Biomedical subjects

A M Genaidy

Publications and source records attributed to A M Genaidy.

At least 19 recordsLinked to original sources

PubMed1995

Active microbreak effects on musculoskeletal comfort ratings in meatpacking plants.

This study was conducted to examine whether a system of active microbreaks can reduce the discomfort perceived by employees in a meatpacking plant. Moreover, the relationship between the discomfort perceived on the job and musculoskeletal capability was investigated. Twenty-eight men employed in a local meatpacking plant participated in a study conducted over a period of four weeks. Results indicated that active microbreaks significantly reduced the level of discomfort perceived by employees during the course of the working day. The subjective ratings of perceived discomfort correlated significantly with anthropometric, strength and background information (R2 = 0.66). The physical characteristics of Caucasian employees were higher than those of their Hispanic counterparts. Moreover, the physical characteristics of meatpacking employees were significantly lower than those reported in the literature for employees engaged in manual handling tasks.

Absenteeism↗

PubMed1995

Can back supports relieve the load on the lumbar spine for employees engaged in industrial operations?

In recent years, there has been an increased use of back supports in US industry to reduce the frequency and concomitant costs of lower-back disorders. The obvious question is, 'Can back supports relieve the load on the lumbar spine for employees engaged in industrial operations?'. This paper is directed towards answering this question because there have been mixed conclusions in the literature reporting on the efficacy of back supports. The literature concerning the biomechanical, physiological and psychophysical effects of back supports on the human spine has been reviewed as well as the use of back supports to control injury in the workplace. A critical assessment of the findings reported by various investigators has been made together with a discussion of the mechanisms used by the trunk muscles to provide extrinsic stability to the spine. It is hypothesized that the extrinsic stability of the spine is manifested through more than one mechanism. These mechanisms may act simultaneously or sequentially to stabilize the trunk. Finally, the ergonomics of back supports as a corporate policy are discussed.

Humans↗

PubMed1995

Use of visual perception in estimating static postural stresses: magnitudes and sources of errors.

Very little is known about the magnitudes and sources of errors associated with the visual estimation of postural classification displayed on TV screens. This study was conducted to address this issue. Sixty-three subjects participated in the experiments. The findings indicate that: (1) subjects found it difficult to evaluate upper extremity postures (particularly the elbow and the wrist), while the postures around the lower back were the easiest to evaluate; (2) the lower extremity positions affected the ability of the subjects to accurately classify postures around the wrist, elbow, shoulder, neck, and lower back, with the estimates being > 70% for sitting and > 60% for standing (except for the elbow); and (3) in general, flexion and extension are easier to evaluate than neutral and non-neutral postures.

Adult↗

PubMed1993

Can visual perception be used to estimate body part angles?

For two decades, observational methods have been used to measure postural loads in industry. These methods depend on the analyst's judgment to characterize correctly the working postures. The errors associated with estimating the body part's angular deviation from the neutral position are not known. Recently, videotaping of a work situation, followed by examination of the tape to assess postural position has become more commonly practised. This study was conducted to determine the error which accompanies the judging (without tools) of postural angles. In the present study, a method was used whereby 20 subjects were asked to report the perceived angles which closely matched the actual shoulder flexion angle displayed on the TV screen. The results showed no significant differences among the three angular ranges ('low', 1-60 degrees; 'medium', 61-120 degrees; and 'high', 121-180 degrees) of shoulder flexion, in terms of algebraic and absolute errors. Subjects tended to slightly overestimate the true angle in the low range and to slightly underestimate the true angle in the medium and high angle ranges. This study suggests that visual perception can be used to estimate shoulder flexion angles displayed on a VDT.

Adult↗

PubMed1993

Spinal compression tolerance limits for the design of manual material handling operations in the workplace.

Spinal compression tolerance limits (SCTL) have been widely used by ergonomists in setting work tolerance limits for manual materials handling (MMH) operations. Thus, the effect of personal and experimental factors on spinal compression tolerance limits (SCTL) is reviewed with the aid of regression and correlation analyses performed on data compiled from the published literature. Tables of SCTL from various sources utilizing large number of specimens and personal factors are presented so that they can be accessed by ergonomists easily. Integrated biomechanical guidelines based on SCTL are provided for the design of MMH operations in the workplace. It is suggested that, in order to reduce the probability of MMH injuries, biomechanical tolerance limits should be set at the damage load instead of the load at fracture. The damage load is the weight which causes the first gross signs of damage such as tissue fluid and blood. An algorithm is described to demonstrate the use of a biomechanics approach to the design of MMH operations.

Adult↗

PubMed1993

A psychophysical approach to determine the frequency and duration of work-rest schedules for manual handling operations.

The primary objectives of this study were: (1) to test whether rest allowances could be ascertained using a psychophysical methodology; and (2) to examine the effects of gender and frequency of handling on work-rest schedules. Two experiments were conducted, each experimental session at 4h. A psychophysical methodology was used where the subject was given control of the working and resting durations. The results of the study indicated that: (1) the total working time decreased and the total resting time decreased with an increase in the frequency of handling; (2) high frequency tasks required more frequent rest allowances; (3) for the same manual handling tasks, women needed more frequent and longer allowances than men; (4) experience with the manual handling of material reduced the variability collected from the psychophysical methodology. The application of the psychophysical methodology in industry is discussed.

Adult↗

PubMed1993

The effects of neutral posture deviations on perceived joint discomfort ratings in sitting and standing postures.

There is a pressing need to rank body deviations from neutral postures which occur due to variety of body movements around different joints. Such knowledge is needed to better understand potentially adverse effects of poor working postures on the industrial population. The main objective of this study was to examine the effects of postural deviations on perceived joint discomfort ratings assessed under similar working conditions. Twelve males and seven females participated in the laboratory study. The results revealed several distinct classes of joint deviations from neutral postures, which need to be assigned different weights of postural stress. A preliminary ranking system for assessment of stressfulness of human body deviations about different joints was proposed.

Adult↗

PubMed1993

Ergonomic risk assessment: preliminary guidelines for analysis of repetition, force and posture.

High repetition, excessive forces and awkward postures are a major cause of musculoskeletal disorders in industry. Thus, the main objective of this paper is to develop, based on the published literature, preliminary ergonomic guidelines for repetition, force, and posture task analysis. A method is also proposed which can be used to compute the interactive effects of repetition, force and posture.

Biomechanical Phenomena↗

PubMed1992

Physical training: a tool for increasing work tolerance limits of employees engaged in manual handling tasks.

The lack of physical fitness is a contributing factor to the etiology of musculoskeletal disorders resulting from the manual handling of material in industry. Thus the major objectives of this paper were (1) to discuss the role of physical fitness in the control of occupational injuries; (2) to review techniques available in the exercise physiology literature for increasing human physical capacity in industry; and (3) to review and evaluate studies on the effects of physical training on individuals engaged in manual handling tasks.

Humans↗

PubMed1992

Occupational biomechanics of the neck: a review and recommendations.

Musculoskeletal disorders of the neck are becoming a major concern in industry. Several studies reported the association of neck pain, discomfort, and symptoms with different occupations in industry. Thus, the main objective of this study is to review and evaluate biomechanical techniques used in analyzing the occupational factors leading to neck pain and disorders. Recommendations for future research are also discussed.

Biomechanical Phenomena↗

PubMed1992

A comparative study of the myoelectric amplitude characteristics for weight-holding tasks.

This study was conducted to examine the effects of load, time, and gender on five amplitude measures of the myoelectric signal (MES) for 10 male and 10 female subjects engaged in upper extremity weight-holding tasks. The results indicated that: (1) measures of amplitude variability (e.g.: standard deviation) are more sensitive to changes in load and time than the full-wave rectified integral and root-mean square indices; (2) both load and time had a significant effect on MES indices, suggesting that amplitude measures may be used as a tool for evaluating the degree of muscular loading and fatigue; (3) females have higher muscular exertion values than males under the same experimental conditions, indicating that females are subjected to higher levels of stresses than males for the same amount of workload. The implications of the results are discussed.

Adult↗

PubMed1991

A training programme to improve human physical capability for manual handling jobs.

The primary objectives of this study were to test whether the muscular endurance, muscular strength, cardiovascular endurance, and workload perception of individuals engaged in combined manual handling tasks could be improved through a short and intensive physical training programme. Two separate experiments were conducted to achieve the objectives of this study. The independent variables studied in each experiment were group type (training and control) and training session. Twenty male subjects participated in these experiments. The task performed in the first experiment was a combined lifting, lowering, pushing, pulling, and carrying activity. The second experiment featured an upper extremity manual handling task. Results indicated that, for both experiments, endurance time increased and heart rate decreased significantly during the course of training. For experiment 1, there were no significant changes in either static or dynamic strength with training. On the other hand, significant increases in static and dynamic strength were observed with the training group of experiment 2. The results of this study suggest that it is possible to improve muscular endurance and cardiovascular endurance with a short and intensive training programme. Moreover, an endurance training programme may increase both static and dynamic strength only if the weight of load handled during the training programme taxes the subject to 50% or more of his/her initial dynamic strength.

Adult↗

PubMed1991

Endurance time and physiological responses to prolonged arm lifting.

The main objective of this study was to examine the effects of prolonged arm lifting tasks on endurance time and physiological responses. Ten male college students participated in the study. The independent variables were the frequency of handling and weight of load. The dependent variables were endurance time, oxygen consumption, minute ventilation, heart rate, and ratings of perceived exertion of the shoulder, arm, back, leg and overall body. The results indicated that: (1) endurance time decreased with an increase in frequency or load; (2) oxygen consumption and heart rate limits were dependent on the interaction of frequency and load; (3) oxygen consumption and heart rate limits for arm lifting were generally lower than limits for leg lifting tasks; and (4) for arm work, average physiological responses recorded over short durations were not significantly different from those based on long durations.

Adult↗

PubMed1990

Improving human capabilities for combined manual handling tasks through a short and intensive physical training program.

The primary objectives of this study were to test whether the muscular endurance, muscular strength, cardiovascular endurance, and workload perception of individuals engaged in combined manual handling tasks could be improved through a short and intensive physical training program. Three groups were formed to achieve the objectives of this study, and five subjects participated in each group. Two groups were trained using the concept of progressive resistance exercise; one group used the concept of six-repetition maximum (6 RM) while the other group followed the ten-repetition maximum (10 RM) protocol. The third group was used as a control group to monitor the effectiveness of the training groups. The training groups required subjects' attendance at 16 sessions for a period of 6 weeks. The control group performed the same tests given to the training group twice, separated by a period of 6 weeks. Endurance time, heart rate, ratings of perceived exertion, and static and dynamic strength were the response variables. Based on the results of this study, the following conclusions could be made: (1) it is possible to significantly improve muscular endurance, muscular strength, and cardiovascular endurance through the short and intensive training protocols examined in this investigation (the 10 RM training protocol, however, yielded better improvement in human physical capability than the 6 RM training protocol); and (2) for a fixed work load, endurance time can increase without changing job demand perception.

Adult↗

PubMed1990

A muscular endurance training program for symmetrical and asymmetrical manual lifting tasks.

The purpose of this study was to test whether the endurance limits of new employees engaged in symmetrical and asymmetrical manual lifting tasks can be significantly increased through a physical training program. Each subject participating in the training program performed a total of 16 sessions. A control group performed two sessions separated by a 4-week interval. The results of this study showed that endurance time increased by 248% for the symmetrical and 46% for the asymmetrical lifting tasks. Furthermore, the frequency of handling increased by 44% and 34% for these tasks, respectively. The control group showed no improvement in terms of endurance time and frequency of handling. The implementation of a physical training program as a tool to control overexertion injuries in industrial settings is outlined.

Accidents, Occupational↗

PubMed1989

Effects of frequency and load to lift on endurance time.

The purpose of the present study was to determine endurance time for manual lifting tasks which were performed over a wide range of loads (5, 10, 15, and 20 kg) and frequencies (4, 6, 8, and 10 times/min) for a lift from floor to table height. Endurance time was defined in this study as the maximum length of time during which an individual was capable of lifting a given load at a given frequency continuously. The upper limit of endurance time was set to 8 h. Eleven male subjects participated in this study, and the lifting technique utilized with the straight back-bent knees method. The results showed that endurance time was significantly reduced with an increase in frequency or load of lift. The lightest frequency-load combination (4 times/min; 5 kg) was maintained by most of the subjects for 8 h. Conversely, the average endurance time for the heaviest frequency-load combination (10 times/min; 20 kg) was about 27 minutes.

Adult↗

PubMed1989

An endurance training programme for frequent manual carrying tasks.

This study was conducted with the aim of testing whether the endurance time of new employees engaged in frequent industrial carrying tasks can be significantly increased through a short training programme (2.5 weeks). Endurance time was here defined as the maximum length of time during which an individual can continuously carry a 20 kg load over a 4 m distance 8 times/min. The results showed that (1) endurance time increased by almost 100% over an 8-session training programme; (2) for a fixed workload, endurance time increased without changing job demand perception; and (3) overall body fatigue may be the limiting factor in frequent carrying tasks.

Adult↗

PubMed1988

Physiological guidelines for the design of manual lifting and lowering tasks: the state of the art.

The goal of many researchers and practitioners of occupational health and safety has been to design manual materials handling (MMH) tasks so as to reduce the frequency and severity of overexertion injuries usually associated with these types of tasks. Physiological limits with respect to the manual lifting and lowering aspects of MMH have been reviewed and evaluated. The information provided by different researchers has been presented in a concise manner that is easily accessed by designers and practitioners of MMH. Recommendations for future research in determining physiological limits of individuals engaged in manual lifting and lowering tasks and other aspects of MMH activities have been provided.

Energy Metabolism↗