Older Adults Exhibit a Reduced Ability to Fully Activate Their Biceps Brachii Muscle

Yue, Guang H.; Ranganathan, Vinoth K.; Siemionow, Vlodek; Liu, Jing Z.; Sahgal, Vinod

doi:10.1093/gerona/54.5.m249

Cited by 109 publications

(99 citation statements)

References 21 publications

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“…Lower threshold of corticospinal excitation in stronger aged individuals aligns with evidence that excitability increases with trainingassociated strength gains (Beck et al 2007 eration with age may manifest strongly for hand muscles (Oliviero et al 2006;Peinemann et al 2001;Rossini et al 1992;Sale and Semmler 2005;Talelli et al 2008b). And since our older subjects were not remarkably weaker (differences of ϳ19% vs. Ͼ30% cited previously) (Lindle et al 1997;Yue et al 1999), alterations in corticospinal properties may have not yet been apparent.…”

Section: Discussionsupporting

confidence: 84%

“…Second, we demonstrate an age-based diver- gence in these relationships, as has been recently observed by others as well (Bernard and Seidler 2012). The dichotomy in roles of M1 in young vs. old may be related to the fact that young individuals show near-maximal neural drive (Yue et al 1999), so M1 may not need to adapt, but, in older individuals, where almost 35% of corticomotor neurons are lost by age 50 (Eisen et al 1996), adaptations in M1 may become critical (Doherty 2003;Henderson et al 1980;Kapur et al 2010). …”

Section: Discussionsupporting

confidence: 84%

“…Weakness is due in part to age-related peripheral neuromuscular degeneration (Doherty 2003;Faulkner et al 2007), but recently, changes within the central nervous system have received attention. This is because degenerative changes, such as reduction in gray matter volume (Good et al 2001), number of motor cortical (Henderson et al 1980) and spinal motor neurons (Doherty 2003), synaptic density (Haug and Eggers 1991), white matter integrity (Davis et al 2009), and descending commands for voluntary activation (Yue et al 1999), exaggerate effects of peripheral degeneration to perpetuate weakness.…”

mentioning

confidence: 99%

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Neurophysiological correlates of aging-related muscle weakness

Plow

Cunningham

Bonnett

et al. 2013

Journal of Neurophysiology

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Muscle weakness associated with aging implicates central neural degeneration. However, role of the primary motor cortex (M1) is poorly understood, despite evidence that gains in strength in younger adults are associated with its adaptations. We investigated whether weakness of biceps brachii in aging analogously relates to processes in M1. We enrolled 20 young (22.6 Ϯ 0.87 yr) and 28 old (74.79 Ϯ 1.37 yr) right-handed participants. Using transcranial magnetic stimulation, representation of biceps in M1 was identified. We examined the effect of age and sex on strength of left elbow flexion, voluntary activation of biceps, corticospinal excitability and output, and short-interval intracortical and interhemispheric inhibition. Interhemispheric inhibition was significantly exaggerated in the old (P ϭ 0.047), while strength tended to be lower (P ϭ 0.075). Overall, women were weaker (P Ͻ 0.001). Processes of M1 related to strength or voluntary activation of biceps, but only in older adults. Corticospinal excitability was lower in weaker individuals (r ϭ 0.38), and corticospinal output, intracortical inhibition and interhemispheric inhibition were reduced too in individuals who poorly activated biceps (r ϭ 0.43, 0.54 and 0.38). Lower intracortical inhibition may reflect compensation for reduced corticospinal excitability, allowing weaker older adults to spread activity in M1 to recruit synergists and attempt to sustain motor output. Exaggerated interhemispheric inhibition, however, conflicts with previous evidence, potentially related to greater callosal damage in our older sample, our choice of proximal vs. distal muscle and differing influence of measurement of inhibition in rest vs. active states of muscle. Overall, age-specific relation of M1 to strength and muscle activation emphasizes that its adaptations only emerge when necessitated, as in a weakening neuromuscular system in aging.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 84%

mentioning

confidence: 99%

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Neurophysiological correlates of aging-related muscle weakness

Plow

Cunningham

Bonnett

et al. 2013

Journal of Neurophysiology

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“…19 Voluntary activation deficit can be quantified by superimposing a supramaximal electrical stimulus on a maximally contracting muscle. 10,19,34,36,37,41 Using this technique, voluntary activation deficits have been reported in patients with osteoarthritis or following knee surgery, including TKA. 18,25,27,28,35 Voluntary activation deficits can result from pain, 27 effusion, 12 and joint damage, 16 all of which are potentially present in patients after TKA.…”

mentioning

confidence: 99%

Neuromuscular Electrical Stimulation for Quadriceps Muscle Strengthening After Bilateral Total Knee Arthroplasty: A Case Series

Stevens¹,

Mizner²,

Snyder‐Mackler³

2004

J Orthop Sports Phys Ther

179

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Study Design: A case series. Objectives: The purpose of this case series was to assess the effect of high-intensity neuromuscular electrical stimulation (NMES) on quadriceps strength and voluntary activation following total knee arthroplasty (TKA). Background: Following TKA, patients exhibit long-term weakness of the quadriceps and diminished functional capacity compared to age-matched healthy controls. The pain and swelling that results from surgery may contribute to quadriceps weakness. The use of high-intensity NMES has previously been shown to be effective in quickly restoring quadriceps strength in patients with weakness after surgery. Methods and Measures: All patients were treated for 6 weeks, 2 to 3 visits per week, in outpatient rehabilitation. Five patients (NMES group) participated in a voluntary exercise program for both knees and NMES for the weaker knee. Three patients (exercise group) participated in a voluntary exercise program for both knees without NMES. For each treatment session, 10 isometric electrically elicited muscle contractions were administered at maximally tolerated doses to the initially weaker leg of the NMES group. Quadriceps strength and muscle activation were repeatedly assessed up to 6 months after surgery using burst superimposition techniques. Results: At 6 months, the weak NMES-treated legs of 4 of 5 patients in the NMES group had surpassed the strength of the contralateral leg. In contrast, none of the weak legs in the exercise group were stronger than the contralateral leg at 6 months. Changes in quadriceps muscle activation mirrored the changes exhibited in strength. Conclusion: When NMES was added to a voluntary exercise program, deficits in quadriceps muscle strength and activation resolved quickly after TKA.

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“…For example, there are a nearly equivalent number of studies which report that voluntary activation is either unaffected by age (e.g., Allman and Rice 2001;Dalton et al 2010;Hunter et al 2008;Jakobi and Rice 2002;Klein et al 2001) or reduced in the old compared to young (e.g., Bilodeau et al 2001;De Serres and Enoka 1998;Yoon et al 2008;Yue et al 1999). Further, muscle relaxation of the elbow flexors is unaffected by age when assessed using peripheral nerve stimulation at rest (Allman and Rice 2001;Dalton et al 2010;Doherty et al 1993) but is markedly slower in old than young adults when tested by TMS during an MVC .…”

Section: Introductionmentioning

confidence: 99%

Effects of aging and sex on voluntary activation and peak relaxation rate of human elbow flexors studied with motor cortical stimulation

Molenaar

McNeil

Bredius

et al. 2012

AGE

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Data are equivocal on whether voluntary activation is preserved or decreased in old compared to young adults. Further, data are scant on the effect of age on the rate of muscle relaxation when the muscle is contracting voluntarily. Assessment of both measures with transcranial magnetic stimulation (TMS) yields information which cannot be obtained with traditional peripheral nerve stimulation. Hence, voluntary activation and peak relaxation rate of the elbow flexors were assessed with TMS during repeated maximal efforts in 30 men and 28 women between the ages of 22-84 years. Voluntary activation was similar for the two sexes (P00.154) and was not affected by age in men (96.2±2.7 %; P00.887) or women (95.1±3.0 %; P00.546). Men had a significantly faster peak rate of relaxation than women in absolute units (−880.0±223.2 vs. −360.2±78.5 Nm/s, respectively; P<0.001) and when normalized to subject strength (−12.5 ± 2.1 vs. −8.7±1.0 s −1 , respectively; P<0.001). Absolute and normalized relaxation rates slowed with age in men (P00.002 and P00.006, respectively), but not women (P00.142 and P00.950, respectively). Across the age range studied, all subjects, regardless of age or sex, were able to achieve high voluntary activation scores for the elbow flexors (~95 %). In contrast, peak relaxation rate was markedly faster in men than women and slowed with age in men but not women. Normalization of relaxation rates to strength did not affect the influence of age or sex.

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Older Adults Exhibit a Reduced Ability to Fully Activate Their Biceps Brachii Muscle

Cited by 109 publications

References 21 publications

Neurophysiological correlates of aging-related muscle weakness

Neurophysiological correlates of aging-related muscle weakness

Neuromuscular Electrical Stimulation for Quadriceps Muscle Strengthening After Bilateral Total Knee Arthroplasty: A Case Series

Effects of aging and sex on voluntary activation and peak relaxation rate of human elbow flexors studied with motor cortical stimulation

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