BACKGROUND:: Creation of vascular access leads to considerable local haemodynamic changes with decreased hand perfusion. Distal limb tissues then represent a model of hand ischaemia effect on muscles. The aim of our study was to investigate how the presence of vascular access influences the hand muscle strength in end-stage renal disease patients. METHODS:: We included 52 chronically haemodialysed patients with upper limb access without clinical signs of hand ischaemia. Muscle strength was evaluated by dynamometry. Finger pressure was measured on the second and fourth fingers and averaged for further analysis. Thenar tissue oxygenation (rSO2) was analysed using near-infrared spectroscopy. All examinations were performed in both the hands. Basic laboratory analysis was added. Data were processed with unpaired t-test and correlation analysis. RESULTS:: Hands with dialysis access had lower values of handgrip strength (54.2 ± 29.1 lbs vs 48.6 ± 23.4 lbs, p = 0.0006), systolic finger pressure (127.1 ± 32.0 mmHg vs 101.4 ± 31.6 mmHg, p < 10-8) and of thenar rSO2 (45.8% ± 12.9% vs 42.5% ± 13.3%, p = 0.002). Muscle strength (handgrip) was directly related to the thenar oxygenation ( r = 0.36; p = 0.014) and to the finger systolic pressure ( r = 0.38; p = 0.007) on the access extremity. On the extremity without dialysis access, handgrip strength was inversely related to patient's age ( r = -0.41, p = 0.003), dialysis vintage ( r = -0.32, p = 0.02) and red cell distribution width ( r = -0.37, p = 0.01). CONCLUSION:: The presence of dialysis access leads to the decrease of finger pressure, oxygenation, and also muscle strength even in the absence of clinically overt hand ischaemia. All these parameters are interrelated. This study underlines the consequences of inadequate muscle perfusion.

• Klíčová slova
• Haemodialysis, hand ischaemia, hand muscle, hand tissue oxygenation, muscle strength, vascular access,
• MeSH
• arteriovenózní zkrat škodlivé účinky   MeSH
• chronické selhání ledvin diagnóza   patofyziologie   terapie   MeSH
• dialýza ledvin * MeSH
• hemodynamika * MeSH
• ischemie krev   diagnóza   etiologie   patofyziologie   MeSH
• kyslík krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• regionální krevní průtok MeSH
• ruka krevní zásobení   MeSH
• senioři MeSH
• síla ruky * MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• kyslík MeSH

The present paper describes the development of a prosthetic hand based on human hand anatomy. The hand phalanges are printed with 3D printing with Polylactic Acid material. One of the main contributions is the investigation on the prosthetic hand joins; the proposed design enables one to create personalized joins that provide the prosthetic hand a high level of movement by increasing the degrees of freedom of the fingers. Moreover, the driven wire tendons show a progressive grasping movement, being the friction of the tendons with the phalanges very low. Another important point is the use of force sensitive resistors (FSR) for simulating the hand touch pressure. These are used for the grasping stop simulating touch pressure of the fingers. Surface Electromyogram (EMG) sensors allow the user to control the prosthetic hand-grasping start. Their use may provide the prosthetic hand the possibility of the classification of the hand movements. The practical results included in the paper prove the importance of the soft joins for the object manipulation and to get adapted to the object surface. Finally, the force sensitive sensors allow the prosthesis to actuate more naturally by adding conditions and classifications to the Electromyogram sensor.

• Klíčová slova
• MyWare sensor, force sensing resistors, human hand anatomy, prosthetic hand,
• MeSH
• lidé MeSH
• protézy - design MeSH
• prsty ruky MeSH
• ruka * MeSH
• síla ruky MeSH
• šlachy MeSH
• umělé končetiny * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Previous research has demonstrated that Maasai and Europeans tend to align in their ratings of the physical strength and aggressiveness of Maasai male faces, calibrated to hand grip strength (HGS). However, perceptions of attractiveness of these faces differed among populations. In this study, three morphs of young Maasai men created by means of geometric morphometrics, and depicting the average sample and two extrema (± 4 SD of HGS), were assessed by men and women from Tanzania, Czech Republic, Russia, Pakistan, China, and Mexico (total sample = 1540). The aim of this study was to test cross-cultural differences in the perception of young Maasai men's composites calibrated to HGS, focusing on four traits: physical strength, attractiveness, aggressiveness, and helpfulness. Individuals from all six cultures were able to distinguish between low, medium, and high HGS portraits. Across all study populations, portrait of Maasai men with lower HGS was perceived as less attractive, more aggressive, and less helpful. This suggests that people from diverse populations share similar perceptions of physical strength based on facial shape, as well as attribute similar social qualities like aggressiveness and helpfulness to these facial images. Participants from all samples rated the composite image of weak Maasai men as the least attractive.

• Klíčová slova
• Aggressiveness, Attractiveness, Composite portraits, Cross-cultural ratings, Geometric morphometrics, HGS, Hand grip strength, Helpfulness, Maasai, Perception, Strength,
• MeSH
• lidé MeSH
• percepce MeSH
• síla ruky * MeSH
• srovnání kultur * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Tanzanie MeSH

PURPOSE: To determine whether there are bilateral and interdigit differences in the maximal force production of experienced climbers and whether these differences are mediated by ability level or preferred style of climbing. METHODS: Thirty-six male climbers (age 30 [9.4] y) took part in a single-session trial to test their maximal force production on both hands. The tests included a one-arm maximal isometric finger flexor strength test (MIFS) and a one-arm individual MIFS. Bilateral differences were analyzed by strongest hand (defined as the hand that produced the highest MIFS value) and dominance (defined as the writing hand). RESULTS: A pairwise t test found that MIFS was significantly greater for the strongest hand (mean difference = 4.1%, 95% CI, -0.052 to 0.029, P < .001), with handedness explaining 89% of the variation. A 2-way mixed-model analysis of variance determined that there were no interactions between preferred style (bouldering or sport climbing) and MIFS or between ability level (advanced or elite) and MIFS. CONCLUSIONS: Climbers have significant finger flexor strength bilateral asymmetries between their strongest and weakest hand. Moreover, when dominance is controlled, this difference in strength is present, with the dominant hand producing more force. Neither preferred style of climbing nor the ability level of the climbers could explain these asymmetries. As such, practitioners should consider regularly monitoring unilateral strength, aiming to minimize the likelihood of large bilateral asymmetry occurring.

• Klíčová slova
• bouldering, dominant, finger strength, force production, injury,
• MeSH
• dospělí MeSH
• funkční lateralita MeSH
• horolezectví * MeSH
• lidé MeSH
• prsty ruky MeSH
• síla ruky MeSH
• sporty * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Impaired physical performance and muscle strength are recognized risk factors for fragility fractures, frequently associated with osteoporosis and sarcopenia. However, the integration of muscle strength and physical performance in the comprehensive assessment of fracture risk is still debated. Therefore, this cross-sectional study aimed to assess the potential role of hand grip strength (HGS) and short physical performance battery (SPPB) for predicting fragility fractures and their correlation with Fracture Risk Assessment Tool (FRAX) with a machine learning approach. METHODS: In this cross-sectional study, a group of postmenopausal women underwent assessment of their strength, with the outcome measured using the HSG, their physical performance evaluated using the SPPB, and the predictive algorithm for fragility fractures known as FRAX. The statistical analysis included correlation analysis using Pearson's r and a decision tree model to compare different variables and their relationship with the FRAX Index. This machine learning approach allowed to create a visual decision boundaries plot, providing a dynamic representation of variables interactions in predicting fracture risk. RESULTS: Thirty-four patients (mean age 63.8±10.7 years) were included. Both HGS and SPPB negatively correlate with FRAX major (r=-0.381, P=0.034; and r=-0.407, P=0.023 respectively), whereas only SPPB significantly correlated with an inverse proportionality to FRAX hip (r=-0.492, P=0.001). According to a machine learning approach, FRAX major ≥20 and/or hip ≥3 might be reported for an SPPB<6. Concurrently, HGS<17.5 kg correlated with FRAX major ≥20 and/or hip ≥3. CONCLUSIONS: In light of the major findings, this cross-sectional study using a machine learning model related SPPB and HGS to FRAX. Therefore, a precise assessment including muscle strength and physical performance might be considered in the multidisciplinary assessment of fracture risk in post-menopausal women.

• MeSH
• hodnocení rizik MeSH
• kostní denzita * fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• osteoporotické fraktury * epidemiologie   etiologie   MeSH
• postmenopauza MeSH
• průřezové studie MeSH
• rizikové faktory MeSH
• senioři MeSH
• síla ruky MeSH
• tělesná a funkční výkonnost MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The human voice carries information about a vocalizer's physical strength that listeners can perceive and that may influence mate choice and intrasexual competition. Yet, reliable acoustic correlates of strength in human speech remain unclear. Compared to speech, aggressive nonverbal vocalizations (roars) may function to maximize perceived strength, suggesting that their acoustic structure has been selected to communicate formidability, similar to the vocal threat displays of other animals. Here, we test this prediction in two non-WEIRD African samples: an urban community of Cameroonians and rural nomadic Hadza hunter-gatherers in the Tanzanian bushlands. Participants produced standardized speech and volitional roars and provided handgrip strength measures. Using acoustic analysis and information-theoretic multi-model inference and averaging techniques, we show that strength can be measured from both speech and roars, and as predicted, strength is more reliably gauged from roars than vowels, words or greetings. The acoustic structure of roars explains 40-70% of the variance in actual strength within adults of either sex. However, strength is predicted by multiple acoustic parameters whose combinations vary by sex, sample and vocal type. Thus, while roars may maximally signal strength, more research is needed to uncover consistent and likely interacting acoustic correlates of strength in the human voice. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part I)'.

• Klíčová slova
• Hadza, acoustic communication, aggression, handgrip strength, nonverbal vocalization,
• MeSH
• agrese MeSH
• akustika MeSH
• hlas * MeSH
• lidé MeSH
• řeč * MeSH
• síla ruky MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

STUDY DESIGN: Matched pair study. INTRODUCTION: Differences in hand-muscle strength/dexterity between dominant (DH) and non-dominant (NDH) hand in Charcot-Marie-Tooth disease (CMT) are not well understood. PURPOSE OF THE STUDY: To compare muscle strength/dexterity between DH and NDH and to correlate manual dexterity, strength and sensory function. PATIENTS AND METHODS: Thirty CMT patients were studied using functional muscle testing (FMT) and strength (dynamometry), dexterity (the Nine Hole Peg Test [NHPT]), and Jebsen-Taylor Hand Function [JTT]), and sensory function (the Nottingham Sensory Assessment [NSA]). RESULTS: Scores were worse for DH than NDH on FMT (p = 0.043) and NHPT (p = 0.014) but not on JTT (p = 0.098), handgrip strength (p = 0.710) or tripod pinch (p = 0.645). NSA did not correlate significantly with any tests (p's0.05). CONCLUSIONS: In CMT disease, DH appears more impaired than NDH in terms of function and dexterity. Greater muscle weakness in DH may also emerge as CMT progresses. LEVEL OF EVIDENCE: 3b.

• Klíčová slova
• Charcot-Marie-Tooth disease, Hand strength, Hereditary motor and sensory neuropathy, Manual dexterity, Sensory function,
• MeSH
• Charcotova-Marieova-Toothova nemoc patofyziologie   MeSH
• dospělí MeSH
• funkční lateralita fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• motorické dovednosti fyziologie   MeSH
• neurologické vyšetření MeSH
• senioři MeSH
• síla ruky fyziologie   MeSH
• svalová síla - dynamometr MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Coupling forces at the interface of the hand-arm system and the vibrating tool have a substantial effect on the actual vibration exposure. The paper presents a method for the qualitative assessment of coupling forces. This method--presently under discussion in the form of a draft standard within DIN (1) and ISO (2)--is mainly based on the results of a joint research project (University of Dortmund, University of Mainz and BIA). The workplace-related determination of a coupling factor can be considered the very heart of the method. For technical reasons, the coupling force is split up into the gripping and the pushing force. The paper describes the requirements applying to the measurement and evaluation. Examples are given to illustrate the determination of coupling forces with a view to assessing vibration exposure.

• MeSH
• hodnocení rizik MeSH
• lidé MeSH
• paže fyziologie   MeSH
• pracovní expozice MeSH
• ruka fyziologie   MeSH
• síla ruky fyziologie   MeSH
• vibrace * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The driving-point mechanical impedance of the human hand-arm system is strongly dependent on the grip force and excitation frequency. In this study, the biodynamic response of the human hand-arm is characterized by three and four degree-of-freedom (DOF) linear and nonlinear mass excited model incorporating grip force dependence of the restoring and dissipative properties. The model parameters are identified by minimizing a constrained objective function compromising impedence magnitude and phase errors between the computed and measured target driving-point mechanical impedance characteristics. The target impedance values are established in the 10 to 1000 Hz frequency range from the measurements performed in the three orthogonal directions (Xh, Yh and Zh) using 2 x g peak acceleration sinusoidal excitation and different magnitudes of constant grip force ranging from 10 to 50 N. The linear and nonlinear models are analyzed to determine the driving-point mechanical impedance characteristics for different levels of grip force. The computed response characteristics are compared to the target values to demonstrate the validity of the proposed models. The results of the study revealed that the four-DOF nonlinear grip force dependent model yields good correlation with the measured response in all three directions, for the range of grip forces considered.

• MeSH
• biologické modely * MeSH
• biomechanika MeSH
• elektrická impedance MeSH
• lidé MeSH
• paže fyziologie   MeSH
• síla ruky fyziologie   MeSH
• vibrace * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The detrimental effects of vibrating hand-held tools upon humans have been known for a long time, and determination of the absorption of vibration energy into the operator's hand and arm could be an alternative method of risk assessment. The energy absorption in the hand and arm during exposure to random vibration has been measured in 84 subjects, 40 males and 44 females. A special handle was used during the measurements. The influence of various experimental conditions, such as vibration level (3-12m/s2), vibration direction (Xh, Yh, Zh), and grip force (25-75 N) were studied. Furthermore, the influence on the absorption of different individual biological factors, such as age, weight, height, hand and arm dimensions as well as blood pressure were also investigated. The subject also provided demographic data through a questionnaire covering work, symptoms of finger blanching and numbness as well as current use of nicotine (snuff of tobacco). The results show that energy absorption is influenced by exposure directions and levels as well as grip forces. Furthermore, the results show that individual biological differences between subjects, for instance age, hand volume and hand thickness, have a significant influence on the amount of absorbed energy. Blood pressure had no influence on the absorption. The same was also found for the subjective reported symptoms of finger blanching or numbness as well as for use of nicotine.

• MeSH
• antropometrie MeSH
• biomechanika MeSH
• dospělí MeSH
• hodnocení rizik MeSH
• lidé středního věku MeSH
• lidé MeSH
• paže fyziologie   MeSH
• ruka fyziologie   MeSH
• síla ruky fyziologie   MeSH
• vibrace * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky kontrolované MeSH
• klinické zkoušky MeSH
• práce podpořená grantem MeSH