Studies of relationships between lumbar disc pressure, myoelectric back muscle activity, and intra-abdominal (intragastric) pressure.
Explore the source record for details and available documents.
Abdomen↗
Biomedical subjects
R Ortengren
Publications and source records attributed to R Ortengren.
Analysis and quantitative myoelectric measurements of loads on the lumbar spine when holding weights in standing postures.
Ten subjects executed a number of weight-holding and force-resisting work tasks while standing either upright or with their trunks in 30 degrees of forward flexion. All tasks involved sagitally symmetric body configurations and were performed isometrically. A simple calculation scheme was devised to predict the lumbar trunk muscle contraction forces and the lumbar spine compression forces required for execution of each task. The myoelectric activity was recorded quantitatively at eight sites over the lumbar trunk muscles and at four sites over the abdominal muscles. Good correlation was found between the predicted muscle contraction forces and the myoelectric activities.
Adult↗
Measurements of trunk movements during work.
To study spinal movements during work, an instrument that measured angles and angle changes in relation to a vertical plane was adapted to continuously measure forward flexion of the trunk. The instrument, which is battery-powered and worn on the back, registers the amount of flexion and its distribution over time during a work cycle by recording the time spent in each of five 18 degrees intervals between 0 degrees and 90 degrees. Also the number of times that the angle of flexion changed from one interval to another is recorded. A total of 43 subjects from three occupations--dentistry, nurses' aide work, and warehouse work--were each tested during a 60 minute work cycle. On the average, the dentists spent most of the time (52.2 minutes) in a semi-flexed position not exceeding 36 degrees and performed eight deep forward flexions (greater than 73 degrees). The nurses' aides spent one-half of the work cycle (34.4 minutes) in an upright position (0-18 degrees) and performed 70 deep forward flexions. The warehouse workers spent less than one-half of the work cycle in an upright position (27.5 minutes) and performed 153 deep forward flexions that nearly always were associated with lifting.
Adult↗