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The purpose of this study was to examine the consistency of measurements of maximal isometric force production in children using an electronic strain gauge. A standardized protocol of force testing from the Tufts Quantitative Neuromuscular Examination was adapted to obtain isometric force measurements in seven muscle groups bilaterally. Ten children with Duchenne's muscular dystrophy (DMD) and 10 age-matched children without DMD were recruited for the study. A generalizability framework was used to examine variations in measurements attributable to group differences, test occasions within the same day, and extremity side. Intertester reliability estimates were also completed on a subsample of children with and without DMD. A three-way analysis of variance between group, sides, and test occasions demonstrated a significant group main effect for all muscle groups. In general, significant main effects were not present for side or test occasion. Test-retest intraclass correlation coefficients (ICCs) for all muscle groups ranged from .88 to .99 for the children with DMD and from .85 to .98 for the children without DMD. Intertester ICCs were slightly lower, ranging from .74 to .97 for the children with DMD and from .71 to .98 for the children without DMD. The results indicate that the electronic strain-gauge protocol produces reproducible force measurements in seven selected muscle groups in children with and without DMD. [Brussock CM, Haley SM, Munsat TL, Bernhardt DB. Measurement of isometric force in children with and without Duchenne's muscular dystrophy. Phys Ther. 1992;72:105-114.], Duchenne's muscular dystrophy (DMD) is a progressive, inherited disease of muscle that affects one of every 3,500 male births. It has recently been demonstrated that DMD is the result of [...]

Background and Purpose. The purpose of this study was to determine the level of muscle force associated with ability to walk in the community without assistance, in the community with assistance, or at home only in individuals with amyotrophic lateral sclerosis (ALS). Subjects and Methods. Percentage of predicted maximal muscle force (%PMF) of lower-extremity muscles was determined, and walking ability was categorized in 118 patients with ALS during periodic visits to the Neuromuscular Research Unit. Data were derived from consecutive visits in which subjects demonstrated declines in walking ability. Means for %PMF of each muscle group and a limb average were calculated at each consecutive visit. Results. The mean lower-extremity average %PMF was: (1) 54.01% (SD = 12.76%) for subjects who walked independently in the community and 50.19% (SD = 14.38%) during the next visit when these same subjects required assistance in the community (difference = 3.82%, 95% confidence interval [CI] = 2.45-5.19); (2) 37.52% (SD = 15.17%) during the last visit that subjects walked with assistance in the community and 32.18% (SD = 13.83%) during the next visit when they walked only at home (difference = 5.33%, 95% CI = 3.61-7.06); and (3) 19.12% (SD = 9.08%) during the visit when subjects were last able to ambulate at home versus 13.70% (SD = 7.36%) when they became unable to walk (difference = 5.42%, 95% CI = 2.97-7.96). Conclusion and Discussion. The findings suggest there are required levels of lower-extremity muscle force for various categories of walking ability. Variations in forces within and between categories of walking ability, however, indicate the complexity of this relationship. [Jette DU, Slavin MD, Andres PL, Munsat TL. The relationship of lower-limb muscle force to walking ability in patients with amyotrophic lateral sclerosis. Phys Ther. 1999;79:672-681.], Key Words: Gait; Muscle performance, lower extremity; Neuromuscular disorders, general. The disablement models[1,2] suggest a relationship between impairments such as diminished muscle force and functional limitations such as difficulty walking. [...]