Exercise-linked improvement in age-associated loss of balance is associated with increased vestibular input to motor neurons

[Research advances in the mechanism of vestibular compensation and treatment]

Unlike other sensory systems, since the vestibular system maintains the tension balance of the entire system in a"push-pull" mode, local dysfunction in the system will cause the balance of the entire system to collapse. Unilateral peripheral vestibular dysfunction will cause severe vestibular symptoms, but it can recover spontaneously within a few days to several weeks. This phenomenon is called "vestibular compensation"（VC）. Since the peripheral vestibular impact in most cases is irreversible, it is widely believed that the central mechanism plays a key role in the vestibular compensation process. Static symptom is fully compensated within a few weeks, which is in parallel with the restored balance in the resting discharge of the vestibular nucleus on both sides; the incomplete compensation of dynamic deficits takes longer and is achieved mainly through the mechanism of sensory substitution and behavioral substitution. Here we briefly reviewed the mechanism of vestibular compensation and treatment in order to provide an insight into further study and clinical treatment strategies.

Appropriate Vestibular Stimulation in Children and Adolescents-A Prerequisite for Normal Cognitive, Motor Development and Bodily Homeostasis-A Review

The structural development of the vestibular part of the inner ear is completed by birth but its central connections continue to develop until adolescence. Their development is dependent on vestibular stimulation-vestibular experience. Studies have shown that vestibular function, modulated by experience and epigenetic factors, is not solely an instrument for body position regulation, navigation, and stabilization of the head and images but also influences cognition, emotion, the autonomous nervous system and hormones. To emphasize the importance of appropriate vestibular stimulation, we present a literature review of its effect on bodily homeostasis, cognition and emotion.

Resistance exercise alleviates the prefrontal lobe injury and dysfunction by activating SESN2/AMPK/PGC-1α signaling pathway and inhibiting oxidative stress and inflammation in mice with myocardial infarction

OBJECTIVES

Myocardial infarction (MI) induces inflammatory response and oxidative stress in the brain, which would be one of the causes of cardiac dysfunction. Exercise training is viewed as a feasible strategy to improve cardiac function of the infarcted heart. The aim of this study was to investigate whether exercise training could alleviate MI-induced prefrontal lobe injury via activating Sestrin2 (SESN2) signaling and inhibiting oxidative stress and inflammation.

METHODS

Male C57BL/6 mice were divided into five groups: control group (CON), aerobic exercise group (AE), resistance exercise group (RE), whole-body vibration group (WBV) and electrical stimulation group (ES); and three groups: sham-operated group (S), sedentary MI group (MI) and MI with resistance exercise group (MRE). After four weeks of training, sensorimotor function, spatial learning, long-term and spatial memory, and cardiac function were detected. Then, mice were euthanized, and the prefrontal areas were separated for HE, Nissl, SESN2, microtubule-associated protein 2 (MAP2), neuron-specific nucleoprotein (NeuN), and TUNEL staining. Activation of SESN2/adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α) signaling pathway and expression of proteins related to oxidative stress, inflammation and apoptosis in the prefrontal lobe were detected by western blotting.

RESULTS

Different types of exercise training all activated the SESN2/AMPK/PGC-1α signaling pathway, and the effect of RE is the best. RE improved sensorimotor, learning, and memory impairments, increased the expressions of antioxidant, anti-inflammatory and anti-apoptotic proteins, reduced oxidative stress, inflammation and apoptosis, ultimately alleviated the prefrontal lobe injury and dysfunction in mice with MI.

CONCLUSION

RE alleviates MI-indued prefrontal lobe injury and dysfunction by inhibiting the levels of oxidative stress, inflammation and apoptosis, partially via activating SESN2/AMPK/PGC-1α signaling pathway.

Leisure Sedentary Time is Associated with Self-Reported Falls in Middle-aged and Older Females and Males: an Analysis of the CLSA

Aim

The purpose of this analysis was to report the prevalence of falls and falls-related injuries among those reporting different volumes of weekly sedentary time, and to understand the association of sedentary time and falls, accounting for functional fitness.

Methods

Baseline and first follow-up data from the Canadian Longitudinal Study on Aging (CSLA) were analyzed (n=22,942). Participants self-reported whether they had a fall in the past 12 months (at baseline) and whether they had an injury that was a result of a fall (follow-up). In-home interviews collected self-reported leisure sedentary time using the Physical Activity Scale for Elderly. Functional fitness was assessed using grip strength, timed-up-and-go, and chair rise tests during clinic visits.

Results

The prevalence of falls was higher among those who reported higher sedentary time. For example, among males aged 65 and older who reported lower sedentary time (<1,080 min/week), the prevalence of falls in the past 12 months (at baseline) was 7.8% compared to 9.8% in those reporting higher sedentary time. The odds of reporting a fall (at baseline) was 21% higher in those who reported higher sedentary time (OR: 1.21; 95%CI: 1.11-1.33) in adjusted models. No associations were found between sedentary time and injuries due to a fall.

Conclusions

Reporting high volumes of sedentary time may increase the risk of falls. Future research using device-based estimates of total sedentary time and breaks in sedentary time is needed to further elucidate this association.

Nutrition Strategies Promoting Healthy Aging: From Improvement of Cardiovascular and Brain Health to Prevention of Age-Associated Diseases

BACKGROUND

An increasing number of studies suggest that diet plays an important role in regulating aging processes and modulates the development of the most important age-related diseases.

OBJECTIVE

The aim of this review is to provide an overview of the relationship between nutrition and critical age-associated diseases.

METHODS

A literature review was conducted to survey recent pre-clinical and clinical findings related to the role of nutritional factors in modulation of fundamental cellular and molecular mechanisms of aging and their role in prevention of the genesis of the diseases of aging.

RESULTS

Studies show that the development of cardiovascular and cerebrovascular diseases, neurodegenerative diseases, cognitive impairment and dementia can be slowed down or prevented by certain diets with anti-aging action. The protective effects of diets, at least in part, may be mediated by their beneficial macro- (protein, fat, carbohydrate) and micronutrient (vitamins, minerals) composition.

CONCLUSIONS

Certain diets, such as the Mediterranean diet, may play a significant role in healthy aging by preventing the onset of certain diseases and by improving the aging process itself. This latter can be strengthened by incorporating fasting elements into the diet. As dietary recommendations change with age, this should be taken into consideration as well, when developing a diet tailored to the needs of elderly individuals. Future and ongoing clinical studies on complex anti-aging dietary interventions translating the results of preclinical investigations are expected to lead to novel nutritional guidelines for older adults in the near future.

Effects of Diet and Lifestyle on Audio-Vestibular Dysfunction in the Elderly: A Literature Review

BACKGROUND

The world's age-related health concerns continue to rise. Audio-vestibular disorders, such as hearing loss, tinnitus, and vertigo, are common complaints in the elderly and are associated with social and public health burdens. Various preventative measures can ease their impact, including healthy food consumption, nutritional supplementation, and lifestyle modification. We aim to provide a comprehensive summary of current possible strategies for preventing the age-related audio-vestibular dysfunction.

METHODS

A PubMed, Embase, and Cochrane review databases search was conducted to identify the relationship between diet, lifestyle, and audio-vestibular dysfunction. "Diet", "nutritional supplement", "lifestyle", "exercise", "physical activity", "tinnitus", "vertigo" and "age-related hearing loss" were used as keywords.

RESULTS

Audio-vestibular dysfunction develops and progresses as a result of age-related inflammation and oxidative stress. Diets with anti-inflammatory and antioxidant effects have been proposed to alleviate this illness. A high-fat diet may induce oxidative stress and low protein intake is associated with hearing discomfort in the elderly. Increased carbohydrate and sugar intake positively correlate with the incidence of audio-vestibular dysfunction, whereas a Mediterranean-style diet can protect against the disease. Antioxidants in the form of vitamins A, C, and E; physical activity; good sleep quality; smoking cessation; moderate alcohol consumption; and avoiding noise exposure are also beneficial.

CONCLUSIONS

Adequate diet or nutritional interventions with lifestyle modification may protect against developing audio-vestibular dysfunction in elderly individuals.

Limits of stability and falls during a multicomponent exercise program in faller older adults: A retrospective cohort study

BACKGROUND/OBJETIVES

Multicomponent exercise programs have been demonstrated to prevent falls in older adults. However, the underlying responsible mechanisms are not clear. We aimed to analyze the association between changes in the limits of stability (LOS) as a relevant balance component, and falls occurrence during a multicomponent physical exercise program.

METHODS

Retrospective study, including ninety-one participants who had experienced a fall in the previous year, and were attended in a falls unit. All of them were included in a twice-a-week multicomponent exercise program during 16 weeks. Pre- and post-program measurements were collected for leg press, gait speed, the short physical performance battery (SPPB), and LOS (point of excursion [POE] and maximal excursion [MEX]) with posturography. Falls occurrence was assessed between the beginning and the completion of the exercise program (16 week).

RESULTS

The mean age was 77.2 years, and 72 were female. Thirty-two participants fell at least once during the exercise period. The global baseline POE was 47.6 %, and the MEX was 64.7 %, and there were no differences between fallers and nonfallers. Nonfallers presented greater improvements in POE (6.3 % versus 1.3 %; p < .05) and MEX (9.2 % versus 3.0 %; p < .01) than fallers. The POE and MEX were independently associated with a reduced probability of having had a fall, OR: 0.95 (95 % CI: 0.91 to 0.99) and 0.94 (95 % CI: 0.90 to 0.99), respectively. Changes in SPPB results or leg press strength were not associated with decreased falls. Adjusted probability of fall occurrence decreased by 5 % and 6 % per 1 % improvement in absolute values in POE and MEX, respectively.

CONCLUSIONS

Improvements in LOS after a multicomponent physical exercise program in older adults with previous falls may be associated with a decreased occurrence of falls.

Sensorimotor Rehabilitation Promotes Vestibular Compensation in a Rodent Model of Acute Peripheral Vestibulopathy by Promoting Microgliogenesis in the Deafferented Vestibular Nuclei

Acute peripheral vestibulopathy leads to a cascade of symptoms involving balance and gait disorders that are particularly disabling for vestibular patients. Vestibular rehabilitation protocols have proven to be effective in improving vestibular compensation in clinical practice. Yet, the underlying neurobiological correlates remain unknown. The aim of this study was to highlight the behavioural and cellular consequences of a vestibular rehabilitation protocol adapted to a rat model of unilateral vestibular neurectomy. We developed a progressive sensory-motor rehabilitation task, and the behavioural consequences were quantified using a weight-distribution device. This analysis method provides a precise and ecological analysis of posturolocomotor vestibular deficits. At the cellular level, we focused on the analysis of plasticity mechanisms expressed in the vestibular nuclei. The results obtained show that vestibular rehabilitation induces a faster recovery of posturolocomotor deficits during vestibular compensation associated with a decrease in neurogenesis and an increase in microgliogenesis in the deafferented medial vestibular nucleus. This study reveals for the first time a part of the underlying adaptative neuroplasticity mechanisms of vestibular rehabilitation. These original data incite further investigation of the impact of rehabilitation on animal models of vestibulopathy. This new line of research should improve the management of vestibular patients.

Muscle synergy differences between voluntary and reactive backward stepping

Reactive stepping responses are essential to prevent falls after a loss of balance. It has previously been well described that both voluntary and reactive step training could improve the efficacy of reactive stepping in different populations. However, the effect of aging on neuromuscular control during voluntary and reactive stepping remains unclear. Electromyography (EMG) signals during both backward voluntary stepping in response to an auditory cue and backward reactive stepping elicited by a forward slip-like treadmill perturbation during stance were recorded in ten healthy young adults and ten healthy older adults. Using muscle synergy analysis, we extracted the muscle synergies for both voluntary and reactive stepping. Our results showed that fewer muscle synergies were used during reactive stepping than during voluntary stepping in both young and older adults. Minor differences in the synergy structure were observed for both voluntary and reactive stepping between age groups. Our results indicate that there is a low similarity of muscle synergies between voluntary stepping and reactive stepping and that aging had a limited effect on the structure of muscle synergies. This study enhances our understanding of the neuromuscular basis of both voluntary and reactive stepping as well as the potential effect of aging on neuromuscular control during balance tasks.

Psychometrics of the Balance Beam Functional Test in C57BL/6 Mice

Aging is associated with a progressive decline in physical function characterized by decreased mobility, which is an important risk factor for loss of independence and reduced quality of life. Functional testing conducted in animals has advanced our understanding of age-related changes in physical ability and contributed to the development of physiologic measurements that can be used to assess functional changes during aging. The balance beam test is one assessment tool used to measure age-related changes in balance and coordination. The goal of this study is to provide analytical examples and psychometric support of a protocol that has been analyzed to show how the number of successive test runs, foot slips, pauses, and hesitations affect the reliability of the primary outcome measure, which is the time to cross the beam. Our results suggest that conducting more than 1 training session, consisting of greater than or equal to 3 successful training runs, followed by at least one test session with no less than 2 successful runs (that is, runs without pauses or hesitations) provides a psychometrically sound outcome. The data presented here indicate that a psychometric approach can improve protocol design and reliability of balance beam measures in mice.