold of <20% can improve risk stratification., (Copyright © 2024 American Society of Nuclear Cardiology. Published by Elsevier Inc. All rights reserved.)

Aim: Chronotropic incompetence and impaired heart rate (HR) recovery are related to mortality. Guidelines lack specific reference values for HR recovery. We defined normal values and studied blunted HR response and recovery, and mortality risk., Methods: We included 9,917 subjects (45% females) aged 18-85 years who performed a cycle exercise test. We defined normal values for peak HR, HR reserve, and HR recovery at 1 and 2 minutes (HRR1 and HRR2) based on individuals apparently healthy (N=2,242). Associations between blunted HR indices (<5th percentile) and mortality over a median follow-up of 8.6 years were analysed using Cox regression and competing risk analysis., Results: All HR indices were age-dependent and independent predictors of all-cause and CV mortality. The 5th percentiles of HR reserve, HRR1, and HRR2 correlated weakly with existing reference values. HR recovery variables were the strongest predictors of all-cause mortality (HRR1, hazard ratio 1.70 [95% confidence interval, 1.49-1.94] and HRR2, 1.57 [1.37-1.79]), including in subjects with normal exercise capacity (HRR1, 1.96 [1.61-2.39] and HRR2, 1.76 [1.46-2.12]). Combining HR indices appeared to increase the risk of all-cause (HRR1 and HRR2, 1.96 [1.68-2.29] and peak HR and HRR1, 1.87 [1.56-2.23]) and CV mortality, although no specific combination was superior for predicting CV mortality., Conclusions: All HR variables were age-dependent and associated with all-cause and CV mortality. Blunted HR recovery variables were the strongest predictors of all-cause mortality, even in subjects with normal exercise capacity. Combined blunted HR indices appeared to add prognostic value., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Predator-prey dynamics in the Arctic are being altered with changing sea ice phenology. The increasing frequency of predation on colonial nesting seabirds and their eggs by the polar bear (Ursus maritimus) is a consequence of bears shifting to terrestrial food resources through a shortened seal-hunting season. We examined antipredator responses in a colony of nesting Common Eiders (Somateria mollissima) on East Bay Island, Nunavut, Canada, which is exposed to established nest predators, such as arctic fox (Vulpes lagopus), but also to recent increases in polar bear nest predation due to the bears’ lost on-ice hunting opportunities. Given eiders’ limited eco-evolutionary experience with bears, we aimed to experimentally contrast eider responses to the recent predation pressure by polar bears to those induced by their more traditional mammalian predator, the arctic fox. Our goal was to characterize whether this population of eiders was vulnerable to a changing predator regime. Using simulated approaches of visual stimuli of both predator types, we measured eider heart rate and flight initiation distance as physiological and behavioral metrics, respectively, to characterize the perceived risk of and subsequent response to imminent threat posed by these two predators that differ in historical encounter rates. Eider heart rates were more responsive to impending visual cues of arctic foxes compared to polar bears, but birds responded behaviorally to all simulated threats with similar flight initiation distances. Results suggest eiders may not perceive the full risk that bears pose as egg and adult predators, and are therefore expected to suffer negative fitness consequences from this ongoing and increasing interaction. Eiders may therefore require conservation intervention to aid in their management.

The agricultural industry of many Southeast Asian countries, including Indonesia, is highly reliant on human labor, with minimal use of modern equipment. Preliminary studies on the paddy planting activity revealed a significant occurrence of musculoskeletal disorders (MSDs) and structure malalignments in the lower extremities. This is because these farmers usually execute paddy planting activities on heavy and muddy terrain with bare feet using more significant lower extremity muscle. The exhaustive activity of muscles leads to an increase in the heart rate response as the muscle demand for energy is higher. This condition causes a decline in muscle performance. Therefore, this research examines the effect of muddy terrain on the lower extremity of 30 experienced rice farmers through simulated rice planting activities in terms of heart rate response and perceived pain. The Suunto wristband and the modified Standardized Nordic Questionnaire (SNQ)-visual analog scales (VAS) for perceived pain questionnaire were used to collect the data of heart rate response and pain perception on the lower extremity, which were compared between muddy (mud force) and flat rigid (no mud force) terrain, respectively. The Repeated Measure ANOVA test revealed that muddy work terrain had a significant effect on heart rate (100.11 ± 1.71 beat per minute) compared to flat rigid terrain (94.13 ± 1.16 beat per minute). Meanwhile, the paired T-test results showed that muddy work terrain had a significant effect on the increase in pain in the farmer's lower extremity when performing rice planting activities compared to flat hard terrain. The results of this study can be used for modifying the work-break interval arrange and as a basis for the development of an assistive device capable of preventing injuries to the lower extremity caused by muddy work surface conditions. [ABSTRACT FROM AUTHOR]

Chronotropic incompetence (ChI) is linked with diminished exercise capacity in heart failure with preserved ejection fraction (HFpEF). Although exercise training has shown potential for improving functional capacity, the exercise modality associated with greater functional and chronotropic response (ChR) is not well-known. Additionally, how the ChR from different exercise modalities mediates functional improvement remains to be determined. This study aimed to evaluate the effect of three different exercise programs over current guideline recommendations on peak oxygen consumption (peakVO 2) in patients with ChI HFpEF phenotype. In this randomized clinical trial, 80 stable symptomatic patients with HFpEF and ChI (NYHA class II-III/IV) are randomized (1:1:1:1) to receive: a) a 12-week program of supervised aerobic training (AT), b) AT and low to moderate-intensity strength training, c)AT and moderate to high-intensity strength training, or d) guideline-based physical activity and exercise recommendations. The primary endpoint is 12-week changes in peakVO 2. The secondary endpoints are 12-week changes in ChR, 12-week changes in quality of life, and how ChR changes mediate changes in peakVO 2. A mixed-effects model for repeated measures will be used to compare endpoint changes. The mean age is 75.1 ± 7.2 years, and most patients are women (57.5 %) in New York Heart Association functional class II (68.7 %). The mean peakVO 2 , percent of predicted peakVO 2 , and ChR are 11.8 ± 2.6 mL/kg/min, 67.2 ± 14.7 %, and 0.39 ± 0.16, respectively. No significant baseline clinical differences between arms are found. Training-HR will evaluate the effects of different exercise-based therapies on peakVO 2 , ChR, and quality of life in patients with ChI HFpEF phenotype. ClinicalTrials.gov (NCT05649787). [ABSTRACT FROM AUTHOR]

Copyright of Adicciones is the property of Sociedad Cientifica Espanola de Estudios sobre el Alcohol and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Renal functional reserve (RFR), defined as the difference between stress and resting glomerular filtration rate (GFR), may constitute a diagnostic tool to identify patients at higher risk of developing acute kidney injury or chronic kidney disease. Blunted RFR has been demonstrated in early stages of hypertension and has been attributed to impaired vascular reactivity due to an overactive sympathetic nervous system (SNS). Objective: The purpose of this study was to investigate whether RFR correlates with other phenotypes expressing overactivity of the SNS in patients with essential hypertension and preserved renal function. Methods: Thirty-six patients with untreated essential hypertension and a GFR >60 mL/min/1.73 m2 were enrolled. The following parameters were measured: RFR, 24-h ambulatory blood pressure (BP) profile, a treadmill stress test, and an echocardiographic examination. Urine and venous samples were obtained at specific time points for the determination of clinical parameters, and both resting and stress GFR were calculated by using endogenous creatinine clearance for the measurement of RFR after an acute oral protein load (1 g/kg). Results: Twenty-one patients had a RFR

Background: Orthostasis is a potent physiological stressor which adapts with age. The age-related accumulation of health deficits in multiple physiological systems may impair the physiological response to orthostasis and lead to negative health outcomes such as falls, depression, and cognitive decline. Research to date has focused on changes with orthostasis at prespecified intervals of time, without consideration for whole signal approaches. Methods: One-dimensional statistical parametric mapping identified regions in time of significant association between variables of interest using a general linear model. Frailty index operationalized accumulated health and social deficits using 32-items from a computer-assisted interview. This study examined the association of frailty index on blood pressure, heart rate, and cerebral oxygenation during an orthostatic test in a sample of 2742 adults aged 50 or older from The Irish Longitudinal Study on Ageing. Results: Frailty index was seen to be negatively associated with cerebral oxygenation changes from baseline over a period of 7 seconds (p = .036). Heart rate and systolic blood pressure were positively and negatively associated with frailty index over periods of 17 seconds (p = .001) and 10 seconds (p = .015), respectively. Conclusions: Statistical parametric mapping demonstrated these significant regions of cerebral oxygenation during orthostasis provide indirect evidence of impaired autoregulation associated with frailty. Statistical parametric mapping also replicated prior relationships in heart rate and systolic blood pressure associated with a higher frailty index. These findings highlight the utility of 1-dimensional statistical parametric modeling in identifying significant regions of interest in physiological recordings. [ABSTRACT FROM AUTHOR]

Background: Childhood obesity tends to persist into adulthood and associated with increase in developing ischemic and non-ischemic cardiovascular diseases. We aimed to evaluate the effect of obesity on cardiac functions, atrial electromechanical coupling, and heart rate response, which are considered to be predictors of atrial fibrillation and sudden cardiac arrest., Methods: Study population included 52 obese children and 52 healthy controls. We performed 12-lead electrocardiography, echocardiographic examination, and treadmill exercise testing. Mitral, septal, and tricuspid segments were analysed by tissue Doppler imaging., Results: Myocardial performance index (p = 0.011, p < 0.001, and p = 0.001, respectively) was higher and E'/A' ratio (p = 0.011, p < 0.001, and p < 0.001, respectively) was lower in obese group than controls. Atrial electromechanical coupling was longer in the obese group at all three segments (p < 0.001, p = 0.009, and p = 0.04, respectively). They had significantly longer interatrial (p < 0.001) and intra-atrial (p = 0.003) electromechanical conduction delay. While chronotropic index was similar between two groups, heart rate reserve was lower in obese children than controls (p = 0.043). The 1st- and 2nd-minute heart rate recovery indices of the obese group were lower compared to controls (p < 0.001 and p = 0.03, respectively). Body mass index was positively correlated with intra- and inter-atrial conduction times, whereas it was negatively correlated with heart rate recovery indices., Conclusion: We showed a deterioration in the diastolic function, atrial conduction, and heart rate response properties in children with obesity. Given the prognostic importance of these parameters, obese patients are might be at risk for atrial fibrillation and severe dysrhythmias from a young age.

Background: Renal functional reserve (RFR), defined as the difference between stress and resting glomerular filtration rate (GFR), may constitute a diagnostic tool to identify patients at higher risk of developing acute kidney injury or chronic kidney disease. Blunted RFR has been demonstrated in early stages of hypertension and has been attributed to impaired vascular reactivity due to an overactive sympathetic nervous system (SNS). Objective: The purpose of this study was to investigate whether RFR correlates with other phenotypes expressing overactivity of the SNS in patients with essential hypertension and preserved renal function. Methods: Thirty-six patients with untreated essential hypertension and a GFR >60 mL/min/1.73 m2 were enrolled. The following parameters were measured: RFR, 24-h ambulatory blood pressure (BP) profile, a treadmill stress test, and an echocardiographic examination. Urine and venous samples were obtained at specific time points for the determination of clinical parameters, and both resting and stress GFR were calculated by using endogenous creatinine clearance for the measurement of RFR after an acute oral protein load (1 g/kg). Results: Twenty-one patients had a RFR <30 mL/min/1.73 m2 and 15 had a RFR above this cutoff. A nondipping pattern of 24-h BP was significantly more frequent in patients with low RFR (57.1 vs. 25.0%, p < 0.05 for systolic BP and 52.3 vs. 10.0%, p < 0.02 for diastolic BP). Moreover, patients with lower RFR values showed a blunted heart rate (HR) response to exercise during treadmill test (r = 0.439, p < 0.05). None of the echocardiographic parameters differed between the two groups of patients. Conclusions: In hypertensive patients with preserved GFR, reduced RFR is related to nondipping BP phenotype as well as to attenuated exercise HR response. Overactivity of the SNS may be a common pathway. Since loss of RFR may represent a risk factor for acute or chronic kidney injury, hypertensive patients with blunted RFR might need a more careful renal follow-up. [ABSTRACT FROM AUTHOR]

The patterns of left ventricular (LV) remodeling in aortic stenosis (AS) are different in men and women. We aimed to assess whether there were also sex differences in measurements obtained on exercise testing. Echocardiography and ETT (modified Bruce) were performed at presentation in 316 patients with moderate or severe AS. An early rapid rise in heart rate (RR-HR) during ETT was defined as achieving at least 85% of target heart rate or ≥50% increase from baseline within the first 6 min. Mean age was 66 ± 12 years in men (n = 212) and 65 ± 12 years in women (n = 104) (p = NS). Men walked longer than women on the treadmill (10.4 ± 4.3 vs. 8.2 ± 4.2 min, p < 0.001) and achieved higher METs (9.2 ± 4.5 vs. 7.6 ± 4.3, p < 0.001), but both sexes achieved similar levels of peak heart rate and blood pressure. During a mean follow up of 34.9 ± 34.6 months, 29 deaths occurred (20 in men and 9 in women, p = 0.821). Age and body mass index were strong determinants of lower METs in men, but not in women, while Zva was a determinant in women but not in men. RR-HR was a strong determinant of lower METs in both sexes. Event-free survival was significantly lower in men with RR-HR but not in women. Exercise capacity was lower in women than men, and the determinants of exercise capacity differed. An RR-HR was a strong determinant of lower METs in both sexes, but predicted all-cause mortality only in men. • Women had lower exercise capacity than men but achieved similar peak heart rate and blood pressure. • Abnormal blood pressure responses and limiting symptoms occurred at similar frequencies in each sex. • A rapid early rise in heart rate (RR-HR) were strong determinants of lower METs in men and women. • A RR-HR was a powerful predictor of all-cause mortality only in men. [ABSTRACT FROM AUTHOR]

This research compared the physical and heart rate demands of three medium-sided games with the same number of players per team (six) but different playing areas throughout four successive working periods. The two games played in relatively larger areas (large and medium) were performed with regular goals and goalkeepers, so the most reduced game (short) was performed without goals. Nine professional soccer players participated in this study. Meaningful differences were found (p

People with schizophrenia die on average 15–20 years earlier than age and gender matched controls in the general population. An essential part of this excess mortality in people with schizophrenia is caused by physical illnesses. Among the physical illnesses, cardiovascular disease (CVD) has been identified as the most common natural cause of death in up to 40–45% of the cases. Chronotropic incompetence (CI) is defined as the inability of the heart to increase its beating frequency in proportion to increased physical activity or higher metabolic demand. It is an established independent cardiovascular risk factor for major cardiac events and overall mortality and might explain adaptation intolerance of the cardiovascular system to even minor exercise courses. CI needs objective exercise testing for definitive diagnosis and therefore represents a biological marker indicating the integrity of the cardiovascular system. It was recently described in patients with schizophrenia and might help explain the reduced physical fitness in these patients and the inability of a subgroup of patients to benefit from exercise interventions. In this study, we tried to replicate the occurrence of CI in an independent sample of patients with schizophrenia and evaluated whether CI can be influenced by a continuous endurance training of 12 weeks. Therefore, we re-analyzed the fitness testing data of 43 patients with schizophrenia and 22 aged and gender matched healthy controls. Parameters of aerobic fitness and chronotropic response to exercise were calculated. Patients with schizophrenia were less physically fit than the healthy controls and displayed a significantly higher heart rate at rest. 10 of 43 patients with schizophrenia and no healthy control subject were classified as chronotropically incompetent. Chronotropic response to exercise did not change significantly after 12 weeks of continuous aerobic exercise training. No differences were observed for baseline heart rate and peak heart rate in both subgroups of schizophrenia patients. Aerobic fitness did not improve significantly in the patients with schizophrenia classified as chronotropically incompetent. Our results confirm the occurrence of CI in patients with multi-episode schizophrenia. This should be taken into account when planning an exercise or lifestyle intervention studies in this population. Schizophrenia patients with CI do not seem to benefit as well as schizophrenia patients without CI from aerobic exercise training interventions. Larger, prospective randomized controlled clinical trials with different training interventions are urgently needed to address the topic of schizophrenia patients not responding to exercise and the relationship to the illness itself.

Background: Impaired exercise capacity is a common feature of congenital heart disease (CHD). In adults with CHD, it has been shown that impaired heart rate response during exercise may contribute to exercise limitation. Systematic data in children and adolescents on this topic is limited. We therefore purposed to assess heart rate response during treadmill exercise testing in children and adolescents with CHD compared to healthy controls.Methods: One hundred and sixty three children and adolescents (103 with CHD, median age 15 years and 60 age-matched controls) performed cardiopulmonary exercise testing and were included in this study. Beyond peak oxygen consumption, increase in heart rate from resting level to peak exercise (heart rate reserve) and decrease of heart rate after peak exercise (heart rate recovery) were measured. Chronotropic index was defined as percentage of age predicted maximal heart rate reserve. According to data from adults on bicycle exercise, chronotropic incompetence was assumed for chronotropic index below 0.8.Results: While resting heart rate was similar between both groups, peak heart rate, heart rate reserve as well as chronotropic index were lower in the CHD group than in controls. Chronotropic index was lowest in patients with single ventricle hemodynamics and correlated with peak oxygen consumption. Heart rate recovery was impaired in the CHD group 1 and 2 min after peak exercise compared to controls and correlated with peak oxygen consumption. Chronotropic index below 0.8 was a relatively frequent finding even in the control group suggesting that the threshold of 0.8 appears inadequate for the identification of chronotropic incompetence using treadmill exercise testing in children. After normalizing to the 2.5th chronotropic index percentile of the control group we obtained a chronotropic incompetence threshold of 0.69.Conclusion: As an adjunct to measurement of peak oxygen consumption, heart rate response to exercise appears to be a physiologically important diagnostic parameter in children and adolescents with CHD. However, interpretation of heart rate response needs to consider specific age characteristics and the mode of exercise test. Our data may help future studies on chronotropic incompetence using treadmill ergometer protocols in children and adolescents.

Purpose: To evaluate differences in side-effects and hemodynamic response between men and women undergoing regadenoson-stress SPECT myocardial perfusion imaging (MPI). Methods: The initial population of the study included 858 consecutive patients who underwent regadenoson-stress MPI at our institution. These patients underwent prospective assessment and classification of regadenoson-induced side-effects in six categories and recording of heart rate (HR) and blood pressure (BP) before and after regadenoson administration. From this initial population, after adjustment with 1:1 propensity matching using gender as the dependent variable and age, BMI, diabetes mellitus, hypertension, smoking, presence of coronary artery disease, LVEF, baseline systolic and diastolic blood pressure (BP) and HR, on-going use of cardio-active medications during test, and abnormal MPI scan as independent variables, a population of 279 pairs of opposite gender was formed and studied. Results: Compared with men, women had a significantly higher rate of any side-effect (71% vs. 58%, p = 0.002), chest pain (23% vs. 12%, p < 0.001), gastrointestinal discomfort (20% vs. 12%, p = 0.01), dizziness (12% vs. 5%, p = 0.002), and headache (20% vs. 13%, p = 0.03) and similar rates of dyspnea and other side-effects. Women demonstrated a higher median HR-response compared with men (41% (− 8, 127) vs. 34% (− 5, 106), p = 0.001) while men demonstrated a lower median systolic BP response (− 3% (− 27, 48) vs. 0% (− 36, 68), p = 0.02) compared with women. Conclusions: Gender is independently associated with a differential response to regadenoson with regard to overall side-effects and HR-response. These observations have the potential of important management and prognostic implications respectively. [ABSTRACT FROM AUTHOR]

Background: Although women with cardiovascular disease experience relatively worse outcomes as compared to men, substantial knowledge gaps remain regarding the unique female determinants of cardiovascular risk. Heart rate (HR) responses to vasodilator stress mirror autonomic activity and may carry important long-term prognostic information in women. Methods and results: Hemodynamic changes during adenosine stress were recorded in a total of 508 consecutive patients (104 women) undergoing clinically indicated 13N-ammonia Positron-Emission-Tomography (PET) at our institution. Following propensity matching, 202 patients (101 women, mean age 61.3 ± 12.6 years) were analyzed. During a median follow-up of 5.6 years, 97 patients had at least one cardiac event, including 17 cardiac deaths. Heart rate reserve (% HRR) during adenosine infusion was significantly higher in women as compared to men (23.8 ± 19.5 vs 17.3 ± 15.3, p = 0.009). A strong association between 10-year cardiovascular endpoints and a blunted HRR was observed in women, while this association was less pronounced in men. Accordingly, in women, but not in men, reduced HRR was selected as a strong predictor for adverse cardiovascular events in a Cox regression model fully adjusted for imaging findings and traditional risk factors (HR 2.41, 95% CI 1.23–4.75, p = 0.011). Receiver operating characteristics (ROC) curves revealed that a blunted HRR <21% was a powerful predictor for MACE in women with a sensitivity of 77% and a specificity of 68%. Conclusion: Blunted HRR to adenosine stress adds incremental prognostic value for long-term cardiovascular outcomes in women beyond that provided by traditional risk factors and imaging findings. [ABSTRACT FROM AUTHOR]

Resting heart rate (HR) plus 20 or 30 beats per minute (bpm), i.e., a simplified substitute for HR at the anaerobic threshold (AT), is used as a tool for exercise prescription without cardiopulmonary exercise testing data. While resting HR plus 20 bpm is recommended for patients undergoing beta-blocker therapy, the effects of specific beta blockers on HR response to exercise up to the AT (ΔAT HR) in patients with subacute myocardial infarction (MI) are unclear. This study examined whether carvedilol treatment affects ΔAT HR in subacute MI patients. MI patients were divided into two age- and sex-matched groups [carvedilol (+), n = 66; carvedilol (−), n = 66]. All patients underwent cardiopulmonary exercise testing at 1 month after MI onset. ΔAT HR was calculated by subtracting resting HR from HR at AT. ΔAT HR did not differ significantly between the carvedilol (+) and carvedilol (−) groups (35.64 ± 9.65 vs. 34.67 ± 11.68, P = 0.604). Multiple regression analysis revealed that old age and heart failure after MI were significant predictors of lower ΔAT HR (P = 0.039 and P = 0.013, respectively), but not carvedilol treatment. Our results indicate that carvedilol treatment does not affect ΔAT HR in subacute MI patients. Therefore, exercise prescription based on HR plus 30 bpm may be feasible in this patient population, regardless of carvedilol use, without gas-exchange analysis data. [ABSTRACT FROM AUTHOR]

Background: In asymptomatic end-stage renal disease (ESRD) patients undergoing vasodilator stress myocardial perfusion imaging (MPI) prior to renal transplantation (RT), the impact of pre-transplant heart rate response (HRR) to vasodilator stress on post-RT outcomes is unknown.Methods: We analyzed a retrospective cohort of asymptomatic patients with ESRD who underwent a vasodilator stress SPECT-MPI and subsequently received RT. Blunted HRR was defined as HRR <28% for regadenoson stress and <20% for adenosine stress. The primary endpoint was major adverse cardiac events (MACE), defined as cardiac death or myocardial infarction. Clinical risk was assessed using the sum of risk factors set forth by the AHA/ACCF consensus statement on the assessment of RT candidates.Results: Among 352 subjects, 140 had an abnormal pre-transplant HRR. During a mean follow-up of 3.2 ± 2.0 years, 85 (24%) MACEs were observed. Blunted HRR was associated with increased MACE risk (hazard ratio 1.72; 95% confidence interval 1.12-2.63, P = 0.013), and remained significant after adjustment for gender, sum of AHA/ACCF risk factors, summed stress score, baseline heart rate, and β-blocker use. HRR was predictive of MACE in patients with normal MPI and irrespective of clinical risk. Blunted HRR was associated with a significant increase in post-operative (30-day) MACE risk (17.9% vs 8.5%; P = 0.009).Conclusion: In asymptomatic ESRD patients being evaluated for RT, a blunted pre-transplant HRR was predictive of post-RT MACE. HRR may be a valuable tool in the risk assessment of RT candidates. [ABSTRACT FROM AUTHOR]

People with schizophrenia die on average 15–20 years earlier than age and gender matched controls in the general population. An essential part of this excess mortality in people with schizophrenia is caused by physical illnesses. Among the physical illnesses, cardiovascular disease (CVD) has been identified as the most common natural cause of death in up to 40–45% of the cases. Chronotropic incompetence (CI) is defined as the inability of the heart to increase its beating frequency in proportion to increased physical activity or higher metabolic demand. It is an established independent cardiovascular risk factor for major cardiac events and overall mortality and might explain adaptation intolerance of the cardiovascular system to even minor exercise courses. CI needs objective exercise testing for definitive diagnosis and therefore represents a biological marker indicating the integrity of the cardiovascular system. It was recently described in patients with schizophrenia and might help explain the reduced physical fitness in these patients and the inability of a subgroup of patients to benefit from exercise interventions. In this study, we tried to replicate the occurrence of CI in an independent sample of patients with schizophrenia and evaluated whether CI can be influenced by a continuous endurance training of 12 weeks. Therefore, we re-analyzed the fitness testing data of 43 patients with schizophrenia and 22 aged and gender matched healthy controls. Parameters of aerobic fitness and chronotropic response to exercise were calculated. Patients with schizophrenia were less physically fit than the healthy controls and displayed a significantly higher heart rate at rest. 10 of 43 patients with schizophrenia and no healthy control subject were classified as chronotropically incompetent. Chronotropic response to exercise did not change significantly after 12 weeks of continuous aerobic exercise training. No differences were observed for baseline heart rate and peak heart rate in both subgroups of schizophrenia patients. Aerobic fitness did not improve significantly in the patients with schizophrenia classified as chronotropically incompetent. Our results confirm the occurrence of CI in patients with multi-episode schizophrenia. This should be taken into account when planning an exercise or lifestyle intervention studies in this population. Schizophrenia patients with CI do not seem to benefit as well as schizophrenia patients without CI from aerobic exercise training interventions. Larger, prospective randomized controlled clinical trials with different training interventions are urgently needed to address the topic of schizophrenia patients not responding to exercise and the relationship to the illness itself. [ABSTRACT FROM AUTHOR]

Background: Usage of wrist-worn activity monitors has rapidly increased in recent years, and these devices are being used by both fitness enthusiasts and in clinical populations. We, therefore, assessed the test–retest reliability of the Polar Vantage M (PVM) watch when measuring heart rate (HR) during various treadmill exercise intensities. Methods: HR was measured every 30 s (simultaneous electrocardiography (ECG) and PVM). Test–retest reliability was determined using an intraclass correlation coefficient (ICC) with 95% confidence intervals (CIs). Standard error of measurement (SEM) and smallest real difference (SRD) were used to determine measurement variability. Results: A total of 29 participants completed the trials. ICC values for PVM during stages 1, 2 and 5 demonstrated good to excellent test–retest reliability (0.78, 0.78 and 0.92; 95% CI (0.54–0.90, 0.54–0.9, 0.79–0.97)). For PVM during stages 0 (rest), 3 and 4, the ICC values indicated poor to good reliability (0.42, 0.68 and 0.58; 95% CI (−0.27–0.73, 0.32–0.85, 0.14–0.80)). Conclusion: This study identified that the test–retest reliability of the PVM was comparable at low and high exercise intensities; however, it revealed a poor to good test–retest reliability at moderate intensities. The PVM should not be used in a clinical setting where monitoring of an accurate HR is crucial to the patients’ safety.

Several predator-prey systems are in flux as an indirect result of climate change. In the Arctic, earlier sea-ice loss is driving polar bears ( Ursus maritimus ) onto land when many colonial nesting seabirds are breeding. The result is a higher threat of nest predation for birds with potential limited ability to respond. We quantified heart rate change in a large common eider ( Somateria mollissima ) breeding colony in the Canadian Arctic to explore their adaptive capacity to keep pace with the increasing risk of egg predation by polar bears. Eiders displayed on average higher heart rates from baseline when polar bears were within their field of view. Moreover, eiders were insensitive to variation in the distance bears were to their nests, but exhibited mild bradycardia (lowered heart rate) the longer the eider was exposed to the bear given the hen's visibility. Results indicate that a limited ability to assess the risks posed by polar bears may result in long-term fitness consequences for eiders from the increasing frequency in interactions with this predator., Competing Interests: We declare we have no competing interests., (© 2023 The Authors.)

Background: Birth asphyxia, defined as 5-minute Apgar score <7 in apneic newborns, is a major cause of newborn mortality. Heart rate (HR) response to ventilation is considered an important indicator of effective resuscitation.Objectives: To describe the relationship between initial HR in apneic newborns, HR responses to ventilation and 24-h survival or death.Methods: In a Tanzanian hospital, data on all newborns ≥34 weeks gestational age resuscitated between June 2013-January 2017 were recorded using self-inflating bags containing sensors measuring ventilation parameters and expired CO2, dry-electrode electrocardiography sensors, and trained observers.Results: 757 newborns of gestational age 38 ± 2 weeks and birthweight 3131 ± 594 g were included; 706 survived and 51 died. Fetal HR abnormalities (abnormal, undetectable or not assessed) increased the risk of death almost 2-fold (RR = 1.77; CI: 1.07, 2.96, p = 0.027). For every beat/min increase in first detected HR after birth the risk of death was reduced by 2% (RR = 0.98; CI: 0.97, 0.99, p < 0.001). A decrease in HR to <100 beats/minute when ventilation was paused increased the risk of death almost 2-fold (RR = 1.76; CI: 0.96, 3.20, p = 0.066). An initial rapid increase in HR to >100 beats/min in response to treatment reduced the risk of dying by 75% (RR = 0.25; CI: 0.14, 0.44, p < 0.001). A 1% increase in expired CO2 was associated with 28% reduced risk of death (RR = 0.72; CI: 0.62,0.85, p < 0.001).Conclusions: The risk of death in apneic newborns can be predicted by the fetal HR (absent or abnormal), initial newborn HR (bradycardia), and the HR response to ventilation. These findings stress the importance of reliable fetal HR monitoring during labor and providing effective ventilation following birth to enhance survival. [ABSTRACT FROM AUTHOR]