Ratings of acceptable load and maximal isometric lifting strengths: the effects of repetition

Abstract

The effects of repetition on psychophysically acceptable loads and maximal isometric lifting strengths were studied in two groups of subjects. In both groups, subjects selected acceptable loads for dynamic lifting between table and floor and were tested for maximal and acceptable lifting strength isometrically at knee and waist levels.In series I, 33 subjects (15 males, 18 females) were tested 4 times with a minimal interval of 5days between tests. In series 11, 12 subjects (8 males, 4 females) were tested daily from Monday to Friday on 2 consecutive weeks.Differences in acceptable isometric lifting strength between the two groups appeared to arise from minor differences in the instructions given; but in neither series was there a significant change in acceptable lifting strength, either dynamic or isometric. In series I, no change was noted in maximal isometric lifting strength. But in series I1 there was a gain in maximal lifting strength at knee level of 25%. Also in series 11, the acceptable isometric lifting strength at waist level was consistently found to be 60% of the acceptable dynamic lifting strength.

The Role of Genetics and Environment in Lifting Force and Isometric Trunk Extensor Endurance

“…21,38,39 The 3 back tests we used were commonly used in the early 1990s in the initial phase of our study data collection. 35 Other back tests (such as submaximal tests and functional performance measures) are more commonly used today due to ongoing development and introduction of new tests and training devices and their wider availability.…”

“…The reliability of isokinetic lifting measurements was determined in a study of working-age adults without known pathology or impairments, and ICCs of .97 and .87 were obtained for intratest and intertest reliability of peak force and total work measurements. 5 The psychophysical lifting test was similar to the "acceptable isometric lifting force test" described by Foreman et al, 38 except the lifting position was at 60 degrees of spinal flexion instead of at knee level. According to Foreman et al, the "acceptable" lifting force is the maximum force a subject exhibits when asked to demonstrate the maximum force that he or she can comfortably maintain for 5 seconds.…”

“…Pearson correlation coefficients of .87 to .96 were reported for intertester reliability of measurements among working-age subjects without known pathology or impairments. 38,39 Isometric trunk extensor endurance was evaluated by timing (in seconds) how long a subject was able to hold the upper part of his body horizontal while lying prone with no support beyond the upper border of the iliac crest. The subject's hands were kept behind the neck, and the thighs and ankles were fixed to the table by 2 wide straps.…”