The effect of different types of cognitive tasks on postural sway fluctuations in older and younger adults: A nonlinear study.

BACKGROUND: There are numerous types of cognitive tasks classified as mental tracking (MT), working memory (WM), reaction time (RT), discrimination and decision-making and verbal fluency (VF). However, limited studies have investigated the effects of cognitive task type on postural control in older adults. PURPOSE: s: The aim of this study was to investigate the effect of aging and several types of cognitive tasks on postural control in terms of nonlinear analysis. METHOD: Postural control was investigated under 6 conditions (single task and dual-task with RT; easy and difficult VF; easy and difficult WM; easy and difficult MT. Outcome measurements were the max Lyapunov, entropy, and correlation dimension at anteroposterior (AP) and mediolateral (ML) directions. RESULTS: The results revealed that within the older group, the AP & ML max Lyapunov at dual-task with difficult WM and MT was significantly higher than all other conditions. In addition, the older group had lower AP entropy at dual-task with easy VF, difficult WM, and easy as well as difficult MT. CONCLUSION: The results can be useful to understand the postural control mechanisms and to detect the alterations following aging and applying different types of cognitive tasks. In addition, the investigated parameters can be a basis for identifying postural control deficiencies.

Comparison of effects of Mulligan taping and Kinesio taping on ankle neuromuscular control in response to a sudden inversion perturbation in individuals with chronic ankle instability.

OBJECTIVES: This study was aimed to compare the effects of Mulligan taping (MT) with Kinesio taping (KT) and the un-taped ankle on neuromuscular control during a sudden inversion perturbation in individuals with chronic ankle instability (CAI). DESIGN: Randomized, single blind cross-over. SETTING: Biomechanics lab. PARTICIPANTS: 16 individuals with chronic ankle instability. MAIN OUTCOME MEASURES: The outcome measures were the onset time and magnitude of short (SLR) and medium latency response (MLR) for peroneus brevis (PB), peroneus longus (PL), tibialis anterior (TA), and soleus (SOL) muscles and the TA/P and SOL/TA antagonist co-activation. RESULTS: In the groups of KT and MT, the onset time was significantly decreased at post-taping compared to pre-taping, such that for the onset time of PB MLR, the groups of KT and MT had an earlier onset time than the un-taped group. For the magnitude of TA SLR and PB MLR, groups exhibited different behaviors. In the KT group, the magnitude was significantly increased post-taping, however, in the MT group, it was decreased. Regarding the TA/P and SOL/TA co-activation, the groups of KT and MT showed significant changes post-taping. CONCLUSION: This study suggests that KT and MT significantly affect neuromuscular control in response to a sudden perturbation in individuals with CAI, although the behavior of KT and MT appears to be somewhat different from each other.

Efficacy of stretching exercises versus transcranial direct current stimulation (tDCS) on task performance, kinematic and electroencephalography (EEG) spectrum in subjects with slump posture: a study protocol.

BACKGROUND: Slump sitting is a common posture in workplaces. There is limited evidence that poor posture impacts the mental state. This study aims to investigate whether slump posture results in more mental fatigue during computer typing, compared with normal posture and also to compare the effectiveness of stretching exercises with tDCS in fatigue monitoring. METHODS: The sample size for this study is set at 36 participants with slump posture and 36 participants with normal posture. In the first step, to find out the differences between normal and poor posture, they will be asked to perform the typewriting task for 60 min. During the first and last 3 min of typing, mental fatigue as the primary outcome using EEG signals and further measures including kinematic behavior of neck, visual analog fatigue scale, and musculoskeletal discomfort will be assessed. Post-experiment task performance will be calculated based on typing speed and typing errors. In the next step, to compare the effect of tDCS and stretching exercises on the outcome measures, the slump posture group will receive these interventions in two separate sessions before the typing task. DISCUSSION: With the assumption of showing significant differences in terms of outcome measures between slump and normal posture groups and also by showing the possible changes of the measures, by using either tDCS as a central modality or stretching exercises as a peripheral modality; the findings may provide evidence to indicate that poor posture has adverse effect on mental state and to introduce the effective method to overcome mental fatigue and promote work productivity. TRIAL REGISTRATION: Registered on the Iranian Registry of Clinical Trials on 21 September 2022, IRCT Identifier: IRCT20161026030516N2.

The effect of exergaming on cognition and brain activity in older adults: A motor- related cortical potential study.

Exergames have positive effects on various cognitive domains. However, to the best of our knowledge, not only have few studies investigated the exergame-induced brain changes, but also in most of them, preparatory brain activity has not been considered. Preparatory brain activity is a particularly relevant aspect for investigating the interaction between cognitive and sensorimotor functions in the brain. Accordingly, the aim of this study was to investigate the effects of an exergame protocol versus traditional motor-cognitive dual-task training on the cognition and proactive components of movement-related cortical potential. A total of 52 older adults were randomly assigned to the intervention (exergame training) and the control group (motor-cognitive dual-task training). The outcome measurements were neurophysiological data (i.e., the amplitude of the late contingent negative variation [CNV], and alpha/beta event-related desynchronization [ERD]), and neuropsychological data (rate-correct score [RCS] in go/no go task and trail-making test [TMT]). The results revealed that both groups had a decreased late CNV, and alpha/ beta ERD in post-training compared to pre-training in Cz and C3 channels. Moreover, both groups had an increased RCS and a decreased TMT-A in post-training compared to pre-training. However, for TMT-B, the results indicated a significant interaction in favor of the exergame group. These findings indicate that in older adults, both interventions may result in increasing inhibitory control, information processing speed, and preparatory brain activity. However, for cognitive flexibility, exergame has an additional effect relative to the control group.

The effect of video game-based training on postural control during gait initiation in community-dwelling older adults: a randomized controlled trial.

PURPOSE: The aim was to investigate the effect of video game training as compared to dual-task training on gait initiation (GI) which is a sensitive indicator of balance deficiency in older adults. METHOD: Sixty-six older adults were allocated to the video game-based training (intervention group) or the motor-cognitive dual-task training (active control group). The outcome measures were the mediolateral (ML)/anteroposterior (AP) displacement and velocity of COP during the phases of GI (anticipatory, weight transition, and locomotor). RESULTS: The results indicated in the anticipatory phase, the ML & AP COP displacement were significantly increased at post-training relative to pre-training across both groups (p < 0.041). In the weight transition phase, the AP COP displacement & ML COP velocity were significantly increased at post-training than pre-training (p < 0.032). However, in the locomotor phase, within the intervention group, the ML COP displacement & ML COP velocity were significantly increased at follow-up as compared to pre-training (p < 0.05), while no such differences were observed within the control group. CONCLUSION: Both treatments were effective in improving COP trajectory during the phases of anticipatory and weight transition, while the intervention group was more effective during the phase of locomotor. So, these treatments can be recommended for clinical settings.Implications for rehabilitationThe video game and dual task training were effective in improving COP trajectory during the phases of anticipatory and weight transition.The video game-based training was more effective during the phase of locomotor.The study findings could have useful implications to further introduce cognition-based rehabilitation programs such as video games for older adults.Rehabilitation professionals could use the video game to improve the postural control of older adults.

Video game and motor-cognitive dual-task training could be suitable treatments to improve dual-task interference in older adults.

The objective of study was to investigate the effects of video game training in comparison with traditional motor-cognitive dual-task training on dual-task interference in older adults. Sixty older adults were allocated to the video game (intervention group) or the motor-cognitive dual-task training (control group). The outcome measures were dual-task cost (DTC) of linear metrics (Standard deviation (SD) of amplitude and velocity) and DTC of nonlinear metrics (approximate entropy, Lyapunov and correlation dimension) acquired from postural sway time series from both the mediolateral (ML) and anteroposterior (AP) directions. The results revealed in both groups, dual-task cost of SD of amplitude and velocity as well as Lyapunov were significantly decreased in post-training and follow-up compared with pre-training (p < 0.017), while there was no significant difference between the groups. Video game and motor-cognitive dual-task training could be recommended as suitable treatments to improve dual-task interference.

Short-term Effects of Elastic Therapeutic Taping on Static and Dynamic Balance in Chronic Stroke.

INTRODUCTION: The current pilot study aimed to examine the short-term effects of ankle Elastic Therapeutic Taping (ETT) on static and dynamic balance. METHODS: Twenty-Four individuals with chronic stroke were assigned to an experimental or control group (n=12/group); they both received Conventional Physical Therapy (CT) for 3 weeks, 3 times per week. The experimental group additionally underwent taping to the ankle of the paretic side continuously for 3 weeks. Standardized measures for static and dynamic balance were administered at pre-test and post-test and analyzed using Wilcoxon and Analysis of Covariance (ANCOVA). RESULTS: The experimental group significantly improved on two measures, Biodex anterior-posterior static (P=0.03) and medial-lateral dynamic (P=0.04) balance indices, compared to the controls. Both groups improved within their respective groups for Berg Balance Scale and Functional Reach (P<0.05). Static balance consistently improved across measures with the experimental intervention with large effect sizes. CONCLUSION: Ankle ETT, combined with CT, may be effective in the short-term for improving static and dynamic balance in stroke, compared to CT alone. A future larger randomized trial with longer follow-up is required to establish this method's effectiveness.

The relative and absolute reliability of center of pressure trajectory during gait initiation in older adults.

It has been thought that for scientific acceptance of a parameter, its psychometric properties such as reliability, validity and responsiveness have critical roles. Therefore, this study was conducted to estimate how many trials are required to obtain a reliable center of pressure (COP) parameter during gait initiation (GI) and to investigate the effect of number of trials on the relative and absolute reliability. Twenty older adults participated in the study. Subjects began stepping over the force platform in response to an auditory stimulus. Ten trials were collected in one session. The displacement, velocity, mean and median frequency of the COP in the mediolateral (ML) and anteroposterior (AP) directions were evaluated. Relative reliability was determined using the intraclass correlation coefficient (ICC), and absolute reliability was evaluated using the standard error of measurement (SEM) and minimal detectable change (MDC95). The results revealed with respect to parameter, one to five trials should be averaged to ensure excellent reliability. Moreover, ICC, SEM% and MDC95% values were between 0.39-0.89, 4.84-41.5% and 13.4-115% for single trial and 0.86-0.99, 1.74-19.7% and 4.83-54.7% for ten trials averaged, respectively. Moreover, the ML and AP COP displacement in locomotor phase had the most relative reliability as well as the ML and AP median frequency in locomotor phase had the most absolute reliability. In general, the results showed that the COP-related parameters in time and frequency domains, based on average of five trials, provide reliable outcome measures for evaluation of dynamic postural control in older adults.

Time and Frequency Domain Analysis of Gait Initiation in Younger and Older Adults.

The purpose of study was to demonstrate age-related changes during gait initiation (GI). Therefore, displacement, velocity, total power, mean and median frequency of COP trajectories were measured during phases of GI in anteroposterior (AP) and mediolateral (ML) directions. The older group demonstrated the slower and lesser displacement in comparison with the younger group during anticipatory phase in AP direction and during locomotor phase in AP and ML directions. In addition, the median and mean frequency were greater in the older relative to the younger group during anticipatory phase in AP direction, while these were lesser in older than younger group during locomotor phase in AP and ML directions. Moreover, total power was greater among older than younger adults during the anticipatory phase in ML direction and during all phases in AP direction. This study suggests that COP-related parameters extracted from time and frequency domains have the ability to demonstrate age-related changes.

Characteristic muscle activity patterns during gait initiation in the healthy younger and older adults.

It is thought that gait initiation (GI) might be an optimal task for identifying postural control deficiencies. Thus, the aim of this study was to clarify the strategies adopted by older subjects during this task. 16 healthy younger and 15 healthy older adults participated in the study. Subjects were instructed to begin forward stepping with their dominant limb in response to an auditory stimulus. The mean muscle activity, co-contraction index, and intra-subject coefficients of variation (intra-subject CVs) of dominant limb muscles in different phases of GI were measured. The level of association between the co-contraction index and intra-subject CV of muscles was also explored. This study showed that in the anticipatory phase, the younger group had larger amplitudes and more intra-subject CVs than older the group, particularly for the tibialis anterior muscle. However, the co-contraction index was greater in older subjects relative to younger subjects. During the weight transition phase, tibialis anterior, semitendinosus and vastus lateralis muscles of older adults had a lower amplitude as compared to younger adults. However, during the locomotor phase, the activity of tibialis anterior was greater in comparison to younger adults. Also, during this phase, similar to the anticipatory phase, the co-contraction index between tibialis anterior and gastrocnemius muscles was greater in older subjects relative to younger subjects. Additionally, the larger co-contraction index of some muscles was associated with smaller intra-subject CV. These findings suggest that muscle behaviors are altered with aging and older adults employ different strategies in the different phases of GI as compared to younger adults.

Preparatory postural adjustments during gait initiation in healthy younger and older adults: Neurophysiological and biomechanical aspects.

The most postural adjustments studies have focused on electromyographic and biomechanical events to identify the mechanisms involved in falling, whereas direct recording of central processor system could be an optimal approach to provide new insights into this field. Therefore, the purpose of this study was to determine neurophysiological and biomechanical aspects of the preparatory postural adjustments during gait initiation (GI) in healthy younger and older adults. 16 healthy younger and 15 healthy older adults participated in the study. Stimuli of warning and response were played with an inter-stimulus interval of 2s and subjects were instructed to begin forward stepping with the dominant limb in response to response stimulus. The contingent negative variation (CNV), onset time of electromyographic activity in leading limb muscles and center of pressure (COP) trajectory in the anticipatory phase of GI were measured. Results revealed the peak time of CNV and mean amplitude of Late CNV were earlier and smaller in older group, respectively. However, peak amplitude of CNV did not differ significantly between groups. Moreover, the older group exhibited a delayed onset activity of gluteus medius and tibialis anterior muscles as well as a slower velocity and lesser backward displacement of COP trajectories in comparison with the younger group. Additionally, there were strong relationships between neurophysiological and biomechanical parameters. Findings suggest the age-related changes in the brain activities and preparatory postural adjustments during GI which could be valuable in designing assessment and prevention approaches for falls in this group of people.

The effect of cryotherapy on the normal ankle joint position sense.

PURPOSE: To determine whether a fifteen-minute water immersion treatment affects the normal ankle joint position sense (JPS) at the middle range of dorsiflexion and plantar flexion actively and passively. METHODS: Thirty healthy female volunteers aged between 18 and 30 years were treated by a 15-minute cryotherapy (6 ± 1°C). The subject's skin temperature over antromedial aspect of dominant ankle was measured by the Mayomed device before, immediate and 15 minutes after water immersion. Ankle JPS was tested trough the pedal goniometer at 3 stages similar to the skin temperature. ANOVA (α = 0.05) was performed on each of variables using SPSS 19.0 software. RESULTS: Skin temperature was seen to decrease after water immersion but subjects did not return to pre-test skin temperature after 15 minutes (P<0.001). The research found no significant difference in JPS at middle range of dorsiflexion and plantar flexion actively and passively before and after cryotherapy. CONCLUSION: These findings suggest that 15-minute water immersion at 6°C dose not significantly alter the middle range of plantar flexion/ dorsiflexion JPS at the ankle and is not deleterious to JPS.