RESUMO
The relationship between the age-associated decline in mitochondrial function and its effect on skeletal muscle physiology and function remain unclear. In the current study, we examined to what extent physical activity contributes to the decline in mitochondrial function and muscle health during aging and compared mitochondrial function in young and older adults, with similar habitual physical activity levels. We also studied exercise-trained older adults and physically impaired older adults. Aging was associated with a decline in mitochondrial capacity, exercise capacity and efficiency, gait stability, muscle function, and insulin sensitivity, even when maintaining an adequate daily physical activity level. Our data also suggest that a further increase in physical activity level, achieved through regular exercise training, can largely negate the effects of aging. Finally, mitochondrial capacity correlated with exercise efficiency and insulin sensitivity. Together, our data support a link between mitochondrial function and age-associated deterioration of skeletal muscle.
Assuntos
Envelhecimento/fisiologia , Metabolismo Energético/fisiologia , Exercício Físico/psicologia , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
INTRODUCTION: Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects. METHODS: Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed. RESULTS: Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036). CONCLUSION: DVA tested while walking on a treadmill, is one of the few "close to reality" functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual "preferred" walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill.
Assuntos
Vestibulopatia Bilateral , Vestíbulo do Labirinto , Idoso , Teste de Esforço , Humanos , Masculino , Pessoa de Meia-Idade , Acuidade Visual , CaminhadaRESUMO
BACKGROUND: Professional organizations recommend against repeat radiographs for routine follow-up of osteoarthrosis. However, clinics frequently obtain radiographs during or before the clinical visit. The purpose of our project was to determine the baseline frequency of unnecessary knee radiographs and whether educational interventions can reduce this frequency. METHODS: This QI project was exempt from IRB review. Radiology reports of knee radiographs were searched in our database filtered by presence of the words "severe", "degenerative", "osteoarthritis", and similar variants. We reviewed 500 consecutive corresponding medical records to confirm the presence of severe osteoarthritis, and presence of a repeat radiograph within 6 months. Indications for repeat radiographs were determined. Repeat radiographs were counted as "non-indicated" when medical records revealed no new symptoms. A focused educational intervention was provided to the orthopedic and family practice departments. An additional 500 radiology reports were evaluated 9 months after intervention in the same manner and the rate of non-indicated radiographs was calculated. Follow-up review of additional 500 radiology reports at 1-year time point was performed. RESULTS: Our initial search returned 1517 reports. Upon evaluation of 500 studies, there were 112/500 repeat radiographs (22%); 77/500 (15%) of knee radiographs were not indicated. Upon initial follow-up evaluation of 500 studies, there were 52/500 repeat radiographs (10%) and 40/500 (8%) radiographs were not indicated. The reduction of unnecessary repeat knee radiographs rate was sustained at 1 year. CONCLUSIONS: Focused educational intervention results in a substantial (50%) reduction of the number of unnecessary repeat knee radiographs in patients with known severe OA.
Assuntos
Osteoartrite do Joelho/diagnóstico por imagem , Melhoria de Qualidade , Procedimentos Desnecessários/estatística & dados numéricos , Centros Médicos Acadêmicos , Feminino , Humanos , Masculino , Auditoria MédicaRESUMO
PURPOSE: The purpose of the study was to determine: (1) the relationship between ankle plantarflexor muscle strength and Achilles tendon (AT) biomechanical properties in older female adults, and (2) whether muscle strength asymmetries between the individually dominant and non-dominant legs in the above subject group were accompanied by inter-limb AT size differences. METHODS: The maximal generated AT force, AT stiffness, AT Young's modulus, and AT cross-sectional area (CSA) along its length were determined for both legs in 30 women (65 ± 7 years) using dynamometry, ultrasonography, and magnetic resonance imaging. RESULTS: No between-leg differences in triceps surae muscle strength were identified between dominant (2798 ± 566 N) and non-dominant limb (2667 ± 512 N). The AT CSA increased gradually in the proximo-distal direction, with no differences between the legs. There was a significant correlation (P < 0.05) of maximal AT force with AT stiffness (r = 0.500) and Young's modulus (r = 0.414), but only a tendency with the mean AT CSA. However, region-specific analysis revealed a significant relationship between maximal AT force and the proximal part of the AT, indicating that this region is more likely to display morphological adaptations following an increase in muscle strength in older adults. CONCLUSIONS: These findings demonstrate that maximal force-generation capabilities play a more important role in the variation of AT stiffness and material properties than in tendon CSA, suggesting that exercise-induced increases in muscle strength in older adults may lead to changes in tendon stiffness foremost due to alterations in material rather than in its size.
Assuntos
Tendão do Calcâneo/fisiologia , Adaptação Fisiológica/fisiologia , Envelhecimento/fisiologia , Força Muscular/fisiologia , Tendão do Calcâneo/diagnóstico por imagem , Idoso , Módulo de Elasticidade/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Dinamômetro de Força Muscular , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologiaRESUMO
The plantarflexors play a crucial role in recovery from sudden disturbances to gait. The objective of this study was to investigate whether medium (months)- or long(years)-term exercise-induced enhancement of triceps surae (TS) neuromuscular capacities affects older adults' ability to retain improvements in reactive gait stability during perturbed walking acquired from perturbation training sessions. Thirty-four adult women (65 ± 7 yr) were recruited to a perturbation training group ( n = 13) or a group that additionally completed 14 wk of TS neuromuscular exercise ( n = 21), 12 of whom continued with the exercise for 1.5 yr. The margin of stability (MoS) was analyzed at touchdown of the perturbed step and the first recovery step following eight separate unexpected trip perturbations during treadmill walking. TS muscle-tendon unit mechanical properties and motor skill performance were assessed with ultrasonography and dynamometry. Two perturbation training sessions (baseline and after 14 wk) caused an improvement in the reactive gait stability to the perturbations (increased MoS) in both groups. The perturbation training group retained the reactive gait stability improvements acquired over 14 wk and over 1.5 yr, with a minor decay over time. Despite the improvements in TS capacities in the additional exercise group, no benefits for the reactive gait stability following perturbations were identified. Therefore, older adults' neuromotor system shows rapid plasticity to repeated unexpected perturbations and an ability to retain these adaptations in reactive gait stability over a long time period, but an additional exercise-related enhancement of TS capacities seems not to further improve these effects. NEW & NOTEWORTHY Older adults' neuromotor system shows rapid plasticity to repeated exposure to unexpected perturbations to gait and an ability to retain the majority of these adaptations in reactive recovery responses over a prolonged time period of 1.5 yr. However, an additional exercise-related enhancement of TS neuromuscular capacities is not necessarily transferred to the recovery behavior during unexpected perturbations to gait in older adults.