Postural sway parameters using a triaxial accelerometer: comparing elderly and young healthy adults

The purpose of this study was to evaluate the sensitivity of 16 parameters derived from acceleration to detect changes caused by age and visual conditions during quiet standing and detect and minimise possible sources of unwanted variability that could affect accelerometer measures on the trunk. Twenty-seven healthy subjects, including 16 elderly (age, 69.3 ± 3.6 years) and 11 young (age, 23.6 ± 2.2 years) subjects, were evaluated. The parameters evaluated include root-mean-square values, fractal dimensions, path length, range, frequency dispersion and power spectrum among others derived from these values. These 16 parameters evaluated for each axis of movement and/or derivations resulted in 59 sub-parameters. These 59 sub-parameters were analysed in the elderly and young groups and under the open-eye and closed-eye conditions. The results showed that 30 sub-parameters detected differences for an age effect with open eyes, 18 detected differences with closed eyes, 25 detected differences for the young group standing with closed–open eyes and 37 detected differences for the elderly with closed and open eyes (p < 0.01). We used simple signal processing for the accelerometry signals to minimise the effects of unwanted variability that could affect the results. The results showed better performance compared with those results published previously using force platforms to evaluate postural sway. The results presented here should be useful for researchers who want to use accelerometry to evaluate steady postural balance.     

The effect of various degrees of foot posture on standing balance in a healthy adult population

Abstract

Purpose: Foot biomechanics plays a significant role in the quality of standing and walking. It has been believed that even minor biomechanical alterations in the foot support surface may influence strategies to maintain body standing balance. Hence, the aim of this study was to investigate the role of various degrees of foot posture on static and dynamic standing balance components in a healthy adult population.

Subjects and methods: A convenience sample of 41 healthy adult subjects with a mean age of 24.3?±?6.4 years and a body mass index (BMI) of 29?kg/m² participated in this study. On the basis of foot posture index (FPI), the participants were allocated into either group A or B. Group A included 16 subjects with an FPI range of 6–11 whereas group B included 25 subjects with an FPI range of 0–5. Standing balance components were analyzed using computerized dynamic posturography (CDP) by the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB) and the limit of stability (LOS).

Results: Spearman’s correlation coefficient showed a significant correlation between the standing dynamic balance and FPI in group B but not in group A. Moreover, it also showed no significant correlation between the standing static balance component and FPI in either group A or B.

Conclusion: This study concluded that higher degrees of FPI might have an effect on standing dynamic balance in healthy subjects. These components may require extra attention during the preventive aspects of rehabilitation.     

Combined effects of aging and obesity on postural control,muscle activity and maximal voluntary force of muscles mobilizing ankle joint

ObjectiveThe aim of the study was to investigate the influence of age and/or obesity on postural control, ankle muscle activities during balance testing and force production capacities.Materials and methods4 groups; control group (CG; n = 25; age = 31.8 ± 7.5 years; BMI = 21.4 ± 2.5 kg/m²), obese group (OG; n = 25; age = 34.4 ± 9.5 years; BMI = 39.6 ± 5.4 kg/m²), elderly group (EG; n = 15; age = 77.1 ± 8.4 years; BMI = 24.4 ± 1.3 kg/m²) and obese elderly group (ObEG; n = 12; age = 78.6 ± 6.6 years; BMI = 34.5 ± 3.1 kg/m²) performed maximal voluntary contraction (MVC) before testing to calculate the maximal relative force of ankle plantar flexor (PF) and dorsal flexor (DF) muscles. Center of pressure (CoP) parameters and the electromyography (EMG) activity of PF and DF muscles were collected during MVC, quiet standing and limit of stability (LoS) testing along antero-posterior and medio-lateral axes.ResultsMaximal relative force was higher in EG and ObEG than CG and OG, respectively (p < 0.001). CoP parameters, distance traveled along the antero-posterior axis and EMG activity of PF were higher in OG, EG and ObEG compared to CG (p < 0.001) and in EG compared to ObEG (p < 0.05).The EMG activity of PF was positively correlated with CoP parameters in OG and ObEG (r > 0.6; p < 0.05). Maximal relative force of PF (r > −0.6; p < 0.05) was negatively correlated with CoP parameters in ObEG and EG.ConclusionObesity-related postural control alteration is associated with increased activity of PF. This neuromuscular adaptation may reflect deteriorations of the proprioceptive system and is likely additional to age-related muscular impairments. This may be a mechanism by which obesity increases postural control alterations in elderly.     

Postural sway parameters using a triaxial accelerometer: comparing elderly and young healthy adults

The purpose of this study was to evaluate the sensitivity of 16 parameters derived from acceleration to detect changes caused by age and visual conditions during quiet standing and detect and minimise possible sources of unwanted variability that could affect accelerometer measures on the trunk. Twenty-seven healthy subjects, including 16 elderly (age, 69.3 ± 3.6 years) and 11 young (age, 23.6 ± 2.2 years) subjects, were evaluated. The parameters evaluated include root-mean-square values, fractal dimensions, path length, range, frequency dispersion and power spectrum among others derived from these values. These 16 parameters evaluated for each axis of movement and/or derivations resulted in 59 sub-parameters. These 59 sub-parameters were analysed in the elderly and young groups and under the open-eye and closed-eye conditions. The results showed that 30 sub-parameters detected differences for an age effect with open eyes, 18 detected differences with closed eyes, 25 detected differences for the young group standing with closed-open eyes and 37 detected differences for the elderly with closed and open eyes (p < 0.01). We used simple signal processing for the accelerometry signals to minimise the effects of unwanted variability that could affect the results. The results showed better performance compared with those results published previously using force platforms to evaluate postural sway. The results presented here should be useful for researchers who want to use accelerometry to evaluate steady postural balance.     

Effect of tongue position on postural stability during quiet standing in healthy young males

Abstract

Background and aims: Role of the neck and jaw sensory motor system in control of body balance has been established. Tongue is an integral part of jaw sensory motor system and helps in execution of purposeful and precise motor tasks like eating, drinking and speaking. The purpose of this study was to evaluate the possible effects of tongue position on the postural control system.

Materials and method: We compared the mean center of gravity (COG) velocity during quiet standing on an unstable surface with eyes closed during two test conditions: (i) with habitual jaw resting position and (ii) with instructed tongue positioned against the upper incisors. One hundred and sixteen normal healthy male subjects (average age 31.56?±?8.51 years and height 170.86?±?7.26?cm) participated in the study. Their COG velocity (deg/s) was measured using the NeuroCom® Balance Master version 8.5.0 (Clackamas, OR, USA).

Results and conclusions: The results show that COG velocity decreased significantly while tongue was positioned against upper incisors in comparison to the habitual jaw resting position. Our findings suggest that the tongue positioning can modulate postural control mechanisms. Tongue positioning against the upper incisors can enhance the postural stability during upright standing on an unstable surface and in the absence of vision in healthy young adults. Our findings can be of value for evaluation and rehabilitation protocols for postural control dysfunction.     

Frecuencia de envejecimiento exitoso y fragilidad. Factores de riesgo asociados

Objective

To determine the frequency of successful aging (SA) and its relationship with frailty in an elderly population.

Functional capacity of the cardiovascular system of elderly people as estimated by heart rate variability

With the aid of mathematical and spectral analysis of the heart rate (HR) wave structure in a dynamic interval tachogram (TG) in elderly subjects, it has been shown that a stable sinus rhythm is typical of the majority of the indigenous population of the rural areas of the North aged 78–97 years and migrants living in the city of Vorkuta aged 60–88 years. The total RR-interval spectrum power (800 ± 98 ms²) in the TGs of the native population is shifted to the very low frequency band (VLF, 52%), which indicates predomination of the humoral-metabolic HR regulation level. The reaction to orthostatic load in elderly subjects is characterized by a significant increase in the total spectrum power, which indicates changes in the autonomic balance of regulation of the wave structure of the HR variability. A low total spectrum power (609 ± 104 ms²) with a predominance of low frequency (LF) waves in the TGs of the migrants at rest reflects the activity of the sympathetic component of HR regulation. The reduction of the parasympathetic regulation and the growth of the sympathetic activity during an active orthostatic test in the migrants is a predictor of cardiovascular diseases. In individual TGs of recipients with HR disorders, the orthostatic test (the redistribution of blood flow in the main vessels) results in a decrease in the number of extrasystoles due to the specific features of the baroreflex regulation mechanisms of the cardiovascular system. The HR variability has been shown to be an indicator of the functional capacity of the cardiovascular system in elderly subjects.     

Effect of a change in step direction from a forward to a lateral target in response to a sensory perturbation

The aim of the current study was to investigate the response of healthy older and young adults to a change in step direction from a forward to a lateral target in response to a sensory perturbation. Nine healthy older (75.1 ± 6.7 years; age range, 65–81 years) and nine young adults (27 ± 3.6 years; age range, 23–31 years) participated in the study. The sensory perturbation was a visual cue presented at random times while subjects stepped over an obstacle from quiet stance. For both young and elderly subjects there was an abrupt change in the slope of both shear ground reaction forces (GRFs) of the stance limb following the perturbation. The slope and peak of the change in GRFs was greater for the young subjects and the onset significantly earlier (205 ms compared to 271 ms). Changes in the GRFs were accompanied by an increase in bilateral gluteus medius and stance limb soleus activity. A late visual cue resulted in a delayed response for elderly subjects. These data show that a stepping response to a sensory perturbation was both delayed and of less magnitude for older adults which has implications for fall risk.     

Ageing Effect Evaluation on HD-sEMG Signals Using CCA Approach

ObjectivesThe objective of the proposed study is to exploit the technology of high-density surface electromyography (HD-sEMG), in order to evaluate the muscle activation in young and elderly subjects during a daily life gesture, namely, Sit To Stand (STS), using wireless connected ambulatory equipment (TMSi©) and Blind Source Separation (BSS) approach with Canonical Correlation Analysis (CCA).Materials and methodsSixteen subjects participated (50% females) divided into two categories (‘H1’: young (30.62 yrs ±5.92, 23.95 kg/m² ±3.08), versus ‘H2’: old (61.87 yrs ±7.98, 23.4 kg/m² ±3.38)), in the recording of HD-sEMG signals, using 32-electrodes square grids (4×8), during Sit To Stand (STS) motion, three times at spontaneous speed. The studied muscle is the Rectus Femoris (RF) muscle. The recorded HD-sEMG signals were analyzed with CCA approach to extract correlation coefficient sets according to two age categories (young versus old), in order to evaluate its discriminating power with ageing. Statistical tests (t-test) were used to evaluate the discrimination for these two categories.ResultsThe calculation of CCA correlation coefficients showed a significant difference between young and old category concerning the mean CCA correlation coefficient (P<0.001***) and also the standard deviation of the CCA correlation coefficients (P<0.0001****).ConclusionThe obtained results are promising and indicate a clear difference between the obtained source variability using CCA method between the young and the old tested subjects during daily life motion. Furthermore, these estimated sources seem to be impacted by both anatomical and functional modifications with ageing.     

Sexual Dysfunction in Sheehan Syndrome

ObjectiveThe study was done to objectively document the sexual function in Sheehan syndrome (SS). SS is not an uncommon cause of hypopituitarism in developing countries. The lack of sex steroids from both ovaries and adrenal glands could lead to sexual dysfunction in SS. Sexual function is a neglected aspect of health in women in developing countries, although it greatly contributes toward the quality of life and feeling of well-being. Objective documentation of sexual function in SS is limited.MethodsThirty-two subjects with SS on conventional therapy (except growth hormone) were evaluated. SS was diagnosed as per standard criteria. Sexual function was assessed by validated questionnaires using the Female Sexual Function Index (FSFI). Thirty healthy women of a similar age range and socioeconomic background were included as comparators.ResultsThe mean age (±SD) of the study population and healthy controls was 39.9 (±8.6) years and 38.2 (±6.8) years, respectively. The median interval between inciting events and diagnosis of SS was 8.3 years (interquartile range, 5.2-13.5 years). Thirty subjects were sexually active. Of the 30 subjects, 28 (93%) had sexual dysfunction, that is, an FSFI score of ≤26.55. The median total FSFI scores of subjects with SS and controls were 20.8 and 29.05, respectively, (P = .001). There was a statistically significant difference for individual parameters of sexual function, including desire, arousal, lubrication, orgasm, and satisfaction, between those with SS and controls. However, the pain during intercourse was not different. FSFI score in subjects with SS was not correlated with any endocrine parameter or duration of the disease since diagnosis.ConclusionSexual dysfunction is very common, affecting >90% of subjects with SS.     

Biomarkers of antioxidant status and lipid peroxidation in elderly patients with hypertension

Objective: The objective of the present study was to examine selected parameters of the blood redox system in elderly patients with hypertension.examine selected parameters of the blood redox system in elderly patients with hypertension. Methods: We analyzed differences in redox-associated molecules and enzymes among elderly hypertensive subjects (age above 65?years, n?=?49) and two groups of normotensive subjects (<65 years old – Control group I; n?=?27, and >65 – Control group II; n?=?30). Results: Decreased activity of antioxidant enzymes, increased lipid peroxidation and reduced production of nitric oxide were observed in hypertensive subjects, compared to healthy younger controls, or those of the same age. In healthy controls, an age-related decrease in the production of nitric oxide and the activities of SOD-1 and GPx-1 was also evident. The pathology of hypertension was characterised by further, significant decreases in the values of these parameters. When the subgroups of females and males were compared to their respective controls, a compromised redox balance was observed that was more evident in female hypertensives. Discussion: Hypertension in elderly patients is accompanied by changes in biomarkers of antioxidant status and lipid peroxidation status, which significantly differ from those observed in healthy ageing subjects. Our study also suggests that the relationship of gender and changes in redox balance with regard to hypertension should be further explored.     

The effects of total ankle arthroplasty on postural stability and loading symmetry in quiet stance

Ankle osteoarthritis is a debilitating condition affecting about 1% of the population with approximately 50,000 new instances annually. One treatment is total ankle arthroplasty (TAA), however, its effects on balance are not well understood. This study analyzed balance over a two-year period following TAA. 408 subjects (177 left, 231 right ankles) diagnosed with end-stage ankle osteoarthritis performed quiet standing trials while center of pressure (COP) data were collected. Data were compared across three time points (pre-op, 1-year, and 2-years post-op) and between surgical and non-surgical limbs using a linear mixed model with significance set at P = 0.05. COP excursions in the feet-together condition were not significantly different between limbs after 2 years in anteroposterior or mediolateral directions (P = 0.06, 0.08) after being significantly different between limbs in the anteroposterior (P = 0.014) and mediolateral direction (P < 0.001) pre-op. The vertical ground reaction force significantly decreased across time in the non-surgical limb, while reciprocally increasing in the surgical limb (P < 0.001). After 2 years, no significant difference in vertical ground reaction force between limbs existed (P = 0.20). Limb asymmetry indices decreased at each time point in both conditions (all P < 0.001) and were not significantly different from zero after 2 years in the feet-together condition (P = 0.290). In conclusion, surgical limb balance improved compared to pre-op, resulting in increased symmetry between limbs after 2 years. Vertical ground reaction forces on both limbs converge and limb asymmetry indices approach zero two years post-op. Differences in the COP excursion-loading symmetry relationship between limbs could be useful for identifying instability in other pathologies.     

Evaluation in humans of ELF-EMF exposure on chromogranin A,a marker of neuroendocrine tumors and stress

ABSTRACT

Chromogranin A (CgA), which is a major protein in adrenal chromaffin cells and adrenergic neurons, is a clinically relevant endocrine and neuroendocrine tumor marker including pheochromocytomas, neuroblastomas, and related neurogenic tumors. In this study, we looked at the effect in humans of chronic daily exposure to a 50-Hz magnetic field. We examined in 15 men (38.0 ± 0.9 years) the effects of chronic daily exposure to a 50-Hz magnetic field for 1–20 yrs both at home and at work. EMDEX II dosimeters were used to record magnetic field all day long every 30 s. for 1 week. The weekly geometric mean of the individual exposures ranged from 0.1 to 2.6 μT. Blood samples were taken hourly between 20:00 h and 08:00 h. CgA patterns of exposed subjects were compared to age-matched controls. The results of exposed subjects were compared with those for 15 unexposed men who served as controls and whose individual exposure was ten times lower ranging from 0.004 to 0.092 μT. This work shows that in the control group the serum CgA levels exhibited a nighttime peak with a progressive decline of the serum concentrations and a nadir in the morning. Both the profile and the serum concentrations of CgA, a marker of neuroendocrine tumors and stress, did not appear to be impaired in the subjects chronically exposed over a long period (up to 20 yrs) to magnetic fields though a trend toward lower levels were found at the highest exposure (>0.3 μT). This does not rule out, however, that the potential deleterious risk of ELF-EMF on frail populations such as children and the elderly may be greater at low exposure and should hence be documented, at least for their residential exposure.     

基于支持向量机的表面肌电信号和加速度融合跌倒识别方法

目的:针对老人易跌倒和跌倒过后可能产生严重后果这一现实问题,通过将表面肌电信号和加速度融合,进一步优化采用支持向量机分类器下的包含跌倒在内的几种不同动作的分类效果。方法:提出基于表面肌电和加速度信号融合的跌倒识别算法,首先采集股直肌,股内侧肌,胫骨前肌和腓肠肌的表面肌电信号以及位于腰部的三轴加速度信号作为实验数据,然后利用滑动窗口法提取表面肌电和加速度信号的均方根值,最后针对人体日常活动和跌倒的运动特征,构建了支持向量机的分类器。结果:实验数据共计320组数据,包括3种日常活动和向前跌倒,其中160组数据作为训练集,另外160组数据作为测试集。对4种动作进行识别实验,算法的准确度为93.23%、灵敏度为92.4%、特异度为100%,达到了良好的分类效果。结论:基于支持向量机的表面肌电信号和加速度融合的跌倒识别算法分类效果良好,对于老人跌倒防护具有现实意义。     

Temporal and topographic characteristics of evoked potentials in the conflict of two consecutive visual stimuli in a working memory task

Behavioral reactions and brain mechanisms involved in processing two matching or mismatching (conflicting) visual stimuli were studied in healthy subjects (mean age 22.57 ± 0.46 years). Line orientations (vertical, horizontal, or 45°) were used as stimuli and were presented with an interval of 1500–1800 ms. The reaction time was shown to increase in the case of a conflict of two orientations as compared with matching orientations. The reaction time depended on the orientation of the reference stimulus and was minimal when a vertical line was used as a reference. An increase in N2 negativity (time window 200–280 ms) in the frontal and parietal cortical areas was identified as an informative indicator of a conflict between the current orientation and the orientation stored in working memory. The dipole sources of N2 were localized to the prefrontal cortex (middle frontal gyrus, frontal pole, and pars orbitalis). The N2 amplitude was found to depend on the orientation of the first stimulus in a pair, being higher in the case of a 45° orientation. The visual areas were shown to play a role in detecting a conflict of two consecutive signals because the early sensory components increased in amplitude. The results implicate cortical structures, including the sensory-specific visual, parietal, and prefrontal areas, in comparing consecutive visual signals and detecting their conflict.     

Enfermedad cardiovascular tras infección por SARS-CoV-2 en pacientes ancianos. Resultados del seguimiento anual de una cohorte de supervivientes

IntroductionAlthough the effects of SARS-CoV-2 infection on the cardiovascular system is well known in the acute phase, the cardiovascular impact of the elderly population surviving COVID-19 respiratory infection after 1 year of follow-up has not been sufficiently studied.MethodsObservational registry of 240 elderly patients (75 years or older), consecutively admitted for COVID-19 respiratory infection and survivors of the same, between March 1 and April 30, 2020, at the Hospital General Universitario de Ciudad Real. The incidence of major cardiovascular events [MACE] (cardiovascular death [CD], acute coronary syndrome [ACS], cerebrovascular disease [CVD], venous thromboembolic disease [VTE] and heart failure [HF]) was prospectively analysed.ResultsThe mean age was 83.75 ± 5.75 years. After a mean follow-up of 352.2 ± 70.4 days, 13.8% of patients died and 9.6% had MACE, the most frequent being heart failure, with no differences in severity or overall course of acute illness. In the multivariate Cox regression model, the risk of developing MACE was higher in patients with chronic obstructive pulmonary disease and (HR 4.29; 95%CI 1.62-11.39; P = .003) and loop diuretic (HR 2.99; 95%CI 1.27-7.07; P = .01).ConclusionsIn elderly COVID-19 survivors, the incidence of MACE after one year of follow-up is high, the main manifestation being heart failure.     

Valoración de la musculatura isquiosural en personas mayores

Objectiveto evaluate hamstring flexibility in older adults.Materials and methodsa total of 177 subjects (13 men and 164 women) aged between 43 and 80 years old (mean age = 63.4 ± 6.7 years) who attended fitness classes were evaluated. The mean height was 161 ± 10 cm and the mean weight was 74 ± 5.6 kg. Hamstring flexibility was evaluated using the straight leg raise test.Resultsthe mean flexion in the right hip was 72° ± 13.2° and the mean flexion of the left hip was 72.4° ± 13.8°. No significant differences were found in the values obtained from the straight leg raise test in the left and right legs. For the right leg, 48.02% of the subjects’ values were within the normal range, while 28.81% showed grade I shortness, and 23.61% showed grade II shortness. For the left leg, 49.94% showed normal values, 29.94% showed grade I shortness, and 22.03% showed grade II shortness.Conclusionshalf of the adults and elderly individuals that took part in the present study had hamstring shortness, which increased in frequency with age.