title: Isometric knee extension force measured using a handheld dynamometer with and without belt-stabilization.
abstract: Although evidence suggests that tester strength limits the magnitude of isometric force that can be measured using a handheld dynamometer (HHD), previous studies have not investigated the actual limits of force magnitude that can be measured by trained testers when a belt is or is not used to stabilize the dynamometer. Therefore, the primary aims of this study were to determine: 1) the magnitude of knee extension forces that could be measured with a HHD with and without belt-stabilization and 2) the relationship between tester characteristics and knee extension strength measured with and without belt-stabilization. The characteristics of 20 trained testers (10 men, 10 women) were determined. Thereafter, they measured isometric knee extension strength using the MicroFET HHD with and without belt-stabilization. Paired t-tests were used to compare maximal knee extension forces under two conditions. Pearson product-moment correlations were calculated to determine the relationship between tester characteristics and knee extension forces measured under the two conditions. Knee extension forces (Newtons) measured using the HHD without belt-stabilization (470.6 ± 179.8) were significantly lower (t= -7.968, p<0.001) than those measured with belt-stabilization (866.9 ± 131.7). Pearson correlations between tester characteristics and knee extension forces measured with no belt-stabilization were all statistically significant (p ≤ 0.002); however, the correlations were not statistically significant under the belt-stabilization condition. The forces that can be measured with a HHD are higher than those suggested by previous researchers. By rectifying limitations imposed by tester strength, use of a belt allows very high knee extension forces to be measured.
authors.affiliation: Physical Therapy Program, Department of Kinesiology, NEAG School of Education, University of Connecticut, Storrs, CT, USA. richard.bohannon@uconn.edu
authors.forename: Richard W
authors.initials: RW
authors.lastname: Bohannon
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kindig
authors.forename: Gregory
authors.initials: G
authors.lastname: Sabo
authors.forename: Allison E
authors.initials: AE
authors.lastname: Duni
authors.forename: Peter
authors.initials: P
authors.lastname: Cram
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007717:Knee / Q000502:physiology*; D008297:Male; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D015588:Observer Variation; D010808:Physical Examination / Q000295:instrumentation*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult