Hand anthropometry in Bangladeshis living in America and comparisons with other populations

An investigation of the hand anthropometric database of agricultural workers and integration of the database into tools and protective gear designs

BACKGROUND: The hand anthropometric data is the baseline for design of hand tools and equipment. OBJECTIVE: This study aimed to generate the hand anthropometric database of male and female agricultural workers and compare it with the hand anthropometric data of other regions of India. The use of collected data is illustrated to design hand tools and protective gear. METHODS: Hand anthropometric data were collected from 228 male and 198 female agricultural workers of northeast India. A total of 35 hand dimensions, stature and body mass from different tribes in the age group of 18–60 years were precisely measured. Measured data were statistically analysed to study the effects of gender, ethnicity, and age on hand dimensions. Correlation coefficients were determined among hand dimensions and linear regression equations were developed between highly correlated dimensions. RESULTS: The results show that all hand dimensions of the male and female subjects are significantly different (p < 0.01). Most of the hand dimensions were significantly different (p < 0.05) among different tribes for the male subjects. However, less number of hand dimensions were significantly different among tribes for the female subjects. Age of the subjects has significant effects (p < 0.01) on dimensions related to thickness, depth and circumference of fingers. The use of these data in the ergonomic design of hand tools and personal protective gear is illustrated to increase safety and comfort as well as efficiency of operators. CONCLUSION: There is a difference in the hand dimensions of different tribes of northeast India. This needs to be considered when designing agricultural hand tools and equipment.

Hand anthropometry survey in Iranian adults and comparisons with other populations

BACKGROUND

Hand anthropometry is useful for designing manual systems such as hand tools, controls, and gloves. There are limited published data on the hand dimensions of Iranian male and female adults.

OBJECTIVE

This study was undertaken to measure the hand anthropometric dimensions in Iranian adults to compare data between two genders and also with the corresponding data from other nationalities.

METHODS

A total of 34 dimensions of the right hand were measured in 217 male and 128 female adults using a digital caliper and tape. The mean, standard deviation, and the main percentiles are summarized in a table and the mean of each dimension is compared by independent t-tests between genders. Hand dimensions are compared between Iranian and other nationalities such as North Colombian, Korean, Turkish, Nigerian, Bangladeshi, Jordanian, and Vietnamese using the published data.

RESULTS

Females had significantly smaller hand dimensions than males in all dimensions ranged from 4.21%to 18.16%, with the largest differences in hand breadths. Compared with other nationalities, the Iranian male and female adults had wider (greater breadth and circumferences) hands with shorter fingers.

CONCLUSIONS

The results showed significant differences of hand anthropometry between Iranian and other nationalities which should be included in the design and selection of hand tools for Iranian population.

Identify dominant dimensions of 3D hand shapes using statistical shape model and deep neural network

Hand anthropometry is one of the fundamentals of ergonomic research and product design. Many studies have been conducted to analyze the hand dimensions among different populations, however, the definitions and the numbers of those dimensions were usually selected based on the experience of the researchers and the available equipment. Few studies explored the importance of each hand dimension regarding the 3D shape of the hand. In this paper, we aim to identify the dominant dimensions that influence the hand shape variability while considering the stability of the measurements in practice. A novel four-step research method was proposed where in the first step, based on literature study, we defined 58 landmarks and 53 dimensions for the exploration. In the second step, 80,000 virtual hand models, each had the associated 53 dimensions, were augmented by changing the weights of Principle Components (PCs) of a statistical shape model (SSM). Deep neural networks (DNNs) were used to establish the inverse relationships from the dimensions to the weight of each PC of the hand SSM. Using the structured sparsity learning method, we identified 21 dominant dimensions that represent 90% of the variance of the hand shape. In the third step, two different manual measuring methods were used to evaluate the stability of the measurements in practice. Finally, we selected 16 dominant dimensions with lower measurement variance by synthesizing the findings in Step 2 and 3. It was concluded that the recognized 21 dominant dimensions can be treated as the reference dimensions for anthropometric study and using the selected 16 dominant dimensions with lower measurement variance, ergonomists are able to generate a 3D hand model based on simple measurement tools with an accuracy of 5.9 mm. Though the accuracy is limited, the efforts are minimum, and the results can be used as an indicator in the early stage of research/design.

Get a Grip: Variation in Human Hand Grip Strength and Implications for Human Evolution

Although hand grip strength is critical to the daily lives of humans and our arboreal great ape relatives, the human hand has changed in form and function throughout our evolution due to terrestrial bipedalism, tool use, and directional asymmetry (DA) such as handedness. Here we investigate how hand form and function interact in modern humans to gain an insight into our evolutionary past. We measured grip strength in a heterogeneous, cross-sectional sample of human participants (n = 662, 17 to 83 years old) to test the potential effects of age, sex, asymmetry (hand dominance and handedness), hand shape, occupation, and practice of sports and musical instruments that involve the hand(s). We found a significant effect of sex and hand dominance on grip strength, but not of handedness, while hand shape and age had a greater influence on female grip strength. Females were significantly weaker with age, but grip strength in females with large hands was less affected than those with long hands. Frequent engagement in hand sports significantly increased grip strength in the non-dominant hand in both sexes, while only males showed a significant effect of occupation, indicating different patterns of hand dominance asymmetries and hand function. These results improve our understanding of the link between form and function in both hands and offer an insight into the evolution of human laterality and dexterity.

Analysis of the external acoustic meatus for ergonomic design: part II - anthropometric variations of the external acoustic meatus by sex, age and side in Chinese population

For devices worn inside the ear, detailed anthropometric data of the external acoustic meatus (EAM) is needed, yet lacking due to the complex and costly methodology associated with attaining such measurements. The purpose of this study was to provide the anthropometric characteristics of the EAM including variations by age group, sex, and side (right/left). 1400 external ears (700 Chinese subjects) were casted and scanned. A total of 23 EAM dimensions of length, width, angle, circumference and area were measured, most of which changed by age group, sex and side. 19 measurements were larger in males and 17 measurements were larger in left-side ears. Except the entrance length and circumference, measurements were not statistically significant between left- and right-side ears. This study provides key anthropometric measurements of the EAM in a Chinese population which can be used for ergonomic design purposes. Practitioner summary: This study provides an available source for anthropometric variations of the external acoustic meatus by age, gender and side in the Chinese population, which can be used as a reference to improve the fit, comfort and function of in-ear wearable devices.

Compensating for Fingertip Size to Render Tactile Cues More Accurately

Fingertip haptic feedback offers advantages in many applications, including robotic teleoperation, gaming, and training. However, fingertip size and shape vary significantly across humans, making it difficult to design fingertip interfaces and rendering techniques suitable for everyone. This article starts with an existing data-driven haptic rendering algorithm that ignores fingertip size, and it then develops two software-based approaches to personalize this algorithm for fingertips of different sizes using either additional data or geometry. We evaluate our algorithms in the rendering of pre-recorded tactile sensations onto rubber casts of six different fingertips as well as onto the real fingertips of 13 human participants. Results on the casts show that both approaches significantly improve performance, reducing force error magnitudes by an average of 78% with respect to the standard non-personalized rendering technique. Congruent results were obtained for real fingertips, with subjects rating each of the two personalized rendering techniques significantly better than the standard non-personalized method.

Hand morphometrics, electrodermal activity, and stone tools haptic perception

OBJECTIVES

Tool use requires integration among sensorial, biomechanical, and cognitive factors. Taking into account the importance of tool use in human evolution, changes associated with the genus Homo are to be expected in all these three aspects. Haptics is based on both tactile and proprioceptive feedbacks, and it is associated with emotional reactions. Previous analyses have suggested a difference between males and females, and during haptic exploration of different typologies of stone tools. Here, we analyze the correlation between electrodermal reactions during stone tool handling and hand morphology to provide evidence of possible allometric factors shared by males and females.

METHODS

Electrodermal analysis was used to investigate some specific parameters involved in these reactions, such as changes in the level of attention and arousal. We analyzed the responses of 46 right-handed adults to 20 distinct stone tools while blindfolded.

RESULTS

Females have smaller hands and a wider range of electrodermal reactions. Within males and females, hand diameters and general hand size do not correlate with the degree of electrodermal level and response.

CONCLUSIONS

Sex differences in electrodemal reaction during stone tool handling are apparently not due to the effect of hand size or proportions. Differences between males and females are better interpreted as real sex differences, either due to a biological or cultural influences. Hand size does not influence the degree of arousal or attention during tool exploration, suggesting that other factors trigger individual reactions. These results add to a general cognitive approach on hand-tool evolution and tool sensing.

Microbial study of household hygiene conditions and associated Listeria monocytogenes infection risks for Peruvian women

OBJECTIVES

To develop an exposure and risk assessment model to estimate listeriosis infection risks for Peruvian women.

METHODS

A simulation model was developed utilising Listeria monocytogenes concentrations on kitchen and latrine surfaces in Peruvian homes, hand trace data from Peruvian women and behavioural data from literature. Scenarios involving varying proportions of uncontaminated, or 'clean', surfaces and non-porous surfaces were simulated. Infection risks were estimated for 4, 6 and 8 h of behaviours and interactions with surfaces.

RESULTS

Although infection risks were estimated across scenarios for various time points (e.g. 4, 6, 8 h), overall mean estimated infection risks for all scenarios were ≥ 0.31. Infection risks increased as the proportions of clean surfaces decreased. Hand-to-general surface contacts accounted for the most cumulative change in L. monocytogenes concentration on hands.

CONCLUSIONS

In addition to gaining insights on how human behaviours affect exposure and infection risk, this model addressed uncertainties regarding the influence of household surface contamination levels. Understanding the influence of surface contamination in preventing pathogen transmission in households could help to develop intervention strategies to reduce L. monocytogenes infection and associated health risks.

Anthropometric characteristics of Chilean workers for ergonomic and design purposes

Obtaining an appropriate match between a product and its end-users requires anthropometric data, which are typically outdated and show variations among different countries. Chile had its anthropometric data taken nearly 20 years ago, thus they are probably outdated. The purpose of this article is to describe some anthropometric characteristics of Chilean workers. An anthropometric survey involving 27 measures and five calculated body dimensions was conducted in 2016. The measurements were based on ISO 7250 and ISO 15535 to ensure the highest standards possible, and a total of 2946 workers, aged from 18 to 76 years old, participated in the survey. The results showed that Chilean workers have smaller dimensions than Dutch and US workers but have larger dimensions than South Koreans. The data presented in this article constitute the most up-to-date anthropometric dataset describing the dimensions of Chilean workers. Practitioner Summary: In Chile, women are smaller and weigh less than men, and both of these populations have high body mass index (BMIs). In addition, the Chilean population exhibits substantial differences compared with other international adult populations. The data presented in this article should be used as a reference when designing for Chilean workers.

The thermoregulatory function of the human hand: How do palm and digit proportions affect heat loss?

OBJECTIVES

The current study assessed whether ecogeographical patterns seen in hand proportions correlate with heat loss directly. Using a brief severe cold immersion experiment on the hand, the influence of hand and digit dimensions on heat loss was evaluated.

MATERIALS AND METHODS

A sample of 113 living individuals were tested. Two-dimensional and three-dimensional scanning techniques were used to assess hand and digit dimensions. Thermal imaging analysis was used to quantify heat loss during a 3-min ice-water immersion of the hands.

RESULTS

When body size was accounted for, hand width and digit length relative to total hand length were significant predictors of heat loss from the hand.

DISCUSSION

The current study provides empirical evidence to support the link between thermodynamic principles relating to surface area-to-volume ratio, and ecogeographical patterns associated with temperature.

Distal Part of the Human Hand: Study of Form Variability and Sexual Dimorphism Using Geometric Morphometrics

Tradičně se lidská ruka studuje prostřednictvím měření a srovnávání jednotlivých segmentů (prstů, článků prstů, záprstních kostí) bez zohlednění jejich vzájemných prostorových souvislostí. Cílem této studie je výzkum vnitro-populační variability formy lidské ruky jako celku v oblasti tříčlánkových prstů se zvláštním zaměřením na sexuální dimorfismus a vztah mezi velikostí a tvarem ruky. Pravé ruce 99 žen a 70 mužů, převážně vysokoškolských studentů, byly ve standardizované poloze z palmární strany zaznamenány běžným stolním skenerem. Na každém dvourozměrném snímku bylo umístěno 16 význačných bodů a byla studována variabilita mezi těmito konfiguracemi prostřednictvím metod geometrické morfometrie. Pro lepší pochopení vnitřních vzorců variability tvaru byl tvarový prostor rozložen na afinní a neafinní podprostor, které byly dále analyzovány samostatně. Převážná část celkové variability byla spojena s afinními tvarovými rozdíly, které jsou identické v celé studované oblasti ruky. Jejich větší část představovala střižnou změnu v proximodistálním směru, menší část pak napínání odpovídající změnám v šířce ruky. Toto napínání také silně korelovalo s velikostí ruky. Mezipohlavní rozdíly představovala afinní změna, ve které byla proximodistální střižná změna neoddělitelně spojena se změnami v relativní šířce ruky. Lokální neafinní pohlavní rozdíly byly zaznamenány v určitých článcích prstů a mohou souviset s rozdíly v poměrech délek prstů. Domníváme se, že oddělení globálních a lokálních sexuálně dimorfních znaků ruky může pomoci blíže ozřejmit původ/počátek jejich dimorfismu v rané ontogenezi – čím lokálnější znak, tím později se v ontogenezi zakládá. Dimorfní znaky lokální a globální by proto mohly být ovlivněny odlišnými ontogenetickými faktory.

Correlações entre força de preensão manual e variáveis antropométricas da mão de jovens adultos

O objetivo do estudo foi correlacionar a força de preensão palmar em diferentes posições de abertura, com variáveis antropométricas da mão. Participaram 73 voluntários de ambos os sexos (40 homens e 33 mulheres), com idade média de 23±4,61 anos. As medidas antropométricas largura da palma, comprimento do dedo indicador, espessura da palma, largura da mão, circunferência da palma e da mão foram realizadas bilateralmente. Para as medidas lineares, utilizou-se um paquímetro digital e, para as medidas de circunferência, a fita métrica. As medidas de força de preensão foram realizadas por meio de um dinamômetro hidráulico (UFTM) Jamar®. Os valores antropométricos foram correlacionados com as medidas de força nas cinco posições de abertura. Os homens e as mulheres tiveram maior força na mão direita e, entre as posições, a maior força dos homens foi na de número 3 (45,5±15,53 kgf) e das mulheres, na de posição 2 (25,5±6,28 kgf). Verificaram-se correlações significativas entre a força e os valores antropométricos nas medidas da largura da mão e circunferência da palma - que representam a maior medida transversal e o maior trofismo da mão, respectivamente, no grupo dos homens e a medida de comprimento do dedo, que representa a maior medida longitudinal no grupo das mulheres. Com isso, pode-se concluir que, para os homens, a maior força está relacionada à maior medida transversal e ao maior trofismo da mão e, para as mulheres, ao maior comprimento longitudinal da mão.