Muscle cross sectional area and grip torque contraction types are similarly related to pQCT derived bone strength indices in the radii of older healthy adults.
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OBJECTIVES: We sought to identify the variance in radius bone strength indices explained by forearm muscle cross sectional area (MCSA) and isometric (ISO), concentric (CON), or eccentric (ECC) grip torque in healthy men and postmenopausal women when gender and body size were controlled for. Additionally we assessed variance in various grip contractions explained by MCSA. METHODS: pQCT estimated bone strength of the radius and forearm MCSA were measured from 45 healthy adults (59.4-/+7.2 yrs). Isokinetic dynamometry was used to assess peak grip torque. Regressions were adjusted for gender and radius length. RESULTS: Peak grip torques were not independent predictors (p>0.05) of distal radius bone strength in compression (bone strength index; BSI(c)) when gender was included in the prediction model. Gender was not a contributor to any model that included MCSA (p>0.05). At the diaphysis all torque measures, MCSA, gender, and length, significantly contributed to predict similar portions (79-80%) of the stress strain index (SSI(p); strength in torsion). MCSA accounted for 68-76% of variance in grip torque (p<0.05). CONCLUSIONS: When estimating radius bone strength, forearm MCSA is a comparable predictor to CON, ISO, and ECC grip torques and is also a good surrogate of these contraction types. (+info)
The reliability of portable fixed dynamometry during hip and knee strength assessments.
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Age and sex differences of controlled force exertion measured by a computer-generated quasi-random target-pursuit system.
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OBJECTIVES: This study examined age and sex differences of controlled force exertion measured by a computer-generated quasi-random target-pursuit system in 207 males and 249 females aged 15 to 86 years. METHODS: The participants matched submaximal grip exertion of their dominant hand to changing demand values, appearing as a moving quasi-random waveform on the display of a personal computer. They performed the test three times with 1-min intervals (one trial was 40 sec). The total sum of the percent of differences between the demand value and the grip exertion value for 25 sec was used as an evaluation parameter. RESULTS: The errors in controlled force exertion tended to increase constantly with age in both sexes. Significant linear regressions were identified, but there was no significant difference in the rate of increase in both sexes. Analysis of variance showed nonsignificant sex differences among means, except for those in individuals older than 60 years; significant differences between means in the groups older than the 40 yr.-old age group and the 20-24 yr.-old group were found in both sexes. CONCLUSIONS: Controlled force exertion did not show a significant sex difference and decreased gradually with age in both sexes, but decreased remarkably after 40 years of age. (+info)