Avaliação da regulação exteroceptiva e interoceptiva do equilíbrio corporal de idosas ativas / Evaluation of exteroceptive and interoceptive regulation of body balance of active seniors

O processo do envelhecimento humano traz consigo um conjunto de alterações para o organismo, dentre elas há a diminuição da eficácia das estratégias motoras do equilíbrio corporal e o aumento do tempo de reação muscular, o que torna o indivíduo mais suscetível à queda. O objetivo deste estudo foi avaliar o desempenho do equilíbrio de um grupo de idosas fisicamente ativas, com ênfase na regulação do sistema visual, vestibular e somatossensorial do equilíbrio estático e dinâmico, bem como sua performance em testes de marcha e flexibilidade. Trata-se de um estudo transversal analítico, realizado com 32 mulheres (67,48±4,88 anos), praticantes regulares de Pilates e hidroginástica. Os instrumentos utilizados foram: Escala do Equilíbrio de Berg (EEB), Timed Up and Go Test (TUG), Teste de Alcance Funcional (TAF) e o Teste de Equilíbrio Corporal (TEC). As idosas foram estratificadas em grupos: G1 (60-64 anos), G2 (65-69 anos), G3 (70-74 anos) e G4 (75-79 anos). A EEB atestou para um equilíbrio conservado [F(3,29)=1,766, p≥0,50], o TUG para independência funcional preservada [F(3,29)=0,418; p≥0,50] e o TAF sem risco para quedas [F(3,20)=2,228; p≥0,50]. O TEC identificou déficit da regulação interoceptiva do equilíbrio para todas as idades e comprometimento regulação interoceptiva do equilíbrio dinâmico para septuagenárias [F(3,29)= 0,301; p≥0,50]. Observou-se correlação moderada entre EEB-TEC (r=0,416; p=0,018), TEC-TUG (r=-345; p=0,013) e negativa entre EEB-TUG (r=-0,427; p=0,013). Sendo que, o TAF não se mostrou equivalente aos demais instrumentos. Conclui-se que mulheres sexagenárias e septuagenárias, praticantes regulares de exercícios físicos, apesar de indicarem bom desempenho nos testes de equilíbrio, marcha e flexibilidade, apresentaram comprometimento dos sistemas de regulação sensorial do equilíbrio estático e dinâmico...(AU)

The process of human aging brings with it a number of alterations to the organism, among them there is a decrease in the effectiveness of the motor strategies of the body balance and the increase of the time of muscular reaction, which makes the individual more susceptible to fall. The aim of this study was to evaluate the balance performance of a group of physically active elderly women, with emphasis on the regulation of the visual, vestibular and somatosensory systems of the static and dynamic balance, as well as their performance in gait tests and flexibility. This is a cross-sectional, analytical study of 32 women (67.48 ± 4.88 years), regular Pilates practitioners, and water aerobics. The instruments used were: Berg Balance Scale (BBS), Timed Up and Go Test (TUG), Functional Reach Test (TAF) and Body Balance Test (TEC). The elderly were stratified into groups: G1 (60-64 years), G2 (65-69 years), G3 (70- 74 years) and G4 (75-79 years). BBS attained a conserved equilibrium [F(3.29)=1.766, p≥0.50], the TUG for preserved functional independence [F(3.29)=0.418; p≥0.50] and TAF without risk of falls [F(3,20)=2,228; p≥0.50]. The TEC identified deficit of interoceptive regulation of balance for all ages and compromise interoceptive regulation of dynamic balance for septuagenarians [F(3,29)=0.301; p≥0.50]. It was observed a moderate correlation between BBS-TEC (r=0.416, p=0.018), TEC-TUG (r=-345, p=0.013) and negative between BBS-TUG (r=-0.427, p=0.013). The TAF did not prove to be equivalent to the other instruments. It was concluded that sexagenarian and septuagenarian women, regular physical exercise practitioners, despite indicating good performance in tests of balance, gait and flexibility, presented impairment of the systems of sensorial regulation of the static and dynamic balance...(AU)

Influência das Funções Executivas Sobre a Marcha e o Equilíbrio de Idosas Praticantes Regulares de Exercícios Físicos / The Influence of Executive Functions on Gaitand Balance among Elderly People Regularly Practicing Physical Exercise

Objetivos: examinar as funções executiva (FE) de idosas fisicamente ativas, determinando sua influência sobre o desempenho em testes de marcha e equilíbrio corporal. Material e Métodos: Trata-se de um estudo observacional exploratório com delineamento transversal. Participaram 74 indivíduos do sexo feminino (66,80±6,73 anos), praticantes regulares de exercícios físicos. Os instrumentos utilizados foram um questionário para incidência de comorbidades, o Miniexame do Estado Mental de Saúde (MEEM), Teste de Fluência Verbal (FV), teste Time Up and Go, versão simples (TUGs), versão motora (TUGm) e versão cognitiva (TUGc), Dynamic Gait Index (DGI) e o Teste de Equilíbrio Corporal (TEC). Resultados: A análise dos dados demonstrou influência das FE sobre o processamento neural, necessário aos ajustes do controle da marcha e do equilíbrio corporal. Da mesma forma, que o déficit nas FE aumenta a probabilidade de queda de mulheres idosas praticantes regulares de exercícios físicos, especialmente, aquelas com baixa escolaridade e em idade superior a 75 anos. A análise de regressão linear múltipla explicou a probabilidade de queda causada pela interferência do déficit cognitivo sobre os testes TUGs (R2=0,497, p<0,001), TUGm (R2=0,479, p<0,001), TUGc (R2=0,405, p<0,001), DGI (R2=0,445, p<0,001) e TEC (R2=0,444, p<0,001). Conclusão: Concluiuse que o déficit cognitivo se apresenta como fator de risco de queda para mulheres praticantes regulares de exercícios físicos. (AU)

Objective: To examine the influence of executive functions (EF) on the performance of gait and body balance tests among elderly people regularly practicing physical exercise. Material and Methods: This was an exploratory observational study with a cross-sectional design. The sample was composed of 74 female subjects (66.80 ± 6.73 years), who were regular physical exercise practitioners. The instruments used for data collection were, as follows: a questionnaire for the incidence of comorbidities, Mental Health Status Mini-test (MMSE), Verbal Fluency Test (VF), Time Up and Go test, simple version (TUGs), motor version (TUGm) and cognitive version (TUGc), Dynamic Gait Index (DGI) and Body Balance Test (TEC). Results: Data analysis revealed the influence of EF on neural processing, necessary for gait control and body balance adjustments. Likewise, the deficit in the EF increases the probability of falling among elderly women practicing regular physical exercises, especially those with low schooling and over 75 years old. Multiple linear regression analysis explained the probability of falling due to cognitive deficit interference on TUGs (R2 = 0.467, p <0.001), TUGm (R2 = 0.479, p <0.001), TUGc (R2 = 0.405, p < 0.001), DGI (R2 = 0.445, p <0.001) and TEC (R2 = 0.444, p <0.001). Conclusion: Cognitive deficit presents as a risk factor for falls among women regularly practicing physical exercises. (AU)

Subsarcolemmal and intermyofibrillar mitochondria proteome differences disclose functional specializations in skeletal muscle.

Skeletal muscle is a highly specialized tissue that contains two distinct mitochondria subpopulations, the subsarcolemmal (SS) and the intermyofibrillar (IMF) mitochondria. Although it is established that these mitochondrial subpopulations differ functionally in several ways, limited information exists about the proteomic differences underlying these functional differences. Therefore, the objective of this study was to biochemically characterize the SS and IMF mitochondria isolated from rat red gastrocnemius skeletal muscle. We separated the two mitochondrial subpopulations from skeletal muscle using a refined method that provides an excellent division of these unique mitochondrial subpopulations. Using proteomics of mitochondria and its subfractions (intermembrane space, matrix and inner membrane), a total of 325 distinct proteins were identified, most of which belong to the functional clusters of oxidative phosphorylation, metabolism and signal transduction. Although more gel spots were observed in SS mitochondria, 38 of the identified proteins were differentially expressed between the SS and IMF subpopulations. Compared to the SS mitochondrial, IMF mitochondria expressed a higher level of proteins associated with oxidative phosphorylation. This observation, coupled with the finding of a higher respiratory chain complex activity in IMF mitochondria, suggests a specialization of IMF mitochondria toward energy production for contractile activity.

Proteolysis activation and proteome alterations in murine skeletal muscle submitted to 1 week of hindlimb suspension.

The aim of this study was to investigate the temporal involvement of different proteolytic systems and muscle proteome changes during experimental disuse atrophy (up to 1 week hindlimb suspension, HS) in murine gastrocnemius muscle. The results showed that proteolysis, cytoprotection mechanisms and signs of cellular infiltration occurred very early. After 1 day of HS, signals of lysosomal activation, rather than programmed cell death (apoptosis), seem to trigger protein breakdown in the whole skeletal muscle. Moreover, the ubiquitin-proteasome pathway remained elevated later whereas all other proteolytic parameters returned to control values when atrophy was fully established. Using proteomics, evidence is provided for metabolic alterations toward glycolysis and for cytoskeleton remodelling suggestive of reduced capacity for force generation. Overall, our data highlight an early and coordinated time-dependent activation of proteolysis, which explains the global proteome alterations observed in gastrocnemius under atrophic conditions.

Influence of knee flexion on plantarflexion moments after open or percutaneous Achilles tendon repair.

BACKGROUND: The influence of the knee angle on plantarflexion moments after Achilles tendon repair has yet to be analyzed. It was hypothesized that flexion of the knee joint will disproportionately influence isometric plantarflexion moments after Achilles tendon repair. MATERIALS AND METHODS: Isometric plantarflexion moments and functional heel rise performance were retrospectively assessed in 32 patients at a mean follow-up of 36.9 (+/- 17.83) months after open or percutaneous repair of acute Achilles tendon rupture. Plantarflexion moments were measured with the knee joint in 0, 30, and 60 degrees of flexion and the ankle joint positioned in neutral, 15 degrees plantar flexion and 15 degrees dorsiflexion. Data were compared between the involved and the noninvolved leg as well as between open and percutaneous repair. RESULTS: Flexion of the knee had no significant effect on isometric plantarflexion moments in either the involved or the noninvolved leg, while at any knee angle, plantarflexion moments decreased from dorsiflexion to plantar flexion. In accordance, dynamic heel rise performance revealed no significant strength deficits between the involved and the noninvolved limb. No overall differences in plantarflexion strength were observed between open and percutaneous Achilles tendon repair. CONCLUSION: The flexion angle of the knee had no influence on plantarflexion moments when comparing the involved with the noninvolved leg after open or percutaneous Achilles tendon repair. Weakness of plantarflexion after open or percutaneous Achilles tendon repair is determined by the position of the ankle joint rather than by the flexion angle of the knee.

Aging impairs skeletal muscle mitochondrial bioenergetic function.

This study investigated the influence of age on the functional status of mitochondria isolated from skeletal muscle of C57BL/6 mice aged 3 and 18 months. We hypothesized that skeletal muscle mitochondria isolated from aged animals will exhibit a decreased respiratory function. Mitochondrial respiratory functional measures (ie, State 3 and 4 respiration, respiratory control ratio and number of nanomoles of ADP phosphorylated by nanomoles of O(2) consumed per mitochondrion) and biochemical markers of oxidative damage (aconitase activity, protein carbonyl derivatives, sulfhydryl groups, and malondialdehyde) were measured in isolated mitochondrial suspensions. Along with traditional tests of mitochondrial function, an in vitro repetitive ADP-stimulation test was used to evaluate the mitochondrial capacity to reestablish the homeostatic balance between successive ADP stimulations. The number of mitochondria per mitochondrial suspension, calculated by transmission electron microscopy, was used to normalize functional and biochemical data. Our results confirm the existence of an age-associated decline in mitochondrial function of mixed skeletal muscle, which is significantly correlated with higher levels of mitochondrial oxidative damage.

Age-induced morphological, biochemical, and functional alterations in isolated mitochondria from murine skeletal muscle.

Several in vitro studies about age-associated skeletal muscle mitochondrial dysfunction are somewhat conflicting, and this might be related to different normalization procedures. The objective of this study was to normalize the functional and biochemical data per number of mitochondria present in a mitochondrial suspension. Functional and biochemical parameters were obtained in mitochondrial suspensions from murine skeletal muscle of different ages. Mitochondrial respiratory function was polarographically measured using a Clark-type oxygen electrode. Biochemical analyses included determination of citrate synthase (CS) activity and total protein content in the mitochondrial suspension. Electron microscopy analysis of the suspensions allowed calculation of the number of mitochondria per milligram of protein. Our results conclude that advanced age is associated with mitochondrial dysfunction; moreover, from the correlation between morphological and biochemical data, it is evident that CS activity in the mitochondrial suspensions is a more accurate marker of mitochondrial mass than is total protein content.

The role of mitochondria in aging of skeletal muscle.

Aging can be characterized as a time dependent decline of maximal functionality that affects tissues and organs of the whole body. Such is induced by the progressive loss of redundant components and leads to an increased susceptibility to disease and risk of death. Regarding the aging of skeletal muscle, it has been pointed out that mitochondria is a key factor behind the loss of redundancy and functionality, since this organelle has a major role in cellular homeostasis particularly at the level of the bioenergetic status. Decreased activities of the mitochondrial electron transport chain complexes and an increased release of reactive oxygen species from mitochondria are well documented with age; it is suggested that the mitochondrial loss of function results from the increased oxidative damage to proteins, lipids, and DNA of this organelle. However, it is important to be aware that the mitochondrial loss of function could also be a consequence, rather than a cause, of the cellular deterioration with age, which compromises mitochondrial biogenesis, mitochondrial protein turnover and autophagocytosis of damaged mitochondria. In this review several topics will be addressed regarding the age-related loss of skeletal muscle redundancy associated with mitochondrial dysfunction, emphasizing hypotheses for underlying mechanisms. In addition, we discuss some of the cellular mechanisms that can be pointed out as being responsible for the age-related mitochondrial dysfunction.

Cellular patterns of the atrophic response in murine soleus and gastrocnemius muscles submitted to simulated weightlessness.

The purpose of the present study was to investigate the mechanisms of cell death (apoptosis vs. necrosis) during muscle atrophy induced by 1 week of hindlimb suspension. Biochemical and morphological parameters were examined in murine soleus and gastrocnemius muscles. A total of 70 male Charles River CD1 mice were randomly assigned to seven groups (n = 10/group): Cont (loading control conditions) and 6HS, 12HS, 24HS, 48HS, 72HS and 1wkHS with respect to the period of hindlimb suspension (HS). Compared to the Cont, skeletal muscle atrophy was confirmed by a significant decrease of 44 and of 17% in fiber cross-sectional areas in the gastrocnemius and soleus, respectively. A significant increase in caspase-3 activity was noticed in 6HS (196%, P < 0.05) and in 12HS (201%, P < 0.05), as well as the amount of cytosolic mono- and oligonucleosomes at 12HS (142%, P < 0.05) and 24HS (203%, P < 0.05) in the gastrocnemius and soleus, respectively. The profile of necrotic markers showed a peak of myeloperoxidase activity at 24HS (170%, P < 0.05) and at 72HS (114%, P < 0.05) in the gastrocnemius and soleus, respectively. The analysis of N-acetylglucosaminidase activity evidenced more increment in the soleus at 72HS (60%, P < 0.05). The analysis of the basal values of these parameters suggested that apoptosis prevailed in the slow-twitch muscle analyzed, whereas lysosomic activity seemed to be more pronounced in the gastrocnemius. The morphological data supported the biochemical results pointing towards a shift from apoptosis to necrosis, which seems to corroborate the aponecrosis theory.