Isometric Handgrip Research Articles

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.

Effects of a 4–Week Detraining Period After 12 Weeks of Combined Training Using Different Weekly Frequencies on Health–Related Physical Fitness in Older Adults

Background: Detraining refers to the decline in physical fitness that occurs after the cessation of exercise, compromising the adaptations resulting from regular exercise training. To understand how long the benefits acquired from an exercise program can be maintained, the present study evaluated the detraining effects of a 4–week exercise cessation period in older adults who performed combined training at various weekly frequencies for 12 weeks. Methods: This randomized controlled trial assigned participants to one of two training programs: a combined training program twice a week (CT2) or four times a week (CT4) over a period of 12 weeks, followed by a four–week detraining period. The resistance training consisted of six bodyweight exercises, while the aerobic training involved either walking or running. Both the CT2 and CT4 groups completed the same total training volume and overload each week; the only difference was the number of training sessions per week. Assessments were conducted at baseline, after the training period, and after the detraining period, and included the 30–s and five–repetition chair–stand tests, isometric handgrip strength, body mass index (BMI), waist circumference, and waist–to–height ratio. Results: Thirty–one participants completed the study (CT2: 17 and CT4: 14). The groups presented similar attendance records during the training period (CT2: 96 ± 18% versus CT4: 94 ± 19%). After the 12–week training period, CT2 and CT4 improved lower limb strength, CT2 improved upper limb strength, and CT4 reduced waist circumference and waist–to–height ratio compared to baseline. After the 4–week detraining period, the lower limb strength remained improved in both groups (CT2: 4 ± 1 repetition; p &lt; 0.001 and CT4: 4 ± 1 repetition; p &lt; 0.001) when compared to the corresponding baseline values. The handgrip strength decreased in CT2 compared to post–training values. And the body composition benefit in CT4 was not sustained after detraining. Conclusions: The effects of 4 weeks of detraining after 12 weeks of training performed two or four times per week are similar on some but not all health-related physical fitness parameters.

Time to target heart rate in dobutamine stress echocardiography is shortened by using dynamic, but not isometric handgrip

Abstract Background Dobutamine stress echocardiography (DSE) is widely used for the detection of obstructive ischaemic heart disease. In our previous study we demonstrated that the magnitude of myocardial injury measured by hsTnT is associated with DSE duration. Shortening of DSE time is therefore desirable. Use of hangrip (HG) during DSE is generally recommended. However, there are no published studies comparing the efect of dynamic and isometric HG on the length of DSE. Purpose To compare the effect of dynamic and static HG on DSE duration. Methods 211 patients undergoing DSE for ischaemia assessment were randomised into no HG (noHG, n=74), isometric HG (isoHG, n=68) and gynamic HG (dynHG, n=69) groups. All patients taking rate limiting medication were instructed to stop it 48 hours prior the test. DSE was performed according to the standard protocol (dobutamine infusion 5, 10, 20, 30, 40 ug/kg/min., increased in 3 min. intervals). HG was applied at the level of 40% maximum isometric muscular effort from the dobutamine dose of 20ug/kg/min. and atropine was administered in 1 min. intervals in 100 ug increments from the dose of 30 ug/kg/min. Patients who did not achieve their target heart rate (HR) or suffered from dobutamine side effects were excluded from the study. Results There were no differences in the groups characteristics (gender p=0.187, known ischaemic heart disease p=0.361, age p=0.128, basal HR p=0.367, target HR p=0.107, achieved HR p=0.257, positive test for ischaemia p=0.583). There was a significant difference in the time to target HR between dynHG and noHG groups (9.97±2.34 vs 11.96±3.02 min., p&amp;lt; 0.001) but not between isoHG and noHG groups (10.76±3.12 vs 11.96±3.02 min., p=0.058). Also, the was a similar difference in the length of dobutamine infusion between dynHG and noHG, but not between isoHG and noHG groups (11.76±2.37 vs 13.78±3.09 min., p&amp;lt; 0.001 and 13.34±4.90 vs 13.78±3.09 min., p=0.308, respectively). No significant correlation was found between the time to target HR and basal (r=0.43) or target HR (r=0.38). Conclusion Dynamic, but not isometric handgrip shortens the length of dobutamine stress echocardiography.

Effects of low-intensity isometric handgrip training on home blood pressure in hypertensive patients: a randomized controlled trial.

We examined if lower intensity isometric handgrip (IHG) training than usual load could significantly reduce home blood pressure (HBP) in treated Japanese hypertensive patients. Sixty patients (mean age, 66.9 years; 44.6% men) with high blood pressure to grade 1 hypertension level were randomly assigned to an IHG or control group. The IHG group performed IHG training for 12 weeks, followed by a 12 weeks of detraining. The control group did not any IHG training. The IHG training comprised four sets of 2-min isometric contractions at 15% of maximum voluntary contraction (MVC) or half than usual, including 1 min of rest between sets, for ≥3 days a week. At the end of the former phase, both morning and evening systolic HBP (HSBP) and evening diastolic HBP (HDBP) were significantly higher than those at baseline in the control group while neither morning nor evening HSBP remained unchanged in the IHG group. Morning HBPs increased at the end of the latter phase than those at the end of the former phase in the IHG group and remained unchanged in the control group. The change (Δ) in morning HSBP from baseline to the end of the former phase was smaller in the IHG group than that in the control group (Δ4.1 mmHg vs. Δ0.0 mmHg, p = 0.05). A similar tendency was observed after adjusting baseline HSBP and seasonal variation (p = 0.06). In conclusion, a 12-week IHG training at 15% of MVC significantly lowered morning HSBP by approximately 4.0 mmHg in treated Japanese hypertensive patients. This study showed that a 12-week IHG training at 15% of MVC lowered morning HSBP by about 4.0 mmHg in treated Japanese hypertensive patients. Continuous low-intensity IHG training may provide a stable hypotensive effect in high blood pressure to grade 1 hypertensive population.

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.

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.

Physiological Response and Sports Injury Risk Relevant Biomechanics in Endurance Obstacle Course Races

Obstacle course races (OCR) have experienced significant growth in recent years, with millions of participants worldwide. However, there is limited research on the specific physiological demands and injury prevention strategies required for these events. This study aimed to analyze the physiological responses and injury risks in participants of a 5 km (Sprint) and 13 km (Super) OCR. Sixty-eight participants were assessed for cortical arousal, leg strength, isometric handgrip strength, blood lactate, heart rate, blood oxygen saturation, body temperature, urine composition, spirometry values, hamstring flexibility, lower limb stability, foot biomechanics, and scapular kinematics, one hour before and immediately after the races. The results showed a significant decrease in leg strength (Sprint: r = −0.56, p &lt; 0.01; Super: r = −0.54, p = 0.01) and urine pH (Sprint: r = −0.70, p = 0.03; Super: r = −0.67, p = 0.01) in both distances, with increases in urine colour, protein, and glucose (Sprint: p &lt; 0.04). In the 13 km race, lower limb stability decreased significantly post-race (r = −0.53, p = 0.01). Positive correlations were found between performance and pre-race handgrip strength (Sprint: r = 0.71, p = 0.001; Super: r = 0.72, p = 0.01) and spirometry values (FVC, FEF 25–75%, FEV1) (Sprint: r = 0.52, p = 0.031; Super: r = 0.48, p = 0.035). Thermoregulation capacity, reflected in a higher pre-race body temperature and lower post-race body temperature, also correlated with improved performance (r = 0.49, p = 0.046). Injury risk increased post-race, with a significant decline in lower limb stability (p &lt; 0.05). These findings highlight the importance of targeted training programs, focusing on grip strength, leg strength, respiratory muscle training, and hydration strategies to optimize performance and reduce injury risk in OCR athletes.

Examining the Independent and Interactive Carryover Effects of Cognitive and Physical Exertions on Physical Performance.

This study compared the effects of prior cognitive, physical, and concurrent exertion on physical performance. Fatiguing cognitive and physical exertions have been shown to negatively affect subsequent task performance. However, it is not clearly understood if concurrent physical and cognitive effort may exaggerate the negative carryover effects on physical task performance when compared to cognitive or physical exertion alone. Twenty-five participants completed four isometric handgrip endurance trials on different days. The endurance trials were preceded by four, 15-minute experimental manipulations (cognitive, physical, concurrent, control). Electromyography (EMG) and force tracing performance were monitored, with handgrip strength measured pre and post. Subjective ratings of mental and physical fatigue, as well as affect, motivation, and task self-efficacy, were also assessed. Handgrip strength decreased following both physical (-14.4% MVC) and concurrent (-12.3% MVC) exertion manipulations, with no changes being observed for the cognitive and control conditions. No differences were observed across conditions for endurance time, EMG, nor tracing performance. When compared to the control conditions, perceptions of mental and physical fatigue were higher following the experimental manipulation. Endurance trial self-efficacy was lower for the mental, physical and concurrent conditions compared to control. The concurrent condition resulted in similar decreases in strength as the physical fatigue condition, but otherwise resulted in similar carryover effects on endurance performance across all conditions. Further study is required at higher exposure levels, or for longer exposure durations, to further probe the influence of concurrent physical and cognitive effort on task performance. Concurrent cognitive and physical effort resulted in similar physical performance decrements to physical effort alone.

Impact of Multi-Professional Intervention on Health-Related Physical Fitness and Biomarkers in Overweight COVID-19 Survivors for 8 and 16 Weeks: A Non-Randomized Clinical Trial.

Considering the diverse symptomatology of COVID-19-ranging from mild to severe cases-multi-professional interventions are crucial for enhancing physical recovery, nutritional status, and mental health outcomes in affected patients. Thus, this study aimed to investigate the effects of such an intervention on health-related physical fitness and biomarkers in overweight COVID-19 survivors with varying degrees of symptom severity after 8 weeks and 16 weeks. This non-randomized clinical trial included 59 overweight COVID-19 survivors (32 males and 27 females) divided into three groups: mild (n = 31), moderate (n = 13), and severe/critical (n = 15). The participants underwent a multi-professional program and were assessed for anthropometric and body composition (primary outcome), as well as physical fitness and biochemical markers (secondary outcome) 8 and 16 weeks before the intervention. After 8 weeks, time effects were observed for the maximum isometric handgrip strength (p < 0.001), maximum isometric lumbar-traction strength (p = 0.01), flexibility (p < 0.001), abdominal strength-endurance (p < 0.001), the sit-and-stand test (p < 0.001), maximum oxygen consumption (p < 0.001), and distance covered in the 6 min walk test (p < 0.001). Additionally, time effects were also observed for fat mass (p = 0.03), body fat percentage (p = 0.02), abdominal circumference (p = 0.01), total cholesterol (p < 0.001), low-density lipoproteins (p < 0.001), and glycated hemoglobin (p < 0.001), with lower values after multi-professional interventions. After 16 weeks, the systolic and diastolic blood pressure showed significant reductions independently of the intervention group (p < 0.001). These findings suggest that multi-professional interventions can provide substantial benefits for post-COVID-19 patients, regardless of the severity of their initial symptoms.

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.

Effect of home-based isometric training on blood pressure in older adults with high normal BP or stage I hypertension: A randomized controlled trial.

This trial analyzes the effects of home-based isometric handgrip training (IHT) and aerobic exercise training (AET) on ambulatory and office blood pressure (BP) in older adults with high normal to established hypertension. This randomized controlled trial included 84 participants (46 women, 71.1 ± 3.6 years, systolic BP [SBP] 137.1 ± 13.8 mmHg, diastolic BP [DBP] 80.8 ± 8.3 mmHg). Participants were randomized into IHT (n = 28), AET (n = 28), or usual medical care plus lifestyle advice (UC, n = 28). Participants performed IHT or AET three times/week for 8 weeks. IHT consisted of 4 × 45 s bilateral contractions at 50% of maximum voluntary contraction with 1-min rest between sets. AET consisted of walking 30 min at 50%-70% of estimated maximum oxygen consumption. UC received standardized medical care including lifestyle advice. Seventy-six participants completed the intervention: 27 in IHT, 26 in AET, and 23 in UC. At baseline, BP values were similar among groups. No differences were observed in 24-h ambulatory, daytime, and nighttime SBP and DBP in any group (p > 0.05). IHT and AET reduced office SBP (-8.0 ± 13.4 mmHg; p = 0.004; -5.6 ± 12.2 mmHg; p = 0.027, respectively). IHT reduced office DBP (-3.3 ± 7.4 mmHg; p = 0.024), but AET did not. No differences occurred in office BP in UC. There was no difference in office BP among groups (p > 0.05). An 8-week home-based IHT and AET failed to reduce ambulatory SBP, while office SBP was reduced by 8/5 mmHg. Only IHT reduced office DBP by 3 mmHg. Thus, IHT and AET may be effective for lowering office BP in older adults with high normal to established 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.

Effects Of Home-based Isometric Handgrip On Blood Pressure In Older Adults With High Blood Pressure

Effects Of Home-based Isometric Handgrip On Blood Pressure In Older Adults With High Blood Pressure

Investigating The Mechanistic Role Of Muscle Growth On Strength In Response To Isometric Handgrip Training

Investigating The Mechanistic Role Of Muscle Growth On Strength In Response To Isometric Handgrip Training

Metric Stability of One Month Handgrip Maximal and Explosive Isometric Strength Measured by Classic and Impulse Contractions

Abstract The aim of this study is to determine the metric stability of the one-month handgrip test (HGT) in order to define the contractile characteristics of the biological variation of maximal isometric strength (F max) and maximal isometric rate of force development (RFD max) of the handgrip in two different testing regimes (classic and impulse). The study was conducted with a total of 16 participants (11 men and 5 women). Testing was performed using an isometric handgrip probe with a standardized test protocol and equipment sports medical solutions (SMS). The results of F max showed a low relative standard error of the mean (RS = 1.33 %), a high value of inter-class correlation (ICC = 0.996), and no statistically significant change in trend (p &gt; 0.05) during the testing period. Therefore, can conclude that the HGT procedure in classic mode can be used as a stable parameter in a human subject sample. However, the RFD max results showed a low RS (2.13 %) and a high ICC value (0.996), but a statistically significant change of trend (p &lt; 0.05) during the measurement period. The regression constant (RCO) trend was 42.629 N/s, which can be attributed to learning or to the adaptive effects of the test procedure, which triggered similar adaptation processes as the training. In general, it can be concluded that the handgrip can be used to sensitively measure the effects of different long-term health improvements, or the effects of different medical/health exercises, rehabilitation programs, effects of medication applications, or dietary supplements for F max. However, further research should be conducted for the RFD max considering the metric stability parameters.

Effects of Slow Breathing Exercises on Cardiac Autonomic Functions in Anxiety Disorder-A Randomised Control Trial.

Anxiety disorders are commonly associated with a higher risk of fatal cardiovascular diseases (CVD). Anxiety disorders lead to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, thus weakening the key neuronal components of the autonomic nervous system (ANS) that are involved in cardiovascular functions, leading to increased cardiovascular risk. Impaired ANS activity, as reduced parasympathetic tone is strongly associated with an increased risk of CVD in anxiety disorders. Slow pranayama influences the ANS by activating the parasympathetic tone and deactivating the sympathetic tone in healthy volunteers and various diseased conditions. Therefore, we aimed to study the effects of slow pranayama and savasana on cardiac autonomic function tests in anxiety disorder patients. Anxiety disorder patients (N = 140) of either sex between the age group 18 and 40 years attending the psychiatry outpatient department (OPD) in JIPMER were recruited for the study and were randomly assigned into the pranayama group and control group. The Pranayama group practised slow pranayama and savasana for 8 weeks along with routine psychiatric care, while the control group continued with routine psychiatric care only. Outcome measures were heart rate variability (HRV), baroreflex sensitivity (BRS), 30:15 ratio during lying to standing, E: I ratio during deep breathing, and ∇DBP during isometric handgrip, which were assessed before and after the intervention period. After 8 weeks in the Pranayama group, the HRV parameters showed significant improvement towards the parasympathetic domain. Also, there was a significant increase in parasympathetic reactivity with a decrease in sympathetic reactivity and significant improvement in BRS. Slow pranayama and savasana practice in anxiety disorder patients as an adjunct to routine psychiatric care effectively improves cardiac autonomic function with a shift towards parasympathetic predominance, with significant improvements in cardiovascular parameters. Slow pranayamas with savasana may be incorporated into the routine care of these patients to enhance their cardiovascular health.

Responses to Valsalva's maneuver in spinal cord injury do not broadly relate to vasoconstrictor capacity.

A blood pressure stabilization during late phase II of Valsalva's maneuver may be utilized to confirm sympathetic vasoconstrictor control after a spinal cord injury. This study investigated whether Valsalva response was predictive of hemodynamics during tilt or isometric handgrip. Presence/absence of Valsalva response was compared to heart rate, mean arterial pressure, leg blood flow, and vascular resistance during head-up tilt and isometric handgrip to fatigue in 14 adults with spinal cord injury from C7 to T12 and 14 controls. Statistics were performed with two-way repeated measure analysis of variance (ANOVA), post hoc t-tests for between-group comparisons, and Mann-Whitney U tests for within-group. In total, six participants with spinal cord injury lacked a blood pressure stabilization for Valsalva's maneuver. However, this was not related to vasoconstrictor responses during the other tests. The groups had similar heart rate and blood pressure changes during tilt, though leg blood flow decreases and vascular resistance increases tended to be smaller at 20° tilt in those with spinal cord injury (p = 0.07 and p = 0.11, respectively). Participants with spinal cord injury had lower heart rates and markedly smaller blood pressure increases during handgrip (both p < 0.05). There were no group differences in leg blood flow, but those with spinal cord injury demonstrated a blunted vascular resistance increase by the final 10% of the handgrip (p < 0.01). Valsalva response was not consistent with hemodynamics during other stimuli, but some individuals evidence increases in sub-lesional vascular resistance to isometric handgrip comparable to controls, suggesting a sympathoexcitatory stimulus may be critical to provoke hemodynamic responses after spinal cord injury.

The effects of sex and contraction intensity on fatigability and muscle oxygenation in trained individuals.

Fatigability varies depending on sex and contraction intensity during sustained exercise. This study examined the responses of time to task failure (TTF), performance fatigability (PF), and muscle oxygenation (SmO2) in males and females during isometric handgrip holds to failure (HTF) at 30% and 60% maximum voluntary isometric contraction (MVIC). Males (n=12) and females (n=12) performed a pre-MVIC, handgrip HTF at randomly ordered percentages of MVIC (either 30% or 60%), followed by a post-MVIC on the dominant arm. During the HTF testing, the TTF and SmO2 responses were recorded, and PF was determined from the pre- to post-MVICs. TTF for 30% MVIC HTF was greater than 60% MVIC HTF (p<0.001), but was not different between males and females (p=0.117). PF exhibited an inverse relationship with intensity for each sex, while males demonstrated greater PF than females for both 30% and 60% MVIC HTF. For the 60% MVIC HTF, males demonstrated greater desaturation than females (CI95% = [-28.1, -2.6%], p=0.021, d=0.621), but not for the 30% MVIC HTF (CI95% = [-12.2, 7.9%], p=0.315, d=0.621). Sex differences in PF and SmO2 may be attributed to the differences in muscle mass, absolute strength, contractile properties, and muscle metabolism between males and females. However, these proposed differences between males and females may not fully inform exercise performance (e.g., TTF). Sex-specific fatigue responses may be affected by complex physio-psychological mechanisms, and therefore, additional investigations under diverse exercise conditions are required to better prescribe exercise for both males and females.

Physical, functional and personal variables affecting shoulder complaints in healthcare workers.

Work-related shoulder disorders adversely affect the quality of life and lead to increased costs related to decreased productivity and injury treatment. Therefore, understanding the relationship between strength, upper extremity function and work ability contributes to the development of interventions aimed to improve the well-being of healthcare workers. Correlate shoulder abduction and handgrip strength with upper extremity function and work ability in healthcare workers with shoulder complaints. 67 workers with shoulder pain in the last year were assessed by Disability of Arm, Shoulder and Hand (QuickDASH), Work Ability Index (WAI), isokinetic shoulder strength and isometric handgrip strength dynamometers. Data were analysed with Spearman's Correlation Coefficient (ρ= 0.05), SPSS 20.0®. 52% males, mean age 48.4 years, 42% physically active, most administrative and general services workers. Low correlation between handgrip strength and QuickDASH (r=-0.359; p = 0.004); low correlation between handgrip strength and WAI (r = 0.359; p = 0.003) and between shoulder abduction strength and the QuickDASH (r = -0.267; p = 0.049); no significant correlation between shoulder abduction strength and WAI (r = 0.001; p = 0.997). Handgrip and shoulder abduction strength were inversely associated with upper extremity dysfunction. Shoulder abduction strength was associated with work ability. The inclusion of strength assessment in workers is important to guide strategies to prevent musculoskeletal disorders.

The effects of low vs. high rating of perceived exertion clamp exercise on performance, neuromuscular, and muscle oxygen saturation responses in females.

This study examined the time course of changes in force, relative to critical force (CF), electromyographic amplitude (EMG AMP), neuromuscular efficiency (NE), and muscle oxygen saturation (SmO2), as well as time to task failure (TTF) and performance fatigability (PF) during isometric handgrip holds to failure (HTF) anchored to the rating of perceived exertion (RPE) at 3 and 7. Ten females completed pre-test maximal voluntary isometric contractions (MVICs), submaximal HTF at four percentages of MVIC, an HTF at RPE = 3 and 7, and post-test MVICs. Analyses included paired samples t-tests, repeated measures ANOVAs and planned comparisons. TTF was not different between RPE 3 (540.4 ± 262.1s) and 7 (592.2 ± 299.6s), but PF for RPE 7 (42.1 ± 19.1%) was greater than RPE 3 (33.5 ± 15.4%) (p < 0.05). There were RPE-dependent decreases in force, EMG AMP, and NE across three discernable phases during the HTF (p < 0.01), but there were no significant changes in SmO2 across time. Although there were overall similar patterns across time for force, neuromuscular, and muscle metabolic responses between the RPE holds, the greater PF at RPE 7 than RPE 3 may be explained by the longer sustained time above CF at RPE 7, resulting in greater accumulation of intramuscular metabolites and afferent feedback. Throughout each trial, it is possible that force was adjusted to avoid the sensory tolerance limit, and the task was ended when force could no longer be reduced to maintain the assigned RPE, resulting in a similar TTF for RPE 7 and RPE 3.