scholarly journals Motor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age-related motor unit remodeling

2016 ◽  
Vol 4 (19) ◽  
pp. e12987 ◽  
Author(s):  
Mathew Piasecki ◽  
Alex Ireland ◽  
Jessica Coulson ◽  
Dan W. Stashuk ◽  
Andrew Hamilton-Wright ◽  
...  
Keyword(s):  
Older People ◽  
Motor Unit ◽  
Tibialis Anterior ◽  
Neuromuscular Transmission ◽  
Master Athletes ◽  
Age Related

scholarly journals INTRINSIC MOTOR NEURONE EXCITABILITY IS REDUCED IN SOLEUS AND TIBIALIS ANTERIOR OF OLDER ADULTS

2021 ◽  
Author(s):  
Lucas B R Orssatto ◽  
David N Borg ◽  
Anthony J Blazevich ◽  
Raphael L Sakugawa ◽  
Anthony J Shield ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Motor Unit ◽  
Tibialis Anterior ◽  
Motor Units ◽  
Motor Neurone ◽  
Age Related ◽  
Inward Currents ◽  
Motor Neurones ◽  
Intrinsic Motor

Age-related deterioration within both motor neurones and monoaminergic systems should theoretically reduce neuromodulation by weakening motor neuronal persistent inward current (PIC) strength. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70±4years) and 17 young adults (29±5 years) to investigate motor unit discharge behaviours. Participants performed triangular-shaped plantar and dorsiflexion contractions to 20% of maximum torque at a rise-decline rate of 2%/s of each participant's maximal torque. Pairwise and composite paired-motor unit analyses were adopted to calculate delta frequency (ΔF) and estimate PIC amplitudes. ΔF has been used to differentiate between the effects of synaptic excitation and intrinsic motor neuronal properties and is assumed to be proportional to PIC amplitude. The results show that soleus and tibialis anterior motor units in older adults had lower ΔFs when calculated with the pairwise (-0.99 and -1.29 pps, respectively) or composite (-1.65 and -2.26 pps, respectively) methods. Older adults' motor units discharged at lower rates (-2.14 and -2.03 pps, respectively) and were recruited at lower torque levels (-1.50 and -2.06% of maximum, respectively) than young adults. These results demonstrate reduced intrinsic motor neurone excitability during low-force contractions in older adults, likely mediated by decreases in the strength of persistent inward currents. Our findings might be explained by deterioration in the motor neurones or monoaminergic systems, and could contribute to the decline in motor function during ageing; these assumptions should be explicitly tested in future investigations.

Motor unit firing rates and contractile properties in tibialis anterior of young and old men

1999 ◽  
Vol 87 (2) ◽  
pp. 843-852 ◽  
Author(s):  
Denise M. Connelly ◽  
Charles L. Rice ◽  
Martin R. Roos ◽  
Anthony A. Vandervoort
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Young Men ◽  
Contractile Properties ◽  
Firing Rates ◽  
Twitch Contraction ◽  
Age Related ◽  
Motor Unit Firing ◽  
Old Men

The effects of aging on motoneuron firing rates and muscle contractile properties were studied in tibialis anterior muscle by comparing results from six young (20.8 ± 0.8 yr) and six old men (82.0 ± 1.7 yr). For each subject, data were collected from repeated tests over a 2-wk period. Contractile tests included maximal voluntary contraction (MVC) with twitch interpolation and stimulated twitch contractions. The old men had 26% lower MVC torque ( P < 0.01) than did the young men, but percent activation was not different (99.1 and 99.3%, respectively). Twitch contraction durations were 23% longer ( P < 0.01) in the old compared with the young men. During a series of repeated brief steady-state contractions at 10, 25, 50, 75, and 100% MVC, motor unit firing rates were recorded. Results from ∼950 motor unit trains in each subject group indicated that at all relative torque levels mean firing rates were 30–35% lower ( P < 0.01) in the old subjects. Comparisons between young and old subjects’ mean firing rates at each of 10%, 50%, and MVC torques and their corresponding mean twitch contraction duration yielded a range of moderate-to-high correlations ( r = −0.67 to −0.84). That lower firing rates were matched to longer twitch contraction durations in the muscle of old men, and relatively higher firing rates were matched with shorter contraction times from the young men, indirectly supports the neuromuscular age-related remodeling principle.

scholarly journals Lifelong exercise is associated with more homogeneous motor unit potential features across deep and superficial areas of vastus lateralis

GeroScience ◽  
2021 ◽  
Author(s):  
Eleanor J. Jones ◽  
Jessica Piasecki ◽  
Alex Ireland ◽  
Daniel W. Stashuk ◽  
Philip J. Atherton ◽  
...  
Keyword(s):  
Motor Unit ◽  
Vastus Lateralis ◽  
Muscle Fibres ◽  
Motor Unit Potential ◽  
Linear Regression Models ◽  
Master Athletes ◽  
Older Athletes ◽  
Age Related ◽  
Intramuscular Electromyography ◽  
Voluntary Contractions

AbstractMotor unit (MU) expansion enables rescue of denervated muscle fibres helping to ameliorate age-related muscle atrophy, with evidence to suggest master athletes are more successful at this remodelling. Electrophysiological data has suggested MUs located superficially are larger than those located deeper within young muscle. However, the effects of ageing and exercise on MU heterogeneity across deep and superficial aspects of vastus lateralis (VL) remain unclear. Intramuscular electromyography was used to record individual MU potentials (MUPs) and near fibre MUPs (NFMs) from deep and superficial regions of the VL during 25% maximum voluntary contractions, in 83 males (15 young (Y), 17 young athletes (YA), 22 old (O) and 29 master athletes (MA)). MUP size and complexity were assessed using area and number of turns, respectively. Multilevel mixed effects linear regression models were performed to investigate the effects of depth in each group. MUP area was greater in deep compared with superficial MUs in Y (p<0.001) and O (p=0.012) but not in YA (p=0.071) or MA (p=0.653). MUP amplitude and NF MUP area were greater, and MUPs were more complex in deep MUPs from Y, YA and O (all p<0.05) but did not differ across depth in MA (all p>0.07). These data suggest MU characteristics differ according to depth within the VL which may be influenced by both ageing and exercise. A more homogenous distribution of MUP size and complexity across muscle depths in older athletes may be a result of a greater degree of age-related MU adaptations.

scholarly journals Developing a recovery-focused therapy for older people with bipolar disorder: a qualitative focus group study

BMJ Open ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. e049829
Author(s):  
Elizabeth Tyler ◽  
Fiona Lobban ◽  
Rita Long ◽  
Steven H Jones
Keyword(s):  
Older Adults ◽  
Bipolar Disorder ◽  
Focus Group ◽  
Older People ◽  
Focus Groups ◽  
Later Life ◽  
Focus Group Study ◽  
Age Related ◽  
Health Related ◽  
Age Related Changes

ObjectivesAs awareness of bipolar disorder (BD) increases and the world experiences a rapid ageing of the population, the number of people living with BD in later life is expected to rise substantially. There is no current evidence base for the effectiveness of psychological interventions for older adults with BD. This focus group study explored a number of topics to inform the development and delivery of a recovery-focused therapy (RfT) for older adults with BD.DesignA qualitative focus group study.SettingThree focus groups were conducted at a university in the North West of England.ParticipantsEight people took part in the focus groups; six older adults with BD, one carer and one friend.ResultsParticipant’s responses clustered into six themes: (1) health-related and age-related changes in later life, (2) the experience of BD in later life, (3) managing and coping with BD in later life, (4) recovery in later life, (5) seeking helping in the future and (6) adapting RfT for older people.ConclusionsParticipants reported a range of health-related and age-related changes and strategies to manage their BD. Participants held mixed views about using the term ‘recovery’ in later life. Participants were in agreement that certain adaptations were needed for delivering RfT for older adults, based on their experience of living with BD in later life. The data collected as part of the focus groups have led to a number of recommendations for delivering RfT for older adults with BD in a randomised controlled trial (Clinical Trial Registration: ISRCTN13875321).

scholarly journals Motor unit number and transmission stability in octogenarian world class athletes: Can age-related deficits be outrun?

2016 ◽  
Vol 121 (4) ◽  
pp. 1013-1020 ◽  
Author(s):  
Geoffrey A. Power ◽  
Matti D. Allen ◽  
Kevin J. Gilmore ◽  
Daniel W. Stashuk ◽  
Timothy J. Doherty ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Neuromuscular Transmission ◽  
Compound Muscle Action Potential ◽  
Motor Units ◽  
Maximum Voluntary Isometric Contraction ◽  
High Performing ◽  
Highly Active ◽  
Age Related ◽  
World Class ◽  
World Champion

Our group has shown a greater number of functioning motor units (MU) in a cohort of highly active older (∼65 yr) masters runners relative to age-matched controls. Because of the precipitous loss in the number of functioning MUs in the eighth and ninth decades of life it is unknown whether older world class octogenarian masters athletes (MA) would also have greater numbers of functioning MUs compared with age-matched controls. We measured MU numbers and neuromuscular transmission stability in the tibialis anterior of world champion MAs (∼80 yr) and compared the values with healthy age-matched controls (∼80 yr). Decomposition-enhanced spike-triggered averaging was used to collect surface and intramuscular electromyography signals during dorsiflexion at ∼25% of maximum voluntary isometric contraction. Near fiber (NF) MU potential analysis was used to assess neuromuscular transmission stability. For the MAs compared with age-matched controls, the amount of excitable muscle mass (compound muscle action potential) was 14% greater ( P < 0.05), there was a trend ( P = 0.07) toward a 27% smaller surface-detected MU potential representative of less collateral reinnervation, and 28% more functioning MUs ( P < 0.05). Additionally, the MAs had greater MU neuromuscular stability than the controls, as indicated by lower NF jitter and jiggle values ( P < 0.05). These results demonstrate that high-performing octogenarians better maintain neuromuscular stability of the MU and mitigate the loss of MUs associated with aging well into the later decades of life during which time the loss of muscle mass and strength becomes functionally relevant. Future studies may identify the concomitant roles genetics and exercise play in neuroprotection.

scholarly journals Losing touch: age-related changes in plantar skin sensitivity, lower limb cutaneous reflex strength, and postural stability in older adults

2016 ◽  
Vol 116 (4) ◽  
pp. 1848-1858 ◽  
Author(s):  
Ryan M. Peters ◽  
Monica D. McKeown ◽  
Mark G. Carpenter ◽  
J. Timothy Inglis
Keyword(s):  
Older Adults ◽  
Lower Limb ◽  
Postural Stability ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Quiet Standing ◽  
Detection Thresholds ◽  
Cutaneous Reflex ◽  
Age Related ◽  
Age Related Changes

Age-related changes in the density, morphology, and physiology of plantar cutaneous receptors negatively impact the quality and quantity of balance-relevant information arising from the foot soles. Plantar perceptual sensitivity declines with age and may predict postural instability; however, alteration in lower limb cutaneous reflex strength may also explain greater instability in older adults and has yet to be investigated. We replicated the age-related decline in sensitivity by assessing monofilament and vibrotactile (30 and 250 Hz) detection thresholds near the first metatarsal head bilaterally in healthy young and older adults. We additionally applied continuous 30- and 250-Hz vibration to drive mechanically evoked reflex responses in the tibialis anterior muscle, measured via surface electromyography. To investigate potential relationships between plantar sensitivity, cutaneous reflex strength, and postural stability, we performed posturography in subjects during quiet standing without vision. Anteroposterior and mediolateral postural stability decreased with age, and increases in postural sway amplitude and frequency were significantly correlated with increases in plantar detection thresholds. With 30-Hz vibration, cutaneous reflexes were observed in 95% of young adults but in only 53% of older adults, and reflex gain, coherence, and cumulant density at 30 Hz were lower in older adults. Reflexes were not observed with 250-Hz vibration, suggesting this high-frequency cutaneous input is filtered out by motoneurons innervating tibialis anterior. Our findings have important implications for assessing the risk of balance impairment in older adults.

scholarly journals Sleep disordered breathing at the extremes of age: the elderly

Breathe ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Alison McMillan ◽  
Mary J. Morrell
Keyword(s):  
Risk Factors ◽  
Older People ◽  
Sleep Disordered Breathing ◽  
Treatment Options ◽  
Current Evidence ◽  
List Type ◽  
Pressure Therapy ◽  
Age Related ◽  
The Impact ◽  
Disordered Breathing

Key pointsSleep disordered breathing (SDB) is common and its prevalence increases with age. Despite this high prevalence, SDB is frequently unrecognised and undiagnosed in older people.There is accumulating evidence that SDB in older people is associated with worsening cardio- cerebrovascular, cognitive and functional outcomes.There is now good evidence to support the use of continuous positive airway pressure therapy in older patients with symptomatic SDB.Educational aimsTo highlight the prevalence and presentation of sleep disordered breathing (SDB) in older people.To inform readers about the risk factors for SDB in older people.To explore the impact of SDB in older people.To introduce current evidence based treatment options for SDB in older people.Sleep disordered breathing (SBD) increases in prevalence as we age, most likely due to physiological and physical changes that occur with ageing. Additionally, SDB is associated with comorbidity and its subsequent polypharmacy, which may increase with increasing age. Finally, the increased prevalence of SDB is intrinsically linked to the obesity epidemic. SDB is associated with serious outcomes in younger people and, likewise, older people. Thus, identification, diagnosis and treatment of SDB is important irrelevant of age. This article reviews the age-related changes contributing to SDB, the epidemiology and the risk factors for SDB in older people, the association of SDB with adverse outcomes, and diagnostic and treatment options for this population.

scholarly journals What influences diet quality in older people? A qualitative study among community-dwelling older adults from the Hertfordshire Cohort Study, UK

2017 ◽  
Vol 20 (15) ◽  
pp. 2685-2693 ◽  
Author(s):  
Ilse Bloom ◽  
Wendy Lawrence ◽  
Mary Barker ◽  
Janis Baird ◽  
Elaine Dennison ◽  
...  
Keyword(s):  
Older Adults ◽  
Cohort Study ◽  
Older People ◽  
Social Engagement ◽  
Community Dwelling ◽  
Related Factors ◽  
Age Related ◽  
Hertfordshire Cohort Study ◽  
The Uk ◽  
Community Dwelling Older Adults

AbstractObjectiveTo explore influences on diet in a group of community-dwelling older adults in the UK.DesignData were collected through focus group discussions with older people; discussions were audio-recorded, transcribed verbatim and transcripts analysed thematically.SettingHertfordshire, UK.SubjectsParticipants were sampled purposively from the Hertfordshire Cohort Study, focusing on those whose diets had been assessed at two time points: 1998–2001 and 2011.ResultsNinety-two adults participated (47 % women; 74–83 years) and eleven focus groups were held. A number of age-related factors were identified that were linked to food choices, including lifelong food experiences, retirement, bereavement and medical conditions, as well as environmental factors (such as transport). There appeared to be variability in how individuals responded to these influences, indicating that other underlying factors may mediate the effects of age-related factors on diet. Discussions about ‘keeping going’, being motivated to ‘not give up’, not wanting to be perceived as ‘old’, as well as examples of resilience and coping strategies, suggest the importance of mediating psychological factors. In addition, discussion about social activities and isolation, community spirit and loneliness, indicated the importance of social engagement as an influence on diet.ConclusionsInterventions to promote healthier diets in older age should take account of underlying psychological and social factors that influence diet, which may mediate the effects of age-related factors.

scholarly journals Poor coherence in older people's speech is explained by impaired semantic and executive processes

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Paul Hoffman ◽  
Ekaterina Loginova ◽  
Asatta Russell
Keyword(s):  
Older Adults ◽  
Older People ◽  
Speech Production ◽  
Semantic Knowledge ◽  
Computational Method ◽  
Cognitive Factors ◽  
Executive Processes ◽  
Age Related ◽  
The World ◽  
Selection Of

The ability to speak coherently is essential for effective communication but declines with age: older people more frequently produce tangential, off-topic speech. The cognitive factors underpinning this decline are poorly understood. We predicted that maintaining coherence relies on effective regulation of activated semantic knowledge about the world, and particularly on the selection of currently relevant semantic representations to drive speech production. To test this, we collected 840 speech samples along with measures of executive and semantic ability from 60 young and older adults, using a novel computational method to quantify coherence. Semantic selection ability predicted coherence, as did level of semantic knowledge and a measure of domain-general executive ability. These factors fully accounted for the age-related coherence deficit. Our results indicate that maintaining coherence in speech becomes more challenging as people age because they accumulate more knowledge but are less able to effectively regulate how it is activated and used.

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