Evidence for a Non-linear Relationship between Leg Strength and Gait Speed

1. DAVID M. BUCHNER,
2. ERIC B. LARSON,
3. EDWARD H. WAGNER,
4. THOMAS D. KOEPSELL and
5. BARBARA J. DE LATEUR

Abstract

Although the relationship between strength and physical performance in older adults is probably non-linear, few empirical studies have demonstrated that this is so. 

In a population-based sample of adults aged 60–96 years (n = 409), leg strength was measured in four muscle groups (knee extensor, knee flexor, ankle plantar flexor, ankle dorsiflexor) of both legs using an isokinetic dynamometer. A leg strength score was calculated as the sum of the four strength measurements in the right leg. Usual gait speed was measured over a 15.2 metre course. 

With a linear model, leg strength explained 17% of the variance in gait speed. Non–linear models (quadratic and inverse) explained significantly more variance (22%). 

The nature of the non-linear relationship was that, in stronger subjects, there was no association between strength and gait speed, while in weaker subjects, there was an association. Body weight and age also explained significant amounts of variance in gait speed, while sex and height did not.

The results supported the hypothesis of a non-linear relationship between leg strength and gait speed that is similar for older men and women. 

This finding represents a mechanism for how small changes in physiological capacity may have substantial effects on performance in frail adults, while large changes in capacity have little or no effect in healthy adults.

• © Oxford University Press

Quelle:  http://ageing.oxfordjournals.org/content/25/5/386.short



Full Text / pdf von:  Evidence for a Non-linear Relationship between Leg Strength and Gait Speed - online im internet - Zugriff vom 02.10.2012:

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Identification of elderly fallers by muscle strength measures

Abstract The original publication is available at http://link.springer.de/link/service/journals/00421/index.htm. For efficient prevention of falls among older adults, individuals at a high risk of falling need to be identified. In this study, we searched for muscle strength measures that best identified those individuals who would fall after a gait perturbation and those who recovered their balance. Seventeen healthy older adults performed a range of muscle strength tests. We measured maximum and rate of development of ankle plantar flexion moment, knee extension moment and whole leg push-off force, as well as maximum jump height and hand grip strength. Subsequently, their capacity to regain balance after tripping over an obstacle was determined experimentally. Seven of the participants were classified as fallers based on the tripping outcome. Maximum isometric push-off force in a leg press apparatus was the best measure to identify the fallers, as cross-validation of a discriminant model with this variable resulted in the best classification (86% sensitivity and 90% specificity). Jump height and hand grip strength were strongly correlated to leg press force (r = 0.82 and 0.59, respectively) and can also be used to identify fallers, although with slightly lower specificity. These results indicate that whole leg extension strength is associated with the ability to prevent a fall after a gait perturbation and might be used to identify the elderly at risk of falling.
Quelle:  http://en.scientificcommons.org/34613507

Full Text / pdf von:  Identification of elderly fallers by muscle strength measures - online im internet - Zugriff vom 02.102012: 

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Mail: info@aktiv-training.de

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