Carter J. Kerk

Exploring Relationships in Body Dimensions

Body girth measurements and skeletal diameter measurements, as well as age, weight, height and gender, are given for 507 physically active individuals – 247 men and 260 women. These data can be used to provide statistics students practice in the art of data analysis. Such analyses range from simple descriptive displays to more complicated multivariate analyses such as multiple regression and discriminant analysis.

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.

The effect of handle height and cart load on the initial hand forces in cart pushing and pulling

The objective of this study was to measure the three-dimensional hand forces people exert to initiate a cart push or pull for two cart loads: 73 and 181 kg, and three handle heights: knuckle, elbow, and shoulder heights. The cart used was equipped with 15.24 cm (6 in) diameter wheels. The floor was covered with carpet tiles. The laboratory-measured hand force exertions were compared to the minimum forces needed to push/pull the cart under the same conditions and to the psychophysical initial push/pull force limits. For pushing and pulling, the measured anterior-posterior hand forces were 2–2.4 times the minimum required forces. For the heavier cart load, lower forces were applied as handle height increased. Pull forces were 7% higher than push forces. The smallest vertical forces were measured at elbow height. Strength capability and gender did not have an effect on the applied forces. The mean strength percentile for the male sample was 64%, while the mean strength percentile for the female sample was 13...

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]).

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.

A COMPREHENSIVE BIOMECHANICAL MODEL USING STRENGTH, STABILITY, AND COF CONSTRAINTS TO PREDICT HAND FORCE EXERTION CAPABILITY UNDER SAGITTALLY SYMMETRIC STATIC CONDITIONS

A new mathematical biomechanics] model has been developed to comprehensively estimate feasible hand force exertion capability under sagittally symmetric static conditions. In the model, a set of 15 linear constraint equations has been developed in three constraint classes: coefficient of friction, stability, and strength. This set of constraints defines a feasible solution space for combinations of horizontal and vertical forces exerted by the hands. Inputs to the model include posture, anthropometry, strength capability, coefficient of static friction, and gender. Examples of lifting and pushing demonstrate some features and advantages of the model. The most promising aspect of this model appears to be its ability to comprehensively combine multiple factors that can affect hand force exertion capability.

The influence of supporting the Oxylog instrument on estimated maximal aerobic capacity during a step test and heart rate in a lifting test

This study investigated the influence of wearing, an Oxylog mask and heart rate monitor while the Oxylog instrument was supported in a stand versus that of wearing the Oxylog mask, heart rate monitor, and the Oxylog instrument, on oxygen consumption (VO2) and heart rate response during a graduated submaximal step test protocol. Also, the predicted maximal aerobic capacities ( VO2max) produced by the two graduated step tests were compared. In addition, differences in the working heart rates in a submaximal lifting test were analyzed in two lifting tests, one with the participant wearing the Oxylog mask, heart rate monitor, and Oxylog instrument and the other required the participant to only wear a heart monitor. Seventeen experienced male manual materials handlers participated in the study, and each treatment was seen by each participant in a randomized Latin Square design. Results from the two investigations indicate that there was no significant difference in the estimated maximal oxygen consumption (p = 0.1384) and no significant difference in the heart rate between the two lift tests. The analysis did show that the 4th stage (participants reaching their physiological limits) of the step tests indicated a statistically significant difference (p = 0.0259 for oxygen consumption, and p = 0.0465 for heart rate).

Effect of menstruation on vibrotactile threshold in the peripheral median nerve

Abstract A four-week vibrometry evaluation was conducted on nine female clerical workers (average age 31) to determine the effect of menstruation on vibrotactile threshold of the median nerve. Each participant was right-handed, asymptomatic for peripheral median nerve sensory dysfunction, and worked at least 20 hours per week. The evaluation concluded that vibrotactile threshold values recorded during menstruation were significantly higher than during nonmenstruation ( p Relevance to industry If vibrotactile threshold testing (vibrometry) is to be used in industry to assess the presence of peripheral median nerve sensory dysfunction, an effective screening protocol needs to account for menstruation status to minimize potential false positive diagnoses.

Limitations of Wrist Strength to Manual Exertion Capability in 2D Biomechanical Modeling

The objective of this study is to evaluate the assumption in biomechanical models that wrist strength does not limit manual exertion capability. An experiment was designed and run on right-handed males to test isometric elbow flexion strength at two included elbow angles: 90° and 135° and in two forearm positions: supinated and mid between supination and pronation. Isometric wrist flexion strength was also measured at the same elbow angles and at two wrist positions in the flexion/extension plane: neutral and 45° extended. Isometric wrist radial deviation strength was measured at the same two elbow angles and at two wrist positions in the radial/ulnar deviation plane: neutral and 30° ulnarly deviated. An equation was developed to calculate the theoretical minimum wrist strength limits for which wrist strength does not limit maximal moments about the elbow. These calculated limits were compared to the corresponding measured wrist strength moments. In general, wrist strength was found to be non-limiting, but in some specific circumstances, it can be limiting. Among the posture/exertion combinations tested, only wrist flexion strength in the extended wrist posture was found to be limiting. There was some evidence that strong-wrist people show less wrist strength limitations than weak-wrist people in some postures. It was also found that the neutral wrist posture is not associated with the highest wrist strength.

Tiospaye in Engineering and Science: Inculcating a sustained culture for recruiting, retaining, and graduating American Indian students

While the general population of South Dakota is 10 percent American Indian, participation in higher education of this group in South Dakota universities remains relatively low, typically around 1.5 percent. Following best practices developed by American Indian educators and tribal colleges, the South Dakota School of Mines and Technology has developed a new program, Tiospaye in Engineering and Science, which offers a new paradigm for recruitment and support for American Indian students. Following the Lakota word for extended family, Tiospaye, the program provides both scholarship support and positive intervention strategies through an extended campus network of support. The program features extensive classroom support through a combination of campus and small group tutoring sessions, designed within department advisors, and a program mentor that offers one-on-one academic advising and mentoring. In this paper, we describe the recruitment process, positive intervention strategies for academic success, and social support networks. We conclude with a discussion of the current status of the program and early assessment results.