Typing performance and body discomfort among overweight and obese office workers: A pilot study of keyboard modification

Obesity in the workplace is associated with loss of productivity, high medical care expenses, and increased rates of work-related injuries and illness. Thus, effective, low-cost interventions are needed to accommodate the size of today's obese office worker while alleviating potential physical harm associated with musculoskeletal disorders. Utilizing a sample of 22 overweight and obese office workers, this pilot study assessed the impact of introducing an alternative, more ergonomically-sound keyboard on perceptions about design, acceptability, and usability; self-reported body discomfort; and typing productivity. Data were collected using self-reported questionnaires and objective typing tests administered before and after the intervention. The intervention duration was six weeks. After switching from their standard work keyboard to an alternative keyboard, all participants reported significant decreases in lower back discomfort (t = 2.14, P = 0.044); although obese participants reported significant decreases in both upper (t = 2.46, P = 0.032) and lower (t = 2.39, P = 0.036) back discomfort. No significant changes were observed in overall typing performance scores from baseline to follow-up. Findings suggest that such interventions may be introduced into the workforce with positive gains for workers without reducing short-term worker productivity.

Occupational risk factors and back injury

Twenty-one risk factors affecting laborers in manual materials handling tasks were analyzed to determine what, if any, statistically significant relationships existed between the factors and the emergence of occupational back injury. The statistically significant risk factors (p ≤ .05) in the univariate analysis were determined to be weight lifted per hour (work intensity), trunk twists per hour, weight lifted per day, frequency of lift, trunk motions per hour, and trunk flexions per hour, with odds ratios (ORs) of 1.28-2.88. In addition, self-reported discomfort in the neck, middle back, knees, and lower back was associated with the outcome of back injury (p ≤ .05, OR 1.75-2.66). In the multivariate analysis, the statistically significant risk factors (p ≤ .05) were weight lifted per hour (work intensity), average weight of lift, and number of trunk twists per hour, with ORs of 1.74-4.98.

SEASONAL CHANGES IN &OV0312;O2max AMONG DIVISION 1A COLLEGIATE WOMEN SOCCER PLAYERS

Aerobic capacity and body composition were measured at 3 time points over a 1-year period in 26 Division 1A women soccer players from Texas A&M University, in order to determine whether there were seasonal changes in these parameters. Subjects were tested in December, immediately following a 4-month competitive season; in April, following 15 weeks of strength and conditioning; and immediately prior to the start of the regular season in August, following a 12-week summer strength and conditioning program. A periodized strength and conditioning program design was incorporated in order to optimize anaerobic and oxidative capacity immediately prior to the regular competitive season. Significant differences in VO2max were measured between August (49.24 +/- 4.38 ml x kg(-1) x min(-1)) and December (44.87 +/- 4.61 ml x kg(-1) x min(-1)). No significant changes in aerobic capacity were found between April (47.43 +/- 4.01 ml x kg(-1) x min(-1)) and August (49.64 +/- 5.25 ml x kg(-1) x min(-1)). Significant increases in body fat were measured between August (15.71 +/- 2.92%) and December (18.78 +/- 2.79%), before and after the competitive season, respectively. No significant changes in body fat were found between April (16.24 +/- 2.95%) and August (15.71 +/- 2.92%). The results of this study suggest that decreases in muscle mass over the course of a regular competitive season contribute to decreases in aerobic capacity in collegiate women soccer players. Although it is unknown whether this decrease in muscle mass is the result of inadequate training or a normal adaptation to the physiological demands imposed by soccer, the results of the current study suggest that resistance training volume should be maintained during the competitive season, in order to maintain preseason levels of muscle mass.

Postural versus chair design impacts upon interface pressure

An investigation of postural and chair design impacts upon seat pan interface pressure has been performed in an effort to identify whether differences in posture or chair design result in greater pressure differences. Investigation of postural variables focused on trunk-thigh angle and use of armrests. Twelve ergonomic office chairs were used to assess chair design differences. Both male and female subjects were included. Gender effects were controlled through use of a repeated Latin square design, with squares defined by gender. Significant gender-based interaction was observed amongst postural treatments and chair effects. Postural treatments, chairs designs, and participant effects all resulted in significant interface pressure differences, though gender-based interaction yielded some non-additivity of results between males and females. The final conclusion drawn from the results is that chair design differences had the greatest effect on seat pan interface pressure, followed by participant effects, and lastly postural treatments.

Personal and non-occupational risk factors and occupational injury/illness

BACKGROUND

The materials handling industry performs is an essential function in the world economy, however, it is plagued with occupationally related injuries and illnesses. Understanding the risk factors may assist this industry in alleviating these injuries and illnesses, as well as their associated costs.

METHODS

Forty-eight personal and non-occupational risk factors were measured and evaluated for statistically significant relationships with occupational injury in 442 volunteer manual material handlers who worked for three different companies, at nine US locations, with 15 different job descriptions. OSHA 200 logs were used to ascertain evidence of occupational injury within this population for 1 year after the testing and measurement was completed.

RESULTS

Higher occurrences of injury were significantly associated with six risk factors in the univariate model (odds ratios 1.51-4.00). The significantly (P < 0.05) related risk factors in the univariate model were aerobic power, smoking status, perceived fitness level, fishing/hunting as a hobby, speed limit obeyance, and witnessing or being involved in a violent fight. In the multivariate analysis, five risk factors (aerobic power, smoking status, percent body fat, body mass index, and sit-and-reach measured flexibility) were significantly (P < 0.05) associated with occupational injury. Odds ratios in the multivariate analysis varied from 1.42 to 10.11.

CONCLUSION

Evidence of an association of occupational injury occurrence with certain risk factors presented in personal and non-occupational univariate and multivariate models is shown. In industry, effective injury reduction programs should go beyond traditional methods of job-related ergonomic risk factors and include personal factors such as smoking, weight control, and alcohol abuse.

A prospective field study of the relationship of potential occupational risk factors with occupational injury/illness

Twenty-one occupationally related risk factors were measured and prospectively evaluated for statistically significant relationships with occupational injury/illness in 442 manual material handlers, working for three different companies, at nine U.S. locations, and encompassing 15 different job descriptions. OSHA 200 logs were used to ascertain evidence of occupational injury/illness (dichotomous) within this population for 1 year after the testing and measurement were completed. The present study demonstrated evidence of a subset of critical variables significantly related to occupational injury/illness occurrence through the significantly related occupational risk factors presented in the univariate and multivariate models. Higher occurrences of injury/illness were significantly associated with nine risk factors in the univariate model, with odds ratios ranging from 1.11-2.27. The significantly (p<0.05) related risk factors in the univariate model were lifting frequency; weight lifted per day; weight lifted per hour; number of trunk flexions per hour; number of trunk twists per hour; number of trunk motions per hour; number of knee flexions per hour; number of shoulder flexions per hour; and static shoulder flexion. In the multivariate analysis two risk factors were associated with occupational injury/illness. The significantly (p<0.05) related risk factors in the multivariate model were lifting frequency (p=0.0010, odds ratio [OR]=4.47, 95% confidence interval [CI]=[2.38-8.40], and average weight of lift (p=0.0001, OR=1.71, 95% CI=[1.29-2.25]).

Ergonomic program effectiveness: ergonomic and medical intervention

The implementation of a successful ergonomic and medical intervention program designed to reduce the number and severity of injuries and illnesses and the associated levels of discomfort in the workplace is presented. Because of the recent activity concerning the on-again-off-again Occupational Safety and Health Administration (OSHA) Ergonomic Program Standard questions have been raised as to the value and effectiveness of an organization's ergonomics program. In light of these concerns, the immense cost associated with work-related injury and illness, and the related pain and suffering associated with such injuries and illnesses, it is important to present a workable and effective ergonomic and medical intervention program. The results of this applied study demonstrate that through the application of an ergonomic and medical intervention program, workplace-related injuries and illnesses can be reduced or eliminated.

The effects of training history, player position, and body composition on exercise performance in collegiate football players

Performance data for 261 NCAA Division 1A collegiate football players were analyzed to determine if player position, body weight, body fat, and training time were correlated with changes in performance in the following events: power clean (PC), bench press (BP), squat (SQ), vertical jump (VJ), 40-yd dash (40yd), and 20-yd shuttle (20yd). Individual positions were combined into the following groups: (A) wide receivers, defensive backs, and running backs, (B) linebackers, kickers, tight ends, quarterbacks, and specialists, and (C) linemen. Increases in body weight were positively correlated with increases in BP and PC performance for all groups. Increases in body fat were negatively correlated with performance in the PC and VJ for all groups. For group C, increases in body fat were also negatively correlated with performance in the 40yd and 20yd. Group and training time exhibited no linear relationship with performance in any of the tested events. No linear relationships were observed between the independent variables and performance in the SQ. When individual training data were analyzed longitudinally, a nonlinear increase in performance in the PC, BP, and SQ was observed as training time increased, with the greatest rate of change occurring between the first and second semesters of training.

Microwave emissions from police radar

This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar.

Factors affecting minimum push and pull forces of manual carts

The minimum forces needed to manually push or pull a 4-wheel cart of differing weights with similar wheel sizes from a stationary state were measured on four floor materials under different conditions of wheel width, diameter, and orientation. Cart load was increased from 0 to 181.4 kg in increments of 36.3 kg. The floor materials were smooth concrete, tile, asphalt, and industrial carpet. Two wheel widths were tested: 25 and 38 mm. Wheel diameters were 51, 102, and 153 mm. Wheel orientation was tested at four levels: F0R0 (all four wheels aligned in the forward direction), F0R90 (the two front wheels, the wheels furthest from the cart handle, aligned in the forward direction and the two rear wheels, the wheels closest to the cart handle, aligned at 90 degrees to the forward direction), F90R0 (the two front wheels aligned at 90 degrees to the forward direction and the two rear wheels aligned in the forward direction), and F90R90 (all four wheels aligned at 90 degrees to the forward direction). Wheel width did not have a significant effect on the minimum push/pull forces. The minimum push/pull forces were linearly proportional to cart weight, and inversely proportional to wheel diameter. The coefficients of rolling friction were estimated as 2.2, 2.4, 3.3, and 4.5 mm for hard rubber wheels rolling on smooth concrete, tile, asphalt, and industrial carpet floors, respectively. The effect of wheel orientation was not consistent over the tested conditions, but, in general, the smallest minimum push/pull forces were measured with all four wheels aligned in the forward direction, whereas the largest minimum push/pull forces were measured when all four wheels were aligned at 90 degrees to the forward direction. There was no significant difference between the push and pull forces when all four wheels were aligned in the forward direction.

Development of a System for Improved Transportation and Handling of Full-Sized Pregnant Sows at a Metropolitan Research Facility

The need of investigators for ready access to neonatal pigs that were less expensive than neonatal miniature swine prompted development of a sow transport system and an in-house farrowing program for full-sized sows. Pregnant sows weighed 200 to 250 kg. Offspring of these large sows may be overlooked for use in research because domestic pregnant sows are presumed to be difficult to transport and handle in urban laboratory animal facilities. In 1994, ergonomists analyzed risk factors involved in a sow transport system designed in 1990 and implemented manual material assist devices. The ergonomic interventions improved safety, decreased expenses, and reduced manpower requirements for handling sows during transit. Engineering solutions provided in 1994 facilitated the transport and handling of more than 80 pregnant sows that were at approximately day 100 of gestation.

Correlation of injury occurrence data with estimated maximal aerobic capacity and body composition in a high-frequency manual materials handling task

This article evaluates the correlation between injury occurrence, step test estimated maximal aerobic capacity (VO2max), and body composition in a high-frequency manual materials handling task. The study used 212 highly trained male manual material handlers working for a major materials handling company. Three locations across the United States (western, midwestern, and southeastern) were chosen based on similarity of size and function. An estimated maximal aerobic capacity was obtained for each participant using a submaximal bench step protocol. Also, a percentage body fat estimation was randomly obtained for approximately 25% of the participants. The correlation between injury occurrences, absolute VO2max, relative VO2max, and percentage body fat were analyzed. Also, the relationship between both VO2max estimations and percentage body fat was analyzed. Finally, the correlation between location VO2max and percentage body fat was studied. Results indicated no significant difference between absolute VO2max, injury, or percentage body fat. Relative VO2max suggested a significant relationship with injury occurrences and body composition. Body composition also indicated a significant correlation with injury occurrences. Finally, location played a significant factor in injury occurrence, step test estimated VO2max, and estimated body composition. This investigation demonstrates significant evidence of the predictability of employee injury occurrence and the fitness estimation methods used. In a high-frequency manual materials handling task, high occurrences of injury were significantly correlated with low estimated relative maximal aerobic capacity and high estimated percentage body fat.

Vibrometry testing for carpal tunnel syndrome: a longitudinal study of daily variations

The method of limits procedure was used to obtain 84 120Hz vibration thresholds, over a 3-month period, on four age-matched women with different levels of carpal tunnel syndrome (CTS). Each woman used a keyboard for 4 hours a day during work. Testing was conducted in a room with a temperature of 28 degrees C +/- 2 degrees C after 20 minutes acclimation. Results indicate vibration thresholds vary significantly from day to day and also demonstrate how a single vibrometry measure may falsely identify the participant's true CTS condition. Specifically, a single measure could account for a negative CTS determinations in affected wrists or positive CTS determinations in healthy wrists. Subsequent analysis revealed menses related fluid retention and day of the week increase the vibration thresholds. Analyzing the levels of fluid retention by day of the week indicates a compounding effect of the personal and occupational risk factors.

The effects of biofeedback on carpal tunnel syndrome

Behaviour modification based on audible electromyographic (EMG) biofeedback signals was used to discourage the awkward hand postures and the exertion of excessive force with the fingers, which are suspected of causing carpal tunnel syndrome (CTS). The null hypothesis was that participation in such a biofeedback programme has no effect on CTS symptoms. Before and during an 8-week study, data were collected from two groups of five female assembly line workers each. The biofeedback group received training and input, while the control group did not. Test results indicated that the null hypothesis could not be rejected.

Age and weight effects on motor nerve conduction time measurements in an asymptomatic industrial population

Motor conduction delay has been demonstrated in patients with carpal tunnel syndrome (CTS), however, there is also evidence that conduction slowing can be effected by other factors, e.g., the aging process. Recent development of the digital electroneurometer, a hand-held, battery-powered device for measuring motor nerve conduction time, has made this test available for CTS screening in industry. A cross-sectional study of 77 industrial workers was performed to determine the relationship between median motor nerve conduction time at the carpal tunnel and select personal factors. Motor nerve conduction time increased with age, length of employment, and weight. However, these variables accounted for only 20.3% of the variance in conduction time. The study indicates users of this device should be aware of these effects, and that other sources of variation must be identified and controlled if motor nerve conduction tests are to be used for CTS screening in industry.

An evaluation of a weightlifting belt and back injury prevention training class for airline baggage handlers

This study evaluated the efficacy of a commercially available weightlifting belt in relation to reduction of lumbar injury incident rate and severity of injuries over an 8-month period. The study used 642 baggage handlers working for a major airline company as participants. Four treatment groups were randomly selected: a group receiving the belt only, a group receiving a 1 h training class only, a group receiving both a belt and a 1 h training class, and a control group receiving nothing. Two treatment groups were added which contained participants who discontinued use of the belt prior to the end of an 8-month study period. Results indicated that there were no significant differences for total lumbar injury incident rate, restricted workday case injury incident rate, lost workdays and restricted workdays rate, and worker's compensation rates. There was, however, a marginal significant difference for lost workday case injury incident rate. Groups with participants who wore the belt for a while then discontinued its use had a higher lost day case injury incident rate than did either the group receiving training only or the control group. Compliance was an overriding factor as the belt questionnaire response indicated that 58% of participants in the belt groups discontinued use of the belt before the end of 8 months. Comments made on the survey forms indicated that the belt was too hot. Similarly, comments suggested that the belt rubbed, pinched, and bruised ribs. Based on these results, the weightlifting belt used for this study cannot be recommended for use in aid of lifting during daily work activities of baggage handlers. Results indicate that use of the belts may, in fact, increase the risk of injury when not wearing a belt following a period of wearing a belt. As industries are experimenting with the use of belts, it is recommended that great care be taken in any further evaluation and close attention directed towards injuries which occur when not wearing the belt following a period of wearing the belt (ie, off-the-job injuries).

Use of motor nerve conduction testing and vibration sensitivity testing as screening tools for carpal tunnel syndrome in industry

Increased attention to carpal tunnel syndrome in industry has resulted in the development of several proposed screening tests. This investigation evaluated the use of two portable devices for measuring motor nerve conduction time and tactile sensitivity to 120 Hz vibration in a field setting. Forty-seven control participants, 63 manufacturing plant workers with and without symptoms of carpal tunnel syndrome, and 22 patients with physician-diagnosed carpal tunnel syndrome were tested with the NervePace electroneurometer and the Vibration II vibration threshold measurement device. Nerve conduction time differed significantly between the controls, the asymptomatic workers, and the participants with carpal tunnel syndrome or symptoms of carpal tunnel syndrome. The vibration threshold was higher in the carpal tunnel syndrome group than in the other groups; however, further examination of the data revealed no differences in threshold unless nerve conduction time exceeded the control mean by at least three standard deviations. The false-negative rates associated with the tests limit their usefulness in screening for carpal tunnel syndrome.

An ergonomics approach to refrigerator design for the elderly person

The objective was to determine a set of refrigerator design guidelines for independent living elderly women. The study was conducted with a refrigerator mockup with interchangeable internal features. Twelve elderly women participated, both in a standing and seated (wheelchair) position. The participants were videotaped as they simulated use of shelves and drawer, and they rated these components and their positions for acceptability of reach, visibility of contents, and personal preference. Participants then used a variety of mockup items to configure the refrigerator to their own preferred design. These were then analysed and synthesised into three 'consensus' designs combining the features of most of the others.