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The repeal of the Direct Ground Combat Assignment Rule has renewed focus on examining performance capabilities of female military personnel and their ability to occupy previously restricted military occupational specialties. Previous research has revealed female Soldiers suffer a greater proportion of musculoskeletal injuries compared to males, including a signicantly higher proportion of lower extremity, knee, and overuse injuries. Potential differences may also exist in musculoskeletal, biomechanical, and physiological characteristics between male and female Soldiers requiring implementation of gender-specic training in order to mitigate injury risk and enhance performance.

Purpose: To examine differences in musculoskeletal, biomechanical, and physiological characteristics in male and female Soldiers.

Methods: A total of 406 101st Airborne Division (Air Assault) Soldiers (348 male; 58 female) participated. Subjects underwent testing for exibility, isokinetic and isometric strength (percent body weight), single-leg balance, lower body biomechanics during a stop jump and drop landing, body composition, anaerobic power/ capacity, and aerobic capacity. Independent t tests assessed between-group comparisons.

Results: Women demonstrated signicantly greater exibility (P<.01-P<.001) and better balance (P.001) than men. Men demonstrated signicantly greater strength (P.001), aerobic capacity (47.5±7.6 vs 40.3±5.4 ml/kg/min, P<.001), anaerobic power (13.3±2.1 vs 9.5±1.7 W/kg, P<.001), and anaerobic capacity (7.8±1.0 vs 6.1±0.8 W/kg, P<.001) and lower body fat (20.1±7.5 vs 26.7±5.7 (%BF), P<.001). Women demonstrated signicantly greater hip exion and knee valgus at initial contact during both the stop jump and drop landing tasks and greater knee exion at initial contact during the drop landing task (P<.05-P<.001).

Conclusions: Gender differences exist in biomechanical, musculoskeletal, and physiological characteristics. Sex-specic interventions may aid in improving such characteristics to optimize physical readiness and decrease the injury risk during gender-neutral training, and decreasing between-sex variability in performance characteristics may result in enhanced overall unit readiness. Identication of sex-specic differences in injury patterns and characteristics should facilitate adjustments in training in order for both sexes to meet the gender- neutral occupational demands for physically demanding military occupational specialties. 

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Background: Work-related musculoskeletal disorders (WMSD) is the most expensive form of work disability. Female sex has been considered as an individual risk factor for the development of WMSD, specifically in the neck and shoulder region. One of the factors that might contribute to the higher injury rate in women is possible differences in neuromuscular control. Accordingly the purpose of this study was to estimate the effect of sex on shoulder joint position sense acuity (as a part of shoulder neuromuscular control) in healthy individuals.

Methods: Twenty-eight healthy participants, 14 females and 14 males were recruited for this study. To test position sense acuity, subjects were asked to flex their dominant shoulder to one of the three pre-defined angle ranges (low, mid and high-ranges) with eyes closed, hold their arm in that position for three seconds, go back to the starting position and then immediately replicate the same joint flexion angle, while the difference between the reproduced and original angle was taken as the measure of position sense error. The errors were measured using Vicon motion capture system. Subjects reproduced nine positions in total (3 ranges × 3 trials each).

Results: Calculation of absolute repositioning error (magnitude of error) showed no significant difference between men and women (p-value ≥ 0.05). However, the analysis of the direction of error (constant error) showed a significant difference between the sexes, as women tended to mostly overestimate the target, whereas men tended to both overestimate and underestimate the target (p-value ≤ 0.01, observed power = 0.79). The results also showed that men had a significantly more variable error, indicating more variability in their position sense, compared to women (p-value ≤ 0.05, observed power = 0.78).

Discussion: Differences observed in the constant JPS error suggest that men and women might use different neuromuscular control strategies in the upper limb. In addition, higher JPS variability observed in men might be one of the factors that could contribute to their lower rate of musculoskeletal disorders, compared to women.

Conclusions: The result of this study showed that shoulder position sense, as part of the neuromuscular control system, differs between men and women. This finding can help us better understand the reasons behind the higher rate of musculoskeletal disorders in women, especially in the working environments. 

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DOI 10.1186/s12891-015-0731-y
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Digital Document (pdf, doc, ppt, txt, etc.)
Language(s): 
English
Date created: 
2015
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The North American work force is still highly sex-segregated, with most members of each sex in jobs composed primarily of workers of the same sex. This division is accentuated when jobs involve physical demands. Women have traditionally been assigned to tasks whose physical demands are considered to be light. Nevertheless, these tasks can have biological effects, sometimes serious. Phenomena related to physical demands of women’s work can be considered in three categories: (a) musculoskeletal and cardiovascular demands of tasks often assigned to women in factories and service work; (b) sex- and gender-specific effects of toxic substances found in the workplace; and (c) interactions between work and the domestic responsibilities of many women. These phenomena are described, using examples recently gathered from workplaces. Effects of biological sex are distinguished, as far as possible, from effects of gender (social roles). 

It is not always easy in practice to distinguish between sex and gender effects. For example, many clinicians attribute differences in profiles of sports injuries to male and female knee anatomy (Fulkerson and Arendt, 2000; Huston et al., 2000; Kirkendall and Garrett, 2000). Examining these studies re- veals that differences in injury profile seem to have been ascribed to sex before considering possible differences in exposure. For example, cited studies often in- volve “athletes” but results are not broken down by sport. Since women and men do not practice the same sports in the same numbers, sex differences in injury rates do not only reflect biological differences between the sexes. In the absence of information on differential exposures of males and females, explanations for dif- ferences center on anatomic specificities.

The question of whether biological differences completely explain pheno- type differences such as health disparities between women and men has a long history (Emslie et al., 1999; Fausto-Sterling, 2000; Spitzer et al., 2004). In the case of occupational health, the information needed to answer the question can be categorised as follows:

 

  1. What are the extent and pattern of work related health differences between women and men workers?

  2. To what extent are apparent differences due to artefacts of institutional rec- ognition, e.g., differences in medical diagnoses (Alexanderson, 1998) or in workers’ compensation decisions (Lippel, 1999, 2000)?

  3. To what extent are these differences due to hormonal or other factors largely determined by the chromosomal complement (sex differences)? 

  4. To what extent are these differences due to education, training, and other social forces that induce males and females to adopt different roles in soci- ety, to be perceived differently by others, and to respond to stimuli in differ- ent ways (gender differences)?

  5. To what extent are these differences due to differential exposure to factors in the physical or social environment at work?

  6. To what extent are these differences due to interactions between the physical or social work environment and sex or gender differences?

  7. This paper will concentrate on information gathered from ergonomic studies, which bears primarily on Questions 5 and 6. The employment context of women and men will be summarised as well as some ways in which their specific insertion in the job market translates into physical job demands. -

 

 

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Language(s): 
English
Date created: 
2004
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Although gender bias in technical fields was observed by the author in the early days of her career, thirty years ago, it was her expectation that attitudes of current students would be much more gender neutral. To test this hypothesis, she assigned students in a Computer Ethics class to write about the Gender Gap in computer fields, then take the Harvard Implicit Association Test (IAT) relating gender and science, and finally to reflect on the results of the IAT. It was the expectation of the author that students today would perceive themselves to be completely unbiased, but would, in fact, be slightly more biased than they believed. Results, however, were both surprising and concerning. This paper discusses the assignment, the results, and reflections on the current state of perceptions of women in the computer field. 

The unpublished paper by Smyth, Greenwald, and Nosek [7] indicates, based on two IAT studies including over 110,000 college graduates and students, that the male students who have the strongest automatic association between men and science are the most likely to major in these fields, while women with similarly strong associations were least likely to do so. This would be consistent with the results in the UTC course, as most of the respondents were men in technical fields. The study [7] also indicated that women who majored in scientific fields tended to have the least automatic association of men with science. Researchers found that “For women in both studies, implicit stereotyping was more strongly related to majoring in STEM [Science, Technology, Engineering, and Mathematics] than was SAT-math performance, an indicator of math ability that is often prominent in models of post-secondary STEM interest and achievement.” This could present questions that are difficult to answer: if the male students in the STEM fields are more likely than the general population to hold stereotypes about the appropriateness of male and female roles in those fields, how does this affect the female students in these majors? And if stereotypical ideas of appropriateness of females in science are an indicator for which women will go into those fields, how can the number of women in STEM areas be significantly increased, both at the university level and in the profession?

This is especially concerning, as some studies indicate that women’s beliefs of male/female abilities affect women’s performance appreciably. In a study by Spencer, Steele, and Quinn, cited in [2], male and female first year psychology students at the University of Michigan were given a test based on the math portion of the Graduate Record Exam. Although all of the students had similar math abilities and backgrounds, the results varied significantly based on what students were told before the test was taken, as seen in Figure 3. If the students were told that “there were no gender differences in test performance,” male and female performance was very similar, and differences were not statistically significant. However, if the students were told that “men tend to do better,” male performance increased slightly,and female performance decreased very significantly. Although this is only one study, it does suggest that student expectations of male and female performance can affect the level of accomplishment of female students in particular. 

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