Non-invasive bio-markers of motor performance with ageing

Abstract

Objective tests of motor function suitable for older people in epidemiological studies and community settings are lacking. The current study aimed to establish non-invasive biomarkers using conventional and novel tests that do not rely entirely on volition, and identify suitable analysis techniques for complex data. It was hypothesised that novel technologies would improve the discriminant validity of motor function testing.

In 138 self-reported healthy males and females (65 young, mean age±SD = 25.7±4.8 years; 73 older, 74.9±5.9 years), nine tests (25 parameters) included: hand grip and quadriceps strength; respiratory muscle strength (peak flow); thigh composition (ultrasound imaging); muscle mechanical properties (Myoton technology); upper limb kinematics (Motor Task Manager); timed up and go; stair climbing; balance. Three questionnaires and one mobility assessment were administered including the health related quality of life (SF36). Four experiments tested hypotheses regarding the influence of recording conditions on mechanical properties to validate the novel MyotonPRO device.
Reliability of all tests was confirmed and, as expected, data indicated reduced function with ageing (all p<0.05), with the majority showing gender differences. Some mechanical properties were significantly influenced by testing site, muscle length, contractile status and prior activity. Seven of the 25 parameters (5novel) had high discriminant ability for classifying healthy adults into age/gender groups analysed by linear discriminant function using a stepwise approach. Novel technologies, notably mechanical properties of muscle and thigh composition (relative contribution of muscle and subcutaneous fat on ultrasound scans), improved classification accuracy (from 75% to 89%) when combined with conventional tests, supporting the hypothesis and providing potential screening tools independent of participant effort. High discriminant ability (73 to 80%) was also found for classification based on functional measures.

This research has advanced the approach to functional assessment and analysis by producing a comprehensive battery of non-invasive biomarkers with high discriminant ability for indicating musculoskeletal health, providing reference data for comparison with clinical populations. The most sensitive novel biomarkers did not require volition, highlighting potential powerful tests for vulnerable older people with pain or cognitive impairment.

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Identifiers

ORCID for M. Stokes: orcid.org/0000-0002-4204-0890

ORCID for D. Samuel: orcid.org/0000-0003-3610-8032

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