Control In Healthy Young Adults Research Articles

Kinematic and neuromuscular characterization of cognitive involvement in gait control in healthy young adults.

The signature of cognitive involvement in gait control has rarely been studied using both kinematic and neuromuscular features. The present study aimed to address this gap. Twenty-four healthy young adults walked on an instrumented treadmill in a virtual environment under two optic flow conditions: normal (NOF) and perturbed (POF, continuous mediolateral pseudorandom oscillations). Each condition was performed under single-task and dual-task conditions of increasing difficulty (1-, 2-, 3-back). Subjective mental workload (raw NASA-TLX), cognitive performance (mean reaction time and d-prime), kinematic (steadiness, variability and complexity in the mediolateral and anteroposterior directions) and neuromuscular (duration and variability of motor primitives) control of gait were assessed. The cognitive performance and the number and composition of motor modules were unaffected by simultaneous walking, regardless of the optic flow condition. Kinematic and neuromuscular variability was greater under POF compared to NOF conditions. Young adults sought to counteract POF by rapidly correcting task-relevant gait fluctuations. The depletion of cognitive resources through dual-tasking led to reduced kinematic and neuromuscular variability and this occurred to the same extent regardless of simultaneous working memory (WM) load. Increasing WM load led to a prioritization of gait control in the mediolateral direction over the anteroposterior direction. The impact of POF on kinematic variability (step velocity) was reduced when a cognitive task was performed simultaneously, but this phenomenon was no modulated by WM load. Collectively, these results shed important light on how young adults adjust the processes involved in goal-directed locomotion when exposed to varying levels of task and environmental constraints.

Perceived cognitive fatigue has only marginal effects on static balance control in healthy young adults.

We examined the influence of perceived cognitive fatigue on static balance control in healthy young adults to gain greater clarity about this issue than provided in previous research. Based on the prevailing assumption in pertinent literature, we hypothesized that the influence of cognitive fatigue on balance control depends on the attentional effort required by the balance tasks being performed. To test this hypothesis, 44 young adults (24 women and 20 men) were alternately assigned to either the experimental group that was cognitively fatigued (using the 16-min TloadDback-task with individualized settings) or the control group (who watched a documentary). Before and after the intervention, the participants performed six balance tasks that differed in (attentional) control requirements, while recording the center of pressure (COP). From these time series, sway variability, mean speed, and sample entropy were calculated and analyzed statistically. Additionally, perceived cognitive fatigue was assessed using VAS scales. Statistical analyses confirmed that the balance tasks differed in control characteristics and that cognitive fatigue was elevated in the experimental group, but not in the control group. Nevertheless, no significant main effects of cognitive fatigue were found on any of the COP measures of interest, except for some non-robust interaction effects related primarily tosample entropy. These results suggest that, in young adults, postural control in static balance tasks is largely automatic and unaffected by task-induced state fatigue.

The Effects of Sternocleidomastoid Muscle Taping on Postural Control in Healthy Young Adults: A Pilot Crossover Study.

Background: Postural control is a complex ability, also controlled by the somatosensory connection of the neck muscles with the vestibular nuclei. This circuit seems to be interested in maintaining head stabilization during movements. The sternocleidomastoid (SCM) muscle is the dominant source of the vestibular afferents as confirmed by neurophysiological acquisition. The aim of this study is to evaluate whether the application of kinesio-tape on the SCM muscle can induce a perturbation of the standing postural control by altering the somatosensory system of the neck muscles. Methods: Thirteen healthy participants (age: 24.46 ± 3.04 yrs; 9 female) were enrolled, and the four kinesio-tape (KT) conditions were performed in a random order: without KT application (Ctrl); right KT application (R-SCM); left KT application (L-SCM); and bilateral KT application (B-SCM). All conditions were performed three times with open eyes and closed eyes. Results: There was a significant increase in the length of the centre of pressure (CoP), in the maximal oscillation, and in the anteroposterior root mean square between the three tape application conditions with respect to the Ctrl condition with open eyes. The same parameters were statistically different when the participants were blindfolded in the B-SCM condition with respect to the Ctrl condition. A statistical decrease in the difference in weight distribution between the two feet was observed in the B-SCM group with respect to the Ctrl group in both open and closed eyes conditions. Conclusions: Our results suggest that KT on the SCM muscles may involve some space-time parameters of postural control. Bilateral KT improved the weight distribution between the feet but showed a parallel increase in anteroposterior oscillations and in the length of the CoP with respect to the Ctrl condition. The perturbation seems to be greater in the somatosensory system when it is working coupled with visual afferences during an upright position.

Dominance of Attention Focus and Its Electroencephalogram Activity in Standing Postural Control in Healthy Young Adults.

Attention focus changes performance, and external focus (EF) improves performance compared to internal focus (IF). However, recently, the dominance of attention focus, rather than the effectiveness of unilateral EF, has been examined. Although the positive effects of EF on standing postural control have been reported, the dominance of attention focus has not yet been examined. Therefore, the purpose of this study was to examine the dominance of attention focus and its neural mechanism in standing postural control using electroencephalography (EEG). A standing postural control task under IF and EF conditions was performed on healthy young men. Gravity center sway and cortical activity simultaneously using a stabilometer and an EEG were measured. Participants were classified into IF-dominant and EF-dominant groups according to their index of postural stability. The EEG was analyzed, and cortical activity in the theta-wave band was compared between the IF-dominant and EF-dominant groups. Significant neural activity was observed in the left parietal lobe of the IF-dominant group in the IF condition, and in the left frontal lobe of the EF-dominant group in the EF condition (p < 0.05). Differences in EEG activity between IF-dominant and EF-dominant groups, in standing postural control, were detected. This contributes to the development of training methods that consider attentional focus dominance in postural control.

Increased Arm Swing and Rocky Surfaces Reduces Postural Control in Healthy Young Adults.

Fall-induced injuries can stem from a disruption in the postural control system and place a financial burden on the healthcare system. Most gait research focused on lower extremities and neglected the contribution of arm swing, which have been shown to affect the movement of the center of mass when walking. This study evaluated the effect of arm swing on postural control and stability during regular and rocky surface walking. Fifteen healthy young adults (age = 23.4 ± 2.8) walked on these two surfaces with three arm motions (normal, held, and active) using the CAREN Extended-System (Motek Medical, Amsterdam, NL). Mean, standard deviation and maximal values of trunk linear and angular velocity were calculated in all three axes. Moreover, step length, time and width mean and coefficient of variation as well as margin of stability mean and standard deviation were calculated. Active arm swing increased trunk linear and angular velocity variability and peak values compared to normal and held arm conditions. Active arm swing also increased participants’ step length and step time, as well as the variability of margin of stability. Similarly, rocky surface walking increased trunk kinematics variability and peak values compared to regular surface walking. Furthermore, rocky surface increased the average step width while reducing the average step time. Though this surface type increased the coefficient of variation of all spatiotemporal parameters, rocky surface also led to increased margin of stability mean and variation. The spatiotemporal adaptations showed the use of “cautious” gait to mitigate the destabilizing effects of both the active arm swing and rocky surface walking and, ultimately, maintain dynamic stability.

Cognitive exergame training and transcranial random noise stimulation effects on executive control in healthy young adults.

Objective: In the present study, we investigated the efficacy of transcranial random noise stimulation (tRNS) combined with an exergame training (physical exercise combined with a videogame) chosen as potential techniques to boost brain functioning and to promote plastic effects in healthy young adults. The aim was to improve the motor response speed and the response time when inhibition was required. Method: Forty-nine participants were randomly assigned to four conditions. The protocol consisted of eight sessions of exergame cognitive training (or no training) associated with the active or sham stimulation of the left dorsolateral prefrontal cortex (left-DLPFC). Results: The results indicated faster simple reaction times following the exergame training, and faster reaction times in Go trials (while the ratio of NoGo trials remained unaltered) following tRNS. No interactions were present between the two procedures. Conclusions: These findings reveal better performance in both tasks with independent effects of the two techniques. Using noninvasive brain stimulation and exergame training may be a viable strategy to increase motor response speed and improve executive control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

UPPER LIMB RELATED FACTORS IN DETERMINING POSTURAL CONTROL

Postural control is an outcome of complex interactions between many systems and structures to control body position in space. Appropriate postural control is necessary for the initiation and continuation of movements in different body parts, such as the upper limbs. Although the importance of maintaining postural control for movement is well recognized, its relationship with upper limb functions is unknown. The present study investigated the factors related to the upper limb in determining postural control in healthy young adults. We included 68 nonsymptomatic individuals in this cross-sectional study. The static and dynamic postural stability and upper limb performance parameters of the participants were evaluated. Multiple Linear Regression analysis was performed to determine the independent determinants of postural control. According to the results of the analysis, Six Minute Peg Board Ring Test (6PBRT) explaining 11% of the variance was the independent determinant of static general stability index (p&lt;0.05). Nine-Hole Peg Test (9HPT) explaining 5.3% of the variance was the independent determinant of static anterior-posterior stability index (p&lt; 0.05). It was concluded that upper limb functions were a determinant of static postural control in non-symptomatic young adults. The 6PBRT and Medicine Ball Chest Launch Test (MBCLT) explaining 16.5% of the variance were found as independent determinants of static medial-lateral stability index (p&lt;0.05). It was concluded that upper limb functions were a determinant of static postural control in non-symptomatic young adults. There was no significant relationship between dynamic stability indices and upper extremity functional parameters (p&gt;0.05). It was concluded that upper limb functions were a determinant of static postural control in non-symptomatic young adults.

History of conditioned reward association disrupts inhibitory control: an examination of neural correlates

The neural processes that support inhibitory control in the face of stimuli with a history of reward association are not yet well understood. Yet, the ability to flexibly adapt behavior to changing reward-contingency contexts is important for daily functioning and warrants further investigation. This study aimed to characterize neural and behavioral impacts of stimuli with a history of conditioned reward association on motor inhibitory control in healthy young adults by investigating group-level effects as well as individual variation in the ability to inhibit responses to stimuli with a reward history. Participants (N = 41) first completed a reward conditioning phase, during which responses to rewarded stimuli were associated with money and responses to unrewarded stimuli were not. Rewarded and unrewarded stimuli from training were carried forward as No-Go targets in a subsequent go/no-go task to test the effect of reward history on inhibitory control. Participants underwent functional brain imaging during the go/no-go portion of the task. On average, a history of reward conditioning disrupted inhibitory control. Compared to inhibition of responses to stimuli with no reward history, trials that required inhibition of responses to previously rewarded stimuli were associated with greater activity in frontal and striatal regions, including the inferior frontal gyrus, insula, striatum, and thalamus. Activity in the insula and thalamus during false alarms and in the ventromedial prefrontal cortex during correctly withheld trials predicted behavioral performance on the task. Overall, these results suggest that reward history serves to disrupt inhibitory control and provide evidence for diverging roles of the insula and ventromedial prefrontal cortex while inhibiting responses to stimuli with a reward history.

Effect of Oyster Meat Preload on Postmeal Glycemic Control in Healthy Young Adults

Objective: Evidence suggests that food preload improves postmeal glycemic profiles, but the effects of marine food are poorly understood. Our study aims to verify the regulating effects of premeal oyster meat (OM) on postprandial blood glucose.Method: Edible parts of the flesh of oyster were prepared for a randomized crossover experiment. After overnight fasting, 20 healthy young men consumed 300 mL of preload drinks with 0 g/kg body weight (BW) (control), 0.1 g/kg BW, and 0.2 g/kg BW. Peripheral blood concentrations of glucose and gastrointestinal hormones were measured before preloading at baseline (0 minutes) and at intervals after the preload and after a preset rice meal. The nutrient composition of OM was analyzed.Results: Compared with other doses, 0.2 g/kg BW OM preload induced higher plasma premeal insulin (p < 0.05), C-peptide (p < 0.05), and glucagon-like peptide-1 (GLP-1; p < 0.05) without altering the glucose concentrations during premeal times. By contrast, 0.2 g/kg BW OM induced less secretion of glucose (p < 0.05) and gastric inhibitory peptide (GIP; p < 0.05), but higher secretion of GLP-1 (p < 0.05) than 0.1 g/kg BW of OM after a meal. During the entire experiment (0–170 minutes), OM reduced the blood glucose (p < 0.05) and GIP (p < 0.05), but increased GLP-1 (p < 0.05). OM was rich in protein (78.4%) and low in fat (6%). Glutamic acid, aspartic acids, glycine, and taurine are the amino acids with high content found in OM.Conclusions: OM preload reduces postmeal glycemia in healthy young people with associated changes in gastrointestinal hormone responses. This effect may be attributed to the rich contents of protein and amino acids of OM.

Contractile properties of superficial skeletal muscle affect postural control in healthy young adults: A test of the rambling and trembling hypothesis.

The rambling and trembling analysis separates the center of pressure (COP) fluctuations into two components: rambling (supraspinal contribution) and trembling (muscle stiffness / reflexive properties contribution). We examined whether the trembling component is correlated to the contractile properties (muscle stiffness and contraction time) of lower limb superficial skeletal muscles to experimentally test the rambling and trembling hypothesis. We hypothesized that muscle stiffness and contraction time, would be: (a) more correlated with; and (b) have a greater impact on the trembling component compared to the rambling component. Thirty-two healthy young adults were recruited for the study and tensiomyography was used to assess mechanical muscle responses to a single electrical stimulus to calculate muscle stiffness and contraction time based on radial muscle belly displacement measurements of lower limb muscles unilaterally. Moreover, upright postural control was assessed using a force plate to record ground reaction forces and moments and calculate the COP fluctuations during two 30 seconds trials. From the COP fluctuations, rambling and trembling time series were extracted, and all fluctuation time series were described using a number of different time-domain and frequency-domain parameters in both the anterior-posterior and medial-lateral directions. Our results demonstrated that both muscle stiffness and contraction time were moderately correlated with time-domain and frequency-domain parameters of the trembling component, as compared with those of the rambling component which was not as well correlated. Moreover, they also predicted the trembling component better. Overall, these results imply that postural control during quiet stance is, in part, related to intrinsic muscle stiffness in the lower extremities. Moreover, we showed that the rambling and trembling hypothesis is effective in separating postural sway fluctuations during upright posture to extract the contributions of muscle stiffness / reflexive properties (trembling), and likely the supraspinal contribution (rambling).

Tasked-Based Functional Brain Connectivity in Multisensory Control of Wrist Movement After Stroke.

In this study we documented brain connectivity associated with multisensory integration during wrist control in healthy young adults, aged matched controls and stroke survivors. A novel functional MRI task paradigm involving wrist movement was developed to gain insight into the effects of multimodal sensory feedback on brain functional networks in stroke participants. This paradigm consisted of an intermittent position search task using the wrist during fMRI signal acquisition with visual and auditory feedback of proximity to a target position. We enrolled 12 young adults, 10 participants with chronic post-stroke hemiparesis, and nine age-matched controls. Activation maps were obtained, and functional connectivity networks were calculated using an independent component analysis (ICA) approach. Task-based networks were identified using activation maps, and nodes were obtained from the ICA components. These nodes were subsequently used for connectivity analyses. Stroke participants demonstrated significantly greater contralesional activation than controls during the visual feedback condition and less ipsilesional activity than controls during the auditory feedback condition. The sensorimotor component obtained from the ICA differed between rest and task for control and stroke participants: task-related lateralization to the contralateral cortex was observed in controls, but not in stroke participants. Connectivity analyses between the lesioned sensorimotor cortex and the contralesional cerebellum demonstrated decreased functional connectivity in stroke participants (p < 0.005), which was positively correlated the Box and Blocks arm function test (r2 = 0.59). These results suggest that task-based functional connectivity provides detail on changes in brain networks in stroke survivors. The data also highlight the importance of cerebellar connections for recovery of arm function after stroke.

Motor control strategies during bimanual isometric force control among healthy individuals

This study aimed to provide a basic description of the motor control strategy during bimanual isometric force control in healthy young adults. Thirty healthy young adults (mean age: 27.4 ± 3.7 years) participated in the study. The subjects were instructed to press both hands simultaneously to match the target force level of 5%, 25%, and 50% bimanual maximum voluntary force using continuous visual feedback. Bimanual motor synergy and bimanual coordination, as well as force asymmetry, force accuracy, and force variability were compared. This study identified the specific motor control strategy of healthy young adults during bimanual isometric force control, indicating that they proportionally increased “good” and “bad” variabilities, resulting in comparable bimanual motor synergy as the target force level increased.

Postural control in healthy young adults using a double seesaw device

Postural control on single and double seesaws was investigated in young healthy adults required to stand as still as possible on two side-by-side seesaws favoring pitch motion and lying on two separate force platforms. The device offers the possibility to get associated or dissociated seesaws and, if dissociated, to induce asymmetric patterns for the centers-of-pressure (CP) under both left and right feet by using different radii for the two seesaws. Substituting a parallelepiped volume to one seesaw offering a firm contact to one foot is also possible. The results indicated that dissociating the two seesaws led to increased resultant CP (CPRes) and vertically projected center-of-gravity movements (CGv) only along the mediolateral axis, whereas a slight decreasing tendency characterized these movements along the antero-posterior axis. When standing on two independent seesaws with different radii, significantly larger CP displacements were seen along the antero-posterior axis under the foot lying on the more stable support, i.e., the seesaw with the longer radius or the parallelepiped volume. In these two asymmetrical conditions, the CPRes output results from a compensatory mechanism, i.e. larger movements under one foot to compensate for the decreased movements occurring under the opposite foot. This postural control strategy is aimed at allowing sufficient CPRes displacements in order to appropriately secure balance. Because of the complex sensorimotor coordination induced, involving differentially in certain cases both legs, the double seesaw device can be viewed as a possible tool for challenging postural control by inducing asymmetrical patterns between left and right feet CP movements.

Increased Postural Demand Is Associated With Greater Cognitive Workload in Healthy Young Adults: A Pupillometry Study.

Introduction: Balance tasks require cognitive resources to ensure postural stability. Pupillometry has been used to quantify cognitive workload of various cognitive tasks, but has not been studied in postural control. The current investigation utilized pupillometry to quantify the cognitive workload of postural control in healthy young adults. We hypothesized that cognitive workload, indexed by pupil size, will increase with challenging postural control conditions including visual occlusion and cognitive dual tasking.Methods: Twenty-one young healthy adults (mean ± standard error of the mean), (age = 23.2 ± 0.49 years; 12 females) were recruited for this study. Participants completed four tasks: (1) standing with eyes open; (2) standing with eyes occluded (3) standing with eyes open while performing an auditory Stroop task; and (4) standing with eyes occluded while performing an auditory Stroop task. Participants wore eye tracking glasses while standing on a force platform. The eye tracking glasses recorded changes in pupil size that in turn were converted into the Index of Cognitive Activity (ICA). ICA values were averaged for each eye and condition. A two-way Analysis of Variance with post-hoc Sidak correction for pairwise comparisons was run to examine the effect of visual occlusion and dual tasking on ICA values as well on Center of Pressure (CoP) sway velocity in anterior–posterior (AP) and medio-lateral (ML) directions. A Pearson’s correlation coefficient was utilized to determine the relationship between ICA values and CoP sway velocity.Results: Significant within-condition effect was observed with visual occlusion for the right eye ICA values (p = 0.008). Right eye ICA increased from eyes open to eyes occluded conditions (p = 0.008). In addition, a significant inverse correlation was observed between right eye ICA values and CoP sway velocity in the ML direction across all the conditions (r = -0.25, p = 0.02).Conclusion: This study demonstrated support for increased cognitive workload, measured by pupillometry, as a result of changes in postural control in healthy young adults. Further research is warranted to investigate the clinical application of pupillometry in balance assessment.

Developing clinically practical transcranial direct current stimulation protocols to improve saccadic eye movement control.

Recent research indicates that anodal transcranial direct current stimulation (tDCS) applied over the frontal eye field (FEF) can improve saccadic eye movement control in healthy young adults. The current research set out to determine whether similar results can be produced using a clinically practical protocol, whether tDCS applied over the dorsolateral prefrontal cortex (DLPFC) might also afford benefits, and whether benefits extend to older adults. Twenty young and 10 older adults completed two active (FEF and DLPFC) and one sham stimulation session. To aid clinical translation, the method of positioning the electrodes entailed simple measurements only. Saccadic performance following anodal tDCS applied over the FEF or DLPFC did not differ from the sham condition in either age group. Additionally, saccadic performance contralateral to the active electrodes showed no evidence of benefits over ipsilateral performance. These results call into question whether the protocol utilized can be applied effectively using only simple measurements to localize the relevant frontal subregion. Future efforts to develop a clinically practical tDCS protocol to improve saccadic eye movement control should include a sham control condition and consider adjusting the tDCS electrode montage and current strength to optimize the chances of conferring benefits in the population under study.

Inducing Proactive Control Shifts in the AX-CPT.

The Dual Mechanisms of Control (DMC) account (Braver, 2012) proposes two distinct mechanisms of cognitive control, proactive and reactive. This account has been supported by a large number of studies using the AX-CPT paradigm that have demonstrated not only between-group differences, but also within-subjects variability in the use of the two control mechanisms. Yet there has been little investigation of task manipulations that can experimentally modulate the use of proactive control in healthy young adults; such manipulations could be useful to better understand the workings of cognitive control mechanisms. In the current study, a series of three experiments demonstrate how individuals can be systematically biased toward and away from the utilization of proactive control, via strategy training and no-go manipulations, respectively. These results provide increased support for the DMC framework, and provide a new basis from which to examine group-based differences and neural mechanisms underlying the two control modes.

The effect of head up tilting on bioreactance cardiac output and stroke volume readings using suprasternal transcutaneous Doppler as a control in healthy young adults.

To compare the performance of a bioreactance cardiac output (CO) monitor (NICOM) and transcutaneous Doppler (USCOM) during head up tilting (HUT). Healthy young adult subjects, age 22±1years, 7 male and 7 female, were tilted over 3-5s from supine to 70° HUT, 30° HUT and back to supine. Positions were held for 3min. Simultaneous readings of NICOM and USCOM were performed 30s into each new position. Mean blood pressure (MBP), heart rate (HR), CO and stroke volume (SV), and thoracic fluid content (TFC) were recorded. Bland-Altman, percentage changes and analysis of variance for repeated measures were used for statistical analysis. Pre-tilt NICOM CO and SV readings (6.1±1.0L/min and 113±25ml) were higher than those from USCOM (4.1±0.6L/min and 77±9ml) (P<0.001). Bland-Altman limits of agreement for CO were wide with a percentage error of 38%. HUT increased MBP and HR (P<0.001). CO and SV readings decreased with HUT. However, the percentage changes in USCOM and NICOM readings did not concur (P<0.001). Whereas USCOM provided gravitational effect proportional changes in SV readings of 23±15% (30° half tilt) and 44±11% (70° near full tilt), NICOM changes did not being 28±10 and 33±11%. TFC decreased linearly with HUT. The NICOM does not provide linear changes in SV as predicted by physiology when patients are tilted. Furthermore there is a lack of agreement with USCOM measurements at baseline and during tilting.

Postural Control in Healthy Young Adults with and without Chronic Motion Sensitivity

Background: Postural control requires complex processing of peripheral sensory inputs from the visual, somatosensory and vestibular systems. Motion sensitivity and decreased postural control are influenced by visual-vestibular con flicts. The purpose of this study was to measure the difference between the postural control of healthy adults with and without history of sub-clinical chronic motion sensitivity using a computerized dynamic posturography in a virtual reality environment. Sub-clinical chronic motion sensitivity was operationally defined as a history of avoiding activities causing dizziness, nausea, imbalance, and/or blurred vision without having a related medical diagnosis. Methods: Twenty healthy adults between 22 and 33 years of age participated in the study. Eleven subjects had sub-clinical chronic motion sensitivity and 9 subjects did not. Postural control was measured in both groups using the Bertec Balance Advantage-Dynamic Computerized Dynamic Posturography with Immersion Virtual Reality (CDP-IVR). The CDP-IVR reports an over-all equilibrium score based on subjects’ center of gravity displacement and postural sway while immersed in a virtual reality environment. Subjects were tested on stable (condition 1) and unstable (condition 2) platform conditions. Results: There was no significant difference between the two groups in terms of mean age, height, weight, body mass index in kg/m2, postural control scores for conditions 2, and average (p>0.05). However, significant differences were observed in mean postural control for condition 1 between groups (p=0.03). Conclusions: Results of this study suggest that healthy young adults without chronic sub-clinical motion sensitivity have better postural control than those with chronic sub-clinical motion sensitivity. Further investigation is warranted to explore wider age ranges with larger samples sizes as well as intervention strategies to improve postural control.

Postural Control in Dual-Task Situations: Does Whole-Body Fatigue Matter?

Postural control is important to cope with demands of everyday life. It has been shown that both attentional demand (i.e., cognitive processing) and fatigue affect postural control in young adults. However, their combined effect is still unresolved. Therefore, we investigated the effects of fatigue on single- (ST) and dual-task (DT) postural control. Twenty young subjects (age: 23.7 ± 2.7) performed an all-out incremental treadmill protocol. After each completed stage, one-legged-stance performance on a force platform under ST (i.e., one-legged-stance only) and DT conditions (i.e., one-legged-stance while subtracting serial 3s) was registered. On a second test day, subjects conducted the same balance tasks for the control condition (i.e., non-fatigued). Results showed that heart rate, lactate, and ventilation increased following fatigue (all p < 0.001; d = 4.2–21). Postural sway and sway velocity increased during DT compared to ST (all p < 0.001; d = 1.9–2.0) and fatigued compared to non-fatigued condition (all p < 0.001; d = 3.3–4.2). In addition, postural control deteriorated with each completed stage during the treadmill protocol (all p < 0.01; d = 1.9–3.3). The addition of an attention-demanding interference task did not further impede one-legged-stance performance. Although both additional attentional demand and physical fatigue affected postural control in healthy young adults, there was no evidence for an overadditive effect (i.e., fatigue-related performance decrements in postural control were similar under ST and DT conditions). Thus, attentional resources were sufficient to cope with the DT situations in the fatigue condition of this experiment.

Effect of induced fatigue on dynamic postural balance in healthy young adults

Background Fatigue may impair the proprioceptive and kinesthetic properties of joints and has been shown to have a negative effect on neuromuscular control, thus increasing the risk for injury. Purpose This study aimed to determine the effect of induced whole-body fatigue on dynamic balance control in healthy young adults. Participants and methods Thirty healthy young participants of both sexes were included in this study; their ages ranged between 18 and 22 years. All of the participants were tested on the Biodex Stability System (BSS) at a stability level 4, subjected to induced fatigue on a treadmill, and then retested directly on the BSS again to evaluate dynamic postural balance. Results There was a significant decrease in the overall stability index, anteroposterior stability index, and mediolateral stability index of dynamic balance at stability level 4 of BSS in healthy young adults as P -values were 0.0001, 0.0001, and 0.0001, respectively. Conclusion and implication It was concluded that induced whole-body fatigue decreased the dynamic postural balance (overall stability index, anteroposterior stability index, and mediolateral stability index) in healthy young adults. This implies that muscles of a fatigued individual are at increased risk for musculoskeletal injury, and steps should be taken during conditioning and rehabilitation programs to prevent muscle fatigue through balance training and endurance exercises to avoid disturbed balance related to fatigue among young healthy adults.