Increase In Heart Rate Research Articles

Chinese elderly's thermo-physiological responses to transient temperature during showering process in winter: Evidence at a nursing home in Chongqing

Showering in winter was a transitional process with a significant rise and drop in temperature as the naked body was exposed to hot water and cold air. It can cause sudden changes in the elderly's thermo-physiology, posing a risk to their physical health due to decreased cardiovascular and thermoregulatory adaptability. To investigate the elderly's thermo-physiological responses to transient temperature during showering in winter, 15 elderly subjects over the age of 60 and 5 younger adults were recruited for a field study at a nursing home in Chongqing. Showering water and bathroom air temperature were monitored. Heart rate, blood pressure and skin temperature were measured using physiological wrist and attached sensors. The variability of thermo-physiological indices was proposed as an indicator to evaluate the effects of transient temperature. The results showed that the temperature difference between water and air ranged from 7.4 to 26.2°C. Every 10°C difference in temperature caused a 10% increase in heart rate, 4% in diastolic blood pressure, and 1% in skin temperature. Thermo-physiological asymmetry between hot and cold stimuli was under 15%. This research can provide references for research on thermo-physiology in transient temperatures and the creation of healthy and intelligent bathroom environments for the elderly.

Hemodynamic analysis of blood flow restriction training: a systematic review

Blood Flow Restriction Training (BFRT) is a low-load training technique that involves applying pressure to partially restrict arterial blood flow while occluding venous return. Despite its growing popularity, there is still no consensus on how combining BFRT with resistance or aerobic training influences hemodynamic responses, or on the safest and most effective methods for implementing it. This review aims to systematically identify the effects of BFRT on hemodynamic parameters. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement guidelines. The Chinese literature search was performed in the China National Knowledge Infrastructure (CNKI) database. English literature search was conducted in the Web of Science, PubMed, and Google Scholar databases. The studies included human subjects, the outcome indicators included hemodynamic evaluation indicators, and only randomized controlled trials and randomized crossover trials were considered. Non-Chinese or English literature, duplicate studies, and those with missing data were excluded. The adapted STROBE checklist was used to assess the risk of bias, 44 articles were included in this review. Results indicated that BFRT has increased heart rate and blood lactate levels, while its effect on blood oxygen saturation varies. Additionally, BFRT significantly enhances cardiac output but may either have no significant effect or cause a decrease in stroke volume. Furthermore, BFRT improves pulse wave velocity from the femur to the posterior tibia, suggesting a positive influence on cardiovascular function. BFRT induces changes in arterial structure and function, with these indicators interacting to produce both positive and negative effects on cardiovascular health. The primary mechanisms by which BFRT influences hemodynamics include the activation of the sympathetic and vagus nerves, as well as the regulation of chemical mediators in body fluids that modulate cardiovascular function. Convenient, economical, non-invasive, and easily measurable hemodynamic indicators are expected to become an efficient tool for evaluating the effects of exercise training. Further research is needed to establish the optimal compression thresholds and durations for different populations and exercise types, as well as to assess the long-term impact of BFRT on hemodynamic parameters.

Long-term dietary allyl isothiocyanate, a TRPA1 agonist, ameliorates cardiac fibrosis and diastolic dysfunction in aged mice.

Transient receptor potential ankyrin 1 (TRPA1) is a sensory channel expressed in vagal afferent nerves that detect noxious stimuli. Trpa1 knockout accelerates age-related cardiac fibrosis and dysfunction in mice. This study investigated whether TRPA1 activation with its selective agonist, allyl isothiocyanate (AITC), prevents cardiac aging. Male and female 18-month-old C57BL/6J mice were randomized to receive either a control diet or a diet containing 15mg of AITC per kilogram of food for 6months. At 24months, aged mice on the control diet exhibited increased left ventricular wall thickness but maintained similar left ventricular volume and preserved systolic function compared to 18-month-old middle-aged mice. Additionally, aged mice on a control diet developed restrictive-like cardiomyopathy, characterized by a pathologically elevated E/A ratio. AITC treatment significantly improved diastolic function by normalizing the E/A ratio (P < 0.01) and shortening isovolumetric relaxation time (P < 0.01), without affecting left ventricular wall thickness, volume, or systolic function. Electrocardiographic analysis demonstrated that AITC treatment significantly increased heart rate variability (P < 0.01) and parasympathetic nervous system index (P < 0.05), indicating enhanced vagal activity. Histological analyses revealed decreased cardiac fibrosis and collagen I/III deposition in AITC-treated mice (all P < 0.01). Proteomics analysis demonstrated that differentially expressed proteins in myocardial tissue were mainly enriched in pathways of collagen metabolism, extracellular matrix-receptor interaction, and fatty acid metabolism. These findings suggest that long-term dietary AITC may improve vagal tone, reduce cardiac fibrosis, and enhance diastolic function in aged mice, potentially through TRPA1 activation. TRPA1 could be a promising therapeutic target for age-related diastolic dysfunction.

Conceptualizing Personality as Individualized Allostasis: Exploring a Balanced Measure of Personality for Psychotherapy/Psychophysiology Integration.

Homeostatic balance provides a conceptual foundation for personality, and balance is a key concept in psychotherapy and psychophysiology. For example, both extreme fear and the absence of fear are considered pathological in both psychotherapy and psychophysiology, whereas a moderate, balanced fear response predicts healthier outcomes. In terms of measurement, however, personality is typically measured using a unipolar approach with more extreme scores (typically higher) indicative of better functioning. The purpose of the present study was to examine whether a moderate, balanced approach to measurement, or individualized allostasis, might better capture healthy functioning. To assess balanced functioning, the Assessment of Schema Adaptability Profile - Revised (ASAP-R) was used, and wellbeing was assessed using the Depression, Anxiety, and Stress scale (DASS) and heart rate variability (HF HRV and RMSSD). The IPIP NEO 120 was used to assess the Big 5 model of personality. Moderate responding on the ASAP-R was related to less self-reported depressive symptoms on the DASS, and increased heart rate variability (HF HRV and RMSSD). Developing personality measures designed to assess moderate responding may be beneficial in the context of psychotherapy/psychophysiology integration.

INTRAVENOUS VERSUS INTRANASAL DEXMEDETOMIDINE: A COMPARATIVE ANALYSIS OF HEMODYNAMIC RESPONSES DURING LARYNGOSCOPY AND ENDOTRACHEAL INTUBATION

Objectives: Laryngoscopy and intubation causes a profound sympathetic response, causing significant increase in heart rate (HR) and blood pressure, potentially leading to complications like laryngospasm and bronchospasm, requiring close monitoring and expert anesthesia care. This study evaluated intranasal and intravenous effectiveness of dexmedetomidine in mitigating adverse hemodynamic consequences to laryngoscopy and intubation, aiming to discern the optimal route for hemodynamic stability. Methods: This double-blinded, randomized study involved 72 adults (18–60 years, American Society of Anesthesiologists I/II) undergoing various surgeries requiring general anesthesia and endotracheal intubation. Group DIV received Inj. Dexmedetomidine 1 μg/kg intravenously as an infusion in 100 mL Normal Saline over 10 min, 40 min before induction of general anesthesia. Group DIN received Inj. Dexmedetomidine 2 μg/kg (1 μg/kg in each nostril) intranasally through atomizer 40 min before induction of general anesthesia. The study’s primary objective was to optimize dexmedetomidine’s route and dosage for minimizing laryngoscopy’s stress response. Secondary outcomes included assessing incidence of any adverse event. Results: Both study groups showed similar demographics, study duration, and baseline hemodynamics. Hemodynamic parameters decreased significantly 30–40 min post-administration of study drug and after induction (p&lt;0.05). Laryngoscopy and intubation increased HR and mean arterial pressure (MAP) where Group DIN HR (98.86±17.16 bpm), MAP (108.5±15.69 mmHg) showed more increase than Group DIV HR (88.89±9.23 bpm) and MAP (102.36±9.06 mmHg). Group DIV showed greater attenuation of hemodynamic parameters at 1, 3, and 5 min post-laryngoscopy (p&lt;0.05). Conclusion: Intravenous dexmedetomidine 1 μg/kg is more effective than intranasal dexmedetomidine 2 μg/kg in attenuating the hemodynamic stress response to laryngoscopy and intubation.

Benefits of Chronic Atrial Pacing in Fontan Physiology with Sinus Node Dysfunction and Preserved Ejection Fraction: Novel Therapeutic Approach for Failing Fontan.

Increased heart rate (HR) can reduce central venous pressure (CVP) in patients with preserved ventricular systolic function. We aimed to investigate whether this theory works in failing Fontan physiology. Pacemaker implantation (PMI) was performed in six Fontan patients (age: 6-40years) with sinus node dysfunction (SND) without junctional rhythm (JR). Baseline median (interquartile [IQR]) values of CVP, ventricular end-diastolic pressure (EDP), and ejection fraction (EF) were 12 (11-15) mmHg, 13 (10-16) mmHg, and 57% (53%-64%), respectively. Before PMI, the relationships among HR, cardiac index (L/min/m2), CVP, and EDP were evaluated using atrial pacing. Additionally, we assessed chronic changes in hemodynamics and hepatorenal function after PMI. During baseline catheterization, HR was 51 (40-58) bpm. Atrial pacing was initiated at 60 (60-63) bpm and increased to 85 (80-93) bpm. Reductions were observed in CVP (from 12 [11-15] to 9 [8-11] mmHg, p < 0.05), EDP (from 13 [10-16] to 8 [6-8] mmHg), and an increase in cardiac index (from 2.7 [2.3-3.0] to 3.4 [3.2-4.1] L/min/m2). After 1year of PMI with HR of 80 (70-83) bpm, sustained improvements were observed, including reductions in CVP (from 12 [11-15] to 10 [9-11] mmHg, p < 0.05), EDP (from 13 [10-16] to 9 [4-9] mmHg, p = 0.06), and ventricular end-diastolic volume index (from 85 [76-98] to 67 [53-76] ml/m2, p < 0.05). Total bilirubin levels and renal resistive index also decreased (both p = 0.06). In conclusion, chronic atrial pacing therapy reduced CVP and ventricular volume in Fontan patients with preserved EF and SND, even in the absence of JR. Proactive PMI may prevent the progression of Fontan-associated end-organ dysfunction in these selected Fontan patients.

Understanding postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (PoTS) is a clinically significant condition affecting numerous patients across the UK. This article aims to enhance understanding and management strategies for registered nurses by exploring its pathophysiology, clinical presentations, diagnostic processes and treatment protocols. PoTS, characterised by an excessive increase in heart rate on standing, presents multifaceted symptoms impacting patients’ quality of life. Effective management requires a multidisciplinary approach encompassing pharmacological treatments, lifestyle modifications and psychological support. This review seeks to provide nurses with the knowledge to improve patient outcomes and advocate for holistic care

Noncontact evaluation of autonomic nervous system activity during exercise by using video analysis

IntroductionAutonomic nervous system activity (ANSA) plays a crucial role in the physical condition experienced during exercise and prolonged physical activity. In other words, ANSA is related to exercise performance and physical condition. Therefore, it is important to continuously monitor ANSA during high-intensity and sustained exercise. To this end, an uncomplicated and noncontact measurement system is preferable. Hence, in this study, we propose a method for the noncontact measurement of capillary contraction and dilation state, representative of ANSA, using a common commercial camera.MethodsSpecifically, we focused on alterations in the green value of facial video images, from which we derived the green-to-blue (G/B) ratio as an indicator of blood vessel dilation and contraction, and to facilitate assessment of their activity. We performed a validation experiment involving exercise tasks using an ergometer in 10 healthy adults (23 ± 1.6 years old). The G/B ratio shows the state of contraction and expansion of facial capillaries, and it was evaluated using heart rate as ground truth data of the fluctuation of autonomic nerve activity.ResultsWe observed an increase in heart rate with decreased G/B ratio during exercise in all subjects. Postexercise, the heart rate decreased but the G/B ratio increased.DiscussionDuring exercise, characterized by dominant sympathetic NSA, the G/B ratio decreased, and recovered after exercise when parasympathetic NSA was dominant. In this way, noncontact evaluation of ASNA was achieved by using the G/B ratio. In the future, this measurement system will be applied to functional tests for heat acclimation.

The Effect of Heart Rate on Quality of Life in Patients with Chronic Heart Failure

Introduction. Chronic heart failure (CHF) leads to a steady deterioration in the quality of life (QOL) and a decrease in exercise tolerance of patients. Numerous studies have confirmed the role of increased heart rate in worsening the prognosis of CHF — heart rate more than 75 bpm needs reduction to optimize the clinical status of patients.The purpose of the study is to analyze the effect of heart rate on QOL and exercise tolerance in patients with CHF with a low left ventricular ejection fraction.Materials and methods. A prospective comparative study was conducted. 80 patients (54 men and 26 women, verage age — (66.3±7.9) years) with postinfarction cardiosclerosis and sinus rhythm, with CHF II–III NYHA functional classes with an ejection fraction less than 40 % were examined.Results. Significantly better QOL indicators were noted in patients with heart rate 60–69 bpm. The lowest indicators of functional activity were noted at 55–59 bpm, and socio-psychological activity at 70–75 bpm. Exercise tolerance is higher in patients with a heart rate of 60–69 bpm, its lowest rates were noted at 70–75 bpm.Discussion. The optimal heart rate range determination in patients with postinfarction cardiosclerosis and CHF allows targeted titration of the β-blocker dosage, achieving an improvement in QOL and the clinical and functional status of patients.Conclusion. In patients with CHF careful selection of β-blockers and ivabradine therapy demonstrates the most optimal indicators of physical activity and QOL with a heart rate of 60–64 bpm and 65–69 bpm.

Pathophysiology and management of postural orthostatic tachycardia syndrome (POTS): A literature review.

Pathophysiology and management of postural orthostatic tachycardia syndrome (POTS): A literature review.

Tragus Nerve Stimulation Attenuates Postural Orthostatic Tachycardia Syndrome in Post COVID-19 Infection.

Postural orthostatic tachycardia syndrome (POTS) is characterized by symptoms of orthostatic intolerance and is frequently observed in post-COVID conditions. We conducted controlled, prospective, and randomized clinical trials to explore the potential therapeutic benefits of low-level tragus stimulation (LL-TS) in patients with POTS following COVID-19 infection. This study enrolled 57 participants with confirmed post-acute COVID-19 who had been diagnosed with POTS. The ear clip was attached to the right tragus of the patients for stimulation (20 Hz with a 1-ms duration) or sham stimulation. They were divided into two groups: the sham LL-TS group (sham stimulation, n = 26) and the LL-TS group (stimulation for 1 month, n = 31). LL-TS was performed 1 h twice daily for 1 month. Postural tachycardia was evaluated at baseline, 1-month visit, and 1-year visit. Heart rate variability (HRV) and plasma neuropeptide Y (NPY) were evaluated at respective time points. The mean age of participants was 31.9 ± 7.2 years (61.4% female). LL-TS significantly attenuated the increase in heart rate from supine to a 10-min stand, as well as the average and maximum heart rates after 1 month of treatment. LL-TS also significantly reduced NPY levels. In addition, LL-TS significantly increased the high frequency (HF), but decreased the low frequency (LF) and LF/HF ratio during the postural test (all p < 0.01). These effects persisted during the 1-year follow-up. LL-TS may be a promising therapeutic approach for attenuating autonomic imbalance in patients with POTS following COVID-19 infection.

High variability in the reproducibility of key hemodynamic responses to head-up tilt.

Increased blood pressure upon standing is considered a cardiovascular risk factor. We investigated the reproducibility of changes in aortic blood pressure, heart rate, stroke volume, cardiac output, and systemic vascular resistance during three passive head-up tilts (HUT) in 223 participants without cardiovascular medications (mean age 46 yr, BMI 28 kg/m2, 54% male). The median time gap between the first and the second HUT was 9 wk and the second and the third HUT was 4 wk. We utilized whole body impedance cardiography and radial artery tonometry as methods. The participants were divided into quartiles of the changes in each hemodynamic variable during the first HUT, and the reproducibility of these changes was tested during successive HUTs. During the first HUT, significant differences were present in all between-quartile comparisons (n = 6) of all variables. The differences persisted as follows: reduction of stroke volume in six out of six (6/6) between-quartile comparisons (P < 0.001), decrease in cardiac output (P < 0.001) and increase in heart rate in 5/6 comparisons (P < 0.001), change in systemic vascular resistance in 3/6 comparisons (P < 0.001), change in aortic systolic blood pressure in 1/6 comparisons (P = 0.043), and change in aortic diastolic blood pressure in none (P = 0.266). To conclude, the reproducibility of upright posture-induced changes is high for stroke volume, cardiac output, and heart rate, moderate for systemic vascular resistance, and modest for aortic blood pressure. Although an increase in blood pressure during upright posture may be a cardiovascular risk factor, this effect may be attributed to other underlying hemodynamic variables that exhibit more reproducible posture-related changes.NEW & NOTEWORTHY We examined the reproducibility of hemodynamic responses to three passive head-up tilts. The associated changes in stroke volume, cardiac output, and heart rate were highly reproducible. Systemic vascular resistance showed moderate reproducibility, whereas blood pressure changes during upright posture were modestly reproducible. If an exaggerated blood pressure response to upright posture is a cardiovascular risk factor, it is likely attributed to other hemodynamic variables that exhibit more reproducible posture-related changes.

In vivo effects of cardiomyocyte-specific β-1 blockade on afterload- and frequency-dependent cardiac performance.

Pharmacologic β-blockade is a well-established therapy for reducing adverse effects from sympathetic overactivity in cardiovascular diseases, such as heart failure. Despite decades of research efforts, in vivo cardiac functional studies using genetic animal models remain scant. We generated a mouse model of cardiomyocyte-specific deletion (cKO) of β-1 adrenergic receptor (ADRB1), the primary subtype expressed in cardiac myocytes, and demonstrated the role of ADRB1 in the maintenance of cardiac function at baseline and during exposure to increase in cardiac afterload by transient aortic occlusion and increasing heart rates (HRs) via atrial pacing. cKO hearts showed mildly depressed baseline left ventricular (LV) function, including slower HR, decreased contractility (dP/dt max/IP), and prolonged relaxation (Tau) in both sexes. Exposure to increased LV afterload depressed LV function in either genotype similarly; however, the functional recovery following the removal of the afterload was severely impaired in cKO hearts, whereas cardiac function was immediately normalized in wild-type (WT) hearts. When HR was altered from 400 to 700 beats/min, cKO hearts were deficient in HR-dependent improvement of cardiac contractility and relaxation, known as positive force-frequency relationship, that was evident in WT hearts. Enhanced phosphorylation of phospholamban by the HR increase was markedly blunted in cKO myocardium versus wild types, whereas CaMKII phosphorylation was comparable between the genotypes, suggesting the critical involvement of PKA. These results provide the first experimental evidence for the role of ADRB1 in cardiomyocytes for maintaining cardiac function at baseline and during acute stress, providing a clinical perspective relating to the management of patients on β-blockers.NEW & NOTEWORTHY Although the benefits of β-1 adrenergic receptor (ADRB1) blockade to cardiovascular disease are established, in vivo role for cardiomyocyte ADRB1 remains undetermined. Generating cardiomyocyte-specific ADRB1 knockout mice, we show that ADRB1 is pivotal to cardiac functional recovery from afterload elevation and heart rate-dependent functional enhancement as well as baseline performance. Our findings highlight the importance of cardiomyocyte ADRB1 in cardiac stress adaptability, which is of clinical importance in the management of patients on β-blockers.

Increased macrophages contribute to thyroid hormone-induced cardiac alterations in mice.

The heart is one of the main targets of thyroid hormone. Patients with hyperthyroidism, a disease with high incidence in the population, have increased arrhythmia risk and cardiac hypertrophy, which is an independent predictor of adverse cardiovascular outcomes. Recent research has revealed the essential roles of leukocytes in cardiac homeostasis and stress-induced responses. Here, we aimed to evaluate the role of immune cells in cardiac changes induced by elevated triiodothyronine (T3) levels. The hyperthyroid condition in mice was mimicked by daily injections (i.p.) of T3 (14 μg/100 g BW) for 7 or 14 days. Increased heart rate and cardiac mass observed after 7 days of T3 treatment was associated with enhanced myocardial population of neutrophils, dendritic cells, and inflammatory phenotypes of monocytes and macrophages, without circulating changes in these cells, as evaluated by flow cytometry. Invitro experiments demonstrated bias toward pro-inflammatory polarization in isolated bone marrow-derived macrophages (BMDM) in response to T3. Interestingly, depletion of macrophages in mice prevented hypertrophic heart growth, tachycardia, and increased gene expression of the pro-inflammatory cytokine interleukin-(IL)-6 caused by hyperthyroid condition. Together, these new findings indicate the involvement of macrophages in the cardiac changes promoted by higher T3 levels. Considering that sustained cardiac growth and tachycardia can potentially lead to heart failure, our results suggest that targeting macrophages might be a novel therapeutic approach for attenuating cardiac disorders caused by hyperthyroidism.

An adaptive protocol to assess physiological responses as a function of task demand in speech-in-noise testing.

Acoustic challenges impose demands on cognitive resources, known as listening effort (LE), which can substantially influence speech perception and communication. Standardized assessment protocols for monitoring LE are lacking, hindering the development of adaptive hearing assistive technology. We employed an adaptive protocol, including a speech-in-noise test and personalized definition of task demand, to assess LE and its physiological correlates. Features extracted from electroencephalogram, galvanic skin response, electrocardiogram, respiration, pupil dilation, and blood volume pulse responses were analyzed as a function of task demand in 21 healthy participants with normal hearing. Heightened sympathetic response was observed with higher task demand, evidenced by increased heart rate, blood pressure, and breath amplitude. Blood volume amplitude and breath amplitude exhibited higher sensitivity to changes in task demand. Notably, galvanic skin response showed higher amplitude during low task demand phases, indicating increased attention and engagement, aligning with findings from electroencephalogram signals and Lacey's attention theory. The analysis of a range of physiological signals, spanning cardiovascular, central, and autonomic domains, demonstrated effectiveness in comprehensively examining LE. Future research should explore additional levels and manipulations of task demand, as well as the influence of individual motivation and hearing sensitivity, to further validate these outcomes and enhance the development of adaptive hearing assistive technology.

The Relationship Between Blood Pressure and Heart Rate Response During Exercise Testing with Microcirculation Indices.

Hypertension is associated with changes in microcirculation, while increased blood pressure (BP) during exercise stress testing has been correlated with adverse outcomes. To evaluate the relationship of microcirculation with exercise BP response in hypertensive individuals. 105 hypertensive individuals underwent exercise stress testing and nail-fold videocapillaroscopy assessment, in order to evaluate the relationship of BP response to exercise with capillary density. A significant negative correlation between diastolic BP at 1-minute recovery and capillary density was revealed (Pearson's r = -0.365, p = 0.043). A significant negative correlation was also observed between capillary density and peak heart rate (HR) (Pearson's r = -0.364, p = 0.024) and HR increase from stage 1 to 2 (Pearson's r = -0.746, p = 0.013). Capillary rarefaction is associated with an abnormal BP and HR response to exercise, highlighting the role of microcirculation in BP regulation during exercise.

Exploring the relationship between sleep patterns, alcohol and other substances consumption in young adults: Insights from wearables and Mobile surveys in the National Consortium on alcohol and NeuroDevelopment in adolescence (NCANDA) cohort.

The use of psychotropic substances has negative short- and long-term health outcomes, including complex direct and indirect effects on sleep and sleep-cardiovascular function. Here, we investigate daily relationships between self-reported substance use and objective measures of sleep and sleep-related heart rate (HR) in community-dwelling young adults. Fifty-five healthy young adults (Mage=23.1±2.29 y, 30 female) in the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study completed a 28-day ecological momentary assessment protocol, including remote sleep and HR measurements via Fitbit devices, as well as daily app-based self-reports of alcohol and other substance use. A total of 1459days of data were collected. Caffeine was the most frequent substance used, followed by alcohol, cannabis, nicotine, and other drugs. The analysis showed that substance use was associated with delays in sleep start and end time, reduced sleep duration and efficiency, and increased wake after sleep onset. Increases in sleep heart rate were associated with prior-day alcohol use. Substance use negatively influences sleep and sleep HR. These preliminary data highlight the potential value of using remote multimodal data collection to investigate the daily relationships between substance use and sleep in young adults, in an ecological setting.

Role of endocannabinoid neurotransmission in the insular cortex on cardiovascular, autonomic and behavioral responses evoked by acute restraint stress in rats

Role of endocannabinoid neurotransmission in the insular cortex on cardiovascular, autonomic and behavioral responses evoked by acute restraint stress in rats

Cardiorespiratory Responses to Flywheel-Based Inertial Training Squats With Varying Moments of Inertia.

Mitchinson, CJ, Best, S, Caruso, J, and Bollinger, LM. Cardiorespiratory responses to flywheel-based inertial training squats with varying moments of inertia. J Strength Cond Res 39(3): 300-306, 2025-Flywheel-based inertial training (FIT) has gained popularity as a means to enhance muscle hypertrophy. Other applications, such as aerobic exercise training, remain unexplored. The aim of this study was to determine the cardiorespiratory responses to acute FIT with varying moments of inertia (MOIs). Overall, 20 (10 M, 10 F) healthy, physically active subjects underwent maximal graded exercise testing and completed 3 bouts of FIT exercise (1 familiarization session and 2 identical data collection sessions). Subjects completed quarter squats (60° peak knee flexion) at a pace of 50 squats·minute -1 until volitional fatigue. Flywheel-based inertial training MOI was increased by 0.005 kg·m 2 every 3 minutes until a final workload of 0.020 kg·m 2 . Heart rate and gas exchange data were collected continuously and averaged over the final 60 s of each stage. Data were analyzed by a linear mixed model. During the final testing session, there was a main effect of MOI to increase heart rate (HR), V̇ o2 , and RER. Men displayed greater oxygen consumption, but asimilar %V̇ o2 peak compared with women. We noted a significant inertia × sex interaction where RER tended to be lesser in women at higher MOI. In the final stage of exercise (MOI: 0.020 kg·m 2 ), HR and V̇ o2 were approximately 75-80 and 55% of peak, respectively, and RER was approximately 0.95-1.00. FIT quarter squats elicit moderate HR and V̇ o2 responses, but near-maximal RER suggests a novel metabolic training stimulus. This exercise may supersede thelactate threshold and may not be sustainable for prolonged times. The physiological and performance effects of training in this manner are unclear.

Interpersonal Physiological Synchrony During Dyadic Joint Action Is Increased by Task Novelty and Reduced by Social Anxiety.

Interpersonal physiological synchrony refers to the temporal coordination of autonomic states during social encounters. Previous studies indicate that physiologicalsynchrony may arise during nonverbal interactions. Nevertheless, the role played by contextual and individual factors in determining its emergence is understudied. In this work, we examined heart rate synchrony during a cooperative joint action task, exploring how task constraints, novelty, and behavioral synchrony influence physiological alignment. To achieve this, we periodically modulated task demands by alternating between peer-to-peer and leader-follower dynamics, as well as between complementary and imitative movements, and their combinations. Additionally, we assessed the role of individual differences by examining the impact of dyad members' Social Anxiety and Perspective Taking levels. We further investigated how task demands and personal traits shape the perceived quality of social interactions and subject-level heart rate variability. Our findings revealed a significant increase in physiological synchrony and a decrease in perceived interaction quality when participants switched to a novel task version (i.e., during switch blocks) compared to task repetition. Task switching was also associated with increased heart rate variability. Notably, Social Anxiety negatively predicted physiological synchrony, suggesting that more socially anxious dyads were less likely to achieve physiological alignment. However, no relationship was observed between physiological synchrony and task performance. Overall, our results suggest that physiological synchrony intensifies when dyads navigate the challenge of learning a novel task together, and that both contextual and individual aspects contribute to its emergence.