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Clinical walk tests may not predict the development of frailty in healthy older adults. With advancements in wearable technology, it may be possible to predict the development of frailty using loading asymmetry parameters during clinical walk tests. This prospective cohort study aimed to test the hypothesis that increased limb loading asymmetry predicts frailty risk in community-living older adults. Sixty-three independently ambulant community-living adults aged ≥ 65 years were recruited, and forty-seven subjects completed the ten-month follow-up after baseline. Loading asymmetry index of net and regional (forefoot, midfoot, and rearfoot) plantar forces were collected using force sensing insoles during a 10 m walk test with their maximum speed. Development of frailty was defined if the participant progressed from baseline at least one grading group of frailty at the follow-up period using the Kihon Checklist. Fourteen subjects developed frailty during the follow-up period. Increased risk of frailty was associated with each 1% increase in loading asymmetry of net impulse (Odds ratio 1.153, 95%CI 1.001 to 1.329). Net impulse asymmetry significantly correlated with asymmetry of peak force in midfoot force. These results indicate the feasibility of measuring plantar forces of gait during clinical walking tests and underscore the potential of using load asymmetry as a tool to augment frailty risk assessment in community-dwelling older adults.
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Fragilidad , Marcha , Vida Independiente , Humanos , Anciano , Masculino , Femenino , Marcha/fisiología , Fragilidad/fisiopatología , Fragilidad/diagnóstico , Anciano de 80 o más Años , Estudios Prospectivos , Zapatos , Anciano Frágil , Caminata/fisiología , Dispositivos Electrónicos VestiblesRESUMEN
Background and Aims: Mild cognitive impairment (MCI) is a widespread condition in older individuals, posing significant risk of dementia. However, limited research has been conducted to explore effective interventions and clarify their impact at the neural level. Therefore, this study aimed to investigate the effects of computerized cognitive training (CCT) and explore the associated neural mechanisms in preventing dementia in older individuals with MCI, with a view to inform future intervention efforts. Methods: We reviewed the effects of CCT on biomarker outcomes in older adults with MCI. The search was conducted for studies published between 2010 and May 10, 2023, using three search engines: PubMed, Scopus, and Cumulative Index to Nursing and Allied Health Literature. The inclusion criteria were as follows: studies that involved participants diagnosed with MCI, included CCT, included quantitative assessment of biomarker results, and conducted randomized controlled trials. Results: Sixteen studies that used biomarkers, including magnetic resonance imaging, electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and blood or salivary biomarkers, were extracted. The results showed that CCT caused changes in structure and function within the main brain network, including the default mode network, and decreased both theta rhythm activity on EEG and prefrontal activity on fNIRS, with improvement in cognitive function. Furthermore, CCT combined with physical exercise showed more significant structural and functional changes in extensive brain regions compared with CCT alone. Virtual reality-based cognitive training improved not only executive function but also instrumental activities of daily living. Conclusion: CCT causes functional and structural changes in extensive brain regions and improves cognitive function in older adults with MCI. Our findings highlight the potential of individualized intervention methods and biomarker assessment according to the specific causes of MCI. Future research should aim to optimize these personalized therapeutic strategies to maximize the benefits of CCT in older adults with MCI.
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BACKGROUND: Backpack syndrome (BS) is a term used to describe symptoms such as shoulder and back pain that are believed to be caused by carrying a backpack. Few studies have investigated the changes in walking and running parameters with and without backpacks. OBJECTIVE: The present study aimed to investigate the differences in walking and running parameters with and without backpacks in primary school children with and without BS. METHODS: This cross-sectional study included 51 children (average age 9.3 years, 6- 12 years). Two questions were asked beforehand: whether the respondents had shoulder or back pain when going to school and present; those who answered that they had pain in both cases were defined as the BS group, while the others were the control group. Walking and running at comfortable speeds and walking and running with a 6 kg backpack on their backs were measured. RESULTS: During walking, there were main effects for speed, cadence, and strike angle with and without the backpack, but no interactions were identified for any of the parameters. In running, however, there were main effects for speed, stride length, strike angle, and lift-off angle, and an interaction effect was observed for speed and stride length. CONCLUSIONS: During walking, carrying a 6âkg backpack increased cadence and walking speed. During running, carrying a backpack caused a decrease in stride length and running speed in the BS group, whereas there was no change in the control group, suggesting that the control and BS groups may respond differently.
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Repetitive peripheral magnetic stimulation (rPMS) is a non-invasive neuromodulation technique. Magnetic fields induced by rPMS pass through almost all materials, and it has clinical applications for neurorehabilitation. However, the effects of rPMS through clothing and orthosis on induced movement and corticospinal excitability remain unclear. The aim of this study was to determine whether rPMS induces movement and enhances corticospinal excitability through hand splint materials. rPMS was applied directly to the skin (L0) and through one (L1) or two (L2) layers of splint material in 14 healthy participants at 25-Hz, 2-s train per 6 s for a total of 20 min. rPMS was delivered to the forearm with the stimulus intensity set to 1.5-times the train intensity-induced muscle contractions under the L0 condition. We recorded induced wrist movements during rPMS and motor-evoked potentials of the extensor carpi radialis pre- and post-application. The results showed that rPMS induced wrist movements in L0 and L1, and it facilitated corticospinal excitability in L0 but not in L1 and L2. This suggests that rPMS can make electromagnetic induction on periphery even when applied over clothing and orthosis and demonstrates the potential clinical applications of this technique for neurorehabilitation.
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Repetitive peripheral magnetic stimulation (rPMS) induces proprioceptive afferents and facilitates corticospinal excitability. Short-term sessions of rPMS combined with motor imagery (MI) enhance corticospinal excitability more than rPMS alone. However, it is not clear how long the intervention of rPMS combined with MI would be needed to facilitate corticospinal excitability. Therefore, we investigated the time course change in corticospinal excitability during the combination of rPMS and MI. Thirteen healthy volunteers participated in a 20-min intervention under the following three experimental conditions on different days: rPMS, MI, and rPMS combined with MI (rPMS + MI). In the rPMS and rPMS + MI, the participants were delivered rPMS, which was 25 Hz, 2 s/train at 1.5 × of the train intensity induced muscle contractions, through the wrist extensor muscles. In the MI and rPMS + MI, the participants repeatedly imagined wrist movements for 2 s. Motor evoked potentials (MEPs) were recorded from the extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles every 5 min for each condition. The MEP amplitudes of the ECR after > 10 min of intermittent rPMS combined with MI were greater than baseline. The MEP amplitude of the ECR in rPMS + MI was greater than that in rPMS condition after 20 min of intervention. The present results suggest that over 10 min of intermittent rPMS combined with MI facilitates corticospinal excitability, and that the effect of rPMS combined with MI on corticospinal excitability might be greater than that of rPMS alone.
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Imagen Eidética , Movimiento , Contracción Muscular , Tractos Piramidales/fisiología , Potenciales Evocados Motores , Femenino , Humanos , Campos Magnéticos , Masculino , Músculo Esquelético/inervación , Músculo Esquelético/fisiología , Propiocepción , Adulto JovenRESUMEN
OBJECTIVE: Repetitive peripheral magnetic stimulation (rPMS) combined with motor imagery facilitates the corticospinal excitability of the agonist muscles. However, the effects of rPMS combined with motor imagery on the corticospinal excitability of the antagonist muscles are unclear. This is an important aspect for applying rPMS in neurorehabilitation for sensorimotor dysfunction. Therefore, we investigated the real-time changes of corticospinal excitability of antagonist muscles during rPMS combined with motor imagery. METHODS: Fourteen healthy volunteers underwent four different experimental conditions: rest, rPMS, motor imagery, and rPMS combined with motor imagery (rPMS + motor imagery). In the rPMS and rPMS + motor imagery conditions, rPMS (25 Hz, 1600 ms/train, 1.5× of the motor threshold) was delivered to the dorsal side of the forearm. In motor imagery and rPMS + motor imagery, the participant imagined wrist extension movements. Transcranial magnetic stimulation was delivered to record motor-evoked potentials of the antagonist muscle during experimental interventions. RESULTS: The motor-evoked potential (normalized by rest condition) values indicated no difference between rPMS, motor imagery, and rPMS + motor imagery. CONCLUSION: These results suggest that rPMS combined with motor imagery has no effect on the corticospinal excitability of the antagonist muscles and highlight the importance of investigating the effects of rPMS combined with motor imagery at the spinal level.
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Potenciales Evocados Motores/fisiología , Imaginación/fisiología , Corteza Motora/fisiología , Músculo Esquelético/fisiología , Tractos Piramidales/fisiología , Estimulación Magnética Transcraneal/métodos , Electromiografía/métodos , Femenino , Humanos , Masculino , Movimiento/fisiología , Adulto JovenRESUMEN
PURPOSE: Both repetitive peripheral magnetic stimulation (rPMS) and transcutaneous electrical current stimulation (TES) could elicit the limb movements; it is still unclear how subjective sensation is changed according to the amount of limb movements. We investigated the pain and discomfort induced by newly developed rPMS and TES of peripheral nerves in the dorsal forearm. METHODS: The subjects were 12 healthy adults. The stimulus site was the right dorsal forearm; thus, when stimulated, wrist dorsiflexion was induced. The rPMS was delivered by the new stimulator, Pathleader at 10 stimulus intensity levels, and TES intensity was in 1-mA increments. The duration of each stimulation was 2 s. The analysis parameters were subjective pain and discomfort, measured by a numerical rating scale. The rating scale at corresponding levels of integrated range of movement (iROM) induced by rPMS or TES was compared. The subjective values were analyzed by two-way repeated measures ANOVA with the stimulus conditions (rPMS, TES) and the seven levels of iROM (20-140 ºs). RESULTS: In the rPMS experiments, stimuli were administered to all subjects at all stimulus intensities. In the TES experiments, none of the subjects dropped out between 1 and 16 mA, but there were dropouts at each of the intensities as follows: 1 subject at 17 mA, 20 mA, 22 mA, 23 mA, 27 mA, 29 mA and 2 subjects at 21 mA, 24 mA, 26 mA. The main effects of the stimulus conditions and iROM were significant for pain and discomfort. Post hoc analysis demonstrated that pain and discomfort in rPMS were significantly lower compared to TES when the iROM was above 60 ºs and 80 ºs, respectively. CONCLUSION: New rPMS stimulator, Pathleader, caused less pain and discomfort than TES, but this was only evident when comparatively large joint movements occurred.
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The aim of the present study was to investigate the effects of repetitive peripheral magnetic stimulation (rPMS) combined with motor imagery (MI) on corticospinal excitability. Ten healthy individuals participated in two kinds of short-term sessions: rPMS combined with MI [magnetic stimulation motor imagery (MSMI)] and rPMS alone (magnetic stimulation) on different days. We measured the motor-evoked potentials before and after the session, and the MI ability of each participant using the Movement Imagery Questionnaire-Revised. The post-session/pre-session motor-evoked potential ratio was larger in the MSMI than in the magnetic stimulation condition, and the difference was correlated to the Movement Imagery Questionnaire-Revised score. This suggests that rPMS combined with MI induced greater corticospinal excitability than rPMS alone. This study highlights the possibility that short-term sessions of rPMS combined with MI could have clinical applications in improving the sensorimotor dysfunctions of stroke patients.
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Encéfalo/fisiología , Excitabilidad Cortical , Imaginación/fisiología , Campos Magnéticos , Tractos Piramidales/fisiología , Adulto , Potenciales Evocados Motores , Femenino , Humanos , Músculo Esquelético/fisiología , Estimulación Magnética Transcraneal , Adulto JovenRESUMEN
It remains unknown whether transcranial alternating current stimulation (tACS) affects episodic memory and the effect of gamma oscillations delivered to the left prefrontal cortex (PFC) on long-term memory retention has not been fully investigated. We examined whether tACS over the left PFC enhances recognition of episodic memory. The study enrolled 36 healthy young adult volunteers. The participants were randomly assigned to either a tACS group [n = 18; 14 females; mean age ± standard deviation (SD): 21.2 ± 0.4 years] or a sham-control group [n = 18; 14 females; mean age ± SD: 21.2 ± 0.4 years]. Participants received either tACS or sham stimulation both during the learning task that was conducted on day 1 and during a recognition task on day 2. The recognition task was also conducted on days 1 and 7, and response accuracy was measured at all three time points (days 1, 2, and 7). Patients in the tACS group were better able to retain long-term memory than those in the sham-control group. These findings suggest that tACS over the left PFC enhances recognition of episodic memory in healthy young adults.
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Memoria Episódica , Corteza Prefrontal/fisiología , Reconocimiento en Psicología/fisiología , Estimulación Transcraneal de Corriente Directa/métodos , Femenino , Humanos , Masculino , Método Simple Ciego , Estimulación Transcraneal de Corriente Directa/tendencias , Adulto JovenRESUMEN
The rubber hand illusion (RHI) is an experimental paradigm known to produce a bodily illusion. Transcutaneous electrical nerve stimulation (TENS) combined with the RHI induces a stronger illusion than the RHI alone. Visuotactile stimulus synchrony is an important aspect of the RHI. However, the effect of TENS and visuotactile stimulus synchrony in TENS combined with the RHI remains unknown. The purpose of this study was to investigate the effects of TENS and visuotactile stimulus synchrony on the embodiment of an artificial hand when using TENS combined with the RHI. The participants underwent four experimental conditions in random order: TENS/noTENS × Synchronous/Asynchronous. TENS was set at an intensity such that it generated a feeling of electrical paresthesia in the radial nerve area of the hand but did not cause pain, i.e., 100-Hz pulse frequency, 80-µs pulse duration, and a constant pulse pattern. A visuotactile stimulus, either temporally synchronous or asynchronous, was generated using paintbrush strokes. To evaluate the outcome measures, the participants completed a questionnaire report and proprioceptive drift assessments (motor response and perceptual response). There were significant main effects of TENS and visuotactile synchrony, but no interaction between these factors, on the results of the questionnaire and the perceptual response. In contrast, there was no significant effect on the result of the motor response. These findings indicate that TENS and visuotactile synchrony might affect differently the embodiment of an artificial hand when using TENS combined with the RHI.
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Miembros Artificiales , Ilusiones/fisiología , Propiocepción/fisiología , Percepción del Tacto/fisiología , Estimulación Eléctrica Transcutánea del Nervio/métodos , Percepción Visual/fisiología , Adulto , Imagen Corporal , Femenino , Mano , Humanos , Masculino , Evaluación de Resultado en la Atención de Salud , Tiempo de Reacción , Encuestas y Cuestionarios , Adulto JovenRESUMEN
This study was performed to investigate the possibility of non-invasive modulation of SEPs by the application of transcranial static magnetic field stimulation (tSMS) over the primary motor cortex (M1) and supplementary motor cortex (SMA), and to measure the strength of the NdFeB magnetic field by using a gaussmeter. An NdFeB magnet or a non-magnetic stainless steel cylinder (for sham stimulation) was settled on the scalp over M1 and SMA of 14 subjects for periods of 15 min. SEPs following right median nerve stimulation were recorded before and immediately after, 5 min after, and 10 min after tSMS from sites C3' and F3. Amplitudes of the N33 component of SEPs at C3' significantly decreased immediately after tSMS over M1 by up to 20%. However, tSMS over the SMA did not affect the amplitude of any of the SEP components. At a distance of 2-3 cm (rough depth of the cortex), magnetic field strength was in the range of 110-190 mT. Our results that tSMS over M1 can reduce the amplitude of SEPs are consistent with those of low-frequency repeated TMS and cathodal tDCS studies. Therefore, tSMS could be a useful tool for modulating cortical somatosensory processing.