Handgrip Exercise Research Articles

The importance of rate controlling medication in the performance and outcome of dobutamine stress echocardiogram in assessing patients with suspected angina

Abstract Background Stress echocardiography (SE) had been recommended by the professional Societies in assessing patients with suspected angina. SE protocols are variable across hospitals and countries in the recommendation of the cessation of rate controlling medication (RCMx) prior to SE. Some expert opinion paper recommends the cessation of beta-receptor blockers (BB) and rate controlling calcium channel blockers 48 hrs prior to SE to improve diagnostic accuracy of the test. This can impact on the efficient management of SE waiting list in addition can result in haemodynamic rebound effect leading to accelerated angina or hypertension. Objective To investigate the efficacy of Dobutamine SE in a cohort of patients where the cessation of rate controlling medication has not been mandated, we reviewed our results over one year period in patients investigated for suspected coronary artery disease (CAD). Method Two hundred and twenty-seven consecutive patients underwent Dobutamine SE between January 2022 and January 2023 in a single centre. In addition to dobutamine the protocol allowed the administration of intravenous Atropine (maximum dose of 1.2mg), and "top up" handgrip exercise at the discretion of the performing cardiologist. We assessed the DSE outcome (positive vs negative), target (85% of maximum age predicted) heart rate (THR) and the achieved peak HR, in the two groups with RCMx and without (No-RCMx). We analysed the patients’ characteristics and 12 months outcome of a combined MACE of death, non-fatal MI, stroke, admission with angina, unplanned revascularisation. Results Of the 227 patients 59% were on No-RCMx (male 49%). 88% of the patients in the RCMx group were on BB and 12 % on other RCMx. The THR was achieved in 74% of the RCMx and 90% in No-RCMx groups p=0.001. Positive Dobutamine SE was observed in 49% (46/93) of patients on RCMx vs 28% (38/134) on No-RCMx (p=0.001). Patients who did not reach THR 41% (15/37) had positive Dobutamine SE compared to 36% (69/190) who reached THR (p=0.626). There was no difference between groups in the peak WMSI. Logistic regression analysis showed that THR is not an independent determinant of positive Dobutamine SE (OR: 1.3, 95% CI 0.47-3.59, p=0.611), but being on RCMx was (OR 2.03, 95% CI 1.06-3.91, p=0.034). The MACE rate was higher in patients where the THR was not achieved (10/37, 27.0%) vs those with THR achieved (12/190, 6.3%) p<0.0001; in both the RCMx (8/24, 33% vs 8/69, 12%, p=0.015) and No-RCMx (2/12, 15% vs 4/121, 3%; p=0.045) groups respectively. RCMx was a determinant of MACE (OR 3.67, 95% CI 1.04-13.02, p=0.043) Conclusion This retrospective analysis of Dobutamine SE data proved same efficacy in patients with and without RCMx investigated for suspected CAD. The use of RCMx proved to be a predictor of both SE and MACE outcome irrespective the achieved THR. Our data show that patients referred for Dobutamine SE on RCMx can continue without impact on the test accuracy.

Exploring stress echocardiography in coronary artery disease: insights from a tertiary echocardiography center

Abstract Background/ Introduction Stress echocardiography (SE) is an established functional test with high sensitivity and specificity for diagnosing obstructive coronary artery disease (CAD). Purpose The present study aimed to document the experience of a tertiary hospital’s echocardiography center in using dynamic echocardiography to assess myocardial ischemia. Methods The study was performed retrospectively, including all patients who underwent SE at our center from January 2021 to December 2021. The goal for each test was to reach 85% of the age-predicted maximal heart rate (HR) (220 minus the subject’s age). The adopted Dobutamine stress protocol involved a continuous intravenous infusion of Dobutamine in 3-minute increments, starting at 10μg/kg/min and gradually increasing to 50μg/kg/min. Handgrip exercises were typically used, along with a small dose of intravenous atropine (0.25mg, up to a maximum of 1 mg) if the endpoint was not reached. Parasternal and apical echocardiographic views were obtained at all stages, and a contrast agent was used when appropriate. All tests were conducted under continuous 12-lead electrocardiographic (ECG) monitoring. Results Out of the 323 subjects [mean age 63.5 ± 10.5 years, 221 males (68.4%)], 123 (38.0%) underwent testing due to suspected CAD symptoms, while the remaining subjects (200 / 62.0%) were tested to reassess known CAD (with or without previous intervention). Twenty-one (7.0%) subjects had a left ventricular ejection fraction (LVEF) ≤40% at rest. The maximum dose of dobutamine most commonly administered was 30 μg/kg/min [137 subjects, (43.0%)], and atropine was given in 51 subjects (16.0%). The target HR was achieved in 291 (90.0%) tests. Eighty-seven (27.0%) SEs utilized a contrast agent in all stages, while in 177 (55.0%) a contrast agent was administered only at rest and peak HR. Major complications, such as acute myocardial infarction or persistent ventricular tachycardia, occurred in 6 patients (1.8%). Specifically, 5 (1.5%) experienced transient ST-segment elevation during the test, and one patient had a lateral myocardial infarction with ST-segment elevation after the test. No allergic reactions were reported. In 226 (70.0%) tests, results were classified as "negative for ischemia up to the achieved HR". In the remaining tests, classified as "positive for ischemia" (97/30.0%), the mean wall motion score index (WMSI) at peak HR was 1.3 ± 0.2 with a mean peak-to-rest ΔWMSI of 0.1 ± 0.1 (Table 1). Conclusion Of all the SEs performed at our center with an indication for assessing myocardial ischemia, 30.0% were positive, while major complications occurred in 1.8% of the subjects.

Descriptive Epidemiology and Prognostic Significance of Diaphragm Thickness in the General Population: The Nagahama Study.

Diaphragm thickness is a potential marker of sarcopenia in addition to muscle mass and strength at extremities. We aimed to clarify the descriptive epidemiology and prognostic significance of diaphragm thickness in the general population. The study participants were 3324 community residents (mean age: 61.4 ± 12.8 years) who participated in a longitudinal cohort study. Clinical parameters were obtained during the follow-up survey of the study population. Diaphragm thickness was measured from B-mode ultrasound images obtained in a supine position. Clinical and physical factors independently associated with diaphragm thickness were assessed by a linear regression model and a causal mediation analysis. All-cause mortality was determined by reviewing residential registry records. Prognostic significance of diaphragm thickness for all-cause mortality was examined using a Cox proportional hazard model analysis. Diaphragm thickness was greater in men than women (end-expiration, β = 0.161, p < 0.001; end-inspiration, β = 0.156, p < 0.001) and associated with waist circumference (end-expiration, β = 0.259, p < 0.001; end-inspiration, β = 0.128, p < 0.001). Handgrip strength, smoking habit, insulin resistance and exercise habit were not associated with diaphragm thickness. Skeletal muscle mass index showed apparent association with diaphragm thickness, though this association was not observed after adjusting for waist circumference. Over a mean follow-up of 1686 days (15 358 person-years), there were 56 cases of all-cause mortality. Weak handgrip strength (hazard ratio = 0.95, p = 0.044) and low forced vital capacity (hazard ratio = 0.57, p = 0.045) were associated with all-cause mortality, though none of the diaphragm thickness parameters showed a significant association (thickness at end-expiration, p = 0.722; thickness at end-inspiration, p = 0.277; thickening fraction, p = 0.219). Waist circumference but not parameters of sarcopenia was independently associated with diaphragm thickness. Diaphragm thickness was not associated with all-cause mortality. Diaphragm thickness may not be a marker of systemic sarcopenia.

Exercise-induced dynamic mitral regurgitation is associated with outcomes in patients with ischaemic cardiomyopathy.

Ischaemic mitral regurgitation (MR) is a dynamic condition influenced by global and regional left ventricular remodelling as well as mitral valvular deformation. Exercise testing plays a substantial role in assessing the haemodynamic relevance of MR and is recommended by current guidelines. We aimed to assess the prevalence, haemodynamic consequences, and prognostic impact of dynamic MR using isometric handgrip exercise. Heart failure patients with ischaemic cardiomyopathy and at least mild MR who underwent handgrip echocardiography at the University Hospital Duesseldorf between January 2018 and September 2021 were enrolled. Patients were followed-up for 1year to assess a combined endpoint including all-cause mortality, heart failure hospitalization, mitral valve surgery/interventions, ventricular assist device implantation and heart transplantation. One hundred thirty-three patients with ischaemic cardiomyopathy were included (age 75±10years; 21% female; LVEF 35±9%). At rest, 70 patients (53%) presented with mild MR, 54 patients had moderate MR (41%), and 9 patients (7%) showed severe MR. Twenty-five patients (20%) with non-severe MR at rest, developed severe MR during handgrip exercise. Patients with dynamic MR had larger left atrial dimensions, increased wall motion score index and larger tenting area at rest. Multivariate analysis identified MR severity during exercise [HR 1.998 (1.367-2.938)] and exercise TAPSE [HR 0.913 (0.853-0.973)] as predictors of the combined endpoint. The haemodynamic changes provoked by isometric exercise unmasked dynamic severe MR in a significant number of patients with non-severe MR at rest. These data may have implications for therapeutic decision-making in symptomatic patients with non-severe MR at rest.

Two-week Paramedic Hospital Training Augments Blood Pressure Response to Isometric Handgrip Exercise in Healthy Young Men.

Persistent stressful situations can have detrimental cardiovascular effects; however, effects on the blood pressure (BP) response to exercise have not been fully examined. This study investigated the impact of a 2-week stressful situation on the exercise pressor response. Eight healthy male university paramedic trainees underwent a 2-week paramedic hospital training and a control period study. Pre- and post-intervention, BP responses to the exercise test (2-min submaximal isometric handgrip [IHG] exercise followed by post-exercise muscle ischemia [PEMI]) and cold pressure test (CPT) were assessed. A stress biomarker, salivary alpha-amylase (sAA) activity, significantly increased after hospital training (Pre: 8.8 ± 4.6; Post: 15.5 ± 7.3 kU/L; P = 0.036), whereas no significant changes were observed in the control period (Pre: 11.3 ± 3.6; Post: 10.4 ± 4.5 kU/L). Although no significant trial (hospital training vs. control)-by-intervention (pre- vs. post-2-week period) interactions were detected in the mean arterial pressure (MAP) response to PEMI or CPT, a significant interaction in the MAP response to IHG exercise was noted (Δ48.9 ± 11.2 to Δ55.5 ± 9.1 mmHg, hospital training; Δ53.2 ± 14.1 to Δ51.2 ± 11.9 mmHg, control; P = 0.035). Consequently, changes in the sAA and MAP pre-intervention to post-intervention showed a significant correlation (τ = 0.397, P = 0.036). Results showed that stressful paramedic hospital training augmented BP response to IHG exercise. This suggests that prolonged stressful situations increase pressor response to exercise, particularly in cases involving healthy young men.

The role of sympathetic control in bone vasculature: insights from spinal cord injury.

Bone vasculature is richly innervated by an extensive network of sympathetic nerves. However, our understanding of bone blood flow regulation and its contribution to human bone health is limited. Here, we further our previous findings by characterizing bone vascular responses in the absence of sympathetic control - studying individuals with spinal cord injury (SCI), a population with known peripheral sympathetic disruption. We assessed tibial vascular responses to isometric handgrip exercise (IHE) in individuals with SCI (n = 12) and controls (n = 12). When sustained to fatigue, IHE increases perfusion pressure and sympathetic vasoconstriction in the non-active tissues of the legs. During IHE, we measured blood pressure, whole leg blood velocity via ultrasound, and tibial perfusion (as hemoglobin content) via near-infrared spectroscopy. Controls demonstrated active sympathetic vasoconstriction in the whole leg (i.e., increased vascular resistance, arterial pressure/leg blood velocity) and tibia (i.e., decreased hemoglobin). In contrast, SCI individuals demonstrated modest whole leg vasoconstriction with lesser increases in vascular resistance than controls (P<.04). Tibial vasculature evidenced absent or blunted vasoconstriction compared to controls (P<.01), indicated by increasing tibial hemoglobin until plateauing at higher pressure levels. This suggests that, in the absence of sympathetic control, tibial vascular response may involve other regulatory mechanisms like myogenic vasoconstriction. Lastly, we leveraged existent whole-body Dual Energy X-ray Absorptiometry scans in a subgroup of nine individuals with SCI and we found a strong relationship between leg bone mineral density (BMD) and tibial hemoglobin at end of IHE (r2 = 0.67, P<.01). Our findings indicate that in the absence of sympathetic mechanisms, myogenic control may play a compensatory role in regulating blood flow, though to a lesser extent in bone compared to muscle. The close relationship between lesser declines in bone blood content and higher BMD underscores the link between blood flow and bone health.

Autonomic modulation with mindfulness-based stress reduction in chronic kidney disease: a randomized controlled trial.

Chronic kidney disease (CKD) is characterized by overactivation of the sympathetic nervous system (SNS) that leads to increased risk of cardiovascular disease. This study was conducted to evaluate the effects of a Mindfulness-Based Stress Reduction (MBSR) programme on SNS activity in CKD patients. Participants with CKD stages III-IV were randomized to the 8week MBSR programme or Health Enhancement Program (HEP; a structurally parallel, active control group). Intraneural measures of SNS activity directed to muscle [muscle sympathetic nerve activity (MSNA)] via microneurography was recorded at rest and during stress manoeuvres (mental arithmetic, handgrip exercise and cold pressor test). Data analyses were performed based on the intent-to-treat principle. In total, 29 participants (64±9years; 86% males) completed the intervention with 17 in the MBSR and 12 in the HEP groups. There was a significant Group (MBSR vs. HEP) by Time (baseline vs. post-intervention) interaction in MSNA reactivity to mental stress (P=0.029), with a significant reduction in the mean ∆MSNA over 3min of mental arithmetic at post-intervention (10.3±4.2-5.9±5.6 bursts/min, P<0.001; Hedges' g=-0.858, 95% confidence interval [-1.578, -0.167]), while no change was observed within the HEP group (P=0.818). Reduced ∆MSNA during handgrip exercise was also observed, while ∆MSNA during the cold pressor test and resting MSNA remained unchanged in both groups from baseline to post-intervention. In this randomized controlled trial, patients with CKD had a reduction of sympathetic reactivity during mental stress and static handgrip exercise following 8weeks of MBSR but not after HEP. Our findings demonstrate that mindfulness training is feasible and may have clinically beneficial effects on autonomic function in CKD. KEY POINTS: Question: Does the Mindfulness-Based Stress Reduction (MBSR) programme reduce sympathetic activity in patients with chronic kidney disease (CKD)? Finding: In this randomized controlled trial including 29 patients with CKD, 8weeks of MBSR decreased sympathetic reactivity to mental stress compared to the control Health Enhancement Program (HEP). Meaning: These finding suggest that mindfulness training may have clinically beneficial effects on autonomic function in CKD.

EJamar: A Novel Exergame Controller for Upper Limb Motor Rehabilitation

This work presents the design of a new game controller device and the development of two exergames (Peter Jumper and Andromeda) for upper limb rehabilitation. The eJamar controller is a novel electromechanical device designed to measure wrist and hand movements, such as pronation/supination, flexion/extension, and ulnar/radial deviation, enabling users to perform control actions in the exergames. One of eJamar’s most significant features is its ability to measure hand grip strength, a function not available in commercial gaming controllers. The exergame Peter Jumper involves a character jumping over obstacles in various environments, promoting hand grip exercises. The exergame Andromeda involves shooting enemy ships, promoting coordination between hand movements and grip strength, making it suitable for different rehabilitation techniques. A testing protocol was applied with eight healthy participants (5F and 3M), who completed a survey evaluating gameplay, usability, and satisfaction of the system. The results demonstrated that the developed exergames are intuitive and easy to play, with participants reporting that a therapist’s presence is not required for gameplay. Hence, it suggests that the developed system can improve the rehabilitation process, promoting wrist–arm movements and grasping actions.

Sympathetic Response to 1-Leg Cycling Exercise Predicts Exercise Capacity in Patients With Heart Failure With Preserved Ejection Fraction.

In heart failure, sympathetic excess and exercise intolerance impair quality of life. In heart failure with reduced ejection fraction, exercise stimulates a reflex increase in muscle sympathetic nerve activity (MSNA) that relates inversely to peak oxygen uptake (V̇O2peak). Whether similar sympathoexcitatory responses are present in heart failure with preserved EF (HFpEF) and relate to V̇O2peak are unknown. In 13 patients with HFpEF (70±6 years), 17 comorbidity-matched controls (CMC; 67±8 years), and 18 healthy controls (65±8 years), we measured heart rate, blood pressure, and MSNA (microneurography) during (1) 7-minute baseline; (2) 2-minute isometric handgrip (40% maximal voluntary contraction) or rhythmic handgrip (50% and 30% maximal voluntary contraction) exercise, followed by 2-minute postexercise circulatory occlusion; and (3) 4-minute 1-leg cycling (2 minutes each at mild and moderate intensity). V̇O2peak was obtained by open-circuit spirometry. Resting MSNA was higher and V̇O2peak was lower in HFpEF versus CMCs and healthy controls (all P<0.05). During handgrip, MSNA increased in all groups (all P<0.05); in HFpEF, MSNA was greater than CMCs and healthy controls during HG and postexercise circulatory occlusion at 40% isometric handgrip (all P<0.05) and HG only at 50% and 30% rhythmic handgrip (all P<0.05). During cycling, MSNA (bursts·min-1) decreased during mild (-4±4; P=0.01) and moderate (-8±6; P<0.001) cycling in healthy controls, was unchanged during mild (+1±7; P=0.42) and moderate (+2±8; P=0.28) cycling in CMCs, yet increased in HFpEF during mild (+8±8; P<0.001) and moderate (+9±10; P<0.001) cycling. In HFpEF, the change in MSNA during moderate cycling related inversely to relative (r=-0.72; R 2=0.51; P<0.01) and percent-predicted (r=-0.63; R 2=0.39; P=0.03) V̇O2peak. No statistically significant relationships were detected in controls (P>0.05). In contrast to CMCs, patients with HFpEF exhibit augmented MSNA at rest and during exercise. The magnitude of such paradoxical sympathoexcitation during dynamic cycling relates inversely to V̇O2peak, consistent with a neurogenic, vasoconstrictor limit on exercise capacity in HFpEF.

Lipoprotein(a) Is Elevated and Inversely Related to Coronary Endothelial Function in People With HIV.

HIV-associated cardiovascular disease (CVD) is increasing in prevalence. The mechanisms underlying the heightened cardiovascular risk faced by people with HIV (PWH), however, remain poorly defined. Recent studies indicate an important role of lipoprotein(a) (Lp[a]) in predicting CVD risk in the general population, but little is known regarding its role in HIV-associated CVD. Thus, we sought to evaluate whether Lp(a) is elevated in PWH and if it is associated with impaired coronary endothelial function (CEF), a known mediator of CVD in PWH. In this cross-sectional study, cardiac magnetic resonance imaging with isometric handgrip exercise, an endothelial dependent stressor, was performed to assess CEF in 65 PWH and 52 controls without HIV. Percent changes in coronary cross-sectional area and coronary blood flow from rest to stress were used to quantify CEF. Lp(a) levels were assessed by immunoturbidimetric assay at the time of magnetic resonance imaging. Lp(a) levels were higher in PWH compared with controls (78 nmol/L [39-137 nmol/L] versus 45.5 nmol/L [18-102.5 nmol/L], P<0.01). Both percent change in coronary cross-sectional area (0.38% [-6.1% to 5.4%] versus 7.43% [2.4%-11.2%], P<0.0005) and coronary blood flow (9.1% [-1.3% to 23.1%] versus 24.1% [3.3%-39.8%], P<0.05) were lower in PWH compared with controls. In PWH, Lp(a) was inversely associated with percent change in coronary cross-sectional area (β=-6.18±1.01%/nmol/L, P<0.001) but not with percent change in coronary blood flow even after adjustment for confounding risk factors. No association between Lp(a) and measures of CEF was observed in individuals without HIV. Lp(a) concentrations are elevated in PWH and inversely related to CEF in PWH.

The relationship between muscle sympathetic nerve activity and serum fatty acid binding protein 4 at rest and during isometric handgrip exercise.

Fatty acid binding protein 4 (FABP4) is highly expressed in adipocytes. Lipolysis, caused by an elevated adrenergic input, has been suggested to contribute to elevated serum FABP4 levels in patients with cardiovascular diseases. However, the relationship between the serum FABP4 and efferent sympathetic nerve activity remains poorly understood. Twenty-one healthy subjects (average age, 29.1 years; 15 men) performed an isometric handgrip (HG) exercise at 30% of the maximal voluntary contraction until they were fatigued. The beat-by-beat heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) were recorded. Blood samples were collected at rest and at the time of peak fatigue. The MSNA, HR, and systolic BP were significantly increased by the HG exercise (all, p < 0.05). MSNA was obtained from 14 patients. The change in the FABP4 on HG exercise was significantly correlated with the change in MSNA (bursts/100 heartbeats) (R = 0.808, p < 0.001) but not with changes in other parameters, which might, in part, reflect an association of efferent sympathetic drive with FABP4. Meanwhile, resting FABP4 levels were not associated with any parameters including MSNA, in healthy individuals. Future studies on patients with elevated sympathetic activity are warranted to examine the relationship further.

The Efficacy of Ischemic Preconditioning on Handgrip Strength and Strength Endurance in Para-Athletes With Spinal-Cord Injury: A Pilot Study.

This pilot study investigated the functional outcomes after ischemic preconditioning (IPC) in high-level para-athletes with spinal-cord injury. Nine athletes completed 2 handgrip exercise trials (an isometric hold to failure at 60% maximal voluntary contraction [ISO] and a progressive, intermittent handgrip to failure [INT]), preceded by either IPC (220mm Hg) or sham (20mm Hg) for six 5-minute periods, in a repeated-measures, crossover design. Although small performance improvements in time to task failure were observed in the ISO (∼5%) and INT (∼8%) IPC conditions, which are similar to those reported elsewhere, no statistical influence was observed (ISO-IPC, 74.2 [32.6]s; SHAM, 70.7 [27.2]s; P = .73; INT-IPC, 426.0 [80.1]s; SHAM, 392.2 [42.5]s; P = .35). Fatigue was evident in the forearm muscle force (maximal voluntary contraction) ISO (mean decline of 178.1 [76.0]N [95% CI, -10.4 to 366.7N]; P < .05) and INT (mean decline of 182.2 [72.5]N [95% CI, 34.5-329.8N]; P < .05) trials but not different between treatments (P > .95). Although small performance improvements in time to task failure were observed, the findings of the present data set suggest that acute bouts of IPC do not meaningfully influence fatigue during handgrip exercise in para-athletes with spinal-cord injury.

Analisis Praktik Klinik Keperawatan pada Pasien St Elevasi Miokard Infark (STEMI) Anterior dengan Inovasi Intervensi Isometric Handgrip Exercise untuk Menurunkan Tekanan Darah

If hypertension is not treated for a long time, it will cause dangerous complications such as stroke, heart attack, heart failure, chronic kidney failure and eye damage (hypertensive retinopathy). One of the non-pharmacological treatments for hypertensive patients is by providing isometric handgrip exercise therapy. The aim of the research was to conduct an analysis of nursing clinical practice in anterior ST elevation myocardial infarction (STEMI) patients using the innovative intervention of isometric handgrip exercise to reduce blood pressure in the ICCU room at Aji Muhammad Parikesit Tenggarong District Hospital. This research method is a One-Shot Case Study, namely a research design where the researcher only carries out one treatment which is thought to have had an effect and then carries out a post-test. The patient in this study was 1 person with the characteristics of a patient diagnosed with a medical diagnosis of ACS Stemi who had high blood pressure. The results of the implementation of isometric handgrip exercise therapy to reduce blood pressure showed significant results during the 3 interventions in which blood pressure was reduced. The conclusion from the results of the analysis carried out showed that there was a change in blood pressure after being given the isometric handgrip exercise intervention

Investigating the Influence of Limb Blood Flow on Contraction-Induced Muscle Growth and the Impact of that Growth on Changes in Maximal Strength.

Changes in skeletal muscle size may be affected by resting blood flow (e.g., nutrient delivery) and this change in size is a hypothesized mechanism for changes in strength. To determine: 1) whether the relationship between isometric training and muscle growth depends on baseline blood flow or is mediated by a change in blood flow and 2) whether muscle growth mediates changes in maximal isometric strength. 179 participants were randomized into: low-intensity isometric handgrip exercise (LI), low-intensity isometric handgrip exercise with blood flow restriction (LI-BFR), maximal handgrip exercise (MAX), and a non-exercise control (CONTROL). Muscle thickness, strength, and resting limb blood flow were measured before and after the six-week intervention. Baseline blood flow did not moderate training effects on muscle thickness changes (MTHchg) (p = 0.666), and moderated mediation tests were non-significant. Although the LI-BFR group showed a significant effect on MTHchg (p = 0.018), MTHchg was not significantly related to handgrip strength change (HGchg) (p = 0.281), suggesting no mediation of the training-to-strength effect by MTHchg. Both the LI-BFR (p = 0.004) and MAX (p < 0.001) groups exhibited positive direct effects on HGchg compared to CONTROL. Furthermore, there were no differences between training groups and CONTROL on blood flow change (BFchg), BFchg and MTHchg were not significantly related, and neither BFchg nor MTHchg predicted HGchg, providing no evidence for mediated pathways. Muscle growth may not have occurred to an extent that would require vascular adaptation. Training maximally induced the greatest strength adaptations but was seemingly not driven by muscle growth.

Sex differences in the impact of ventricular-arterial coupling on left ventricular function in patients with hypertension.

Increased arterial stiffness elevates aortic load, which can have adverse impacts on left ventricular (LV) function and contribute to the onset of heart failure. This impact is known to be more pronounced in women. Optimal coordination between ventricular contraction and the arterial system is required to maintain efficient cardiac function. This study aimed to investigate sex differences in the impact of ventricular-arterial coupling (VAC) on LV function in patients with hypertension at rest and after handgrip exercise. Echocardiographic indexes of LV volumes, systolic function, and diastolic function were obtained in the usual way. Effective arterial elastance (EA) and index (EAI) were calculated from stroke volume measured using LV outflow waveform. Effective LV end-systolic elastance (ELV) and index (ELVI) were obtained using the single-beat method. Central aortic pressure waveform was recorded using the applanation tonometry. Characteristic impedance (Zc) of aortic root and reflection magnitude (RM) was calculated after Fourier transformation of both aortic pressure and flow waveforms. Sixty-four patients (31 women and 33 men) with hypertension were enrolled. Women showed higher ELVI (1.33±0.34 vs. 1.10±0.29 mmHg/ml∙m2, P = 0.004) and EAI (1.14±0.25 vs. 0.93±0.26 mmHg/ml∙m2, P = 0.001), but VAC was not different (women: 0.88±0.17 vs. men: 0.85±0.11, P = 0.431). Zc and RM were not different between women and men. After handgrip exercise, an increase in ELVI (P = 0.021) and a decrease in VAC (P = 0.035) were observed specifically in men, with no corresponding changes noted in women. In women, VAC was significantly associated with E' velocity (beta -0.344, P = 0.029) and left ventricular global longitudinal strain (beta 0.470, P = 0.012) after adjustment, but in men, no association was found. Hypertensive women demonstrated greater stiffness in both the left ventricle and arterial systems, along with impaired LV contractile reserve in response to handgrip exercise, as compared to men. The ventricular-arterial mismatch had a notable impact on LV diastolic and systolic dysfunction only in women, but not in men.

Limb-Specific Comparison of Flow-Mediated Dilation in Abdominal Obese Pre-menopausal Women

PurposeNormal aging can lead to arterial wall stiffening and development of atherosclerosis; however, the effects of overweight conditions can expedite the dysfunction of arterial health. In an earlier study, we identified in a group of abdominal obese pre-menopausal woman that during menses, these women had decreased vascular conductance of the brachial artery during dynamic hand-grip exercise. Endothelial function in abdominal obese (AO) premenopausal women could be associated with being highly sedentary which attenuates dilatory responses to FMD of both upper and lower limb vascular function. We hypothesized that the AO women would exhibit limb-specific differences in artery dilation with reduced dilation in the popliteal artery as compared to the brachial artery.MethodsArtery dilatory responses in the brachial and popliteal arteries were assessed using flow-mediated dilation (FMD) in age-matched sedentary controls and AO groups during menses.ResultsSignificant differences were found between groups including % BF, BMI, weight, waist to hip ratio, fasting blood glucose, and oxLDL. A between-group comparison revealed significantly lower percent dilation of the popliteal artery in AO participants compared to controls (p < 0.05) not present in the brachial arteries. Our results also indicate a difference in the time-to-peak (TP) of dilation between the control (33.38 ± 3.232) and AO (62.104 ± 5.813) groups (p < 0.01). Following FMD correction with shear rate as the covariate, significant differences in FMD between the brachial and popliteal artery were abolished.ConclusionWe conclude that young, AO women show a limb-specific difference in dilation of the upper and lower extremities when compared to controls. Thus, reductions in FMD of the popliteal artery could be due to impaired dilation of the downstream resistance vasculature preventing increases in shear within the leg conduit arteries not as significantly in the arms.

Regional cerebral perfusion and sympathetic activation during exercise in hypoxia and hypercapnia: preliminary insight into'Cushing's mechanism'.

We examined the interactive influence of hypoxia and exercise, and hypercapnia and exercise,on regional cerebral perfusion and sympathetic activation. Twenty healthy young adults (seven women) completed study trials including (1) rest in normoxia ( : ∼96%, : ∼36mmHg), normocapnic hypoxia ( : ∼84%, : ∼36mmHg), and normoxic hypercapnia ( : ∼98%, : ∼46mmHg) and (2) unilateral rhythmic handgrip exercise (45% of maximal voluntary contraction at 1Hz for 3min) under the same gas conditions. Based on the exercising arm, blood flow in the contralateral internal carotid (ICABF) and ipsilateral vertebral (VABF) arteries, anterior and posterior cerebral O2 delivery ( ), and muscle sympathetic nerve activity (MSNA) were measured in each trial. During exercise in hypoxia, ICABF, VABF, anterior and posterior were significantly lower, whereas total MSNA was significantly greater, than the sum of the responses evoked by either hypoxia or exercise alone. During exercise in hypercapnia, ICABF and anterior were significantly greater, whereas MSNA was lower, than the sum of the responses evoked by either hypercapnia or exercise alone. The VABF and posterior responses to hypercapnic exercise were not different from the summated responses. These findings suggest that the brain is hypoperfused and sympathetic outflow potentiated during hypoxic exercise, and that the brain is hyperperfused and sympathetic discharge constrained during hypercapnic exercise. The contrasting consequences for cerebral perfusion and sympathetic activation indicate a potential involvement of Cushing's mechanism in the autonomic control during exercise in healthy humans. KEY POINTS: Brain O2-demand and -supply are mismatched, and muscle sympathetic nerve activity (MSNA) is enhanced in humans exercising at high altitude; the link between the two phenomena remains elusive. We evaluated the isolated and interactive effects of exercise, hypoxia, and hypercapnia on blood flow in the internal carotid (ICABF) and vertebral (VABF) arteries, and MSNA. The interaction of hypoxia and exercise was hypo-additive for ICABF and VABF and anterior and posterior cerebral O2 delivery ( ), but hyper-additive for MSNA. The interaction of hypercapnia and exercise was hyper-additive for ICABF and anterior , additive for VABF and posterior , and hypo-additive for MSNA. These observations indicate that a suboptimal brain perfusion during hypoxic exercise coincides with a potentiated sympathetic outflow, while a (supra-)optimal brain perfusion during hypercapnic exercise coincides with a suppressed sympathetic outflow. Our findings suggest that Cushing's mechanism may play a role in the autonomic control in exercising humans.

Detecting muscle fatigue among community-dwelling senior adults with shape features of the probability density function of sEMG

BackgroundPhysical exercise is an important method for both the physical and mental health of the senior population. However, excessive exertion can lead to increased risks of falls, severe injuries, and diminished quality of life. Therefore, simple and effective methods for fatigue monitoring during exercise are highly desirable, particularly in community settings. The purpose of this study was to explore the possibility of real-time detection of exercise-induced fatigue using surface Electromyogram (sEMG) features, including the kurtosis and skewness of the Probability Density Function (PDF) in the community settings to solve the issues of low sensitivity and high computational complexity of commonly used sEMG features.MethodssEMG signals from six forearm muscles were recorded during hand grip tasks at 20% maximal voluntary contraction (MVC) task-to-failure contractions from 30 healthy community-dwelling elders at their respective community centers. PDF shape features of the sEMG, namely kurtosis and skewness, were computed from 25 s of non-fatigue stable phase and 25 s of fatigue data for comparison. Statistical tests were conducted to compare and test for the significance of these features. We further proposed a novel fatigue indicator, Temporal-Mean-Kurtosis (TMK) of channel-averaged kurtosis, to detect fatigue with relatively low computational complexity and adequate sensitivity in community settings. ANOVA and post-hoc analyses were performed to examine the performance of TMK.ResultsStatistically significant differences were found between the non-fatigue period and the fatigue period for both kurtosis and skewness, with increasing values when approaching fatigue. TMK was shown to be sensitive in detecting fatigue with respect to time with lower computational complexity than the Sample Entropy.ConclusionThis study investigated PDF shape features of sEMG signals during a handgrip exercise to identify muscle fatigue in older adults in community experiments. Results revealed significant changes in kurtosis upon fatigue, indicating that PDF shape features were suitable convenient detectors of muscle fatigue in community experiments. The proposed indicator, TMK, showed potential sensitivity in tracking muscle fatigue over time in community-based settings with limited computational complexity, highlighting the promise of sEMG’s PDF features in detecting muscle fatigue among the elderly.

Sex-based differences in the blood pressure responses to muscle metaboreflex activation are consistent between limb and respiratory muscle.

The purpose of this study was to compare sex-based differences in the mean arterial blood pressure (MAP) response to limb and inspiratory metaboreflex activation, during relative and absolute workloads. Healthy males (n = 9) and females (n = 8) completed pulmonary function testing, forearm volume and circumference measurements, and bouts of limb and inspiratory muscle exercise. The exercises performed included bouts of rhythmic handgrip exercise (RHG) and inspiratory pressure threshold loading (PTL) to task failure, performed in a randomized order and separated by 30 minutes of rest. Participants performed both RHG and PTL at predetermined relative (R) and absolute (A) workloads, while cardiopulmonary measurements were recorded continuously. A time-dependent rise in MAP was observed in all participants, regardless of sex, muscle, or workload (P < 0.001). MAP was greater in males than females during all exercise bouts regardless of muscle group or workload (P < 0.001). The change in MAP from baseline was also greater in males (R-RHG: Δ31 ± 12 mmHg; R-PTL: Δ31 ± 9; A-RHG: Δ35 ± 6; and A-PTL: Δ30 ± 7) than females (R-RHG: Δ21 ± 7 mmHg; R-PTL: Δ13 ± 7; A-RHG: Δ21 ± 7; and A-PTL: Δ14 ± 3) (P < 0.001). Results from this study show that when the forearm and diaphragm perform the same relative or absolute work, the blood pressure response is statistically similar, and both responses are greater in males than females. The findings from the present study suggest that the sex-based difference in the response to metaboreflex activation is similar between the limb and respiratory musculature.NEW & NOTEWORTHY With rhythmic handgrip exercise and inspiratory pressure threshold loading there was a time-dependent rise in the blood pressure that was significantly lower in females than males. The blunted blood pressure response in females was present whether handgrip or inspiratory workload was relative or absolute. An attenuated cardiovascular response to high levels of limb or respiratory muscle work may have implications for whole body exercise in health and disease.

Isometric handgrip versus aerobic exercise: a randomized trial evaluating central and ambulatory blood pressure outcomes in older hypertensive participants.

It remains unclear whether the hemodynamic effects of isometric handgrip exercise (IHG) are comparable to those of aerobic exercise (AE). This study investigated the efficacy of IHG in reducing central and ambulatory blood pressure in older hypertensive participants and compared its effects with AE. In a three-arm randomized controlled trial, 54 older hypertensive participants (age range: ≥60; mean age: 69 years) underwent 12 weeks of either IHG training (n = 17), AE training (n = 19), or were part of a no-exercise control group (n = 18). IHG participants engaged in bilateral handgrips using a digital device, four times for 2 min each at 30% of maximal voluntary contraction. AE participants undertook brisk walking and cycling exercises at moderate intensity for 30 min, thrice weekly. Baseline and postintervention measurements included resting office, central, and 24-h ambulatory blood pressures. Both IHG and AE interventions led to significant reductions in office and ambulatory systolic blood pressure compared to control group (P < 0.05 for both), with no marked difference in the magnitude of systolic blood pressure reductions between the two groups. Notably, the IHG group exhibited greater reductions in office, central, and ambulatory diastolic blood pressure compared to the AE group and control group. While both IHG and AE effectively lowered ambulatory systolic blood pressure, IHG demonstrated superior efficacy in reducing central and ambulatory diastolic blood pressure. Consequently, IHG training presents a promising alternative antihypertensive therapy for hypertensive participants over the age of 60.