Handgrip Exercise Research Articles

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

AbstractWe 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%, : ∼36 mmHg), normocapnic hypoxia (: ∼84%, : ∼36 mmHg), and normoxic hypercapnia (: ∼98%, : ∼46 mmHg) and (2) unilateral rhythmic handgrip exercise (45% of maximal voluntary contraction at 1 Hz for 3 min) 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. imageKey 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.

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

Objective: 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. Methods: 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. Results: 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. Conclusion: 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.

Prevalence, mechanisms and prognostic impact of dynamic mitral regurgitation unmasked by handgrip exercise in patients with hypokinetic non-dilated and dilated cardiomyopathy

Abstract Background Recent studies suggest that mitral regurgitation (MR) is a dynamic condition influenced by global and regional left ventricular (LV) remodeling as well as mitral valvular deformation. Exercise testing plays a substantial role in assessing the hemodynamic relevance of MR and is recommended by current guidelines. Handgrip exercise may serve as alternative exercise intervention to bicycle exercise, as it is easy to perform even bedside. However, there are no data yet, on the prevalence, mechanisms and prognostic impact of dynamic MR in patients with dilated cardiomyopathy using isometric exercise testing. Aims We aimed to assess the prevalence, hemodynamic consequences, and prognostic impact of exercise-induced changes in MR in patients with hypokinetic non-dilated and dilated cardiomyopathy. Methods Patients with hypokinetic non-dilated and dilated 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 one year to assess clinical outcomes. We assessed all-cause mortality, HF-associated hospitalizations, MV surgery, transcatheter edge-to-edge repair (TEER), left ventricular assist device implantation and heart transplantation during follow-up. Results Fifty-eight patients were included (mean age 70±15 years; 41% female; mean LVEF 37±10%). At rest, 28 patients (48%) presented with mild MR, and 30 patients (52%) had moderate MR. Fifteen patients (26%) with non-severe MR at rest, developed dynamic severe MR during handgrip exercise. Patients with dynamic severe MR had advanced MR at rest, larger left atrial dimensions, and increased mitral annulus diameter (all p<0.01). During exercise, LVEDVi, LVESVi and parameters of local left ventricular remodeling (tenting height, tenting area) were increased in patients with dynamic severe MR compared to those with non-severe MR (all p<0.05). During one-year follow-up, there was no difference regarding all-cause mortality and HF hospitalizations in patients with dynamic severe MR and non-severe MR (Log-rank test Chi2 0.262; p=0.609)(Figure 1). However, patients with dynamic severe MR more often underwent mitral valve surgery/intervention than patients with non-severe MR (Log-rank test Chi2 29.41; p<0.001)(Figure 1). Conclusion Our results demonstrate that the evaluation of non-ischemic MR only at rest underestimates the full severity of the lesion. Handgrip exercise unmasks severe MR in every fourth patient with non-severe MR at rest. These data may have implications for therapeutic decision-making in symptomatic patients with hypokinetic non-dilated and dilated cardiomyopathy and non-severe MR at rest. TEER might present an effective treatment option to improve clinical outcomes in patients with non-ischemic cardiomyopathy and non-severe MR at rest but dynamic severe MR during exercise.Figure 1

Is muscle sympathetic nerve activity associated with cerebral blood velocity? A partial coherence analysis.

Despite some evidence, the role of sympathetic nerve activity in the regulation of cerebral blood flow remains controversial. In humans, muscle sympathetic nervous activity (MSNA) is the only direct measure of sympathetic nerve activity that can be recorded with sufficient temporal resolution, to allow association with dynamic regulation of cerebral blood velocity (CBv). This study tested the hypothesis that MSNA is associated with the regulation of CBv at rest and during different physiological maneuvers. Nine healthy subjects underwent two sympathoexcitatory maneuvers: i) isometric handgrip exercise (HGR), and ii) cold pressor test (CPT). Mean arterial pressure (MAP, oscillometric method), CBv (transcranial Doppler ultrasound), and MSNA (microneurography) were measured continuously during experimental protocols. Ordinary and partial coherences of the MAP, CBv and MSNA time series were estimated by transfer function analysis in the low-frequency range (LF: 0.07-0.20 Hz), using MAP and MSNA as inputs and CBv as the output variable. When the influence of MSNA was taken into account, the partial coherences between MAP and CBv were considerably reduced at baseline (P<0.01), HGR (P=0.02), and CPT (P<0.01). Similarly, when the influence of MAP was taken into account, the coherence between MSNA and CBv was considerably reduced at baseline (P<0.01), HGR (P=0.02), and CPT (P=0.01), leading to the conclusion, that MSNA was associated to dynamic regulation of CBv. Partial coherence analysis is a promising method for assessing the influence of the sympathetic nervous system on cerebral hemodynamics.

The relationships between age, sex and exercise intensity on cerebral artery haemodynamics during isometric handgrip exercise.

Age and sex may alter the cerebral blood flow (CBF) responses to acute isometric exercise, via associated elevations in mean arterial pressure (MAP) and sympathetic activation. Our aim was to determine the relationships between age, sex and exercise intensity on cerebrovascular responses to isometric handgrip exercise. In 78 healthy adults (18-80 years, N=42 female), cerebrovascular responses were assessed during two minute isometric exercise bouts at three intensities (15, 30, 45% maximal voluntary contraction). Intracranial responses of the middle cerebral artery (MCA) and posterior cerebral artery (PCA) velocity (v) were measured using transcranial Doppler ultrasound. Extracranial responses of the internal carotid artery (ICA) and vertebral artery (VA) were assessed using Duplex ultrasound. Cardiopulmonary haemodynamic and neural parameters were measured throughout, including muscle sympathetic nerve activity, end-tidal carbon dioxide, and MAP. There were significant positive relationships between exercise intensity and the cerebral responses of the MCAv (P<0.001) and PCAv (P=0.005). There were no effects of intensity on ICA and VA responses (P>0.05), despite intensity-dependent increases in MAP (P<0.001). The increased MCAv response to exercise was blunted with advancing age (P=0.01) with no influence of sex (P=0.86). The present study provides data on age, sex and intensity specific relationships with intracranial and extracranial cerebrovascular responses to isometric exercise. Despite similar ICA, VA, and PCA responses, MCAv responses were attenuated with advancing age during handgrip exercise with no sex dependent influence. Further, intracranial responses were intensity dependent, whereas extracranial blood flow, shear-stress and velocity responses were similarly increased at all intensities during handgrip exercise.

Effectiveness of Isometric Handgrip Exercise on Blood Pressure in Hypertensive Patients in Tenajar Lor Village, Kertasemaya District, Indramayu Regency

Uncontrolled hypertension may result in numerous consequences; effective management is essential to regulate blood pressure in hypertensive individuals by both pharmacological and non-pharmacological interventions. Isometric handgrip exercise is a non-pharmacological therapy. This study sought to assess the impact of isometric handgrip exercise on blood pressure in hypertensive individuals in Tenajar Lor Village, Kertasemaya District, Indramayu Regency. This research design employs a quasi-experimental framework featuring a two-group pre- and post-test methodology alongside a control group design. The study sample comprised 30 respondents, categorized into intervention and control groups. The isometric handgrip exercise intervention was conducted daily for five successive days. The Wilcoxon test results indicated that the intervention group had an average systolic mean rank of 8.00 with a p-value of 0.000, and a diastolic mean rank of 7.50 with a p-value of 0.000. The control group exhibited a mean rank of 2.00 for systolic measurements with a p-value of 0.083, and a mean rank of 3.13 for diastolic measurements with a p-value of 0.157. The Mann-Whitney test yielded the average blood pressure disparity between the intervention and control groups. The p-values obtained were 0.001 for systolic blood pressure and 0.006 for diastolic blood pressure (p &lt; 0.05). This study concludes that isometric handgrip exercise influences blood pressure in hypertensive patients. Individuals with hypertension are advised to perform isometric handgrip exercises autonomously at home. Healthcare professionals, particularly nurses, implement isometric handgrip exercises to regulate blood pressure in individuals with hypertension.

Resistance- and endurance-trained young men display comparable carotid artery strain parameters that are superior to untrained men.

Central arterial stiffness, a predictor of cardiovascular risk, attenuates with endurance-exercise in ageing populations. However, in young individuals, this effect is inconsistent and emerging evidence suggests resistance-exercise may increase arterial stiffness. Two-dimensional (2D)-Strain imaging of the common carotid artery (CCA) is more sensitive at detecting endurance-training induced alterations in CCA stiffness than conventional methods, but has not been used to examine CCA stiffness in young resistance-trained individuals. Therefore, we compared CCA 2D-Strain parameters at rest, during acute exercise and recovery between resistance-trained, endurance-trained, and untrained young men. Short-axis CCA ultrasound images were obtained from 12 endurance-trained [27yrs (95%CI; 24-29)], 14 resistance-trained [24yrs (23-26)] and 12 untrained [23yrs (22-24] men at rest, during isometric handgrip (IHG) exercise and recovery. 2D-Strain analysis quantified CCA peak circumferential strain (PCS) and systolic (S-SR) and diastolic (D-SR) strain rates. Conventional stiffness indices included aortic pulse-wave velocity, CCA β-stiffness (β1) and Petersons elastic modulus (Ep). Resting conventional stiffness indices were not different between groups (P > 0.05). Resting PCS and S-SR were comparable between resistance- [11.6% (10.6-12.5) and 1.46s-1 (1.37-1.55), respectively] and endurance-trained [11.4% (10.7-12.2) and 1.5s-1 (1.38-1.62)] men and superior to untrained men [9.5% (9.19-9.9); P < 0.004 and 1.24s-1 (1.17-1.31); P < 0.018)]. Both trained groups displayed comparable reductions in PCS and S-SR during IHG, which returned to resting values during recovery (P < 0.001), whereas these parameters remained unchanged in untrained men. D-SR decreased during IHG in all groups (P < 0.001), but to a lesser extent in endurance-trained men (P < 0.023), whereas β1 and Ep increased to a similar magnitude in all groups and returned to resting values during recovery (P < 0.001). Resistance- and endurance-trained men display comparable CCA 2D-Strain parameters that are superior to untrained men, which contends previous reports that resistance-training increases CCA stiffness.

Acute impact of inorganic nitrate supplementation after ischemia and during small muscle mass exercise in postmenopausal females: A pilot study.

Menopause is associated with reduced endothelial-dependent vasodilation and increased cardiovascular disease (CVD) risk. Dietary nitrate, a non-pharmacological approach, may increase vasodilatory capacity consequentially reducing CVD risk. We investigated macro- and microvascular function after acute nitrate supplementation in postmenopausal females (PMF). Vascular function was studied with flow-mediated vasodilation (FMD) and near-infrared post occlusive reactive hyperemia (PORH). Incremental handgrip exercise was performed to investigate blood flow and tissue oxygenation. We hypothesized acute dietary nitrate would not impact resting endothelial measures but would increase post ischemic vasodilation and incremental exercise blood flow. Late-phase PMF (n = 12) participated in a randomized crossover design with 140 mL of nitrate-rich (NR) beetroot juice or nitrate-poor black currant juice. Testing included a 5-min FMD, a 3-min ischemic exercise FMD, and incremental exercise at 10%, 15%, and 20% maximal voluntary contraction to measure blood flow and pressure responses. A p ≤ 0.05 was considered significant. One-way ANOVA indicated lower resting pressures, but no change to FMD, or PORH in either protocol. Two-way repeated measures ANOVA indicated NR supplementation significantly reduced mean arterial pressure at rest and during incremental exercise at all intensities without changes to blood flow. Acute nitrate is effective for resting and exercising blood pressure management in PMF.

Effect of Curcumin Intake on Skeletal Muscle Oxygen Saturation Parameters in Older Participants.

Aging is associated with increased reactive oxygen species (ROS) and reduced bioavailability of nitric oxide (NO). Curcumin has been shown to increase NO bioavailability due to its ability to neutralize ROS, preventing oxidative stress. The present study aimed to investigate the effect of curcumin intake on skeletal muscle oxygen parameters and exercise tolerance in response to exercise in older people. Changes in circulating levels of NO metabolites were also investigated. Older subjects consumed 10 g of turmeric root extract from Curcuma longa L. (containing 95.33% of the total curcuminoids) or placebo in a randomized, double-blind, crossover study. A time of 2 h after ingestion, the participants performed one set of rhythmic handgrip exercise until the limit of tolerance, followed by 5 min of recovery. During exercise and exercise recovery, skeletal muscle oxygen saturation parameters were recorded. During exercise, the amplitude of deoxyhemoglobin was greater after curcumin intake compared to placebo (CUR: 13.11 ± 9.52 vs. PLA: 10.22 ± 8.39 μM, p = 0.030). Furthermore, a faster skeletal muscle oxygen resaturation during exercise recovery was observed after curcumin compared to placebo (CUR: 1.01 ± 0.65 vs. PLA: 0.32 ± 0.20%.s-1, p = 0.004). These results were associated with significant changes in plasma nitrite (CUR: 6.82 ± 11.68 vs. PLA: -4.94 ± 17.28%, p = 0.028). There was no statistical difference in the total hemoglobin, exercise time until fatigue, and plasma nitrate between groups. The present study suggests that curcumin improves muscle oxygenation status at the capillary level in older adults by possibly improving muscle oxygen extraction and/or delivery, with no effect on exercise tolerance.

Neurovascular coupling during dynamic upper body resistance exercise in healthy individuals.

During unilateral static and rhythmic handgrip exercise, middle cerebral artery blood velocity (MCAv) increases in the contralateral side to the exercising limb. However, whether this neurovascular coupling-mediated increase in contralateral MCAv is apparent against a background of fluctuating perfusion pressure produced by dynamic resistance exercise (RE) is unclear. We examined the cerebral haemodynamic response to unilateral dynamic RE in 30 healthy individuals (female=16, mean±SD: age, 26±6 years; height, 175±10cm; weight, 74±15kg; body mass index, 24±5kgm-2). Participants completed four sets of 10 paced repetitions (15 repetitionsmin-1) of unilateral bicep curl exercise at 60% of the predicted one-repetition maximum (7±3kg). Beat-to-beat blood pressure, bilateral MCAv and end-tidal carbon dioxide were measured throughout. One-way ANOVA was used to analyse cardiovascular variables and two-way ANOVA to analyse dependent cerebrovascular variables (side×sets, 2×5). A linear mixed model analysis was also performed to investigate the effects of end-tidal carbon dioxide and mean arterial blood pressure on MCAv. In comparison to baseline, within-exercise mean arterial blood pressure increased (P<0.001) across the sets, whereas bilateral MCAv decreased (P<0.001). However, no significant interaction effect was observed for any dependent variables (all P>0.787). The linear mixed model revealed that end-tidal carbon dioxide had the greatest effect on MCAv (estimate=1.019, t=8.490, P<0.001). No differences were seen in contralateral and ipsilateral MCAv during dynamic RE, suggesting that neurovascular coupling contributions during dynamic RE might be masked by other regulators, such as blood pressure.

Peripheral chemoreflex restrains skeletal muscle blood flow during exercise in participants with treated hypertension.

We tested the hypothesis that in human hypertension, an increased tonicity/sensitivity of the peripheral chemoreflex causes a sympathetically mediated restraint of nutritive blood flow to the exercising muscles. Fourteen patients with treated hypertension (age 69±11 years, 136±12/80±11mmHg; mean±SD) were studied under conditions of intravenous 0.9% saline (control) and low-dose dopamine (2µgkg-1min-1) to inhibit the peripheral chemoreflex, at baseline, during isocapnic hypoxic rebreathing and during rhythmic handgrip exercise (3min, 50% maximum voluntary contraction). At baseline, dopamine did not change mean blood pressure (95±10 vs. 98±10mmHg, P=0.155) but increased brachial artery blood flow (59±20 vs. 48±16mlmin-1, P=0.030) and vascular conductance (0.565±0.246 vs. 0.483±0.160mlmin-1mmHg-1; P=0.039). Dopamine attenuated the increase in mean blood pressure (∆3±4 vs. ∆8 ±6mmHg, P=0.007) to isocapnic hypoxic rebreathing and reduced peripheral chemoreflex sensitivity by 28±37% (P=0.044). Rhythmic handgrip exercise induced increases in brachial artery blood flow and vascular conductance (both P<0.05 vs. rest after 45s) that were greater with dopamine than saline (e.g. Δ76±54 vs. Δ60±43mlmin-1 and Δ0.730±0.440 vs. Δ0.570±0.424mlmin-1mmHg-1, respectively, at 60s; main effect of condition both P<0.0001). Our results indicate that the peripheral chemoreflex is tonically active at rest and restrains the blood flow and vascular conductance increases to exercise in treated human hypertension. KEY POINTS: It was hypothesised that in human hypertension, an increased tonicity/sensitivity of the peripheral chemoreflex causes a sympathetically mediated restraint of nutritive blood flow to the exercising muscles. Treated patients with hypertension (n=14) were studied under conditions of intravenous 0.9% saline (control) and low-dose dopamine (2 µgkg-1min-1) to inhibit the peripheral chemoreflex. Low-dose dopamine reduced resting ventilation and peripheral chemoreflex sensitivity, and while mean blood pressure was unchanged, brachial artery blood flow and vascular conductance were increased. Low-dose dopamine augmented the brachial artery blood flow and vascular conductance responses to rhythmic handgrip. These findings indicate that the peripheral chemoreflex is tonically active at rest and restrains the blood flow, and vascular conductance increases to exercise in treated human hypertension.

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 (M; n=9) and females (F; 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: ∆31±12 mmHg; R-PTL: ∆31±9; A-RHG: ∆35±6; A-PTL: ∆30±7) than females (R-RHG: ∆21±7 mmHg; R-PTL: ∆13±7; A-RHG: ∆21±7; A-PTL: ∆14±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.

Descending motor drive does not interact with muscle metaboreflex for ventilation regulation during rhythmic exercise in healthy humans.

The muscle metaboreflex effect on pulmonary ventilation (V̇E) regulation is more apparent during rhythmic exercise than rest, possibly because this reflex interacts with other mechanisms regulating V̇E during voluntary contractions, such as central command. Therefore, we tested whether one part of central command, the descending component of motor execution (i.e., descending motor drive), and the muscle metaboreflex interact synergistically to regulate V̇E. Thirteen healthy adults (9 men) completed four experiments in random order under isocapnia. The muscle metaboreflex was activated by rhythmic handgrip exercise at 60% maximal voluntary contraction (MVC) force with the dominant hand. Then, the muscle metaboreflex remained active during a 4-minute recovery period via post-exercise circulatory occlusion (PECO), or it was inactivated, maintaining free blood flow to the dominant upper limb. During the last 2-minutes of the handgrip exercise recovery, participants either performed rhythmic voluntary plantar flexion with the dominant leg at 30% MVC torque to generate descending motor drive or the dominant leg's calf muscles were involuntarily activated by electrical stimulation at a similar torque level (i.e., without descending motor drive). V̇E increased to a similar level during handgrip exercise in all conditions (≈22 L/min, P = 0.364). PECO maintained V̇E elevated above recovery with free blood flow (≈17 L/min vs. ≈13 L/min, P = 0.009). However, voluntary and involuntary plantar flexion with or without PECO evoked similar V̇E responses (∆ ≈ 4 L/min, P = 0.311). Therefore, an interaction between descending motor drive and muscle metaboreflex is not ubiquitous for V̇E regulation during rhythmic exercise.

Smaller Left Ventricular Size But Preserved Function in Adolescents and Adults Born Preterm.

Prematurely born adults have increased risk for cardiovascular disease. There are limited cardiac data on US-born preterm individuals. We aimed to determine whether adolescents and adults born prematurely have altered left ventricular (LV) structure and function, and to interrogate diastolic function using isometric handgrip exercise. Adolescents and adults born moderately to extremely preterm (≤32 weeks gestation or <1500 g birth weight) were recruited from the Parkland Health Neonatal Intensive Care Unit Registry. Full-term participants were recruited from the local area. Study procedures included anthropometrics and vitals, handgrip testing, and echocardiography performed at rest and during isometric handgrip exercise. Data were reported as mean±SD. The study enrolled 107 preterm and 48 term participants. Preterm participants (gestational age: 29.5±2.5 weeks) were shorter with higher body mass index (P<0.001) compared with term participants. Preterm participants exhibited smaller LV end-diastolic volume index (50.8±10.1 versus 56.9±10.0 mL/m2, P<0.001), LV stroke volume index (29.6±6.0 versus 34.1±6.5 mL/m2, P<0.001), and LV mass index (67.2±13.1 versus 73.3±14.2 g/m2, P=0.002) compared with term individuals. Preterm participants also had subclinical reductions in LV peak systolic tissue velocity and peak early diastolic tissue velocity lateral at rest. Isometric handgrip exercise promoted a reduction in diastolic function and an increase in hemodynamic measures, but changes during isometric handgrip exercise were similar between groups. Adolescents and adults born preterm exhibit overall normal cardiac function despite smaller cardiac volumes and mass compared with individuals born full term. Effects are most pronounced at the lowest gestational ages.

Penerapan Isometric Handgrip Exercise untuk Menurunkan Tekanan Darah pada Penderita Hipertensi di Wilayah Puskesmas Pucangsawit

Background: Hypertension that occurs in the world of the entire world population is 22% (WHO, 2021). Based on data obtained from the Pucangsawit Community Health Center, in 2023 there were 1,623 cases of Primary Hypertension. Isometric handgrip exercise therapy is a non-pharmacological therapy to help lower blood pressure. Objective: determine changes in blood pressure values in two respondents with hypertension before and after being given isometric handgrip therapy. Method: This research is a case study research using descriptive methods, namely by observing and interviewing two respondents with hypertension who are at risk of developing kidney disease and other diseases with a decrease in blood pressure results that become normal. Results: There was a decrease in blood pressure values in Mrs. S from 143/90 mmHg to 135/85 mmHg, while in Mr. N decreased from 160/98 to 150/90 mmHg. Conclusion: after applying isometric handgrip therapy to Mrs. S and Mr. N there is a decrease in blood pressure values ​​in hypertensive sufferers. This shows that the isometric handgrip can reduce blood pressure to normal.

Dynamic cerebral autoregulation during repeated handgrip exercise: comparisons with spontaneous rest and sit-stand maneuvers.

Induced arterial pressure oscillation may improve the assessment of dynamic cerebral autoregulation (dCA) with transfer function analysis (TFA). This study investigated dCA during repeated handgrip exercise (RHE) compared with spontaneous rest and sit-stand maneuvers (SSM), often used in cerebrovascular research. After a 5-min rest, 20 healthy young adults (10 women and 10 men) underwent 5 min of RHE (30% maximal voluntary contraction) and SSM at 0.05 Hz and 0.10 Hz each in random order. Power spectral density (PSD) and TFA gain, phase, coherence of mean arterial pressure (MAP), and blood velocity in the middle cerebral artery (MCAvmean) were measured in very low (VLF: 0.02-0.07 Hz) and low (LF: 0.07-0.20 Hz) frequencies. End-tidal CO2 (EtCO2) was continuously recorded throughout data collection. Compared with rest, RHE increased the PSD of MAP and MCAvmean in VLF (444% and 273%, respectively) and LF (1,571% and 1,765%, respectively) (all P < 0.001). Coherence increased during RHE (VLF: 131%, LF: 128%) and SSM (VLF: 166%, LF: 136%) compared with rest (all P < 0.05). TFA gain and phase were similar between RHE and rest, but VLF gain was higher, whereas VLF and LF phases were lower during SSM than RHE (all P < 0.05). EtCO2 was higher during SSM than rest and RHE (both P < 0.05), with the individual EtCO2 changes positively correlated with VLF gain (r = 0.538, P < 0.001). These results indicate that RHE significantly increases arterial pressure oscillation and TFA coherence and may improve dCA assessment in individuals unable to perform repeated postural changes.NEW & NOTEWORTHY This is the first study investigating dynamic cerebral autoregulation (dCA) during light-intensity repeated handgrip exercise (RHE) compared with rest and sit-stand maneuvers (SSM) using transfer function analysis (TFA). Compared with rest, RHE significantly increased oscillations of arterial blood pressure and cerebral blood velocity and coherence, whereas SSM exhibited the highest oscillations and coherence. These findings suggest that RHE may serve as an alternative method for assessing dCA in individuals unable to perform repeated postural changes.

Arterial blood pressure regulation during prolonged isometric exercise in artistic gymnastic athletes compared to controls.

The aim of this cross-sectional study was to examine the baroreflex sensitivity alterations in regulating arterial blood pressure during prolonged isometric exercise at different intensities in elite artistic gymnastic athletes compared to non-athletes. Fourteen young males participated in the study; 7 international level artistic gymnastics athletes and 7 physically active students inexperienced to isometric or resistance training. On two occasions, both groups performed 3 minutes of isometric handgrip exercise either at 30% or 50% of maximum voluntary contraction (MVC), in a randomized order. Force production, arterial blood pressure and baroreflex sensitivity through finger plethysmograph were continuously recorded. At rest, arterial blood pressure was normal in both groups (systolic blood pressure [SBP], athletes [A]: 128±9.0 mmHg, non-athletes [NA]: 130±7.2 mmHg, P=0.62; DIA, A: 75.6±5.2, NA: 78.5±4.6, P=0.31) but baroreflex sensitivity (BRS) was higher in athletes than in non-athletes (A: 16.6±7.4, NA: 12.0±7.9, P=0.02). During prolonged isometric exercise at 30% MVC, blood pressure was similar between groups (SBP, A: 176.9±16 mmHg vs. NA: 189.5±15.1 mmHg P=0.9, diastolic blood pressure [DBP], A: 108±11 mmHg vs. NA: 118±11 mmHg, P=0.6) and BRS was still higher in athletes (A: 13.28±5.75 ms/mmHg vs. NA: 6.72±3.83, P=0.04), whereas at 50% MVC, blood pressure was lower in the athletes compared to the control group (SBP, A: 182.5±15 mmHg vs. NA: 222.1±19.3 mmHg, P=0.001; DBP A: 115±14 mmHg vs. NA: 141±20 mmHg, P=0.02,without statistically significant difference in BRS between groups (A: 7.39±5.34 ms/mmHg vs. NA: 3.9±1.73 ms/mmHg, P=0.44). The results of our cross-sectional study revealed that after years of exposure in high amounts of training loads, baroreflex sensitivity is increased in healthy athletes probably in order to prevent excessive increases in blood pressure during exercise.

Endothelial Dysfunction in Youth-Onset Type 2 Diabetes: A Clinical Translational Study.

Youth-onset type 2 diabetes (Y-T2D) is associated with increased risk for coronary atherosclerotic disease, but the timing of the earliest pathological features and evidence of cardiac endothelial dysfunction have not been evaluated in this population. Endothelial function magnetic resonance imaging may detect early and direct endothelial dysfunction in the absence of classical risk factors (severe hyperglycemia, hypertension, and hyperlipidemia). Using endothelial function magnetic resonance imaging, we evaluated peripheral and coronary artery structure and endothelial function in young adults with Y-T2D diagnosed ≤5 years compared with age-matched healthy peers. We isolated and characterized plasma-derived small extracellular vesicles and evaluated their effects on inflammatory and signaling biomarkers in healthy human coronary artery endothelial cells to validate the imaging findings. Right coronary wall thickness, coronary artery flow-mediated dilation, and brachial artery flow-mediated dilation were measured at baseline and during isometric handgrip exercise using a 3.0T magnetic resonance imaging. Human coronary artery endothelial cells were treated with Y-T2D plasma-derived small extracellular vesicles. Protein expression was measured by Western blot analysis, oxidative stress was measured using the redox-sensitive probe dihydroethidium, and nitric oxide levels were measured by 4-amino-5-methylamino-2',7'-difluororescein diacetate. Y-T2D (n=20) had higher hemoglobin A1c and high-sensitivity C-reactive protein, but similar total and LDL (low-density lipoprotein)-cholesterol compared with healthy peers (n=16). Y-T2D had greater coronary wall thickness (1.33±0.13 versus 1.22±0.13 mm; P=0.04) and impaired endothelial function: lower coronary artery flow-mediated dilation (-3.1±15.5 versus 15.9±17.3%; P<0.01) and brachial artery flow-mediated dilation (6.7±14.7 versus 26.4±15.2%; P=0.001). Y-T2D plasma-derived small extracellular vesicles reduced phosphorylated endothelial nitric oxide synthase expression and nitric oxide levels, increased reactive oxygen species production, and elevated ICAM (intercellular adhesion molecule)-mediated inflammatory pathways in human coronary artery endothelial cells. Coronary and brachial endothelial dysfunction was evident in Y-T2D who were within 5 years of diagnosis and did not have severe hyperglycemia or dyslipidemia. Plasma-derived small extracellular vesicles induced markers of endothelial dysfunction, which corroborated accelerated subclinical coronary atherosclerosis as an early feature in Y-T2D. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02830308 and NCT01399385.

Pengaruh Isometric Handgrip Exercise terhadap Tekanan Darah pada Lansia dengan Hipertensi di Desa Gringging Kabupaten Sragen

Background: The prevalence of hypertension in Indonesia in 2021 reached 34.1% or more than 70 million people, and in Central Java in 2021 hypertension patients reached 37.57%. One of the interventions that supports is isometric handgrip exercise, to reduce blood pressure. Objective: To determine the effect of isometric handgrip exercise on blood pressure in elderly with hypertension in Gringging Village, Sragen Regency. Methods: The type of research is quantitative, the research method uses Pre-Exsperiment with One Group Pre Test-Post Test design. Using nonprobability sampling technique with purposive sampling method. Sampling as many as 15 respondents. The research instrument uses a sphygmomanometer. Data analysis with wilcoxon test. Results: in the study isometric handgrip exercise was given for 5 consecutive days with a time of 3 minutes and each hand got 2 contractions with a duration of 45 seconds per contraction. The results of the Wilcoxon test obtained a p-value of 0.000 &lt;0.05. Conclusion: There is a significant effect of isometric handgrip exercise on blood pressure in elderly with hypertension in Gringging Village, Sragen Regency.