Predicting maximal grip strength using hand circumference

Grip strength of law enforcement officers and its implications

Grip strength (GS) plays a vital role for law enforcement officers (LEOs). This study aimed to establish a baseline for LEO GS, compare it with the general population, determine the correlation between LEO GS and body dimensions, and evaluate the implications for occupational performance. A total of 756 male and 218 female LEOs from across the U.S. participated in the study. On average, male LEOs exhibit stronger GS (49.53 kg) than female officers (32.14 kg). Significant differences between LEOs and the general population were observed. GS correlated with hand breadth, hand length, stature, and bideltoid breadth. Approximately 26%-46% of males and 5%-39% of females were identified as being at risk of health, fit, or occupational performance based on their measured GS. Enhancing GS training or avoiding implementing heavy equipment (such as pistols with heavy trigger weight), could improve officer occupational performance, safety, or health.

Body surface scan anthropometrics are associated with grip strength in the general population

BACKGROUND AND AIM

Body shape and anthropometrics are well-known risk factors for cardiovascular diseases (CVD) and mortality. Hand-grip strength (HGS) is also a meaningful marker of health and a promising predictor of CVD and mortality. There is a lack of studies that have systematically investigated associations between body shape and anthropometrics with HGS. In a population-based study, we investigated if anthropometric markers derived from 3D body scanning are related to HGS.

METHODS AND RESULTS

We used the data of 1,599 individuals aged 36 to 93 years, who participated in the Study of Health in Pomerania. A total of 87 anthropometric markers, determined by a 3D body scanner, were included in the analysis. Anthropometric measurements were standardized and used as exposure variables. HGS was measured with a hand dynamometer and used as outcome. Sex-stratified linear regression models adjusted for age and height were used to relate standardized anthropometrics and HGS. Anthropometric markers were ranked according to -log-p-values. In men, left and right forearm circumference, left arm length to neck (C7), left forearm length, and forearm-fingertip length were most strongly related to HGS. In women, right forearm circumference, forearm-fingertip length, shoulder breadth, left forearm circumference, and right wrist circumference showed the most significant associations with HGS. The final prediction models contained 13 anthropometric markers in males (R2=0.54) and eight anthropometric markers in females (R2=0.37).

CONCLUSIONS

The identified parameters may help estimate HGS in the clinical setting. However, studies in clinical settings are essential to validating our findings.

Assessment of the upper limb function, strength, and mobility in treatment-naive children with spinal muscular atrophy Types 2 and 3

INTRODUCTION/AIMS

Current upper limb assessments in pediatric spinal muscular atrophy (SMA) may not adequately capture change with disease progression. Our aim was to examine the relationship between motor function, strength, and hand/finger mobility of the upper limb in treatment-naïve children with SMA Types 2 and 3 to assess new methods to supplement current outcomes.

METHODS

The Revised Upper Limb Module (RULM), grip and pinch strength, and hand/finger mobility data were collected from 19 children with SMA Types 2 and 3 aged 5.2-16.9 years over a year.

RESULTS

A median loss between 0.5 and 2.5 points in the RULM was seen across all SMA subgroups with the biggest median loss recorded between 10 and 14 years of age. The grip strength loss was -0.06 kg (-4.69 to 3.49; IQR, 1.21); pinch improvement of 0.05 (-0.65 to 1.27; IQR, 0.48); hand/finger mobility test improvement of 4 points (-24 to 14; IQR, 6.75) for the whole cohort. Significant correlations were found between the RULM and grip strength (p < .001), RULM and pinch strength (p < .001), RULM and revised Brooke (p < .001), grip strength and pinch strength (p < .001).

DISCUSSION

The combined use of the RULM, dynamometry, and hand mobility provide insight about correlations between function and strength in children with SMA. The RULM and grip strength assessments captured a significant decline in upper limb function, whereas the pinch and finger/hand mobility showed an improvement over the course of 1 year and these results should be considered for future studies.

Comparison of finger flexion strength and muscular recovery of male lead sport climbers across climbing classes

BACKGROUND/OBJECTIVE

The purpose of this study was to compare finger flexor strength (FS), finger flexor muscle recovery (FR), and forearm circumference (FC) across three different climbing classes in male lead sport climbers.

METHODS

A total of 37 male lead sport climbers were classified into low (LC), intermediate (IC), and advanced classes (AC) categories according to the International Rock Climbing Research Association (IRCRA) Scale. All participants measured FS three times for both open grip (OG) and crimp grip (CG). Following FS measurement, the FR was observed immediately after the all-out training. The FC was measured twice using an inelastic tape.

RESULTS

The FS differed significantly across climbing classes for both grip styles and hands, regardless of dominant hand, with the higher classes showing greater FS (all, p ≤ 0.001). FR was significantly higher in AC compared to IC and LC at 5 min (all, p ≤ 0.001), 10 min (all, p ≤ 0.005) and 15 min (all, p ≤ 0.005). The FC showed significant differences with climbing classes for both forearms.

CONCLUSION

Climbing classes are associated with differences in FS, with higher class corresponding to greater FS. Similarly, climbing classes are linked to FR and FC, with higher classes being associated with faster recovery and larger FC.

Are the digit ratio (2D:4D) and hand grip strength related to Parkinson disease in elderly males?

BACKGROUND

Sex hormones affect the pathogenesis of Parkinson patients and it has been suggested that gender is the most important factor in the development and progression of Parkinson's disease. Studies have shown that the second to fourth digit ratio (2D:4D) is affected by the prenatal testosterone and estrogen levels and can predict predisposition to disease. In addition, decreased muscle strength in people with Parkinson's has been repeatedly reported. Hand grip strength (HGS) is a suitable measure to evaluate the musculoskeletal system among the elderly and it is considered as an indicator of the overall strength of the body. This study aimed at investigating the relationship between Parkinson's disease and HGS and 2D:4D ratio.

METHODS

In this study 117 elderly men with Parkinson disease (mean age of 61.66 ± 11.28 years) and 156 healthy control subjects (mean age of 61.86 ± 6.29 years) participated. After determining the level of disability of Parkinson patients by a neurologist (level of disability in the range of 1-4), anthropometric indices (height, weight, length of the second and fourth fingers) and maximum HGS were measured.

RESULTS

Although 2D:4D ratios (right and left hand) of male patients with Parkinson's disease were higher than those of healthy males, this difference was not statistically significant (P = 0.12, P = 0.40; respectively). Conversely, HGS for the right and left hands of Parkinson patients were significantly lower than those of healthy males (P = 0.02, P = 0.03; respectively). The results showed a significant negative relationship between Parkinson disease and the right and left HGS (R = -0.16, P = 0.005; R = -0.17, P = 0.003; respectively). Parkinson disease had no significant relationship with 2D:4D of the right hand, left hand, mean finger ratio and DR-L 2D:4D (P > 0.05). The regression results showed that the right and left HGS were not able to predict Parkinson disease (P = 0.25, P = 0.16; respectively).

CONCLUSION

We concluded that HGS was negatively associated with the Parkinson disease, but conversely, 2D:4D may not be a valuable biomarker of elevated risk of Parkinson in elderly males.

Hand grip strength should be normalized by weight not height for eliminating the influence of individual differences: Findings from a cross-sectional study of 1,511 healthy undergraduates

Background

Hand grip strength (HGS) is a fast, useful, and inexpensive outcome predictor of nutritional status and muscular function assessment. Numerous demographic and anthropometric factors were reported to be associated with HGS, while which one or several factors produce greater variations in HGS has not been discussed in detail. This is important for answering how should HGS be normalized for eliminating the influence of individual differences in clinical practice.

Aims

To compare the contribution of age, sex, height, weight, and forearm circumference (FCF) to variations in HGS based on a large-scale sample.

Methods

We enrolled 1,511 healthy undergraduate students aged 18-23 years. Age, weight, height, and sex were obtained. HGS was measured using a digital hand dynamometer, and FCF was measured at the point of greatest circumference using a soft ruler in both hands. Pearson's or Spearman's correlation coefficients were calculated with data of women and men separated and mixed for comparison. Partial correlation analysis and multivariate linear regression were used to compare the effect of variables on HGS.

Results

Analysis results confirmed the correlates of higher HGS include higher height, heavier weight, being men and dominant hand, and larger FCF. The correlation between HGS and FCF was the highest, and the bivariate correlation coefficient between weight and HGS was largerata of women and men were mixed, than that between height and HGS. When data of women and men were mixed, there were moderate correlations between HGS and height and weight (r = 0.633∼0.682). However, when data were separated, there were weak correlations (r = 0.246∼0.391). Notably, partial correlation analysis revealed no significant correlation between height and HGS after eliminating the weight effect, while the correlation between weight and HGS was still significant after eliminating the height effect. Multivariate linear regression analyses revealed sex was the most significant contributor to the variation in HGS (Beta = -0.541 and -0.527), followed by weight (Beta = 0.243 and 0.261) and height (Beta = 0.102 and 0.103).

Conclusion

HGS and FCF reference values of healthy college students were provided. Weight was more correlate with hand grip strength, at least among the healthy undergraduates.

Clinical trial registration

http://www.chictr.org.cn/showproj.aspx?proj=165914, identifier ChiCTR2200058586.

Ratings of Hand Activity and Force Levels among Women and Men Who Perform Identical Hand-Intensive Work Tasks

We compared hand activity and force ratings in women and men doing identical hand-intensive work tasks. Musculoskeletal disorders are more common in women and hand-intensive work leads to an increased risk of these disorders. Knowledge of the gender influence in the rating of work exposure is lacking. The aim of this study was to investigate whether women and men performing identical hand-intensive work tasks were equally rated using hand activity and normalized peak force levels with the Hand Activity Threshold Limit Value^®. Fifty-six workers participated, comprising 28 women-men pairs. Four observers-two woman-man pairs-were also involved. Self-ratings and observers' ratings of hand activity and force level were collected. The results of these ratings showed no significant gender differences in self-rated hand activity and force, as well as observer-rated hand activity. However, there was a significant gender difference in the observer-rated force, where the women were rated higher (mean (SD): women 3.9 (2.7), men 3.1 (1.8) (p = 0.01)). This difference remained significant in the adjusted model (p = 0.04) with grip strength and forearm-finger anthropometrics. The results provide new insights that observers' estimates of force can be higher in women compared with men in the same work tasks. Force should be further investigated and preferably compared to objective measurements.

Predicting handgrip power of young adult population among major ethnic groups of Sabah: a multivariate analysis

Background

Handgrip power is an essential indicator of health, vital for grasping or gripping sports, and crucial for providing information related to work capacity. The present study investigated any linear relationship of handgrip power with hand anthropometric variables (hand length, handbreadth, middle finger length, second inter-crease length of the middle finger, and hand span), gender, and ethnicity in young adults of Sabah.

Methods

In this cross-sectional study (from January 2020 to December 2021), the adult Sabahan population (18-25 years) was stratified into four ethnicities (KadazanDusun, Bajau, Malay, and Chinese) and was further stratified as males and females. Then, 46 subjects were randomly selected from each gender, and the ethnic group met the intended sample size. The hand dimensions were measured using a digital calliper, and the handgrip power was measured using a portable dynamometer. The relationship between the response variable and explanatory variables was analyzed at first through simple linear regression and then multiple linear regression. R², adjusted R², and standard errors of the estimates were used to compare different models. Statistical analyses were performed using IBM SPSS Statistics 27 and StatCrunch.

Results

The study found a linear relationship between gender, height, hand length, handbreadth, hand span, middle finger length, and second inter-crease length of both hands with the corresponding hand’s grip power. The highest percentage (68% and 67%) of handgrip variability was demonstrated by the model predicting handgrip power for right-handed subjects, followed by the general models without stratifying based on hand dominance which was able to explain 63% and 64% of the variability of handgrip power. The study proposes the models for predicted right (RHGP) and left handgrip power (LHGP) of 18 to 25 years old adults from major ethnic groups of Sabah RHGP = − 18.972 − 8.704 Gender + 7.043 Right hand breadth and LHGP = − 11.621 − 9.389 Gender + 5.861 Left hand breadth respectively.

Conclusion

The predicted handgrip power would be a key to selecting a better player or a better worker or assessing the prognosis of a disease or the wellbeing of a person. The study can be further expanded to all ethnicities and ages of people of Sabah or even Malaysia.

Handgrip strength and its correlation with anthropometric determinants and hand dimensions in children aged 6-12 years: A cross-sectional study

BACKGROUND

Handgrip strength is considered an important interpreter of general health, and hand functions in children. It is mainly influenced by anthropometric determinants and hand dimensions.

OBJECTIVE

To assess the handgrip strength and their association with anthropometric determinants, hand circumference, hand span, and hand length among school children in both the dominant and non-dominant hand.

METHODS

Anthropometric measurements, hand circumference, hand span, hand length, and grip strength measurements were obtained from 133 school children of both genders aged 6-12 years. A Jamar hand-held dynamometer was used to measure handgrip strength and the hand dimensions with a tape measure in cm.

RESULTS

Significant differences were found between the handgrip strength among boys and girls. The dominant hand was found to be sturdier than the non-dominant hand in both genders. We also found a significant correlation of anthropometric determinants and hand dimensions with handgrip strength. Age, BMI, hand circumference, hand span, and hand length had a strong correlation with grip strength (p < 0.01).

CONCLUSIONS

The study revealed the reference values and concluded its correlations with hand dimensions among school children aged 6-12 years and this information can serve as a manual for interpretation of handgrip strength measurements in children.

Predicting the handgrip strength across the age span: Cross-validating reference equations from the 2011 NIH toolbox norming study

STUDY DESIGN

This is a cross-sectional observational study.

BACKGROUND

Reference equations for describing hand-grip strength across the age span were derived from the 2011 NIH Toolbox norming study.

PURPOSE

The purpose of this study was to cross-validate reference equations by evaluating its predicting power on a separate, independent data set from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) study METHODS: Observed hand-grip strength data from 13,676 noninstitutionalized participants were obtained from the NHANES study. Best values (best from 3 trials) and the mean values (averaged from 3 trials) were determined for each hand. Using the age (yr), height (m), and weight (kg), we computed predicted grip strength values for dominant and nondominant hands using the reference equations. For validation, three predictability measures: the correlation coefficient, residuals, and accuracy, were used along with the Bland-Altman plot.

RESULTS

The predicted values highly correlated with observed values (r = 0.90, ICC = 0.89). In predicting best values, means (SD) of residuals were 1.41 (5.57) and 1.03 (5.44) kg for dominant and nondominant hands, respectively. In predicting mean values, means (SD) of residuals were -0.23 (5.42) and -0.54 (5.31) kg for dominant and nondominant hands, respectively. Root mean square error ranged from 4.10 (female's nondominant mean values) to 6.74 (male's dominant best values). About 5.56% fell outside of the 95% confidence interval of the prediction.

CONCLUSIONS

We acknowledged that the two studies' hand-grip protocols (NIH Toolbox, NHANES) were different. Results provided the preliminary predicting performance of the reference equations derived from the NIH Toolbox study.

Handgrip as a measure of muscle strength and its physiological dependence on therapeutic variables: A randomized case

Clinical and medical data findings have traditionally been more representative of male than female subjects, and when combined, have not clearly differentiated between the groups. In this study there were no research questions initially contemplated, as the data were obtained from an educational setting, where participants completed tasks as part of a pedagogical program of preparation. The nature of the post-hoc analysis renders the study as a hypothesis-generating type rather than a hypothesis-testing one. It began as a cross-sectional quantitative analysis of performance on a task to explore the relationship between hand grip and three independent physiological variables. The data collected from all subjects were randomized since the total group of participants contained a disproportionate number of females as compared to males, this being a result of a demographic predominance of female students in a program of teacher preparation. Graphical analysis with the slope taken as a measure of hand grip dependence on three independent variables, and the correlation value used as a measure of association between variables yielded discernible differences. The grip strength dependence on the hand size as well as the wrist thickness show consistently significant differences for females only, with t test of significance (p < .001), and large effect size differences based on Cohen's d values of 3.08 and 1.92, respectively. The significance of the finding that female grip strength depends the most on wrist thickness has implications for rehabilitative and therapeutic settings.

Anthropometrics and electromyography as predictors for maximal voluntary isometric wrist torque: Considerations for ergonomists

The purpose of this study was to evaluate anthropometry and forearm muscle activity as predictors of maximal isometric wrist torque. Thirteen anthropometric measures, forearm electromyography from flexor carpi radialis (FCR) and extensor carpi radialis (ECR), and maximal isometric wrist flexion/extension torque were obtained from 25 male participants. Pearson correlation coefficients assessed relationships between peak isometric torque and: (1) anthropometrics, (2) FCR and ECR activation, (3) FCR/ECR antagonist/agonist coactivation ratios. Based on significant correlations, linear regression equations were developed (SPSS v.25; p < 0.05). Hand thickness, forearm circumference and ECR activation or hand thickness, elbow circumference, FCR activation and body weight were most highly correlated with extension or flexion torque, respectively. Hand thickness, forearm circumference, and ECR activation (R² = 54.5%; p = 0.001) and hand thickness, elbow circumference, FCR activation (R² = 68.3%; p < 0.001) explained similar variance in torque regressions as did the addition of body weight to extension (R² = 58.0%; p = 0.001) and flexion (R² = 69.9%; p < 0.001) torque regression equations, respectively. Circumference measurements, a pseudo for muscle size, and activation amplitude influenced wrist force output more than limb length or coactivation.

Metacarpal squeezing reduces grip strength

Unduly tight plaster hand casts may narrow the metacarpal joint space, hindering rehabilitation. This study investigated how metacarpal narrowing affects grip strength. Forty-two adult volunteers with no other pathology were included. Dominant and non-dominant hand grip strength was measured with a digital hand dynamometer (Jamar plus, China). Metacarpal width was measured with a metal caliper, and the caliper was then fixed at 10% narrowing of the joint space, and a second measurement of grip strength was taken. The measurements were thus taken twice each in the dominant and non-dominant hand, and the average of the two was recorded. A total 336 measurements were taken in the dominant and non-dominant hands of 42 individuals at two time points. There was no significant difference in grip strength between dominant and non-dominant hands (p = 0.183). After 10% narrowing, both the dominant and the non-dominant hand showed a mean 33.4% reduction in grip strength: i.e., squeezing the metacarpus with a caliper significantly reduced grip strength in both dominant and non-dominant hands (p = 0.01). The study thus showed that grip strength will decrease significantly when the metacarpus is squeezed by a tight cast. Although the patient does not feel the 10% narrowing of the metacarpus, it is clear that hand muscle mass may be adversely affected in the long term.

Body muscle gain and markers of cardiovascular disease susceptibility in young adulthood: A cohort study

BACKGROUND

The potential benefits of gaining body muscle for cardiovascular disease (CVD) susceptibility, and how these compare with the potential harms of gaining body fat, are unknown. We compared associations of early life changes in body lean mass and handgrip strength versus body fat mass with atherogenic traits measured in young adulthood.

METHODS AND FINDINGS

Data were from 3,227 offspring of the Avon Longitudinal Study of Parents and Children (39% male; recruited in 1991-1992). Limb lean and total fat mass indices (kg/m2) were measured using dual-energy X-ray absorptiometry scans performed at age 10, 13, 18, and 25 y (across clinics occurring from 2001-2003 to 2015-2017). Handgrip strength was measured at 12 and 25 y, expressed as maximum grip (kg or lb/in2) and relative grip (maximum grip/weight in kilograms). Linear regression models were used to examine associations of change in standardised measures of these exposures across different stages of body development with 228 cardiometabolic traits measured at age 25 y including blood pressure, fasting insulin, and metabolomics-derived apolipoprotein B lipids. SD-unit gain in limb lean mass index from 10 to 25 y was positively associated with atherogenic traits including very-low-density lipoprotein (VLDL) triglycerides. This pattern was limited to lean gain in legs, whereas lean gain in arms was inversely associated with traits including VLDL triglycerides, insulin, and glycoprotein acetyls, and was also positively associated with creatinine (a muscle product and positive control). Furthermore, this pattern for arm lean mass index was specific to SD-unit gains occurring between 13 and 18 y, e.g., -0.13 SD (95% CI -0.22, -0.04) for VLDL triglycerides. Changes in maximum and relative grip from 12 to 25 y were both positively associated with creatinine, but only change in relative grip was also inversely associated with atherogenic traits, e.g., -0.12 SD (95% CI -0.18, -0.06) for VLDL triglycerides per SD-unit gain. Change in fat mass index from 10 to 25 y was more strongly associated with atherogenic traits including VLDL triglycerides, at 0.45 SD (95% CI 0.39, 0.52); these estimates were directionally consistent across sub-periods, with larger effect sizes with more recent gains. Associations of lean, grip, and fat measures with traits were more pronounced among males. Study limitations include potential residual confounding of observational estimates, including by ectopic fat within muscle, and the absence of grip measures in adolescence for estimates of grip change over sub-periods.

CONCLUSIONS

In this study, we found that muscle strengthening, as indicated by grip strength gain, was weakly associated with lower atherogenic trait levels in young adulthood, at a smaller magnitude than unfavourable associations of fat mass gain. Associations of muscle mass gain with such traits appear to be smaller and limited to gains occurring in adolescence. These results suggest that body muscle is less robustly associated with markers of CVD susceptibility than body fat and may therefore be a lower-priority intervention target.

Prediction equation of hip external rotators maximum torque in healthy adults and older adults using the measure of hip extensors maximum torque

BACKGROUND

The use of predictive equation of muscular torque can reduce physical effort and time spent during evaluation.

OBJECTIVES

To establish, validate, and test the accuracy of a prediction equation to estimate the hip external rotators (HER) torque in adults and older adults by means of hip extensors (HEX) torque measurement.

METHODS

Eighty-three healthy adults (development set) were assessed to test the association of HEX and HER torques and to establish the prediction equation. A separate 36 adults and 15 older adults (validation sets) were assessed to test the ability of the equation to estimate HER torque. Hip isometric strength was assessed by a handheld dynamometer.

RESULTS

Simple linear regression analysis revealed that HEX torque was associated with HER torque (r=0.80; p<0.0001), resulting in the following prediction equation: HERtorque=-0.02+(0.58 * HEXtorque). Paired t-test revealed no difference between directly measured and predicted values of HER torque in adults (mean difference=0.02; 95% CI=-0.115, 0.072) and older adults (mean difference=0.05; 95% CI=-0.02, 0.12).

CONCLUSION

The HEX and HER torques were strongly correlated. The prediction equation was valid, accurate, and can be used to estimate HER muscle strength in healthy adults and older adults, requiring only the direct measurement of HEX torque.

Normative values of handgrip and pinch strengths in healthy female college students in Riyadh, Saudi Arabia: a cross-sectional study

Background

Handgrip strength (HGS) and pinch strengths (PS) are the common measures to evaluate hand function and predict general health. Normative values of HGS, PS, and prediction equations of HGS for healthy young adult women have not been reported yet in Saudi Arabia. The aims of the study were to determine the HGS and PS normative values and develop the prediction equations for the established HGS in a sample of healthy female college students, aged 19–25 years. In this descriptive cross-sectional study, 139 healthy female college students were recruited randomly from King Saud University (KSU). Both HGS and PS in kilograms were measured using a Jamar hand dynamometer and pinch gauge respectively with standard testing protocol and instructions.

Results

HGS significantly increased with progress in age, while there was no significant effect of age on PS. HGS and PS of the dominant hand were statistically greater than those of the nondominant hand (P < 0.05) in most ages. There were significant correlations between dominant HGS, age (r = 0.7, P < 0.001), palmar width (r = 0.74, P < 0.001), and level of physical activity (r = 0.60, P < 0.001). Regression analysis revealed that palmar width and age were the predictors of dominant HGS and accounted for 55% and 14% of the variation, respectively.

Conclusions

Normative values can be used as a clinical reference in the evaluation of hand function in the rehabilitation process with consideration of age and palmar width for a particular population.

A deep learning-based method for grip strength prediction: Comparison of multilayer perceptron and polynomial regression approaches

The objective of this study was to accurately predict the grip strength using a deep learning-based method (e.g., multi-layer perceptron [MLP] regression). The maximal grip strength with varying postures (upper arm, forearm, and lower body) of 164 young adults (100 males and 64 females) were collected. The data set was divided into a training set (90% of data) and a test set (10% of data). Different combinations of variables including demographic and anthropometric information of individual participants and postures was tested and compared to find the most predictive model. The MLP regression and 3 different polynomial regressions (linear, quadratic, and cubic) were conducted and the performance of regression was compared. The results showed that including all variables showed better performance than other combinations of variables. In general, MLP regression showed higher performance than polynomial regressions. Especially, MLP regression considering all variables achieved the highest performance of grip strength prediction (RMSE = 69.01N, R = 0.88, ICC = 0.92). This deep learning-based regression (MLP) would be useful to predict on-site- and individual-specific grip strength in the workspace to reduce the risk of musculoskeletal disorders in the upper extremity.

Maximum handgrip strength as a function of type of work and hand-forearm dimensions

BACKGROUND

Handgrip strength is a measurement of upper extremity functionality and an indicator of overall physical ability.

OBJECTIVES

The objective of this study was to compare maximum handgrip strength (MGS) between manual workers and office employees and to investigate if the expected difference is related to the anthropometric dimensions of the workers' hands and forearms.

METHODS

This was a cross-sectional study with a sample of 1740 male workers (905 light manual workers; and 835 office employees), aged 20-64 years. Maximum voluntary contractions were obtained using a JAMAR dynamometer according to the methodology proposed by the American Society of Hand Therapy (ASHT). The highest value obtained from three trials was considered as the MGS for each side. Six anthropometric dimensions (i.e., hand length, palm length, forearm length, hand breadth, wrist circumference and forearm circumference) were measured by digital caliper and tape measure.

RESULTS

Maximum handgrip strength of light manual workers (52.7±8.5 kg) was significantly higher than that of office employees (47.3±8.4 kg) (p < 0.001). Maximum handgrip strength was positively correlated with Hand breadth (r = 0.781 for light manual workers and r = 0.766 for office employees; p < 0.001) and Forearm circumference (r = 0.741 for light manual workers and r = 0.752 for office employees; p < 0.001); the only dimensions which were significantly different between the two studied job groups.

CONCLUSIONS

The results of this study revealed that light manual workers are approximately 12.4% stronger than office employees in terms of maximum handgrip force. It is therefore imperative to consider the observed differences in clinical, workstations, and hand tool designs in order to increase efficiency and comfort at work.

Association of Body Shape Index (ABSI) with Hand Grip Strength

Hand grip is a leading measure of muscle strength and general health, yet its association with body shape is not well characterized. Here, we examine correlations between grip strength, a body shape index (ABSI), and body mass index (BMI) in the 2011-2014 United States National Health and Nutrition Examination Survey cohorts. Grip strength was found to correlate negatively with ABSI (though positively with BMI), suggesting that those with a more central body profile tend to be weaker than others with the same weight. Individuals with low grip strength, as well as those with high ABSI, were more likely to die during follow up, whereas there was no association of BMI with mortality hazard. Transforming the grip strength, ABSI, and BMI by taking their logarithm prior to standardization did not meaningfully change the associations seen. These findings suggest that combining anthropometrics (ABSI, BMI) with grip strength may better identify individual mortality hazard in research studies and clinical practice.

Normalized grip strength is a sensitive outcome measure through all stages of Duchenne muscular dystrophy

OBJECTIVE

The main aim was to explore the changes in hand-grip strength in patients with Duchenne muscular dystrophy (DMD) aged 5-29 years. Secondary aims were to test the effect of mutation, ambulatory status and glucocorticoid use on grip strength and its changes over time and to compute the number of subjects needed for a clinical trial to stabilize grip strength.

METHODS

The analysis was performed on data collected during five international natural history studies on a cohort of DMD patients. Two hundred and two patients with genetically proven DMD were pooled from five different natural history studies. Excepting 13 patients with only one visit, the mean duration of follow-up was 2.2 ± 1.6 years. A total of 977 measurement points were collected. Grip strength was measured on the dominant side with a high precision dynamometer. The analysis was performed using absolute values and normalized values expressed in percentage of predicted values for age.

RESULTS

For absolute values, grip strength typically increased in ambulatory boys and decreased in non-ambulatory patients. However, when normalized, grip strength was already reduced at age 5 years and thereafter continued to fall away from normal values. The weaker the patients, the less strength they are prone to lose over again.

INTERPRETATION

Grip strength constitutes a sensitive and continuous outcome measure that can be used across all stages of DMD. Its measurement is easy to standardized, can be used in ambulatory and non-ambulatory patients and does not present any floor or ceiling effect. It is thus attractive as an outcome measure in therapeutic trials.

Investigation on the Cooperative Grasping Capabilities of Human Thumb and Index Finger

The maximum cooperative grasping mass and diameter of the human thumb and index finger were investigated by 7560 grasp-release trials on various masses of solid cylinders and various sizes of rings. The maximum grasping mass of the participants’ thumb-index finger depended on gender, age and the sum of thumb-index finger lengths (P < 0.05), but not on the hand-used and ratio of index finger to thumb length (P > 0.05). The maximum grasping diameter of the participants’ thumb-index finger depended on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length (P < 0.05), but not on the gender and hand-used (P > 0.05). There was a non-linear regression model for the dependence of the maximum grasping mass on gender, age and the sum of thumb-index finger lengths and another non-linear regression model for the dependence of the maximum grasping diameter on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length. Two regression models were useful in the optimal size design of robotic hands intending to replicate thumb-index finger grasping ability. This research can help to define not only a reasonable grasp mass and size for a bionic robotic hand, but also the requirements for hand rehabilitation.

Reference values and associated factors of hand grip strength in elderly Saudi population: a cross-sectional study

Background

Hand grip strength (HGS) is an important function of upper extremities for older adults. Several studies have shown the importance of measuring HGS in different settings. Current established normative values of HGS are applicable for Western countries. However, there is limited information of normative values of HGS after considering demographics in Saudi population. Therefore, this study aimed to establish normative values of HGS stratified by age and gender, and to determine the association of anthropometric measurements with the HGS in Saudi population.

Methods

A cross-sectional study included a total of 1048 participants (mean age 73 ± 5 years). Grip strength was calculated by the average peak force of three trials for the dominant hand using a dynamometer. Sociodemographic data on age, gender, marital status, educational levels were collected. Anthropometric measurements including height, body mass index, arm circumference, and upper arm length were obtained. The sample was categorized into three age groups: 65–69 years, 70–74 years, and 75–80 years. Linear regression analysis was used to assess the association between the sociodemographic and anthropometric data and HGS.

Results

The mean values of HGS (kg) for men for each age group were 36.9 ± 8.3 for the younger group, 35.7 ± 7.4 for the 70–74 years group and 30.5 ± 7.1 for the older group. The mean values of HGS for women for each group were 23.2 ± 4.7 for the younger group, 21.1 ± 4.6 for the 70–74 years group and 18.8 ± 4.9 for the older group. The HGS was negatively associated with the age for men (B = -.40, 95% confidence interval (CI) [−.52, −.29], p < 0.001) and women (B = -.30, 95% CI [− 0.38, − 0.22], p < 0.001), and positively associated with the arm length in men (B = .87, 95% CI [.60, 1.15], p < 0.001). The HGS was positively associated with the educational level in men (B = .66, 95% CI [.09,1.21], p = .02), but negatively associated in women (B = -.42, 95% CI [− 0.75, − 0.08], p = .01).

Conclusion

This study is the first that established normative values of HGS for older adults in Saudi Arabia. Future research may benefit from the current normative value of HGS in Saudi population for geriatric rehabilitation programs.

Anthropometric Obesity Indices, Body Fat Percentage, and Grip Strength in Young Adults with different Physical Activity Levels

The purposes of this study were to determine whether moderately physically active (MPA) and highly physically active (HPA) male (n = 96, age = 22.5 ± 1.7 years) and female (n = 85, age = 21.3 ± 1.6 years) young adults differed in their anthropometric obesity indices (AOIs), body fat percentage (BF%), and muscular strength, and also to examine the associations between physical activity level (PAL) and the abovementioned variables. Participants were measured for body height and weight, BF%, waist and hip circumferences, and maximal isometric grip strength. According to their PAL, estimated by the short version of the International Physical Activity Questionnaire, they were assigned to MPA and HPA subgroups. Regardless of gender, results indicated that participants in the MPA groups had significantly higher values of body weight, waist and hip circumference, BF%, and BMI than participants in the HPA groups. No significant differences were found between physical activity groups in terms of grip strength. The AOIs and BF% were found to be significantly and negatively correlated with the PAL in both genders. In conclusion, the findings of the study suggest that high habitual physical activity is associated with lower adiposity markers. However, the differences in the hand grip strength of the contrasting activity groups were negligible.

25-Hydroxyvitamin D levels and its relation to muscle strength, maximal oxygen consumption, and body mass index in young and middle adulthood women

Introduction

Vitamin D is a potent secosteroid hormone that provides many health benefits. The ubiquitous nature of vitamin D receptor (VDR) suggests widespread effect.

Purpose

The purpose of this study was to investigate the relationship between 25-hydroxyvitamin D (25OHD) levels and muscle strength, maximal oxygen consumption (VO₂max), and body mass index (BMI) in Iranian young and middle adulthood women.

Participants and methods

A cross-sectional descriptive study was conducted in 182 healthy Iranian women within the age range of 26–60 years. Body weight and height were measured, and BMI was calculated. VO₂max was determined by the Rockport test. Muscle strength was determined by the chest press, leg press, and hand grip test. Also, circulating levels of 25OHD were evaluated.

Results

Results showed a significant relationship between 25OHD levels and BMI, VO₂max, and muscle strength (chest press, leg press, hand grip dominant hand [HGDH], and hand grip nondominant hand [HGNDH]) in young and middle adulthood women (BMI in young and middle adulthood: r=−0.48, P<0.001 and r=−0.27, P=0.01, respectively; VO₂max in young and middle adulthood women: r=0.69, P<0.001 and r=0.57, P<0.001, respectively; chest press, leg press, HGDH, and HGNDH in young adulthood: r=0.58, r=0.59, r=0.65, and r=0.42, respectively, P<0.001; and in middle adulthood: r=0.73, r=0.34, r=0.66, and r=0.55, respectively, P≤0.001). Multiple linear regression analysis showed that higher levels of VO₂max, HGDH, and chest press predicted higher 25OHD levels in the young adulthood women (R²=0.75; β=0.39, β=0.35, and β=0.30, respectively; P<0.001). Moreover, VO₂max and HGDH were the strongest predictor of 25OHD levels in the middle adulthood women (R²=0.71; β=0.35, β=0.40, respectively; P<0.001).

Conclusion

Based on the results, it could be concluded that VO₂max and strength are useful indirect marker for 25OHD levels in the young and middle adulthood women. It also seems that VO₂max and HGDH strength had stronger associations with 25OHD levels in the young adulthood women, and chest press and HGDH had stronger associations with 25OHD levels in the middle adulthood women.

Grip and pinch strength: Reference values for children and adolescents from India

PURPOSE

The purpose of the study was to provide reference values for grip and pinch strength for healthy children and adolescents in India.

METHODS

Grip and pinch strength were recorded for 900 participants stratified into 5 chronological age groups (5-6, 7-9, 10-12, 13-15 and 16-18 years). Grip strength was measured using a Jamar Dynamometer and pinch strength using a Martin vigorimeter.

RESULTS

The difference in grip and pinch strength between age groups was significant (p< 0.001 respectively). A linear rise in grip strength was noted from age groups of 5-6 years to 16-18 years. Moderate to strong positive association was observed between grip and pinch strength and upper extremity anthropometric characteristics (i.e., palmar width, hand span, hand length, arm length, forearm length, and upper limb length) from age groups of 5-6 years to 16-18 years. Boys demonstrated greater grip and pinch strength compared to girls in all age groups (p< 0.001). No difference was observed between the dominant and non-dominant hand in all age groups.

CONCLUSIONS

Findings from the present study provide reference values for grip strength, tip to tip, key and tripod pinch for healthy Indian children and adolescents from 5-18 years of age, which will be useful to guide rehabilitation outcomes in routine clinical practice.

The motor unit number index (MUNIX) profile of patients with adult spinal muscular atrophy

OBJECTIVE

Objective of this study is the comprehensive characterisation of motor unit (MU) loss in type III and IV Spinal Muscular Atrophy (SMA) using motor unit number index (MUNIX), and evaluation of compensatory mechanisms based on MU size indices (MUSIX).

METHODS

Nineteen type III and IV SMA patients and 16 gender- and age-matched healthy controls were recruited. Neuromuscular performance was evaluated by muscle strength testing and functional scales. Compound motor action potential (CMAP), MUNIX and MUSIX were studied in the abductor pollicis brevis (APB), abductor digiti minimi (ADM), deltoid, tibialis anterior and trapezius muscles. A composite MUNIX score was also calculated.

RESULTS

SMA patients exhibited significantly reduced MUNIX values (p < 0.05) in all muscles, while MUSIX was increased, suggesting active re-innervation. Significant correlations were identified between MUNIX/MUSIX and muscle strength. Similarly, composite MUNIX scores correlated with disability scores. Interestingly, in SMA patients MUNIX was much lower in the ADM than in the ABP, a pattern which is distinctly different from that observed in Amyotrophic Lateral Sclerosis.

CONCLUSIONS

MUNIX is a sensitive measure of MU loss in adult forms of SMA and correlates with disability.

SIGNIFICANCE

MUNIX evaluation is a promising candidate biomarker for longitudinal studies and pharmacological trials in adult SMA patients.

Comparison of the Grip Strength Using the Martin-Vigorimeter and the JAMAR-Dynamometer: Establishment of Normal Values

BACKGROUND/AIM

The JAMAR-Dynamometer and the Martin-Vigorimeter are frequently used tools in a hand surgeon's daily routine. This survey is primarily concerned with the establishment of valid conversion factors for measured values of both instruments, as well as the investigation of influence of anatomical characteristics and age and sex on maximal measured grip strength.

PATIENTS AND METHODS

We registered anamnestic data and specific anatomical conditions in 339 patients, maximal grip strength was measured using all notches of both instruments.

RESULTS

We found moderate to very high correlation comparing all 28 settings in both instruments. The influence of the hand's anatomy on the grip strength was greater using the JAMAR-Dynamometer than it was using the Martin-Vigorimeter.

CONCLUSION

The high reproducibility allowed us to calculate multiplying factors for the conversion of measured data for all settings of both tools. Therefore, the amount of data for meta-analyses relating to hand surgical issues can be significantly increased.

Investigation of the relationship between anthropometric measurements and maximal handgrip strength in young adults

BACKGROUND

To identify physical measures that predict maximal handgrip strength (MHGS) and provide evidence for identifying lack of sincerity of effort when assessing upper extremity weakness.

OBJECTIVE

This study investigated anthropometric measurements associated with MHGS of healthy young adults.

METHODS

A convenience sample of 150 healthy adults ages 19 to 34 years old completed the MHGS assessment, which was measured using a Jamar dynamometer according to the protocol of the American Society of Hand Therapists, for both dominant and non-dominant hands. Several anthropometric data were collected, which included height, body weight, forearm length, forearm circumference, hand length, and hand width.

RESULTS

Multivariable linear regression analysis indicated gender and hand width were uniquely and significantly associated with participants' MHGS for dominant and non-dominant hand and accounted for more than 60% of the variance, with R2 = 0.60, P < 0.001 for the dominant hand model and R2 = 0.64, P < 0.001 for the non-dominant hand model.

CONCLUSIONS

Among the forearm and hand anthropometric measures, hand width is the best predictor of MHGS in both the non-dominant and dominant hands for healthy young adults.

Reference values of intrinsic muscle strength of the hand of adolescents and young adults

STUDY DESIGN

A cross-sectional clinical measurement study.

INTRODUCTION

Measuring intrinsic hand muscle strength helps evaluate hand function or therapeutic outcomes. However, there are no established normative values in adolescents and young adults between 13 and 20 years of age.

PURPOSE OF THE STUDY

To measure hand intrinsic muscle strength and identify associated factors that may influence such in adolescents and young adults through use of the Rotterdam intrinsic hand myometer.

METHODS

A total of 131 participants (male: 63; female: 68) between 13 and 20 years of age completed the strength measurements of abductor pollicis brevis, first dorsal interosseus (FDI), deep head of FDI and lumbrical of second digit, flexor pollicis brevis (FPB), and abductor digiti minimi. Two trials of the measurements of each muscle were averaged for analyses. Self-reported demographic data were used to examine the influences of age, sex, and body mass index (BMI) on intrinsic hand muscle strength.

RESULTS

Normative values of intrinsic hand muscle strength were presented by age groups (13, 14, 15-16, 17-18, 19-20 year olds) for each sex category (male, female). A main effect of sex, but not age, on all the muscles on both the dominant (FPB: P = .02, others: P < .001) and non-dominant (FDI: P = .005, FPB: P = .01, others: P < .001) sides was found. A significant effect of BMI was found on dominant (P = .009) and non-dominant abductor pollicis brevis (P = .002). In addition, FDI (P = .005) and FPB (P = .002) were stronger on the dominant side than the non-dominant side.

DISCUSSION

Intrinsic hand muscle strength may be influenced by different factors including sex, BMI, and hand dominance. A larger sample is needed to rigorously investigate the influence of age on intrinsic strength in male and female adolescents and young adults.

CONCLUSION

The results provide reference values and suggest factors to be considered when evaluating hand function and therapeutic outcomes in both clinical and research settings. Further study is recommended.

LEVEL OF EVIDENCE

VI.

Reference equations for handgrip strength: Normative values in young adult and middle-aged subjects

BACKGROUND & AIMS

Handgrip strength (HS) has been widely used as a functionality parameter of the upper limbs (UL) and general health. The measurement of HS by dynamometry is a low cost, non-invasive method of simple applicability, widely used in pulmonary rehabilitation and in critical care units. However, there are no reports in the literature of reference equations for the Brazilian population involving young and middle-aged adults. The aim of this study was to establish reference equations to predict normal HS for young and middle-aged adults through demographic and anthropometric data.

METHODS

This is a cross-sectional study with a sample of 80 healthy subjects (40 men and 40 women), aged 20-60 years. Inclusion criteria were: 1) BMI between 18.5 and 30 kg/m²; 2) presence of dominant hand; 3) no cardiac, pulmonary, metabolic, or neurologic diseases; 4) lack of musculoskeletal disorders; 5) no history of fractures or trauma of the UL. Anthropometric measurements of the UL were obtained by a tape (hand length and width, forearm circumference and length). The dominance of hands was defined by the Dutch Handedness Questionnaire. HS measures were obtained by a manual hydraulic dynamometer, according to the recommendations of the American Association of Hand Therapists. Data were analyzed with SPSS for Windows, version 17.0, and treated with descriptive and inferential analysis. Normality was evaluated by Kolmogorov-Smirnov. Pearson or Spearman coefficients and multiple regression analysis were also used.

RESULTS

HS was significantly higher for men compared to women, and also higher for the dominant hand (HSD) compared to the non-dominant hand (HSND) (p < 0.05). No significant differences were found for HS between the age groups 20-30, 30-40, 40-50 and 50-60 years (p > 0.05). No correlation was found between HS and age. A weak correlation was found between HS and BMI. A moderate correlation of HS was observed with weight and height. Finally, moderate and high correlations were found between HS and anthropometric variables of UL. The best reference equations with R², adjusted to 0.71 and 0.70, were respectively: HSD_kg = -15.490 + (10.787 × Gender _{male=1; female=0}) + (0.558 × Forearm circumference) + (1.763 × Hand Length); HSND_kg = -9.887 + (12.832 × Gender _{male=1; female=0}) + (2.028 × Hand Length).

CONCLUSION

The variability of HS is largely explained by gender, forearm circumference, and hand length.

Hand grip strength determination for healthy males in Saudi Arabia: A study of the relationship with age, body mass index, hand length and forearm circumference using a hand-held dynamometer

Objectives To determine whether age, body mass index (BMI), hand length and forearm circumference were predictive of hand grip strength in healthy Saudi Arabian adult males. Methods This cross-sectional descriptive study recruited healthy adult male volunteers. Their anthropometric characteristics including age, BMI, hand length and forearm circumference were measured using routine techniques. Hand grip strength was assessed using a Jamar® Hydraulic Hand Dynamometer. The data were analysed using Pearson correlation coefficient ( r) as well as by a stepwise multiple linear regression analysis. Results The study included 116 healthy males who satisfied the inclusion criteria. A Pearson correlation coefficient matrix demonstrated that all the four measures, age, BMI, hand length and forearm circumference, were significantly correlated with hand grip strength. Age had an inverse correlation with hand grip strength. The anthropometric measures of hand length, age and forearm circumference accounted for 44.2% (R² 0.442) of the variation of the hand grip strength. Conclusion Hand length, age and forearm circumference significantly impacted on hand grip strength in Saudi Arabian healthy adult males.

The Relationship of Physical Activity and Anthropometric and Physiological Characteristics to Bone Mineral Density in Postmenopausal Women

The aim of this study is to investigate the relationship of physical activity and anthropometric and physiological characteristics to bone mineral density (BMD) in postmenopausal women. Ninety-seven postmenopausal women with an average age of 50.71 ± 6.86 yr were selected to participate in this study. After completing consent forms and the questionnaire on physical activity, the amounts of calcium and 25-hydroxyvitamin D levels in participants' blood were measured by blood tests. The BMDs of the subjects in the lumbar spine (L2-L4) and hip were measured by dual-energy X-ray absorptiometry device and the results were recorded. Also, anthropometric characteristics including height, weight, body fat percentage, body mass index, waist-to-hip ratio (WHR), digit ratio (2D:4D), skeletal muscle mass index, hand and calf circumferences and physiological parameters, including handgrip strength, quadriceps isotonic extension strength and balance of the subjects, were measured. The results showed that the 2D:4D ratio and skeletal muscle mass index had a significantly positive relationship with BMD of the lumbar spine (p ≤ 0.05) and the hip (p ≤ 0.05). Also, there was a negative relationship between the BMD of lumbar spine and hip and WHR (p ≤ 0.05). Moreover, there was a positive relationship between the calf circumferences and lumbar spine BMD (p ≤ 0.05). Contrary to this, there was no significant relationship between the calf circumference and the hip BMD, and between hand circumference with lumbar spine and hip BMD (p > 0.05). Results of physiological indices showed a significant positive relationship between physical activity, handgrip strength, quadriceps isotonic extension strength, standing on 1 foot with the lumbar spine and hip BMD (p ≤ 0.05). But the relationship was not observed between BMD and the ability to squat down on the floor (p > 0.05). Based on these results, it seemed that we can use some physiological and anthropometric indices that are important determinants of BMD and risk of osteoporosis in postmenopausal women.

Associations between Handgrip Strength and Ultrasound-Measured Muscle Thickness of the Hand and Forearm in Young Men and Women

It is unknown whether muscle size of intrinsic hand muscles is associated with handgrip strength. To investigate the relationships between handgrip strength and flexor muscle size of the hand and forearm, muscle thickness (MT) of 86 young adults (43 men and 43 women) between the ages of 18 and 34 y was measured by ultrasound. Two MTs (forearm radius and forearm ulna MT) in the anterior forearm, two MTs (lumbrical and dorsal interosseous MT) in the anterior hand and handgrip strength were measured on the right side. Linear regression with part (also referred to as semipartial) correlation coefficients revealed that forearm ulna MT positively correlated with handgrip strength in both men (part = 0.379, p = 0.001) and women (part = 0.268, p = 0.002). Dorsal interosseous MT correlated with handgrip strength in women only (part = 0.289, p = 0.001). Our results suggest that the forearm ulna and dorsal interosseous MTs for women and forearm ulna MTs for men are factors contributing to prediction of handgrip strength in young adults.

Grip strength measured by high precision dynamometry in healthy subjects from 5 to 80 years

BACKGROUND

Grip strength is a variable which may be important to measure and follow in various populations. A new dynamometer with high accuracy and sensitivity has recently been developed to assess grip strength. The objectives of this work were to provide norms of maximal isometric grip strength measured with this new dynamometer (the MyoGrip device), to assess the reliability of measurements, to compare the measurements obtained with MyoGrip and Jamar dynamometers and finally to establish predictive equations from a population of healthy subjects (children and adults).

METHODS

Measurements of maximal isometric grip strength using the MyoGrip and the Jamar (which is considered as the gold-standard) were performed on 346 healthy subjects aged from 5 to 80 years. Test-retest reliability for both devices was assessed on 77 subjects. Predictive equations were computed on subjects younger than 60 years of age in order to avoid the effects of aging on strength.

RESULTS

This study provides norms for isometric grip strength for health subjects from 5 to 80 years. Reliability of the MyoGrip device was excellent (intraclass correlation coefficient: 0.967). Despite good correlation between devices, the Jamar tended to overestimate maximal grip strength by about 14 %. A single predictive equation for men and women, adults and children incorporating hand circumference only can be used to compute the predicted theoretical maximal grip strength.

CONCLUSIONS

The MyoGrip device is a reliable tool for measuring isometric grip strength. Owing to its unique metrological features, it can be used in very weak patients or in any situation where high precision and accuracy are required.

Estimation of sarcopenia prevalence using various assessment tools

BACKGROUND

Sarcopenia is defined as a progressive and generalized loss of muscle mass with either a loss of muscle strength or a loss of physical performance but there is no recommendation regarding the diagnostic tools that have to be used. In this study, we compared the prevalence of sarcopenia assessed using different diagnostic tools.

METHODS

To measure muscle mass, muscle strength and physical performance, we used for each outcome two different diagnostic tools. For muscle mass, we used Dual Energy X-Ray Absorptiometry (DXA) and bio-electrical impedance analysis (BIA); for muscle strength, we used a hydraulic dynamometer and a pneumatic dynamometer; for physical performance we used the Short Physical Performance Battery test (SPPB test) and the walk speed. Eight diagnostic groups were hereby established.

RESULTS

A total of 250 consecutive subjects were recruited in an outpatient clinic in Liège, Belgium. Estimated prevalence of sarcopenia varied from 8.4% to 27.6% depending on the method of diagnosis used. Regarding muscle mass, BIA systematically overestimated muscle mass compared to DXA (mean estimated prevalence with BIA=12.8%; mean prevalence with DXA=21%). For muscle strength, the pneumatic dynamometer diagnosed twice more sarcopenic subjects than the hydraulic dynamometer (mean estimated prevalence with PD=22.4%; mean estimated prevalence with HD=11.4%). Finally, no difference in prevalence was observed when the walking speed or the SPPB test was used. A weak overall kappa coefficient was observed (0.53), suggesting that the 8 methods of diagnosis are moderately concordant.

CONCLUSION

Within the same definition of sarcopenia, prevalence of sarcopenia is highly dependent on the diagnostic tools used.

Variation in work tasks in relation to pinch grip strength among middle-aged female dentists

OBJECTIVES

We aimed to investigate the relationship of task variation during dental work history with pinch grip strength among dentists.

METHODS

We measured pinch grip strength among 295 female Finnish dentists aged 45-63 years. Variation in dental work tasks during work history was empirically defined by cluster analysis. Three clusters of task variation emerged: low (most work time in restoration treatment/endodontics), moderate (about 50% in the former and 50% in prosthodontics/periodontics/surgery), and high (variable tasks including administrative duties). Hand radiographs were examined for the presence of OA in the wrist and each joint of the 1-3rd fingers. Information on hand-loading leisure-time activities, and joint pain was obtained by questionnaire. Glove size was used as a proxy for hand size. BMI (kg/m2) was based on measured weight and self-reported height.

RESULTS

Dentists with low variation of work task history had an increased risk of low pinch grip strength in the right hand (OR 2.3, 95% CI 1.2-4.3), but not in the left (1.13, 0.62-2.08), compared to dentists with high task variation, independent of age, hand size, hand-loading leisure-time activities, BMI and symptomatic hand OA.

CONCLUSION

The dentists with the most hand-loading tasks were at an increased risk of low pinch grip strength, independent of e.g. symptomatic hand OA. It is advisable among dentists to perform as diverse work tasks as possible to reduce the risk of decreased pinch grip strength.

Test-retest reliabilities of hand-held dynamometer for lower-limb muscle strength in intellectual disabilities

The primary purpose of this study was to investigate the test-retest reliabilities of hand-held dynamometer (HDD) for measuring lower-limb muscle strength in intellectual disabilities (ID). The other purposes were to: (1) compare the lower-limb muscle strength between children with and without ID; (2) probe the relationship between the muscle forces and agility performance in ID; and (3) explore the factors associated with muscle strength in ID. Sixty-one participants (30 boys and 31 girls; mean age=14.1 ± 3.3 year) were assessed by the HDD using a "make" test. The comparative group consisted of 63 typically developing children (33 boys and 30 girls; mean age=14.9 ± 2.1 year). The ID group demonstrated lower muscle groups than in typically developing group. Except for the ankle plantarflexors (ICC=0.69, SEM=0.72), test-retest analysis showed good intrarater reliability with ICC ranging from 0.81 to 0.96, and intrarater SEM values ranged from 0.40 to 0.57. The HDD has the potential to be a reliable tool for strength measurement in ID. Muscle strength was positively related to agility performance. Regression analysis indicated that height, weight, BMI, and activity level were significant predictors of muscle strength in ID.

Stature is an essential predictor of muscle strength in children

Background

Children with growth retardation or short stature generally present with lower strength than children of the same chronological age. The aim of the study was to establish if strength was dependent on variables related to stature in a population of healthy children and to propose practical predictive models for the muscle functions tested. A secondary aim was to test for any learning effects concerning strength measured at two successive visits by children.

Methods

Hand grip, elbow flexion and extension, and knee flexion and extension were measured by fixed dynamometry in 96 healthy subjects (47 girls and 49 boys, aged from 5 to 17 years).

Results

For the present paediatric population, muscle strength was highly dependent on height. Predictive models are proposed for the muscle functions tested. No learning effect between the first and the second visit was detected for any of the muscle functions tested.

Conclusions

This work shows that strength measurements using fixed dynamometry are reliable in children when using appropriate standardization of operating procedures. It underlines the particular relationship between body stature and muscle strength. Predictive equations may help with assessing the neuromuscular involvement in children suffering from various disorders, particularly those affecting their stature.

Could questions on activities of daily living estimate grip strength of older adults living independently in the community?

The aim of this study was to identify questions that could estimate grip strength. Twenty-six questions about the degree of perceived difficulty performing manual tasks as well as two questions concerning self-rated grip strength were developed and completed by 123 community-dwelling older adults, followed by grip strength measurements using a Martin vigorimeter. Multiple regression analyses with all of the participants revealed that the question about the difficulty of opening a jar (question 4) was most associated with grip strength. When analyses were done by gender, the same question showed the best correlation for women, whereas the one for men was self-rated grip strength compared with people the same age (question 28). For the women, age and question 4 together explained 54% of the variance in their grip strength and for the men, age and question 28 explained 46%. Further studies are needed to identify other information that could help to better estimate grip strength for use in epidemiological surveys.

Analysis of fatigue and tremor during sustained maximal grip contractions using Hilbert-Huang Transformation

The objective of this study was to evaluate muscle fatigue and tremor during a Sustained Maximal Grip Contraction (SMGC) using the Hilbert-Huang Transformation (HHT). Thirty-nine healthy subjects volunteered for the study and performed a 25-s SMGC. Fatigue parameters such as the relative force output (RFO) were calculated from the residual of SMGC after applying Empirical Mode Decomposition (EMD). Using the energy spectrum of the Intrinsic Mode Functions (IMF) obtained using HHT, isometric force tremor was identified from the 4 to 12 Hz region in IMF3 and IMF4. Data were analysed for five consecutive 5-s epochs to identify changes in fatigue and tremor over time. The HHT method was able to identify a greater resistance to fatigue in women compared to men (p≤0.05) and in non-dominant hands compared to dominant hands (p≤0.05). Consistent with the results for fatigue, women had less tremor than men (p≤0.05), while non-dominant hands trembled less than did dominant hands (p≤0.05). Higher levels of tremor were observed for non-fatigue-resistant subjects for both 10-15 s and 15-20 s epochs (p≤0.05). The HHT is an appropriate method to identify both fatigue and tremor during SMGC. It would be of interest to apply this method to the study the elderly or patients with neuromuscular disorders.