Mechanisms that contribute to differences in motor performance between young and old adults

Enoka, Roger M.; Christou, Evangelos A.; Hunter, Sandra K.; Kornatz, Kurt W.; Semmler, John G.; Taylor, Anna M.; Tracy, Brian

doi:10.1016/s1050-6411(02)00084-6

Cited by 474 publications

(512 citation statements)

References 84 publications

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“…Latash (2008) argued that constraining the use of motor abundance (leading to lower synergy indexes) may be an adaptive strategy to cope with age-related decline in sensorimotor processing and increasing neuromuscular noise (Enoka et al, 2003). This view is partly compatible with results from simulation studies in a stochastic optimal control framework (Todorov and Jordan, 2002), in which motor behavior is modeled based on the assumption that biological controllers minimize variation in elemental variables mainly along dimensions that affect the task outcome ("minimal intervention principle").…”

Section: Introductionmentioning

confidence: 77%

“…Recently, Latash (2008, section 6.4) proposed that constraining motor abundance may be an adaptive "choice" for a system faced with sensorimotor decline and increased neuromuscular noise (Enoka et al, 2003), a view partly supported by earlier modeling results (Todorov and Jordan, 2002). In the present study, older participants may have perceived the task as more challenging or may have been operating closer to their performance limits than the younger participants, and this may have influenced them to rely on a more conservative control strategy of constraining motor abundance.…”

Section: Discussionmentioning

confidence: 99%

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Normal aging reduces motor synergies in manual pointing

Verrel

Lövdén

Lindenberger

2012

Neurobiology of Aging

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Depending upon its organization, movement variability may reflect poor or flexible control of a motor task. We studied adult age-related differences in the structure of postural variability in manual pointing using the uncontrolled manifold (UCM) method. Participants from 2 age groups (younger: 20 -30 years; older: 70 -80 years; 12 subjects per group) completed a total of 120 pointing trials to 2 different targets presented according to 3 schedules: blocked, alternating, and random. The age groups were similar with respect to basic kinematic variables, end point precision, as well as the accuracy of the biomechanical forward model of the arm. Following the uncontrolled manifold approach, goal-equivalent and nongoal-equivalent components of postural variability (goal-equivalent variability [GEV] and nongoal-equivalent variability [NGEV]) were determined for 5 time points of the movements (start, 10%, 50%, 90%, and end) and used to define a synergy index reflecting the flexibility/stability aspect of motor synergies. Toward the end of the movement, younger adults showed higher synergy indexes than older adults. Effects of target schedule were not reliable. We conclude that normal aging alters the organization of common multidegree-of-freedom movements, with older adults making less flexible use of motor abundance than younger adults.

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Section: Introductionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Normal aging reduces motor synergies in manual pointing

Verrel

Lövdén

Lindenberger

2012

Neurobiology of Aging

View full text Add to dashboard Cite

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“…Position of the index finger was assessed via a potentiometer where the rotational axis was aligned with the MCP joint and securely attached along the length of the index finger. EMG was amplified (300 X) and band-pass filtered (20 Hz high pass, 1 kHz low pass) using a CED1902 (Cambridge Electronic Design, Cambridge, UK). EMG, position and acceleration signals were digitized at 2 kHz using a CED1401 interface (Cambridge Electronic Design), before being recorded and stored offline for analysis.…”

Section: Experimental Arrangementmentioning

confidence: 99%

“…Although age-related differences in neuromuscular function are well established [20] our understanding of the CNS mechanisms contributing to this movement deficit in old adults is limited. One factor that may contribute to this impaired motor performance is changes in inhibitory neurotransmission within primary motor cortex (M1) mediated by the neurotransmitter gamma amino-butyric acid (GABA).…”

Section: Introductionmentioning

confidence: 99%

Intracortical Inhibition Assessed with Paired-Pulse Transcranial Magnetic Stimulation is Modulated during Shortening and Lengthening Contractions in Young and Old Adults

Opie

Semmler

2016

Brain Stimulation

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In all cases accepted manuscripts should: link to the formal publication via its DOI  bear a CC-BY-NC-ND license -this is easy to do, click here to find out how  if aggregated with other manuscripts, for example in a repository or other site, be shared in alignment with our hosting policy  not be added to or enhanced in any way to appear more like, or to substitute for, the published journal article Embargo 1935-861X Brain Stimulation 129 May 2017 Age-and movement-related changes in intracortical inhibitionPage 2 AbstractBackground: The modulation of intracortical inhibition is thought to be impaired in older

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“…The age-related decline in motor function (Enoka et al 2003;McNeil et al 2007;Nardone et al 1995;Stelmach et al 1989;Woollacott 1998, 1999) is not only associated with alterations affecting the muscular (McNeil et al 2007) but also the neural system (Enoka et al 2003). During voluntary contractions and responses to sudden perturbations of a limb or whole body, motor neurone activity is modulated by both the descending input and sensory feedback (Nielsen 2004).…”

Section: Introductionmentioning

confidence: 99%

Modulation of reflex responses in activated ankle dorsiflexors differs in healthy young and elderly subjects

2011

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During voluntary contractions, motor neurone activity is modulated by descending input and sensory feedback. Impaired excitatory afferent feedback with ageing may, therefore, alter motor control. This study investigated the age-related changes in afferent feedback through the recording of reflex responses during voluntary muscle activation. Short-and long-latency components of the stretch reflex and Hoffmann reflex (H-reflex) were recorded during voluntary contractions (10% of maximal voluntary contraction; MVC) of the ankle dorsiflexor muscles of young and elderly adults (C70 years). Furthermore, the modulation of spinal reflex excitability was analyzed at different torque levels (10-50% MVC). The short-latency stretch reflex and the H-reflex areas were similar in the two age groups at 10% MVC whereas the area of the long-latency component of the stretch reflex augmented with ageing (P \ 0.05). However, the area of the H-reflex increased linearly with the level of contraction up to 50% MVC in young adults, whereas it slightly increased to 30% MVC and plateaued thereafter in elderly adults. The absence of age-related changes in the shortlatency stretch reflex and H-reflex areas suggests that the reflex circuitry and the sensitivity of the muscle spindles are not substantially affected by ageing. The modest increase in the H-reflex area with the contraction intensity in elderly adults, however, indicates that the modulation of afferent feedback is reduced with advancing age. This observation, associated with a greater long-latency stretch reflex, suggests that elderly adults rely more on central than peripheral mechanisms to regulate motor output of the dorsiflexor muscles.

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Mechanisms that contribute to differences in motor performance between young and old adults

Cited by 474 publications

References 84 publications

Normal aging reduces motor synergies in manual pointing

Normal aging reduces motor synergies in manual pointing

Intracortical Inhibition Assessed with Paired-Pulse Transcranial Magnetic Stimulation is Modulated during Shortening and Lengthening Contractions in Young and Old Adults

Modulation of reflex responses in activated ankle dorsiflexors differs in healthy young and elderly subjects

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