Search PubMed⌕ Search

Biomedical subjects

A Mital

Publications and source records attributed to A Mital.

At least 55 records · Page 3Linked to original sources
PubMed1987

Maximum weights of asymmetrical loads acceptable to industrial workers for symmetrical manual lifting.

This paper presents 'maximum acceptable weight of lift' design databases for lifting asymmetrical loads by industrial male and female workers. These databases were developed by first collecting experimental data on experienced and inexperienced workers under identical conditions (Study A) and then applying the trends developed, as a result of data comparison, to the data collected on inexperienced workers in a separate independent study (Study B) dealing with lifting asymmetrical loads. Several different task variables are accounted for in the data. These include the following: lifting height (floor to knuckle, knuckle to shoulder, and shoulder to reach); frequency of lift (2, 4, and 6 lifts/min; box-size (30.48, 45.72, and 60.96 cm long in the sagittal plane); and load asymmetry (indicated by the offset of the center of gravity in the frontal plane: 0, 12.7, and 25.4 cm from the mid-sagittal plane; the 0 cm center of gravity (c.g.) offset indicates symmetrical load).

Adult↗
PubMed1987

Biomechanical analysis of manual lifting tasks.

This paper presents the findings of a study conducted to determine peak forces generated in the human spine while the individual is engaged in lifting maximum acceptable weight. Calculations of forces and moments, acting on each body segment, were based on film data collected on four individuals for twelve variations of the manual lifting task. The variations were defined by: box-size (three different boxes were used), presence or absence of handles, and symmetry and asymmetry of the lifting task (sagittal and nonsagittal lifting). In general, lower loads were accepted for lift when lifting asymmetrically or when lifting boxes without handles or when lifting bigger boxes. However, peak forces (compressive and shear forces in the spine and ground reaction forces) for these situations were not always lower than those generated when handling either compact boxes or boxes with handles or when lifting boxes symmetrically in the sagittal plane. On the basis of these results, it was concluded that lifting loads asymmetrically or in boxes without handles or in bulky boxes is relatively much more stressful than lifting the same load symmetrically or in boxes with handles or in compact boxes.

Adult↗
PubMed1986

The cost/accuracy approach: a method for selecting filming rate for manual materials handling activities.

This paper presents a method for determining filming rate for developing kinetic biomechanical models of manual materials handling activities. Using a high-speed camera, manual lifting activities were filmed at 500 frames per second. Different framing rates were then simulated by skipping one or more film frames. The data analysis indicated that selection of filming rate on the basis of cost and accuracy trade-off is superior to existing framing rate selection criteria. The proposed method can be used for other similar activities.

Journal Article↗
PubMed1986

Development of a safety index for manual lifting tasks.

The concept of a safety index (SI) for assigning a worker to a particular manual lifting task is developed, and a simple formula for its calculation is presented. The proposed index is based upon the combined measure of acceptability of the biomechanical and physiological stress responses of the worker to a lifting task. Individual capacity norms, as opposed to the norms usually given based on population percentiles, are also defined. Numerical examples are given to illustrate the SI approach.

Journal Article↗
PubMed1986

Effect of body posture and common hand tools on peak torque exertion capabilities.

An experimental investigation was conducted to investigate the effects of body posture and of different types of common non-powered hand tools on maximum volitional torque exertion capabilities of males and females. Thirty-six males and 14 females applied peak torque in 21 different body postures while using nine different hand tools. The data analysis indicated that, for both males and females, the magnitude of volitional torque is strongly influenced by the type of tool used and the posture assumed. Between the two, however, the effect of hand tool is more profound. The correlation between the tool type and volitional torque was of the order of 0.71. No other variable was as strongly correlated with volitional torque. Maximum volitional torque profiles, as a function of posture and tool type, are provided for males and females.

Journal Article↗
PubMed1986

Prediction of maximum acceptable weight of lift in the horizontal and vertical planes using simulated job dynamic strengths.

An investigation was undertaken to determine the feasibility of predicting maximum weights of lift that are acceptable to individuals by measuring the individuals' simulated job dynamic strengths. Since almost all manual materials handling jobs are dynamic in nature, it was hypothesized that correlations between maximum weights acceptable for lifting and the dynamic strengths measured under similar conditions would be high compared to isometric strengths. If so, then a relatively simple procedure can be developed to estimate what people are willing to lift safely. With the use of a specially designed and constructed three-dimensional dynamic strength simulator, 19 males and 6 females lifted loads in two vertical and two horizontal planes. Their dynamic strengths also were measured under identical conditions. The correlations between simulated job dynamic strengths and acceptable weights of lift were much higher (0.52 to 0.67) compared to correlations between isometric strengths and acceptable weights of lift (0.29 to 0.38). This also confirmed earlier findings that dynamic strengths are more suitable predictors of the maximum weights people are willing to handle. Simple equations are presented between simulated job dynamic strengths and maximum acceptable weights of lift in the horizontal and vertical planes. These equations demonstrate that dynamic strength can be used reliably when matching jobs with individuals.

Adult↗
PubMed1983

Subjective estimates of one-handed carrying tasks.

In this study, ten male and five female subjects, ranging between 21 and 23 years in age and in excellent physical health, voluntarily participated. Four different shapes of containers, 8.5 and 12.3 litres in capacity, were used to carry loads for distances of 100, 200, and 300 ft (30.48, 60.96, and 91.44 m, respectively). Individuals first subjectively estimated how much weight they could carry in a given type of container for the required distance and then verified it by actual carrying. The preferred (stronger) hand was used to hold the containers. In addition to the weight acceptable for comfortable carrying, pulse rate and ratings of perceived exertion (RPE) of the arm and whole body were also used as response measures. Results indicated that subjects could quite accurately estimate the amount of weight they could carry comfortably in one hand. RPE for one-handed carrying tasks was not one-tenth of the pulse rate as is the case for whole body tasks. The average pulse rate was 100 beats/min for the weights selected. Shape of the containers significantly influenced the amount of weight subjects were willing to carry in one hand. The acceptable amount of weight decreased with distance, but was found to increase with volume.

Journal Article↗
PubMed1983

Perceived exertion of physical effort for various manual handling tasks.

Ten trained male students between 18 and 28 years of age participated in a study, designed to determine the relationship between perceived exertion and physiological costs of exertion during various manual lifting and lowering tasks. Perceived exertion was defined as one's subjective rating of the intensity of work being performed. Five subjects performed lifting tasks and another five performed lowering tasks. Weight of load lifted or lowered (6.8, 13.6, 20.5 kg), frequency of lift or lower (3, 6, 9 times/min), height of lift or lower (floor to 76 cm, 76 to 127 cm, floor to 127 cm), box width (38, 66 cm), box length (38, 66 cm) and angle of twist of the body (0 degree, 90 degrees) were the independent variables studied. Heart rate, oxygen consumption, and ratings of perceived exertion (RPE) were the response measures. RPE was found almost linearly related to heart rate and oxygen consumption when lifting or lowering loads. For lifting tasks, the coefficient of correlation between RPE and heart rate was 0.673. In the case of lowering tasks, this coefficient was 0.604. When oxygen consumption was considered, the corresponding coefficients for lifting and lowering were 0.734 and 0.619, respectively. The correlation of RPE with the physiological response variables indicates that the severity of manual materials handling tasks in industry can be evaluated quickly and inexpensively by using perceived exertion ratings (RPE).

Adolescent↗