Counting Backwards Research Articles

Effects of Simultaneous Cognitive Task on Gait Event Accuracy with Auditory Stimuli: Comparison between Young Adults in Their 20s and the Elderly in their 70s

The purpose of this study was to compare the difference in the accuracy of gait events between young and older adults during metronomic walking by auditory cueing. Additionally, age-specific changes in the gait event accuracy according to additional simultaneous cognitive tasks were examined. The time interval (or temporal error) between the auditory cue (i.e., metronome) and the heel contact was used as the accuracy of the gait event. Fifteen young group (YG, 24.7 ± 0.8 years) and 14 elderly (EG, 78.4 ± 5.5 years) people participated in the experiment. The temporal errors under two gait conditions (MET: walking with metronome; MET + BC: walking with metronome while counting backward) were compared for each group. The results revealed that all the temporal errors of EG were significantly greater than those of YG. While the addition of simultaneous cognitive tasks resulted in a significant increase in temporal error in both age groups, the coefficient of variation (CV) of the temporal error significantly increased only in the EG group. In other words, although heel contact accuracy with auditory stimuli was affected by the simultaneous cognitive task in both groups, it was demonstrated that the variability of the error in the young adults remained constant. Therefore, the time error measurement used in this study has the potential to be used as a tool to judge the gait instability of the elderly compared with young adults.

Coordination between motor and cognitive tasks in dual task gait

BackgroundDual Task (DT) paradigms are frequently used by researchers and clinicians to examine the integrity of motor processes in many movement disorders. However, the mechanism of this interaction is not fully understood. Therefore, the aim of this study was to examine the within-stride interactions between cognitive and motor processes during dual task gait (DT). Research questionDo healthy young adults coordinate gait with secondary task processing? If so, is cognitive task processing capability associated with the coordination observed? MethodsNineteen healthy young adults walked for two minutes on a motorized treadmill whilst counting backwards in sevens from three-digit numbers. The coordination of calculation verbalizations with gait parameters were assessed across six phases of the gait cycle. Mid verbalization time points (VERMid) were used as points of high cognitive processing of the dual task and compared with the end of the verbalizations (VEREnd) as points of low cognitive processing. ResultsVERMid and VEREnd did not systematically occur in any phase of the gait cycle. However, 10/19 and 9/19 participants showed non-random distributions of verbalizations for VERMid and VEREnd time points respectively (p < 0.01), indicating that these walkers coordinated gait with the cognitive task. Analysis of subgroups of Verbalization Coordinators and Non-Coordinators showed slower verbalization response durations (VRD) for VERMid Coordinators compared to VERMid Non-Coordinators, indicating that VERMid Coordinators found the cognitive tasks more demanding. No differences were found in VRD for VEREnd Coordinators and VEREnd Non-Coordinators. SignificanceIt was found that cognitive processing is coordinated with gait phases in some but not all healthy young adults during DT gait. When demands on cognitive processes are high, healthy young adults coordinate cognitive processing with phases of gait. Analysis of within-stride coordination may be of use for studying clinical conditions where gait and attentional cognition performance breaks down.

Current Fertility Status Does Not Predict Sociosexual Attitudes and Desires in Normally Ovulating Women.

Previous research has found that women at peak fertility show greater interest in extra-pair sex. However, recent replications have failed to detect this effect. In this study, we add to this ongoing debate by testing whether sociosexuality (the willingness to have sex in the absence of commitment) is higher in women who are at peak fertility. A sample of normally ovulating women (N = 773) completed a measure of sociosexuality and had their current fertility status estimated using the backward counting method. Contrary to our hypothesis, current fertility was unrelated to sociosexual attitudes and desires, even when relationship status was included as a moderator. These findings raise further doubts about the association between fertility and desire for extra-pair sex.

Comparison of postural control in older adults under different dual-task conditions: A cross-sectional study

Backgroundand purpose: Performing a cognitive task while maintaining postural stability, known as “dual-task” condition, can increase the cognitive demand and reduce the postural control capacity. The inability to allocate attention to postural control under dual-task conditions may lead to balance impairments, particularly in older adults. The present study aimed to compare the effects of different dual-task conditions of backward counting (BC) and visual attention (VA) on older adults’ postural balance performance. MethodsTwenty asymptomatic volunteers (mean age: 70.4 ± 4.1 years) were recruited. Participants stood on a foam surface placed over a force plate, and displacement and sway velocity of their center of pressure (COP) in anterior-posterior (AP) and medial-lateral (ML) directions were recorded under three conditions: BC dual-task, VA dual-task (control of center of mass with a laser pointer), and quiet stance as the control task (CT). ResultsRepeated measures ANOVA showed a significant difference in AP and ML sway velocities between conditions with p-values of 0.039 and 0.042, respectively. The LSD post-hoc test revealed that the BC task significantly increased AP sway velocity compared to the CT (p = 0.013), and the VA task significantly increased ML sway velocity compared to the CT (p = 0.034) and the BC tasks (p = 0.026). There were no statistically significant differences between conditions for ML (p = 0.058) and AP (p = 0.350) displacements and total sway velocity (p = 0.051). ConclusionOlder adults’ postural stability can be impaired under dual-task conditions and the present study revealed that various dual tasks increase postural sway in different directions.

Gait impairments on single and dual tasks in cerebral amyloid angiopathy

AbstractBackgroundCerebral Amyloid Angiopathy (CAA) is a small vessel disease wherein amyloid beta protein is deposited in the vessels of the cerebral cortex and leptomeninges. Little is known about CAA and gait impairment, even though gait is known to be affected by Alzheimer’s disease (AD). We hypothesized that gait would be impaired in CAA compared to normal controls (NC), and that more complex mental tasks would elicit further impairments in AD compared to CAA.MethodParticipants were NC (n=44), non‐demented CAA (n=31), and mild AD‐dementia (n=16). The ProtoKinetics Walkway was used to capture footfalls over a 6 m walk during a single task (walking only) and two dual tasks of differing complexity (counting backwards by ones [simple task] and naming animals [complex task]). For gait velocity, the dual task cost was calculated as the percent change during dual task compared to preferred pace walking. Analysis of covariance was used to test group differences, controlling for age, sex, and height.ResultCAA participants were older and more likely to be men (Table 1). Gait parameters during preferred pace walk, dual task with counting backwards, and dual task with animal naming are shown in Tables 2‐4. Across all three tasks, both CAA and AD performed poorer than NC on mean Stride Length, Stride Length variability, mean Stride Time, mean Velocity, and mean Cadence. However, mean Stride Width, and Stride Width variability did not differ. There were no differences between CAA and AD (Tables 2‐4). On measures of Velocity, the dual task cost for going from single task to counting backwards (simple dual task) was greater in AD than NC but not in CAA than NC (Table 5). The dual task cost for going from single task to naming animals (complex dual task) was greater in AD than CAA and NC.ConclusionGait is impaired in CAA to a similar extent as in AD, however dual task cost was higher for AD possibly because of greater cognitive impairment. Future research should investigate causes of gait impairments in CAA, including the effects of hemorrhagic and ischemic lesions such as white matter hyperintensities.

RELIABILITY OF CENTER OF PRESSURE-BASED MEASURES DURING DUAL-TASK POSTURAL CONTROL TESTING IN A YOUTH POPULATION.

Dual-task assessments can identify changes in postural control during recovery from a concussion. However, developing postural control in children presents a challenge when using adult balance assessments to examine children. The purpose of this study was to investigate the reliability of a cognitive dual-task postural control testing protocol among a youth sample with no history of concussion or exposure to head impacts. Reliability pilot study. Testing comprised nine 120 second trials of standing on a force plate collecting data at 250 Hz. Test conditions included no dual-task, counting backwards by 2, counting backwards by 3, listening, and the Stroop test. Subjects completed each test with open and closed eyes, except for the Stroop test. The force plate was used to measure the subjects' center of pressure (COP) trajectory. Nine healthy, youth subjects (average age: 11.6 ± 0.5 years) with no history of concussion or exposure to head impacts participated. Reliability was good (>0.6) or excellent (>0.75) for COP speed, sway, and sample entropy measures for several test conditions. The eyes open, no task condition produced the lowest COP measures. No differences were observed between the other dual-task conditions. Given its high measures of reliability, this dual-task protocol might be able to detect postural control changes in concussed youth athletes. 2.

Intention to Respond in a Special Way Protects against Forgetting Associations Even When Working Memory Is Occupied

Abstract In 2 experiments, subjects engaged in 6 or 7 124-trial blocks of a continuous memory-updating paradigm with study and test trials intermixed. They studied name–location associations and were tested for the location most recently associated with a given name. On study trials, all responses were to be made on a right-hand map. On default test trials, responses were also to be made on the right-hand map, but on special test trials, designated as such during study (by showing the associations in green), responses were to be made on a left-hand map. Both default and special test trials occurred after short (2-back) and long (8-back) retention intervals. In the penultimate (Experiment 1) or last (Experiment 2) block, trials occurred under conditions in which working memory was occupied with a concurrent secondary counting backwards task. Memory for the name–location associations was better with short than with long retention intervals and was better when special (rather than default) responses were to be made, especially at the long retention interval, even with counting backwards. Thus, the intention to respond in a special way protects against forgetting associations, and this protection is not simply due to holding the information from the special trials in working memory.

The impact of distinct cognitive dual-tasks on gait in Parkinson's disease and the associations with the clinical features of Parkinson's disease.

To investigate the impact of distinct cognitive dual-task abilities in patients with Parkinson's disease (PD) and compare the impact of these dual-tasks in association with the severity of PD and its clinical features. Modified Hoehn and Yahr Scale, UPDRS, and Standardized Mini-Mental State Examination (SMMSE) were evaluated in all PD patients. The subtype of PD and the presence of freezing of gait (FOG) were also evaluated. The Timed Up and Go (TUG) test was applied under single- and dual-task conditions including the digit span-forwards, digit span-backwards, delayed recall memory, counting down the days, counting backwards from 20, and animal fluency tests. Most of the cognitive dual-tasks resulted in deterioration in gait performance in our PD subjects. Remarkably, the completion time of TUG duration under single- and dual-task of counting down days was higher in the FOG (+) PD subjects (p = 0.008, p = 0.050, respectively). Besides, the TUG duration under the dual-task of counting down days was found to be positively correlated with the UPDRS-motor scores and FOG scores. We think that the concurrent execution of the dual-task of counting down days, which requires complex attentional skills, may disturb gait via a mechanism of overloading of the attentional reserves proceeding gait which is already defective in PD subjects. The neural correlate of this domain and its significance in performing dual-tasks in PD should be investigated in future large-scale studies. The results of these studies may provide substantial perspectives regarding the pathophysiology of gait disturbance in PD.

Does the transcranial direct current stimulation improve dual-task postural control in young healthy adults?

Some studies have suggested that postural balance improved after a single session of transcranial direct current stimulation (tDCS), whereas others have found minimal, if any, effects on postural performance. To address the issue of replication in tDCS studies, we re-tested the anodal tDCS effects of left dorsolateral prefrontal cortex while performing a dual-task by increasing the attentional demands associated with more challenging proprioceptive conditions. Twenty-four young adults (mean age: 21.3 ± 1.2years) were randomly divided into two groups (a "real tDCS" vs. a "sham tDCS" group) were asked to maintain a quiet stance on a force platform. Eight trials were conducted, with eyes open and eyes closed, standing on a firm and foam surface and performing a simple and dual-task (backward counting). The postural performance was assessed by various centre-of-pressure parameters before and immediately after a 20-min tDCS session. No main effect of group and no interaction considering this factor were observed, regardless of the centre-of-pressure variables (all p values > 0.1). No evidence of a more efficient postural control emerged after a tDCS session. Beyond promising research on tDCS to maximize cognitive and behavioural enhancement, the current results indicate that caution needs to be taken when drawing firm conclusions, at least in young healthy adults.

Dual-task gait speed assessments with an electronic walkway and a stopwatch in older adults. A reliability study.

Slow gait speed prospectively predicts elevated risk of adverse events such as falls, morbidity, and mortality. Additionally, gait speed under a cognitively demanding challenge (dual-task gait) predicts further cognitive decline and dementia incidence. This evidence has been mostly collected using electronic walkways; however, not all clinical set ups have an electronic walkway and comparability with simple manual dual-gait speed testing, like a stopwatch, has not yet been examined. Our main objective was to assess concurrent-validity and reliability of gait speed assessments during dual-tasking using a stopwatch and electronic walkway in older adults with mild and subjective cognitive impairment (MCI and SCI). Cross-sectional, reliability study. Clinic based laboratory at an academic hospital in London, ON, Canada. 237 walk tests from 34 community-dwelling participants (mean age 71.84 SD 5.38; 21 female - 62%, 13 male - 38%) with SCI and MCI. were included from the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) study. Each participant performed seven walk tests: three single gait walks at their normal pace, three dual-task walks (walking and counting backwards by one, by sevens, and naming animals), and one fast walk. Gait speed (cm/s) for each walk was measured simultaneously with an electronic walkway (Zeno Mat®) and a handheld stopwatch (Ultrak chronometer®). Dual-task cost (DTC) was calculated for the three individual dual-task walks as [((single gait speed-dual-task gait speed)/single gait speed)∗100]. Level of agreement between the two measurement methods was analyzed using Pearson correlations, paired t-tests, and Bland-Altman plots. Gait speed was consistently lower when measured with the stopwatch than with the electronic walkway (mean speed difference: 10.6cm/s±5.1, p<0.001). Calculating DTC, however, yielded very similar results with both methods (mean DTC difference: 0.19±1.18, p=0.872). The higher the DTC, the closer the measurement between methods. Assessing and calculating DTC with a stopwatch is simple, accessible and reliable. Its validity and reliability were high in this clinical sample of community older adults with SCI and MCI.

Dorsolateral prefrontal cortex-based control with an implanted brain\u2013computer interface

The objective of this study was to test the feasibility of using the dorsolateral prefrontal cortex as a signal source for brain–computer interface control in people with severe motor impairment. We implanted two individuals with locked-in syndrome with a chronic brain–computer interface designed to restore independent communication. The implanted system (Utrecht NeuroProsthesis) included electrode strips placed subdurally over the dorsolateral prefrontal cortex. In both participants, counting backwards activated the dorsolateral prefrontal cortex consistently over the course of 47 and 22 months, respectively. Moreover, both participants were able to use this signal to control a cursor in one dimension, with average accuracy scores of 78 ± 9% (standard deviation) and 71 ± 11% (chance level: 50%), respectively. Brain–computer interface control based on dorsolateral prefrontal cortex activity is feasible in people with locked-in syndrome and may become of relevance for those unable to use sensorimotor signals for control.

Weaker Braking Force, A New Marker of Worse Gait Stability in Alzheimer Disease.

Background: Braking force is a gait marker associated with gait stability. This study aimed to determine the alteration of braking force and its correlation with gait stability in Alzheimer disease (AD).Methods: A total of 32 AD patients and 32 healthy controls (HCs) were enrolled in this study. Gait parameters (braking force, gait variability, and fall risk) in the walking tests of Free walk, Barrier, and Count backward were measured by JiBuEn® gait analysis system. Gait variability was calculated by the coefficient of variation (COV) of stride time, stance time, and swing time.Results: The braking force of AD was significantly weaker than HCs in three walking tests (P < 0.001, P < 0.001, P = 0.007). Gait variability of AD showed significant elevation than HCs in the walking of Count backward (COVstride: P = 0.013; COVswing: P = 0.006). Fall risk of AD was significantly higher than HCs in three walking tests (P = 0.001, P = 0.001, P = 0.001). Braking force was negatively associated with fall risks in three walking tests (P < 0.001, P < 0.001, P < 0.001). There were significant negative correlations between braking force and gait variability in the walking of Free walk (COVstride: P = 0.018; COVswing: P = 0.013) and Barrier (COVstride: P = 0.002; COVswing: P = 0.001), but not Count backward (COVstride: P = 0.888; COVswing: P = 0.555).Conclusion: Braking force was weaker in AD compared to HCs, reflecting the worse gait stability of AD. Our study suggests that weakening of braking force may be a new gait marker to indicate cognitive and motor impairment and predict fall risk in AD.

The Effects of Cognitive Task and Change of Height on Postural Stability and Cardiovascular Stress in Workers Working at Height.

The purpose of the study was to analyze the effects of cognitive task and change of height on the postural stability and cardiovascular stress of at-height workers. The study included 32 healthy men aged 25–47. Due to the type of work performed, two groups were identified: at‒height workers, HW (n = 16), and office workers (mainly work at desk with a computer) OW (n = 16). The objective measures of postural stability (posturography) and cardiovascular stress (heart rate monitor) were evaluated for both groups at two different platform heights (ground level and 1 m above the ground) with or without cognitive task (backward counting). The increased height and the cognitive task were found to significantly affect measures of postural stability and cardiovascular stress. It was observed that in inexperienced OW employees, higher platform height and performing a cognitive task meant that posture stability significantly decreased, while cardiovascular stress and difficulties in maintaining balance increased. In HW group postural stability is less affected by distress conditions than in OW group.

The associations between dual-task walking under three different interference conditions and cognitive function

Background & aimsDual-task walking is an emerging marker of cognitive impairment. However, there is uncertainty regarding which dual-task test and measure to use. The aims of this study were to determine the association between three different dual-tasks and 1) global cognition and 2) individual cognitive domains. MethodsParticipants (n = 91) were adults aged between 56–83 years (mean 68.8, SD 6.7). Under single- and dual-task, gait speed was obtained using a computerized mat. For the dual-task there were three conditions: 1) reciting alternate letters of the alphabet (DT-alpha); 2) counting backwards in 3 s (DT-counting); and 3) recalling words from a shopping list (DT-recall). Dual-task interference in gait and cognition were calculated as: (dual task–single task)/single task×100 and summed to obtain total interference. The cognitive domains of executive function, processing speed, working memory, verbal fluency, visuospatial function and verbal memory (recall and recognition) were assessed using a battery of neuropsychological tests. Raw test scores were subjected to principal component analysis to derive a global cognition score. Partial correlations were used to determine the strength of associations between single- and dual-task measures and cognitive scores, adjusting for age, sex and education. ResultsThe strongest significant associations for each cognitive outcome variable were between greater total interference under DT-alpha and lower global cognition (r = 0.25), working memory (r = 0.28) and verbal memory [recognition] (r = 0.21), greater gait interference under DT-alpha and slower processing speed (r = 0.43) and single-task gait speed and verbal fluency (r = 0.23). Associations between dual-task measures and cognition were generally weaker under the DT-counting and DT-recall. SignificanceCalculating total and gait interference during DT-alpha may be the most useful in order to identify adults with poorer cognition.

Influence Of Single Bouts Of Different Exercise Intensities On Dual-tasking Efficiency In Healthy Individuals

PURPOSE: Dual-tasking refers to concurrent performance of two physical or mental tasks. Considering the critical role of dual-tasking in daily life, it is important to develop interventions to improve its efficiency or slow down its decline with age or disease. The specific purpose of this research was to study the effects of single bouts of a moderate-intensity (MI) or high-intensity interval training (HIIT) exercise on the efficiency of the extended cognitive Timed Up and Go (ETUGcog) test, which involves concurrent performance of physical and mental tasks. METHODS: 17 males and females aged 23-35 years underwent two different single bouts of exercise sessions, a HIIT and a MI, on separate occasions, based on established protocols. Each session began with ETUGcog prior to exercise as pre-test. ETUGcog involves simultaneous performance of an extended version of Timed Up & Go test (the physical task), while counting backwards by sevens starting from a given number (the mental task). The post-tests were administered immediately after the exercise when the subject cooled down to 10% above resting HR (10%HR), and 24 hours later. The test parameters that were recorded are the number of correct responses while counting backwards until test completion, and time to complete test. RESULTS: Correct responses after a HIIT session were significantly higher than pre-test responses when tested at 10%HR (5.18 + 1.43 vs 4.24 + 1.82, p=0.02), and 24 hours later (5.82 + 2.24 vs 4.24 + 1.82, p=0.002). No such improvements were seen after a MI session, as correct post-test responses at 10%HR (5.18 + 2.98) and 24 hours later (5.06 + 2.75) were similar to pre-test responses (4.79 + 2.47), with p>0.05 in both paired comparisons. Also, the times to complete ETUGcog tests were not significantly different when comparing the pre-test to both post-test times, with p>0.05, in both types of exercise sessions. CONCLUSIONS: A single bout of high-intensity, but not moderate intensity exercise, might improve dual-tasking efficiency by increasing cognitive processing speeds, without delaying activity completion times, and improvements can last a full day. This could be due to neuroplastic improvements in brain’s cognitive areas in the prefrontal cortex, caused by blood flow increases sufficient with high intensity, but not with lower intensity exercise.

How Dominant Hand and Foot Dexterity May Reveal Dementia Onset: A Motor and Cognitive Dual-Task Study.

The combined provision of an arising number of dementia cases, and the substantial absence of effective treatments, led the scientific community toward the identification of early phases of this condition. Such an effort aims at the recognition of therapeutic windows and the characterization of the disease's different grades. In the last years, Motor and Cognitive Dual-Tasks (MCDT) have been widely used to address the early diagnosis of several neurocognitive disorders, among which dementia. Here we present different protocols: the walking MCDT, the toe-tapping MCDT, and the forefinger-tapping MCDT. Moreover, each task has been performed under different cognitive conditions: no cognitive effort, counting backwards by 1, 3, and 7. In this work, we report the results obtained through the combination of different motor and cognitive tasks, and we present 2 brand-new MCDT protocols, attempting to identify a sweet-spot for early diagnosis of dementia.

Changes In Dual-task Gait Speed Following A 10-week Golf Program In Older Adults

PURPOSE: To examine the change in dual-tasking ability during gait in response to a golf exercise program in healthy, older adults. BACKGROUND: The ability of older adults to perform dual-tasking during gait has been studied as a predictor of fall risk. Therefore, it is important to investigate exercise programs that not only improve fitness and balance in older adults, but also enhance the ability to dual-task. METHODS: Fifteen healthy, older adults without previous golf experience were enrolled in a golf program with fitness testing before and after the intervention. One participant had to drop out of the study due to a work-related injury at week 8. Dual-task performance was measured using a fast-gait task while counting backwards by threes on a ProtokineticsTM walking mat. Cognitive cost was determined by normalizing the dual-task responses to a seated counting task. Paired t tests were run to determine significance. Results are presented as mean±SD. Cohen’s d effect sizes were calculated and reported as small=0.2, medium=0.5, and large=0.8. RESULTS: Gait speed during the dual-task was significantly increased following the golf program with a large effect size (1.75±0.19m/s to 1.91±0.22m/s; p=0.007; d=0.85). This increase in gait speed coincided with increases in both average stride length (2.3%; p=0.061; d=0.55) and average cadence (5.8%; p=0.059; d=0.55). Cognitive dual cost did not change between pre and post testing but trended towards improving (40.94%; p=0.207; d=0.35). CONCLUSION: Golf is a unique, multimodal activity that has a beneficial impact on fitness in healthy, older adults. This study demonstrated that a golf program can improve the ability to perform dual tasking. Participants were able to increase their gait speed without compromising the amount of numbers they could recite correctly. The participants trended towards an improved correct response rate following the program as shown by the improvement in cognitive dual cost. Golf should be encouraged as a physical activity program for older adults. Supported by R&A Grant GHA0012017.

Lower Extremity Neuromuscular Alteration During Dual Cognitive Standing Balance Tasks In Adults Diagnosed With Hiv

Individuals diagnosed with human immunodeficiency virus (HIV) often present with impaired postural control as a consequence of proprioceptive alteration, due to secondary effects of prescription medication. PURPOSE: This study seeks to evaluate lower extremity neuromuscular activation during dual postural control tasks in individuals living with HIV. METHODS: Twenty-three participants of Hispanic-latino origin diagnosed with HIV (18 male and 5 female, average age 55± 1.7 years) with an average CD4 count of 698.8 (22 years of HIV diagnosis) enrolled in this study. Surface electromyography (EMG) on the tibialis anterior (TA) and gastrocnemius (GA) muscles was used on the participant’s dominant leg. Each task took approximately 15 seconds to finish. Each participant was instructed to quietly stand in a bi-pedal posture on a balance foam. Four single balance and dual cognitive-balance tasks (count backwards from 100 in increments of 3) were performed on the balance foam. RESULTS: The variables of interest in this study were 1) time to peak, 2) decay and, 3) duration of muscle activation for TA and GA. A repeated measure ANOVA analysis was used to compare all variables of interest. No significant difference is indicated between duration and decay of muscle activation for TA and GA across the various tasks assessed. Throughout the cognitive balance task, GA time to peak activation was slower (P< 0.001) during eyes closed (EC) head movements (HUD) ( 7.7 +/- 0.7 seconds) when compared to HUD with eyes open (EO) (0.3+/-0.2 secs) and, eyes open (EO 0.5+/-0.2 secs). CONCLUSIONS: As the GA plays a major role in static balance, an increased fall risk could be resultant of this delay in time to peak onset. As such, our research recommends lower extremity electromyography and strength assessment in this population to forestall or decrease fall hazards.

Correlations Between Dual-task Costs In Clinic Versus Laboratory Movements

Identifying increases in injury-relevant biomechanics when athletes are distracted by a secondary task may be important for assessing performance and injury risk in athletic environments. It is unknown if this dual task cost (DTC) measured during detailed motion capture testing is associated with DTC on simple clinical tests. Such a relationship may prove useful for improving clinically feasible return-to-play assessments. PURPOSE: Investigate whether dual-task ability spans clinical and laboratory methods of assessment. METHODS: Twenty-three female soccer players (21 ± 3yrs, 1.7 ± 0.1m, 64 ± 10kg) completed an agility drill requiring two 90° turns and one 180° turn. This was completed in isolation (baseline) and under three dual-task conditions: counting backwards by seven (S7), dribbling a soccer ball (BH), and combined ball dribbling and counting tasks (BHS7). Agility drill DTC (aDTC) was calculated as the percent change in completion time between dual-task and baseline conditions. A jump-land-jump task from a 30 cm box was also completed while 3D kinematics and kinetics were recorded. Dual task jump conditions included working memory (WM), working memory + visual attention task (WMV), and unanticipated working memory + visual attention task (UWMV) tasks. Biomechanical DTC (bDTC) was calculated as the percent change in peak knee valgus moment (pkVM) between dual-task jump landings and a single-task jump landing. Spearman’s rho correlations were run between all combinations of aDTC and bDTC (Figure 1).RESULTS: Increases in aDTC for the S7 condition were associated with increases in bDTC for the WMV (ρ=0.49, p=0.02) and the WM (ρ=0.43, p=0.04) conditions. No other relationships reached significance (i.e., p>0.05). CONCLUSION: Dual-task ability spanned clinical and laboratory assessments when the secondary task was an anticipated cognitive task. Further research is needed to establish the clinical utility of these relationships.

Differential effects of working memory load on priming and recognition of real images.

Several studies have explored the effects of divided attention on priming, but little is known about the impact of working memory load on implicit visual memory. The aim of this study was to determine whether there are differential effects of working memory load on a visual priming task compared to a recognition task. In the encoding phase, participants were presented with real-object pictures and asked to classify them semantically. At retrieval, 40 studied and 40 new images were presented (partially masked) for 100ms, and participants had to identify the object. Each trial was immediately followed by a recognition test, in which the unmasked image was shown again, and participants had to indicate whether it had been presented at encoding or not. Regarding working memory load, participants performed a task in which a load was imposed in half of the trials. Twenty-four participants concurrently performed an articulatory suppression task, another group of 24 subjects performed an executive demanding task, and a third group of 24 participants performed a spatial tapping task. Working memory load failed to diminish performance on both priming and recognition tests in the articulatory suppression condition. However, the backward counting and the tapping tasks influenced recognition, rather than priming. The relative pattern of backward counting effects on recognition and priming were then broadly replicated in a follow-up experiment using an adapted priming task (N = 24). Results suggest that a concurrent load has a more robust effect on recognition than on priming, especially when the working memory task is executively demanding.