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Purpose. This study aimed to investigate the effects of using hand grip or resisted wrist extension as the reference contraction, and two electrode positions, on field recordings of forearm extensor muscle activity. Materials and methods . Right forearm extensor muscle activity was recorded using two electrode pairs (over the most prominent part (position 2) and proximal to that (position 1)) during one working day in 13 female hotel housekeepers. Each subject performed the two maximal voluntary contractions (MVCs), and the electrical activity obtained during these (maximal voluntary electrical activity (MVE)) was used for normalization. Each set of recordings was analysed twice, once using hand grip as the MVC and once using resisted wrist extension. Results . Resisted wrist extension showed a higher group mean MVE than hand grip. Position 2 had higher correlation between MVE and force during the MVCs. The workload during cleaning was lower when using resisted wrist extension as reference than when using hand grip (24%MVE vs 46%MVE; p  = 0.002 at position 2) for the 90th percentile. The workload (99th percentile) was overestimated in two subjects when using hand grip as reference. Conclusions. Problems associated with poorly activated forearm extensors can be overcome by using resisted wrist extension as reference.

Background: Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable., Objective: To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning., Methods: Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions., Results: The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip., Conclusions: The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.

Background: Malnutrition and poor functional reserves place patients at risk for negative surgical outcomes. In this prospective study we aimed to measure preoperative nutritional and sarcopenia risk and evaluate their impact on postoperative outcomes. Methods: Adults scheduled to undergo elective general and gastrointestinal surgery were screened for nutrition risk using the Malnutrition Universal Screening Tool screening tool. Sarcopenia risk was measured using the SARC‐F tool and hand‐grip strength. Patients were followed postoperatively. Incidence of complications, length of stay (LOS), readmission rates, and need for step‐down care were recorded. Results: One hundred and twenty‐two patients were included. Mean age was 53.8 years (standard deviation [SD] 16.44). Sixty‐six (54%) were scheduled for day‐case procedures, and 56 (46%) for nonday‐case procedures. About 18.9% (n = 23) were at nutritional risk preoperatively. Ten patients (8.2%) had probable sarcopenia based on SARC‐F, whereas seven (5.7%) had measurably reduced HG. Incidence of postoperative complications was 23.8% (n = 29). Nutrition risk was associated with the development of complications (p = 0.018). In the nonday‐case group, nutritional risk was associated with greater LOS (p = 0.013). Older age was associated with need for step‐down care (p = 0.002) as was SARC‐F (p = 0.003). Conclusions: Preoperative nutritional screening can predict postoperative complications and LOS, whereas sarcopenia screening is predictive of the need for step‐down care after discharge. Screening tools are quick and inexpensive and could provide valuable information to clinicians and allow patients the opportunity to enhance their physical preparedness for surgery thereby mitigating their risk for negative surgical outcomes. Key points: Simple, inexpensive preoperative screening tools can predict postoperative outcomes: nutritional risk as measured by the Malnutrition Universal Screening Tool (MUST) was associated with increased incidence of postoperative complications and length of stay (LOS), whereas the SARC‐F screening tool for sarcopenia was predictive of the need for step‐down care postoperatively.Routine use of nutritional and sarcopenia screening tools in a preoperative surgical outpatient setting tools can provide clinically relevant information to clinicians and allow patients the opportunity to enhance their physical preparedness for surgery thereby mitigating their risk for negative surgical outcomes. [ABSTRACT FROM AUTHOR]

Lateral epicondylitis (LE) is one of the most common work-related complications characterized by pain, decreased grip strength and dysfunction of upper limb. Although conservative management such as physiotherapy and orthosis is reported as first line of treatment, sufficient evidence to decide their effectiveness is lacking and remains controversial. The current study evaluated and compared the efficacy of a custom-made extension wrist hand orthosis adjunct to usual physiotherapy and therapeutics alone for subjects with LE. Prospective randomized single-blinded clinical trial. 62 subjects with LE were selected as samples using convenience method in this experimental study. They were randomly divided into two groups: usual physiotherapy only and its combination with orthosis. Pain and grip strength were measured using Visual Analog Scale and Jamar hydraulic digital hand dynamometer. Muscle activity of extensor carpi radialis brevis during hand gripping was measured using surface electro-myographic by PowerLab electromyography (AD Instruments, Castle Hill, Australia). Data analysis and comparison were performed for baseline and post-intervention (12 weeks). After 12 weeks of treatment, there were significant differences in mean scores of pain (1.22 ± 0.51, p = 0.001), maximum voluntary grip strength (5.82 ± 7.84, p = 0.04), and extensor carpi radialis brevis muscle activation (0.082 ± 0.094, p = 0.02) between the therapeutics alone group and the therapeutics plus orthosis group. Compared to therapeutics alone, those getting a combination of physiotherapy and orthosis had greater treatment efficacy (p < 0.05). Both postintervention (12-week) treatments could affect pain scores, grip strength, and extensor muscle activation. Custom-made extension wrist hand orthosis adjunct to usual physiotherapy is more effective than therapeutics alone in subjects with LE. Therefore, the use of wrist orthosis adjunct to physiotherapy should be recommended in rehabilitation settings for LE. • Lateral epicondylitis (LE) is a common work-related complication of upper limb. • Orthosis and therapy can affect pain, grip strength, and extensor muscle activity in LE. • Wrist orthoses reduce pain and apply counter force to reduce load on extensor tendon. • WHO adjunct to physiotherapy is primary practice strategy for rehabilitation in LE. [ABSTRACT FROM AUTHOR]

Background CrossFit is characterized by a diverse range of exercises recruiting different muscles and requiring different muscle functions. A characterization of muscular performance parameters in this population is needed. Purpose To determine reference values for various aspects of muscular performance of muscles of the trunk, thigh, hip, and mass grasp in CrossFit participants. Also, this investigation aimed to compare the strength measures between male and female CrossFit participants, as well as between dominant and non-dominant limbs. Design Descriptive, Cross-sectional. Setting Laboratory. Methods Isometric strength of trunk extensors (TE) and mass grasp was measured with handheld and Jamar dynamometer respectively. An isokinetic dynamometer was used to assess the muscle performance of the knee flexors (KF) and extensors (KE) (at 60º/s and 300º/s), and hip flexors (HF), extensors (HE), and abductors (HA) (60º/s and 240º/s ). Reference values for torque, work, power, fatigue, flexor:extensor ratio for the knee (hamstring:quadriceps - H:Q) and hip (HF:HE) joints were calculated. The torque and work values were normalized by the body mass. Mixed multivariate and univariate analyses of variance and independent t-tests were used for statistical analyses to compare between sexes and limbs. Results Participants included 111 individuals (58 males and 53 females) with at least one year of experience in CrossFit. Normative data are provided for the outcome variables. Males had greater values of muscular performance parameters than females in most variables (p<0.05). Also, the dominant limb had greater mass grasp strength (p<0.002), greater KE power at 60º/s (p=0.015), lower H:Q ratio at 60º/s (p=0.021) and 300º/s (p=0.008), and lower KE fatigue (p=0.002). Conclusion This study provides reference values for the trunk extensors, mass grasp, knee, and hip muscle performance in male and female CrossFit practitioners. Their muscle performance profile was characterized by few inter-limb asymmetries, and males demonstrated greater muscular performance outcomes than females, even after normalization by body mass. These reference values can be used for comparisons in research and clinical settings. Level of Evidence 3b [ABSTRACT FROM AUTHOR]

Background: Electromyographic systems are widely used in scientific and clinical practice. The reproducibility and reliability of these measures are crucial when conducting scientific research and collecting experimental data.Objective: To test the reliability of surface electromyography signals from both the Flexor Digitorum Superficialis (FDS) and Extensor Carpi Radialis Brevis (ECRB) muscles of both the left and right arms during an individual, static multi-planar maximum voluntary contraction handgrip task using the Myon 320 system (Myon AG, Switzerland).Methods: Eight right-handed male participants performed two maximal handgrip tests in five separate wrist positions using both hands. Muscle activity was recorded from both forearms. Reliability was measured using the Standard Error of Measurement (SEM), Coefficient of Variation (CV) and Intra-class correlation coefficients. Wrist joint position correlations within and between the FDS and ECRB muscle activities were also analysed.Results: Absolute reliability was shown across all positions for both hands with CV and SEM recorded at below 10%. The output measures indicate that the Myon 320 system (Myon AG, Switzerland) produces good to fair reliability when assessing forearm muscle activity. Correlations in the left FDS muscles were negative. Correlations between the left ECRB and left FDS muscles were variable but positive between the right ECRB and right FDS muscles.Conclusions: The data sets retrieved from all participants were reliably evaluated. Wrist position correlations within and between the FDS and ECRB muscles may have been influenced by hand dominance. The findings demonstrate that the methods and systems outlined in this study can be used reliably in future research. [ABSTRACT FROM AUTHOR]

Background: Grip strength has been identified as an important indicator of health status and predictor of clinical outcomes. The gold standard for measuring grip strength is the JAMAR® Hydraulic Hand Dynamometer. Less expensive dynamometers are available but have not been validated within a hospital setting. Objectives: To validate the Camry Digital Handgrip Dynamometer (Model EH101) against the validated JAMAR® Dynamometer (Model J00105) in a hospital population. Methods: A cross-sectional observational study with a randomised single-blind cross-over component was conducted on consenting adult patients admitted to general hospital wards. The best of three measurements taken using the dominant hand was used for analysis. Results: Fifty-one participants (median [interquartile range] age 42 [30–58] years; n = 27 [52.9%] female) were included. The mean difference between the Jamar® and Camry measurements was 1.9 kg ± 3.6 kg (t -value 0.9; p = 0.4). There was a strong positive correlation between the Jamar® and the Camry devices (R = 0.94; r ² = 0.88; p < 0.0001). Excellent agreement was found between Jamar® and Camry measurements (interclass correlational coefficient 0.97, 95% CI 0.94–0.99, p < 0.0001). Hand dominance significantly affected the agreement between devices (p = 0.002). Conclusions: The Camry Digital Handgrip Dynamometer is a valid tool for assessing grip strength in hospitalised adult patients. Clinical implications: The Camry Digital Handgrip Dynamometer could be used as an inexpensive tool to measure grip strength. [ABSTRACT FROM AUTHOR]

Aim of the Study: To know if there is correlation between handgrip strength and shoulder rotator cuff function. Materials and Method: total of 60 healthy, male volunteers with no history of shoulder, upper limb or neck injury comprised the study group. The mean (SD) age was 20 ± 0.64 years (range 20 years to 25 years). Grip strength (measured with hand grip dynamometer) and lateral rotator strength (measured with Manual Muscle Testing) was measured at neutral, 90abduction, and 90abduction with 90 external rotation. Results: The correlation test reviled that there is significant correlation between handgrip strength and lateral rotator cuff function in neutral and 90° abduction and lateral rotation. While it showed negative correlation between in 90° abduction position. Conclusion: This cross-sectional study concluded that there is positive correlation between neutral and 90° abduction and negative correlation in 90° abduction position. [ABSTRACT FROM AUTHOR]

Background: Childhood obesity leads to major disabilities in the adulthood. Hand grip strength testing is suggested as a component of the physical fitness test, because hand grip strength can be used to assess the general muscle strength Objective: The objective of the study is to find out the association between BMI categories and hand grip strength among the school going children between 11 and 14 years of age Materials and Method: 100 school children between 11 and 14 years from the schools in thiruvananthapuram city were included in the study using simple random sampling method. BMI percentile has been calculated for all the students. They were divided into three BMI categories. i.e., Normal weight, Overweight and Obese. Hand grip strength was measured using a Jamar Analogue Hand Dynamometer with participants seated, their elbow by their side and flexed to right angles, and a neutral wrist position. Maximum of three trials of grip strength for both right and left hand, has been documented. Result: The result was analyzed using SPSS software version 24. The statistical tool used was pearson correlation. The pearson correlation for the Left and Right hand grip was -.847, P value was. 000 which shows that there is a significant correlation at 0.01 level between BMI percentile and hand grip. Also the value shows that the correlation is negative, i.e., as the BMI percentile increases the hand grip decreases and vice versa. Conclusion: The study concludes that there is a negative correlation between BMI percentile and hand grip i.e., as the BMI percentile increases the hand grip decreases and vice versa in children aged between 11 and 14 years old. [ABSTRACT FROM AUTHOR]

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Summary: The current study examined the relationship between vitamin D status and muscle strength in young healthy adults: residents (>6 months) and newcomers (0-3 months), originally from sunny climate countries but currently living in the northeast of Scotland. Our longitudinal data found a positive, albeit small, relationship between vitamin D status and knee extensor isometric strength. Introduction: Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures. Methods: Vitamin D status was assessed in a healthy young adults from sunny climate countries ( n = 71, aged 19-42 years) with 56% seen within 3 months of arriving in Aberdeen [newcomers; median (range) time living in the UK = 2 months (9-105 days)] and the remainder resident for >6 months [residents; 23 months (6-121 months)]. Participants attended visits every 3 months for 15 months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee). Results: There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1 nmol/L increase in 25(OH)D, peak torque would increase by 1 Nm ( p = 0.04). Conclusions: This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study aimed to examine the relationship between hand-grip force and maximum inspiratory pressure (PImax) in healthy young and middle-age individuals. METHODS: All individuals underwent assessment of inspiratory muscle strength by maximum inspiratory pressure using a U-type water manometer and evaluation of hand-grip force by a hydraulic hand dynamometer. RESULTS: The correlation of PImax and hand-grip force was strong (r = 0.76). A multilinear regression model was built to investigate the ability of various parameters, such as hand-grip force, sex, and body mass index measurements, to predict PImax. PImax can be accurately predicted by 80% (r = 0.76) with a simple equation of easily evaluable factors, such as hand-grip force, body mass index, and sex. CONCLUSION: The results showed significant correlation between hand flexors' force and strength of inspiratory muscles in healthy individuals. This appears to be an easy way to evaluate the results indirectly and can help to assess the relationship between hand flexor and inspiratory muscle capacity, especially the diaphragm. Our study should be viewed as a hypothesis-generating one, and further studies are required in the population of critically ill or difficult-to-wean patients. (ClinicalTrials.gov registration NCT02423616.) [ABSTRACT FROM AUTHOR]

Currently, the physiological mechanisms that allow elite level climbers to maintain intense isometric contractions for prolonged periods of time are unknown. Furthermore, it is unclear whether blood flow or muscle oxidative capacity best governs performance. This study aimed to determine the haemodynamic kinetics of 2 forearm flexor muscles in 3 ability groups of rock climbers. Thirty-eight male participants performed a sustained contraction at 40% of maximal voluntary contraction (MVC) until volitional fatigue. Oxygen saturation and blood flow was assessed using near infrared spectroscopy and Doppler ultrasound. Compared to control, intermediate, and advanced groups, the elite climbers had a significantly (P < 0.05) higher strength-to-weight ratio (MVC/N), de-oxygenated the flexor digitorum profundus significantly (P < 0.05) more (32, 34.3, and 42.8 vs. 63% O2, respectively), and at a greater rate (0.32, 0.27, and 0.34 vs. 0.77 O2%·s−1, respectively). Furthermore, elite climbers de-oxygenated the flexor carpi radialis significantly (P < 0.05) more and at a greater rate than the intermediate group (36.5 vs. 14.6% O2and 0.43 vs. 0.1O2%·s−1, respectively). However, there were no significant differences in total forearm ∆ blood flow. An increased MVC/N is not associated with greater blood flow occlusion in elite climbers; therefore, oxidative capacity may be more important for governing performance. [ABSTRACT FROM AUTHOR]

Currently, direct empirical evidence exists about the amount of mechanical load that climbers apply to each finger during several hand grips specific to sport climbing, but not yet in a specific hanging position. The objectives of this study are a) to draw and build a solid and rigid support that simulates the real action of a hand grip in a hanging position in sport climbing, to enable the measurement of the mechanical load endured by the fingers in a hanging position and in addition, b) to describe the distribution of mechanical load among fingers as a function of the level of climbing during different hand grips in a hanging position. Thirty young male participants took part in the initial phase of reliability of the measurements, while another 64 male climbers participated in the subsequent study phase to check the relations between independent and dependent variables. The level ofon sight climbingand the total practice experience were used to define the groups. The research task consisted of performing hanging positions on the created support in order to measure the mechanical load endured by the fingers in the three most characteristic hand grips in climbing (crimp, half crimp and slope). It has been concluded that the performance level of the climbers had no influence on the production of a pattern of differentiated finger mechanical load during the research task. [ABSTRACT FROM PUBLISHER]

Abstract: Objective: To investigate if, following stroke, sustained involuntary activity after voluntary contraction (e.g., grip) of the long finger flexor muscles of the paretic hand is attributable to augmented serotonin release from brainstem pathways, affecting excitability of spastic motoneurons. Methods: This single-dose placebo-controlled study examined whether a serotonin receptor (5-HT2) antagonist, cyproheptadine hydrochloride, could reduce delay in muscle relaxation of a key paretic long finger flexor muscle immediately after grip for persons with stroke. Time to initiate the long finger flexor muscle contraction, grip and pinch strengths, and clinical hand function scores (the Action Research Arm Test and the Box and Block Test) were also assessed. Results: Cyproheptadine hydrochloride reduced mean delays in finger relaxation (n =13; from 7.2 to 4.1s; SEM=1.2s; p =.026) in comparison to placebo, while leaving grip and pinch strengths and time to initiate the muscle contraction largely unaffected. Reduction in the relaxation time alone did not lead to increased clinical hand function scores. Conclusions: The findings support the supposition that monoaminergic brainstem pathways may be disinhibited following stroke, thereby resulting in increased delays in muscle relaxation. Significance: Treatments to reduce delay in muscle relaxation may facilitate hand rehabilitation in persons with stroke. [Copyright &y& Elsevier]

It is generally considered that variation in mechanical exposure is beneficial from the viewpoint of preventing musculoskeletal disorders. An approach to quantifying the functional similarity of manual tasks was developed and tested by using three handgrips: power grip (PG); pulp pinch (PP); lateral pinch (LP). Changes in maximal voluntary contraction (MVC) forces were measured during 15 combinations of 2-min duration, 30% MVC isometric contraction in 25 participants. Strength changes in PG were found to be substantially different from LP; when the two grips were alternated, strength dropped to 85.1% MVC whereas after PG alone, strength dropped to 59.3% MVC. The findings suggest that PG and LP are functionally different enough for their alternating use to contribute to increased exposure variation during manual activities. Statement of Relevance: The paper describes how to determine if two tasks, when performed alternately, are different enough to reduce fatigue, increase work capacity and potentially prevent musculoskeletal disorders. Better understanding of the differences between tasks has the potential to improve job design by allowing better choice of tasks that combine to define a job. [ABSTRACT FROM AUTHOR]

Motor fatigue is a common complaint of polio survivors and has a negative impact on activities of daily living. The aim of this study was to establish a normative database for hand grip strength and fatigue and to investigate differences between prior-polio subjects and normal controls. Static and dynamic hand grip fatigue and maximum voluntary isometric contraction (MVIC) of hand grip were measured in subjects with a prior history of polio (n = 44) and healthy controls (n = 494). A normative database of fatigue was developed using four indices of analysis. Compared with healthy controls, subjects with prior polio had significantly reduced hand grip strength but developed greater hand grip fatigue in only one fatigue index. Quantitative measurement of fatigue in the prior-polio population may be useful in order to detect change over time and to evaluate treatment strategies. [ABSTRACT FROM AUTHOR]