Maximum Grip Strength Research Articles

Correlation between Muscle Mass and Fragility Parameters in the Elderly

ntroduction: The frailty syndrome is an unstable condition related to the elderly’s functional decline and vulnerability to maintain homeostasis in the face of stressful factors. Grip strength is used as a predictor of general strength status, is closely related to mortality and disability and is related to several factors such as muscle mass. Objective: To evaluate the correlation between muscle mass and frailty parameters in the elderly. Methodology: An analytical, prospective, cross-sectional observational study was carried out. Elderly people aged 60 years or more, of both sexes, members of one of the elderly groups of the Integrated Health Center at Universidade Anhembi Morumbi were included in the research. The phenotype of Fried et al., [1]. was used to classify frailty, handgrip strength, gait speed (seconds at a distance of 4.6 meters), unintentional weight loss (greater than or equal to 4.5 kg), were evaluated. Exhaustion report (CES-D Depression Scale) and level of physical activity, measured through session 4 of the IPAQ long version. Bioelectrical impedance was performed using a tetrapolar device (Quantum II, RJL System, Clinton Twp, MI, USA). Results: It was observed that the groups were similar to each other, except for height, as the non-frail ones were taller and had greater maximum handgrip strength. There was a statistical trend (p=0.05) in relation to BMI. In the group without frailty, there was a moderate and positive correlation between skeletal muscle and maximum grip strength (r=0.7; p<0.02). In the frail group there was no significant correlation (r=0.3; p<0.10). In assessing the correlation between skeletal muscle and age, no significant correlation was observed in the nonfrail group (r=0.2; p<0.57) or in the frail group (r=0.3; p<0.11). When evaluated between skeletal muscle and basal metabolism in the group without frailty, there is a strong and positive correlation (r=0.8; p<0.01), which did not occur in the frail group (r=-0, 1; p<0.79). Finally, the non-frail and frail groups did not present a significant correlation between skeletal muscle and gait speed (r=-0.3; p<0.39; r=-0.2; p<0.19, respectively). Conclusion: The frail elderly have lower maximum handgrip strength compared to the non-frail elderly, but no correlations were observed between skeletal muscle and the variables maximum grip strength, age, basal metabolism and gait speed. In turn, the non-frail elderly showed a moderate and positive correlation between skeletal muscle and the variables maximum grip strength and basal metabolism, but there was no correlation between skeletal muscle and the variables age and gait speed.

Dough kneading exposure at the kitchen workstation: Influence on handgrip strength and implications for therapy in hand rehabilitation.

Dough kneading is a commonly performed activity in the kitchen, which influences hand grip strength. To study the influence of dough kneading exposure on hand grip strength and to evaluate the effect of dough kneading intervention on hand grip strength with the purpose of recommending dough kneading as a therapeutic exercise for improving hand grip strength. One hundred and fifty healthy females with varying levels of exposure to dough kneading, stratified as occupational dough kneaders, habitual dough kneaders and non-kneaders, were studied. Hand grip strength of all participants was measured with a standard protocol using the Jamar dynamometer. Hand grip strength of occupational, habitual and non-kneaders was compared. Non-kneaders followed a 6-week intervention of dough kneading and grip strength was recorded post-intervention. Comparison of hand grip strength between the three groups revealed significant difference (p value < 0.001). Linear contrast analysis, revealed the least hand grip strength in non-kneaders compared to habitual and occupational dough kneaders, with occupational dough kneaders presenting maximum hand grip strength (p value < 0.001). Significant improvement was demonstrated in hand grip strength post-intervention in non-kneaders (p value < 0.001). Findings suggest that exposure to dough kneading has a positive influence on hand grip strength. Hand grip strength of non-kneaders was lowest compared to habitual and occupational kneaders. Kneading intervention improved hand grip strength and hence can be used therapeutically as a safe, low cost exercise in hand rehabilitation.

Training and detraining management of performance measures by Yoga among middle-aged blue-collar men

To observe the effect of yogasanas and yoga breathing maneuvers (YBM) on body flexibility, balance, muscular strength and reaction time on middle aged blue-collar individuals, 8 healthy blue collar, males (age 37±6.2 years) were trained in yoga for 12 weeks. First 6 weeks, they practiced mostly yogasanas. From 7th week, progressively the YBM practice increased up to 12th week. Their body flexibility, balance, maximal hand grip strength (HGS) and HGS endurance at 50 % maximal strength for both hands, back -leg strength (BLS), reaction times for both visual (VRT) and auditory (ART) mode, were measured before and at the end of 6th and 12th weeks yoga training. Data was analysed by ANOVA. With more yogasanas practice, their body flexibility improved from base line 14.1±4.5 cm to 18.3±4.3 cm (P&lt;0.001, magnitude 29.8%) after 6 weeks of yoga training. With proportionately greater YBM practice, still it increased in lower magnitude (9.3%) to 20±4.6 cm (p&lt;0.001) after 12 weeks of training. Balance showed similar pattern of changes like flexibility. In VRT, baseline value of 281.4±16.4ms reduced to 271.14±16.1 ms and 251.7±15.4 ms after 6 weeks and 12 weeks respectively, indicating greater reaction time improvement by YBM. ART also showed similar pattern of changes. Left and Right HGS endurance have improved by 19% and 23.1% respectively, after 6 weeks. BLS and HGS improved in small magnitude. Detraining and age related deterioration of body flexibility, balance, reaction time and strength endurance could be controlled by yogasanas. YBM have greater positive role in reaction time.

Association of aerobic fitness and grip strength with cognitive and academic performance in Arab children.

This study investigated the association between aerobic and muscular fitness with the cognitive control and academic performance of preadolescent Arab children. Ninety-three children aged 10-13years (mean=11.5, SD=0.5) representing eight Arab nations (Egypt, Saudi Arabia, Sudan, Syria, Jordan, Lebanon, Yemen, and Morocco) participated in this cross-sectional study. The participants completed tests for aerobic (progressive aerobic cardiovascular endurance run) and muscular (maximum grip strength) fitness, and cognitive control (flanker task). We assessed their academic performance based on their overall grade point average (GPA). Our analyses revealed that greater aerobic fitness was associated with higher GPA scores and greater muscular fitness was associated with a shorter response time in a task condition requiring extensive cognitive control (incongruent condition). No association was found between aerobic fitness and flanker task performance nor between muscular fitness and GPA. These results bridge the knowledge gap on the associations of physical fitness to the cognitive control and academic performance of Arab children, suggesting that the positive associations found in Western and Asian literature can be generalized to the Arab context.

EFFECT OF WRIST WRAP IN HANDGRIP STRENGTH IN CROSSFIT.

Analyze wrist wrap influence on the values of maximum handgrip strength and dynamic resistance. A controlled randomized cross-over trial including 54 Crossfit participants randomly assigned to two groups. Group 1 began the series of tests with control wrapping, and Group 2 started with functional wrapping. Alternate series of four dynamic grip strength resistance tests were performed, and the resistance and fatigue values were calculated. The values obtained from the grip tests did not indicate any effect from the wrist wrap for an increase in maximum grip strength (35.7 vs. 35.6 kg; p=0.737) or greater endurance (78.2 vs. 77.8%; p=0.549). Fatigue was also equal in both groups (mean differences between the groups: 0.1 kg, CI= -0.7-0.8; p=0.779). The hypothesis that using a wrist wrap increases maximum strength and dynamic handgrip endurance was rejected in this study. Evidence Level I; Randomized control trial .

Association of handgrip strength and depression in medical undergraduate students during COVID-19 pandemic

Background: COVID-19 pandemic has affected the life of all individuals including medical undergraduate students, both physically as well as mentally. Handgrip muscle strength is the maximum force developed during maximal voluntary contraction under a given set of conditions using a handgrip dynamometer. Various studies have concluded that muscle strength can be a predictor of depressive symptoms among the elderly population. Not much attention has been given to assess similar correlation in younger generation. Aim and Objective: The aim of the study was to assess the correlation of maximal hand grip strength with depression among young population especially medical undergraduates during COVID-19 pandemic. Materials and Methods: The present study was conducted on 50 medical students in 18–24 years age group (25 male and 25 female) in North India. The grip strength of dominant as well as non-dominant hand was measured thrice at an interval of 1 min, and highest reading recorded was considered to be the maximum hand grip strength for each student. Depression, anxiety, and stress symptoms were assessed using DASS 21scale. Results: Data were analyzed on Microsoft excel. It was noted that handgrip strength in both male and female students were decreased. Overall students were having symptoms of depression, anxiety and stress. Conclusion: The present study suggests that there should be awareness of and sensitivity to student’s mental health during the COVID-19 pandemic. Handgrip strength can be a reliable method of identifying stressed individuals and is a safe, cheap, time economical, and easy to perform method for a large number of participants.

Effect of premodulated interferential current versus diadynamic current on the management of lateral elbow tendinopathy

Abstract Study aim: To compare the effect of premodulated interferential current (PREMOD IFC) and diadynamic current (DD) with exercise training on the management of lateral elbow tendinopathy (LET). Material and methods: One hundred and four patients with unilateral LET from both genders (55 females and 49 males) were randomly allocated into two groups. Group A received PREMOD IFC in addition to the exercises, and group B received DD with the same exercises. The outcomes were maximum grip strength assessed by the hand dynamometer, the pinch strength assessed by the pinch gauge dynamometer, and pain and functional disability of the forearm assessed by a patient-rated tennis elbow evaluation (PRTEE) questionnaire. All participants received electrical stimulation, consisting of three sessions per week for six weeks. Results: The mean PRTEE score, and grip strength were significantly improved after six weeks in favour of group A, while there was no significant difference between the two groups in pinch strength. (p &lt; 0.05). Conclusion: The results revealed that the combination of PREMOD IFC with exercises could improve pain, functional disability, and grip strength compared to DD with exercises in LET patients without a significant difference between the two groups in pinch strength.

The Association Between Red Cell Distribution Width and Grip Strength in Older Adults.

Background The red cell distribution width (RDW), an index of variation of erythrocyte volume (anisocytosis), has traditionally been used in the differential diagnosis of anemia. However, recent studies reported that increased RDW may be associated with adverse aging-related health outcomes. Methods The present cross-sectional study analyzed data from the National Health and Nutrition Examination Survey to examine the association between RDW categories (≤ 13.0%, 13.1 - 14.0%, 14.1 - 15.0%, ≥ 15.1%) and maximum grip strength (GS) (kg) in a nationally representative sample of adults aged 60 years and older.Anemia was defined according to the WHO criteria as a hemoglobin concentration of < 13 g/dl in men and < 12 g/dl in women. Results A total of 2,955 participants with a mean age of 69.3 years represented the study sample. General linear models demonstrated that men and women with RDW ≥ 15.1% were 3.2 kg and 1.4 kg weaker than their counterparts with RDW ≤ 13.0%, respectively. Notably, non-anemic older men in the highest RDW category had a mean GS 3.9 kg lower than those in the lowest RDW category. In contrast, this association was attenuated in women without anemia. Conclusion RDW was inversely associated with GS, particularly in older men. Moreover, this association remained unchanged even among men without anemia.

Linear and Nonlinear Associations Between Vitamin D and Grip Strength: A Mendelian Randomization Study in UK Biobank.

Low vitamin D status is a widespread phenomenon. Similarly, muscle weakness, often indicated by low grip strength, is another public health concern; however, the vitamin D-grip strength relationship is equivocal. It is important to understand whether variation in vitamin D status causally influences muscle strength to elucidate whether supplementation may help prevent/treat muscle weakness. UK Biobank participants, aged 37-73 years, with valid data on Vitamin D status (circulating 25-hydroxyvitamin D [25(OH)D] concentration) and maximum grip strength were included (N = 368,890). We examined sex-specific cross-sectional associations between 25(OH)D and grip strength. Using Mendelian randomization (MR), we estimated the strength of the 25(OH)D-grip strength associations using genetic instruments for 25(OH)D as our exposure. Crucially, because potential effects of vitamin D supplementation on strength could vary by underlying 25(OH)D status, we allowed for nonlinear relationships between 25(OH)D and strength in all analyses. Mean (SD) of 25(OH)D was 50 (21) nmol/L in males and females. In cross-sectional analyses, there was evidence of nonlinear associations between 25(OH)D and strength, for example, compared to males with 50 nmol/L circulating 25(OH)D, males with 75 nmol/L had 0.36 kg (0.31,0.40) stronger grip; males with 25 nmol/L had 1.01 kg (95% confidence interval [CI]: 0.93, 1.08) weaker grip. In MR analyses, linear and nonlinear models fitted the data similarly well, for example, 25 nmol/L higher circulating 25(OH)D in males was associated with 0.25 kg (-0.05, 0.55) greater grip (regardless of initial 25(OH)D status). Results were similar, albeit weaker, for females. Using two different methods to triangulate evidence, our findings suggest moderate to small causal links between circulating 25(OH)D and grip strength.

THE EFFECTS OF A HAND-BASED HOME-TRAINING PROGRAM ON FINE FORCE PERCEPTION IN OLDER ADULTS

Abstract The ability to use and manipulate the hands is essential for completing daily activities such as dressing, food preparation, and medication adherence, but declines with age. Assessments of hand function typically include measures of maximum strength despite our recent findings that fine force control may be more indicative of function than strength. The purpose of this study was to determine the effectiveness of a hand-based intervention on improving various aspects of hand function in older adults. Eleven older adults (mean age: 77±6.8y, 7 females) completed a 6-week home-based training program consisting of a series of sensorimotor tasks. Hand assessments included tactile sensation, dexterity, maximum grip and pinch strength, and fine force control using a pinch force matching paradigm. In the fine force task, participants were given a reference force (25% MVC) and were instructed to match the force without visual feedback using either the same (ipsilateral) or opposite (contralateral) hand as the reference force. After the training program, older adults displayed a 35% reduction (p &amp;lt; 0.01) in matching error during the contralateral fine force control task. Additionally, both tactile sensation and dexterity showed improvements in the dominant hand (p &amp;lt; 0.05). No differences were observed in maximum pinch or grip strength. We observed improvements in fine force control, tactile sensibility, and dexterity, all of which contribute to hand function needed for daily activities, as a result of the home-based intervention. These results underscore the importance of measuring different aspects of hand function and the need for additional hand-based interventions in the aging population.

PRESURGICAL GRIP STRENGTH PREDICTS POSTSURGICAL OUTCOMES IN OLDER ADULTS

Abstract Muscle weakness is a strong predictor of a myriad of health outcomes among older adults. However, measures of muscle strength are not incorporated in healthcare settings which is partly due to a lack of established clinical applicability. Maximal grip strength was measured in 11,668 older patients (73.2+/-6.0 yrs, 50.3% female) during a standard presurgical consultation. Each kilogram of maximal grip strength was associated with approximately 1-hour shorter length of stay. Patients categorized as having weak muscle strength according to sex-based norms had a higher 30-day post-surgery mortality than their non-weak counterparts (Odds Ratio: 2.5, p=0.002 after statistical adjustment of age, sex, race and disease history). Additionally, patients with weak muscle strength were less likely to be discharged home than patients without weakness (68.8% vs. 83.9% returning home, p&amp;lt;0.01). Grip strength is a consistent predictor of post-surgical outcomes that might be used to improve care management.

Lateral Epikondilitli Hastalarda Fizyoterapi Yaklaşımlarının Kısa Dönem Etkinliğinin Karşılaştırılması

The study aimed to investigate the short-term effects of radial nerve self-mobilization [RNSM], manual therapy [MT], and extracorporeal shock wave therapy [ESWT] on pain, pain-free grip strength, functional status, and patient satisfaction in patients with Lateral Epicondylitis [LE] and to determine the superiority of these methods to each other. 48 patients diagnosed with LE were included in the study and were randomly divided into three groups. RNSM was applied to all patients as a home program. The first group [n=16] received only the RNSM as a home program, the MT group [n=16] received MT combined with RNSM, and the ESWT group [n=16] received ESWT combined with RNSM. The RNSM was applied five days per week, and the MT and ESWT for two sessions per week for three weeks. Pain severity, pain-free handgrip strength, functionality levels, and patient satisfaction were evaluated before and after three weeks of treatment. The pain level significantly decreased, and handgrip strength and functionality increased in all groups after three weeks [p&amp;lt;0.001]. In comparison between the groups, the decrease in pain level, the increase in maximum grip strength, and patients' overall satisfaction scores were found to be higher in the MT group than in the ESWT, and only the RNSM groups [p&amp;lt;0.05]. MT application combined with radial nerve self-mobilization exercises in the treatment of LE appears to be more effective.

Patterns of Changes in Respiratory Muscle Strength over 1 Year in Non-Sarcopenia, Sarcopenia, and Severe Sarcopenia

In this prospective longitudinal cohort study, we explored the characteristics of older people with lower respiratory muscle strength, according to sarcopenia severity, over the course of 1 year. The maximum expiratory pressure (MEP), grip strength, walking speed, and skeletal muscle mass index of 58 participants (28 men, 30 women; mean age, 76.9 ± 7.7 years) were measured at baseline and at the 1-year follow-up. Participants were classified into a decreased MEP group (n = 29; MEP decreased by ≥10% after 1 year) and a non-decreased MEP group (n = 29; MEP decreased by <10%). Sarcopenia status in the mild direction at baseline was significantly associated with MEP decline after one year. Repeated two-way analysis of variance showed significant main effects of measurement time (p < 0.001) and severity of sarcopenia (p = 0.026), as well as a significant interaction effect (p = 0.006). Surprisingly, MEP decreased significantly in the non-sarcopenia and sarcopenia groups, but not in the severe sarcopenia group. Thus, individuals without sarcopenia and those with moderate sarcopenia at baseline are predisposed to MEP decline and should be closely monitored for signs of such decline and associated adverse events.

Functional fitness predicts global cognition scores

AbstractBackgroundAlzheimer’s disease (AD) is the 5th leading cause of death and the 6th most burdensome disease among US older adults. Given the concern with public health, understanding modifiable risk factors contributing to cognitive decline is imperative. With preliminary symptoms of cognitive decline occurring long before diagnosis, the ability to identify modifiable risk factors is key to primary prevention and maintenance of cognition. Often among individuals with AD, physical function is concurrently impaired. Thus, the primary aim of the present investigation is to determine the ability to predict global cognition scores from commonly used physical function assessments.MethodCommunity‐dwelling adults 60 years and older completed all assessments. Global cognition (percentile score) was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). All participants were free from mild cognitive impairment, dementia, and probable dementia. Physical function variables included maximal hand grip strength (average of right and left hands), lower‐body peak force development during a sit‐to‐stand task, and 10‐mfast walking time. Linear regression analysis was performed to determine the proportion of variance accounted for by the independent variables (sex, hand grip strength, peak force, 10‐meter walk time). Semi‐partial correlations were performed to determine the unique contribution from each independent variable.Result27% of the variance in global cognition was accounted for when including all independent variables. Semi‐partial correlations revealed the largest unique contribution was from the 10‐meter fast walking time, accounting for 19% of the variance (p &lt; .001). Lower‐body peak force production accounted for 9% (p &lt; .001). Sex accounted for 2.6% (p =.04) and hand grip strength accounted for 2% (p = .055).ConclusionThe current investigation provides support for the predictive capabilities of physical function assessments on cognitive ability—in particular, the time to complete a 10‐meter walk. This is paramount to future efficacious treatments with the inconsistent nature of current cognitive testing and implementation, primarily because of difficulties accessing qualified neuropsychological professionals. The physical function assessments presented here are cost effective and may serve as an early warning sign to cognitive decline.

A novel sensor-embedded holding device for monitoring upper extremity functions.

There are several causes that can lead to functional weakness in the hands or upper extremities (UE), such as stroke, trauma, or aging. Therefore, evaluation and monitoring of UE rehabilitation have become essential. However, most traditional evaluation tools (TETs) and assessments require clinicians to assist or are limited to specific clinical settings. Several novel assessments might apply to wearable devices, yet those devices will still need clinicians or caretakers to help with further tests. Thus, a novel UE assessment device that is user-friendly and requires minimal assistance would be needed. The cylindrical grasp is one of the common UE movements performed in daily life. Therefore, a cylindrical sensor-embedded holding device (SEHD) for training and monitoring was developed for a usability test within this research. The SEHD has 14 force sensors with an array designed to fit holding positions and a six-axis inertial measurement unit (IMU) to monitor grip strength, hand dexterity, acceleration, and angular velocity. Six young adults, six healthy elderly participants, and three stroke survivors had participated in this study to see if the SEHD could be used as a reference to TETs. During result analyses, where the correlation coefficient analyses were applied, forearm rotation smoothness and the Purdue Pegboard Test (PPT) showed a moderate negative correlation [r (16) = -0.724, p < 0.01], and the finger independence showed a moderate negative correlation with the PPT [r (10) = -0.615, p < 0.05]. There was also a highly positive correlation between the maximum pressing task and Jamar dynamometer in maximum grip strength [r (16) = 0.821, p < 0.01]. These outcomes suggest that the SEHD with simple movements could be applied as a reference for users to monitor their UE ability.

Strength-mass scaling law governs mass distribution inside honey bee swarms

To survive during colony reproduction, bees create dense clusters of thousands of suspended individuals. How does this swarm, which is orders of magnitude larger than the size of an individual, maintain mechanical stability? We hypothesize that the internal structure in the bulk of the swarm, about which there is little prior information, plays a key role in mechanical stability. Here, we provide the first-ever 3D reconstructions of the positions of the bees in the bulk of the swarm using x-ray computed tomography. We find that the mass of bees in a layer decreases with distance from the attachment surface. By quantifying the distribution of bees within swarms varying in size (made up of 4000–10,000 bees), we find that the same power law governs the smallest and largest swarms, with the weight supported by each layer scaling with the mass of each layer to the approx 1.5 power. This arrangement ensures that each layer exerts the same fraction of its total strength, and on average a bee supports a lower weight than its maximum grip strength. This illustrates the extension of the scaling law relating weight to strength of single organisms to the weight distribution within a superorganism made up of thousands of individuals.

Body composition and grip strength constraints in elite male rink-hockey players of contrasting ethnicity

Rink hockey is a highly specialized and physiological demanding sport with sparse research regarding the game and athletes’ characteristics. A cross-sectional study was developed to characterize the body composition and grip strength of elite male rink hockey players and to establish the relationship between ethnicity on body composition and grip strength. A sample of 100 elite rink-hockey athletes aged 26.59 ± 6.02 participated in the study, comprised of 69 Caucasian male adults aged 27.58 ± 6.44 years and 31 Black African male adults aged 24.39 ± 4.27. Body composition was assessed by anthropometric measurements. Static grip strength was assessed with an adjustable dynamometer. Multiple regression analysis was applied to understand which variables constraints body fat percentage (BF) and grip strength. Body mass showed an average of 76.36 ± 9.18 kg for 175.80 ± 5.87 cm of height and BF% of 10.82 ± 5.07%. Maximal right grip strength was 50.91 ± 6.26 kg and 50.27 ± 6.23 kg for left grip strength. Four predictors accounted for 70.01% of the variance of BF%: abdominal circumference (p < 0.001), right thigh circumference (p < 0.001), right calf circumference (p = 0.001) and ethnicity (p = 0.016). Three predictors accounted for 13.1% of the variance of right grip strength: ethnicity (p = 0.013), chronological age (p = 0.024) and right distal thigh circumference (p = 0.014). Results suggest that elite rink hockey athletes have a specific anthropometric identity, which at the elite level may lead to reduced body fat and greater handgrip strength. Ethnicity seems to predict body fat and grip strength in elite rink hockey athletes.

Weight History Association With Current Cardiorespiratory And Muscular Fitness

High cardiorespiratory and muscular fitness are often associated with lower body fat mass. Age-associated increases in body mass might be attenuated by maintaining a higher level of fitness into middle-age. PURPOSE: This study aimed to compare the cardiorespiratory and muscular fitness of individuals who have maintained body mass during adulthood to those who have had substantial increases and/or decreases in body mass in adulthood. METHODS: Obese, overweight, and non-obese adults were recruited to participate. Long-term health and weight history was collected retrospectively on 79 individuals. Total body composition, maximal oxygen consumption, grip strength, and maximal isometric knee extension strength were measured. Participants were subsequently categorized based on short term and long-term weight loss history, cardiorespiratory fitness, and muscle function for further analysis. RESULTS: Participants (31 Male, 45 female, aged 41.0 ± 12.3 years) were 29.2 ± 10.1% body fat having gained 9.3 ± 11.7 kg since 20 years of age. Current cardiorespiratory fitness as indicated by relative maximal oxygen consumption was 36.6 ± 12.0 ml*kg-1*min-1. No significant relationship existed between weight gain since age 20 and current cardiorespiratory fitness (r = -0.12). No differences in weight history were observed after classification of participants into high vs. low cardiorespiratory fitness nor high vs. low muscular fitness. CONCLUSIONS: Current cardiorespiratory and muscular fitness are independent of past body weight history. Despite the limitations of retrospective analysis of weight history and inability to determine previous levels of fitness, these results imply that high fitness might not be protective against age-associated body mass increases, but also that low fitness might not destine an individual to larger than normal gains in body mass

The Effect Of Isometric Hand-grip Exercise With Blood Flow Restriction On Hemodynamic Responses

Several studies have examined the effect of isometric handgrip exercise at submaximal intensities on cardiovascular system. However, few studies have focused on hemodynamic responses and muscle fatigue while exercising with blood flow restriction (BFR). PURPOSE: This crossover study examined the hemodynamic responses and muscle fatigue of an isometric, low intensity hand grip exercise protocol performed under blood flow restriction. METHODS: Twenty-four healthy adult volunteers (12 women and 12 men, age: 23.3 ± 1.9, BMI: 24.9 ± 6.2 kg/m2) performed 4 sessions of isometric hand grip exercise at 30% of maximal isometric strength using a grip dynamometer. Each session lasted 2 min and was performed in two conditions, without (control-C) and with blood flow restriction- BFR on different days. Blood flow restriction was achieved by applying a blood flow restriction cuff at a pressure of 140 mmHg. Hemodynamic responses (systolic and diastolic arterial blood pressure-SBP and DBP, heart rate-HR, and oxygen saturation- OS SpO2) and muscle fatigue (maximal isometric grip strength- IMVC and Borg scale) were assessed before, at the end of each exercise session, and 15 minutes after exercise performed under the two different conditions. Two-way ANOVA with repeated measures was used for statistics and data are given as mean(SD). RESULTS: Outcomes measures mean score (SD) for each time point of measurement in the two exercise conditions.* Between groups significant comparisons in the post hoc testing. BFRT: Blood Flow Restriction Training, Control: Conduction of exercise with no blood restriction, HR: Heart Rate, SBP: Systolic Blood Pressure, DBP: Diastolic Blood Pressure, OS: Oxygen Saturation, IMVC: Isometric Maximal Voluntary Contraction CONCLUSIONS: A submaximal isometric hand grip exercise does not induce significant hemodynamic changes, though it causes a more intense feeling of fatigue.

Distinct neural representations for prosocial and self-benefiting effort

Prosocial behaviors-actions that benefit others-are central to individual and societal well-being. Although the mechanisms underlying the financial and moral costs of prosocial behaviors are increasingly understood, this work has often ignored a key influence on behavior: effort. Many prosocial acts are effortful, and people are averse to the costs of exerting them. However, how the brain encodes effort costs when actions benefit others is unknown. During fMRI, participants completed a decision-making task where they chose in each trial whether to "work" and exert force (30%-70% of maximum grip strength) or "rest" (no effort) for rewards (2-10 credits). Crucially, on separate trials, they made these decisions either to benefit another person or themselves. We used a combination of multivariate representational similarity analysis and model-based univariate analysis to reveal how the costs of prosocial and self-benefiting efforts are processed. Strikingly, we identified a unique neural signature of effort in the anterior cingulate gyrus (ACCg) for prosocial acts, both when choosing to help others and when exerting force to benefit them. This pattern was absent for self-benefiting behaviors. Moreover, stronger, specific representations of prosocial effort in the ACCg were linked to higher levels of empathy and higher subsequent exerted force to benefit others. In contrast, the ventral tegmental area and ventral insula represented value preferentially when choosing for oneself and not for prosocial acts. These findings advance our understanding of the neural mechanisms of prosocial behavior, highlighting the critical role that effort has in the brain circuits that guide helping others.