Gender inequality and sexual height dimorphism in Chile.

Chile has experienced significant improvements in its economy; thus, a secular trend in height has been observed in its population. Gender equality has also improved hand in hand with active policies addressing the gender gap in several dimensions (work, education, health) and overall economic improvement. This study examined changes in sexual height dimorphism in four samples of Chilean male and female working-age subjects and attempted to establish associations with gender equality and welfare. Sexual height dimorphism was calculated and compared with gender equality and overall welfare indicators between 1955 and 1995. Sexual height dimorphism reduction was seen to be strongly associated with greater gender equality and some general welfare indicators, such as the infant mortality rate. Gross domestic product per capita was not associated with sexual height dimorphism, but it showed significant associations with gender equality indicators. Overall, the gender gap has been reduced in Chile, which can be observed through improvements in gender equality indicators and a reduction in height dimorphism, mainly in areas associated with women's health. However, gender equality is still far behind in terms of female labour participation and women in political power, which require attention and further improvements.

Educational level and its relationship with body height and popliteal height in Chilean male workers.

A secular trend in body height has been experienced in many nations and populations, hypothesized to be the result of better living conditions. Educational level has been shown to be closely associated with body height. This study examined the changes in body height and popliteal height in a group of adult Chilean male workers by age cohort and the relationship of these with educational level. The body heights and popliteal heights of 1404 male workers from the Valparaíso and Metropolitan regions of Chile were measured in 2016. The sample was grouped by level of education (primary, secondary, technical and university) and age (21-30, 31-40 and 41-50 years). Robust ANOVA and post-hoc analyses using a one-step modified M-estimation of location were conducted based on bootstrap resampling. Both body height and popliteal height increased from the older to the younger age cohort. The largest increase was from the 41-50 to the 21-30 group, with a 1.1% increase in body height and 1.7% increase in popliteal height. When educational level was introduced into the analysis there was a marked increase in both body height and popliteal height for each cohort, but only in primary- and secondary-educated workers. Despite showing an overall increase in body height and popliteal height, younger workers with the highest levels of education showed fewer differences between them than did older workers with less education. The differences were larger in the older than in the younger cohorts. Similarly, this trend was less clear in workers with higher levels of education (technical and university), probably because of a dilution effect caused by increased access to higher education by workers in the lower income quintiles.

Multi-finger synergies and the muscular apparatus of the hand.

We explored whether the synergic control of the hand during multi-finger force production tasks depends on the hand muscles involved. Healthy subjects performed accurate force production tasks and targeted force pulses while pressing against loops positioned at the level of fingertips, middle phalanges, and proximal phalanges. This varied the involvement of the extrinsic and intrinsic finger flexors. The framework of the uncontrolled manifold (UCM) hypothesis was used to analyze the structure of inter-trial variance, motor equivalence, and anticipatory synergy adjustments prior to the force pulse in the spaces of finger forces and finger modes (hypothetical finger-specific control signals). Subjects showed larger maximal force magnitudes at the proximal site of force production. There were synergies stabilizing total force during steady-state phases across all three sites of force production; no differences were seen across the sites in indices of structure of variance, motor equivalence, or anticipatory synergy adjustments. Indices of variance, which did not affect the task (within the UCM), correlated with motor equivalent motion between the steady states prior to and after the force pulse; in contrast, variance affecting task performance did not correlate with non-motor equivalent motion. The observations are discussed within the framework of hierarchical control with referent coordinates for salient effectors at each level. The findings suggest that multi-finger synergies are defined at the level of abundant transformation between the low-dimensional hand level and higher dimensional finger level while being relatively immune to transformations between the finger level and muscle level. The results also support the scheme of control with two classes of neural variables that define referent coordinates and gains in back-coupling loops between hierarchical control levels.

Anticipatory synergy adjustments: preparing a quick action in an unknown direction.

We studied a mechanism of feed-forward control of a multi-finger action, namely anticipatory synergy adjustments (ASAs), prior to a quick force correction in response to a change in the gain of the visual feedback. Synergies were defined as co-varied across trials adjustments of commands to fingers that stabilized (decreased variance of) the total force. We hypothesized that ASAs would be highly sensitive to prior information about the timing of the action but not to information on its direction, i.e., on whether the gain would go up or down. The subjects produced accurate constant total force by pressing with four fingers on individual force sensors. The feedback signal could change from veridical (the sum of finger forces) to modified, with the middle finger force multiplied by 0.2 or by 1.8. The timing of the gain change and its direction could be known or unknown to the subject in advance. When the timing of the gain change was known, ASA was seen as a drop in the synergy index starting about 250-300 ms prior to the first visible correction of the total force. When the gain change timing was unknown, ASAs started much later, less than 100 ms prior to the total force correction. The magnitude of synergy index changes was significantly larger under the "time known" conditions. Information on the direction of the visual gain change had no effect on the ASA timing, while the ASA magnitude was somewhat larger when this information was not available to the subject. After the total force correction, the synergy index was significantly larger for the force signal computed using the modified gain values as compared to the synergy index value for the actual total force. We conclude that ASAs represent an important feed-forward motor control mechanism that allows preparing for a quick action even when the direction of the action is not known in advance. The results emphasize the subtle control of multi-finger synergies that are specific to the exact contributions of individual fingers to performance variables. The data fit well the central back-coupling hypothesis of synergies and the idea of control with referent body configurations.

Developing countries and the use of ISO Standard 11228-3 for risk management of Work-Related Musculoskeletal Disorders of the Upper Limbs (WRMSDs-ULs): The case of Chile.

Work-Related Musculoskeletal Disorders of the Upper Limbs (WRMSDs-ULs) are one of the most common occupational diseases worldwide. Repetitive motion is one of the main risk factors associated with these conditions. Several efforts have been made within the scientific community in order to develop specific methods to assess the risk that repetitive work represents. Furthermore, internationally coordinated work has resulted in the generation of a series of ISO standards to address issues around ergonomics in the workplace. In 2012, Chile adopted the ISO11228-3 standard checklist in its regulatory process, creating the first technical standard of risk management for repetitive motion. The aim of this study is to present the results of a nation-wide online survey of Chilean Health and Safety Practitioners and Ergonomists, which was conducted in order to identify their level of application experience, most commonly adopted practices, and opinions on the first Chilean Standard for WRMSDs-ULs risk assessment. A second aim is to discuss common issues and possible improvements in public policies, and the adoption of international instruments by developing countries. A total of 331 respondents completed the survey (183 Ergonomists and 148 non-ergonomist). It was observed that a number of the participants consider that the adaptation of the ISO standard has several issues, ranging from simple ones as wording and format to more complex ones regarding overall structure, logic, and ease of use. One of the main issues expressed is the fact that during the adaptation process the instrument is applied in multitask jobs, without providing clear instructions or training. Furthermore, among the top three most used assessment methods were RULA and REBA, which are posture-driven, instead of methods validated for repetitive motion. The issues detected by the Chilean OHS practitioners are common in developing countries, where an intersection of lack of resources, public agency authoritarianism, and poor communication between public-private and public-public organizations contribute to poor consultation, validation, and adaptation processes. Suggestions to improve the current Chilean standard, as well as considerations for developing countries, are presented.