REPRODUCIBILITY OF COMPUTER MEASUREMENT OF MAXIMAL ISOMETRIC STRENGTHAND ELECTROMYOGRAPHY IN SEDENTARY MIDDLE-AGED WOMEN

The objectives of this study were (i) to determine the reproducibility of computer measurements of isometric strength and related electromyo graphy in several muscle groups in sedentary middle-aged women, (ii) t o evaluate the effects of different digital signal averaging methods o n the reproducibility, (iii) to determine the final test score to be p referred in terms of improved reproducibility of isometric strength me asurements, and (iv) to evaluate potential advantages provided by the computer measurement. Fifteen subjects were measured three times withi n a 2-week period. The measurements consisted of recordings of maximal isometric strength and rate of force production during trunk extensio n and flexion, leg extension and dominant forearm flexion with simulta neous recordings of surface electromyography, except in the trunk flex ors. The following four final test scores were determined for each tri al: the maximum of the three scores, the mean of the two highest score s, the median of the three scores and the mean of the three scores. Th e scores for the strength measurement were generally more reproducible (coefficient of variation, CV, approximately 6% and intraclass correl ation coefficient ICCC, approximately 0.90) than those of the other me asurements (CV>10%, ICCC 0.13-0.97). There was no obvious preference f or any type of final test score or for the width of the averaging wind ow in the computer analysis. For isometric strength the reproducibilit y of the computer measurements was comparable to that of the voltmeter assessments. Computer analysis seems to be a versatile method for det ermining parameters of neuromuscular performance with reasonable repro ducibility.