Effects of Backpack Carriage on Dual-Task Performance in Children During Standing and Walking

Dual-task costs in speed tasks: a comparison between elite ice hockey, open-skill and closed-skill sports athletes

Introduction

Ice hockey is a high pace sports game that requires players to integrate multiple skills. Players face perceptive, cognitive, and motor tasks concurrently; hence, players are regularly exposed to dual- or multi-task demands. Dual-tasking has been shown to lead to decreased performance in one or both performed tasks. The degree of performance reductions might be modulated by the exhaustion of cognitive resources. Literature on dual-task paradigms that combine sport-relevant elements is scarce. Therefore, a novel paradigm combining cyclical speed of the lower extremities and concurrent visuo-verbal speed reading was tested and validated. Additionally, to understand the nature of dual-task costs, the relationship between these costs and cognitive performance was assessed. We hypothesized occurrence of dual-task costs in all athletes without relationship to single task performance. Differences in dual-task cost were expected between open-skill and closed-skill sports, as well as differing expertise levels. Level of cognitive function was expected to explain some variance in dual-task cost.

Methods

A total of 322 elite athletes (120 ice hockey, 165 other team sports, 37 closed-skill sports) participated in this study. Each athlete performed a tapping task, a visuo-verbal speed-reading task, and both tasks simultaneously. All ice hockey athletes performed additional cognitive tests assessing processing speed, spatial working memory, sustained attention, two choice reaction time, and motor inhibition.

Results

The results of paired-sample t-tests confirmed significant dual-task costs for all sport groups (p < 0.001). Single-task performance and dual-task costs correlated weakly in a positive direction. A one-way ANOVA revealed significantly greater costs in closed-skill sports athletes than in ice hockey and other sports athletes. No significant differences in dual-task costs were found between teams of differing expertise levels. Lastly, no significant regression model was found to predict dual-task costs from cognitive test performance.

Discussion

Our study suggests that this novel dual-task paradigm was successful in inducing dual-task costs for all elite athletes. Since it distinguishes between closed-skill and open-skill sports athletes, it might be a valuable diagnostic tool for performance and for talent development of open-skill athletes. Dual-task costs could not be relevantly predicted via cognitive performance measures, questioning cognitive resource theories as an explanation for dual-task costs.

Dual-task interference as a function of varying motor and cognitive demands

Multitasking is a critical feature of our daily lives. Using a dual-task paradigm, this experiment explored adults’ abilities to simultaneously engage in everyday motor and cognitive activities, counting while walking, under conditions varying the difficulty of each of these tasks. Motor difficulty was manipulated by having participants walk forward versus backward, and cognitive difficulty was manipulated by having participants count forward versus backward, employing either a serial 2 s or serial 3 s task. All of these manipulations were performed in single-task conditions (walk only, count only) and dual-task conditions (walk and count simultaneously). Both motor performance variables (cycle time, stride length, walking velocity) and cognitive variables (counting fluency, counting accuracy) were assessed in these conditions. Analyses of single-task conditions revealed that both motor and cognitive manipulations predictably influenced performance. Analyses of dual-task performance revealed influences of motor and cognitive factors on both motor and cognitive performance. Most centrally, dual-task costs (normalized difference between single- and dual-task conditions) for motor variables revealed that such costs occurred primarily for temporal or spatiotemporal gait parameters (cycle time, walking velocity) and were driven by cognitive manipulations. Dual-task cost analyses for cognitive measures revealed negative dual-task costs, or dual-task benefits, for cognitive performance. Finally, the effects of dual-task manipulations were correlated for motor and cognitive measures, indicating dual-task performance as a significant individual difference variable. These findings are discussed with reference to theories of attentional allocation, as well as the possible role of auditory–motor entrainment in dual-task conditions.

Effects of backpack-induced fatigue on gait ground reaction force characteristics in primary school children with flat-foot deformity

This study aimed to assess the effects of backpack carriage in different weights and muscle fatigue on the GRF components in primary school children with flat-foot deformity. The GRF components from 42 primary school children (21 with low arch, and 21 with normal) were collected before and after backpack-induced fatigue protocol during shod walking with backpacks in weight 7.5, 10, 12.5 and 15% of the child's bodyweight. The amplitudes of Fx2 of 10%BW and Fz3 of 7.5%BW in the flatfeet group were less than in the healthy group without fatigued condition. (P < 0.05). After fatiguing, the amplitudes of Fx2 of 7.5%BW, Fz3 of 12.5 and 15%BW were significantly decreased in the low arch group than those in the healthy subjects (P < 0.05). Within-group comparisons of measured Fx2 of 10%BW, Fy1 (7.5,10 and 15%BW), Fy2 of 7.5%BW, FZ1 (7.5,10 and 15%BW), FZ2 (7.5,10 and 15%BW), and TTP of TFz1 of 7.5%BW, TFz3 (7.5,10 and 12.5%BW), Loading rate (7.5,10 and 15%BW) were significantly different from pre- to post-fatigue in the flatfeet group(P < 0.05). Within-group comparisons of measured Fy1 of 10%BW, Fy2 (7.5% and 10%BW), FZ1 (7.5% and 10%BW), FZ2 (7.5% and 10%BW), and TTP of TFz3 of 7.5%BW, Loading rate (7.5% and 10%BW) were significantly different from pre- to post-fatigue in the healthy group (P < 0.05). It seems that TTP of GRF variables does have clinical importance for rehabilitation of flatfeet deformity. Carrying heavy backpacks and backpack-induced fatigue had different effects on GRF characteristics among children with low and normal foot arch.

Noon is the best time to perform a dual task while cognitive performance may be boosted by concurrent performance of a physical task

BACKGROUND

Dual-task is the concurrent performance of two independent single tasks (ST) that have distinct goals. Daily variations in performance of singular cognitive or motor tasks are reported in the literature.

RESEARCH QUESTION

To investigate whether performance of a dual-task (DT) varies based on the time of day and whether there is interference between the motor and cognitive aspect of DT.

METHODS

Participants performed a 10 Meter Walk Test (10MWT) for motor and a Stroop Test for cognitive task. The DT activity combined both STs. All participants performed three trials for all three conditions at three different times of the day (morning, noon, afternoon), on separate testing days.

RESULTS

Data were collected on 42 participants. Most participants were female (28/42), average age of 27.95 ± 9.28 years, and BMI of 25.58 ± 4.49 Kg/m2. Walking velocities in ST were consistently faster than in DT, p < .0005. In DT conditions, the participants walked faster at noon (1.21 ± 0.13 m/s) compared to the morning (1.16 ± 0.15 m/s, p = 0.01) or the afternoon (1.16 ± 0.18 m/s, p = 0.04). The participants' score on the DT-Stroop test were only different at noon (11.43 ± 2.28) when compared to morning (10.67 ± 1.34, p = 0.006). The percentage DT-Cognitive interference effect was 26.1 % in the morning, 11.8 % at noon and 13.4 % in the afternoon. The Motor interference was -14.6 % in the morning, -12.2 % at noon and -13.8 % in the afternoon.

SIGNIFICANCE

Noon is the best time to perform a dual task condition. Noon consistently exhibited the least motor or cognitive interference. Conversely, the maximum boost in cognitive performance was observed in the mornings.

Effects of motor and cognitive manipulation on the dual-task costs of center of pressure displacement in children, adolescents and young adults: A cross-sectional study

BACKGROUND

Dual-task paradigms allow to establish a relationship between motor and cognitive performance. The attentional resources needed to accomplish dual-tasks are influenced by age and task complexity. We investigated the dual-task costs for center of pressure displacement following manipulated motor and cognitive tasks in children, adolescents and young-adults.

METHODS

Thirty children, 24 adolescents and 32 young-adults performed motor (postural stability) and cognitive (arithmetic) tasks under single and dual-task conditions. Complexity was manipulated by changing the base of support (standard, narrow, standard_on_foam, narrow_on_foam) for motor tasks and the difficulty level of cognitive tasks via serial subtraction (by 5 and by 3). Dual-task costs were calculated based on area and velocity of center of pressure.

FINDINGS

Dual-task costs based on area during easy cognitive tasks were lower for children than young-adults. Under all the cognitive conditions, dual-task costs were lower on narrow than on standard bases of support. For all the tested bases of support, dual-task costs based on velocity were lower for more complex cognitive tasks than for easy tasks.

INTERPRETATION

In children, more than in adults, dual-task demanded central adaptations which increased area of center of pressure displacement. Mechanical reasons, which might limit the increase in center of pressure displacement when dual-tasking, may explain the lower dual-task costs in narrow bases compared to standard ones. Possibly, high cognitive demands may lead the participants to prioritize the motor task to keep balance, resulting in smaller increases in center of pressure displacement velocity during dual-task when compared to easier cognitive tasks.

The Acute and Chronic Effects of Dual-Task on the Motor and Cognitive Performances in Athletes: A Systematic Review

Athletes must distribute their attention to many relevant cues during a match. Therefore, athletes’ ability to deal with dual-tasks may be different from the non-athlete population, demanding a deeper investigation within the sports domain. This study aimed to systematically review the acute and chronic effects of dual-tasks in motor and cognitive performances in athletes from different modalities. The search for articles followed all the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The keywords used were: “dual-task” OR “double task” OR “multi-task” OR “divided attention” OR “secondary task” OR “second task” AND “working memory” OR “visual” OR “decision making” OR “gaze behavior” OR “attention” AND “sports” OR “athletes” OR “players”. The Scopus, Pubmed, and Web of Science databases were screened for studies comparing single and dual-tasks, in which the participants were athletes competing at any level, and in which at least one of the following variables were investigated: working memory, decision-making, visual search behavior, perception, anticipation, attention, or motor tasks. Articles were screened using pre-defined selection criteria, and methodological quality was assessed by two researchers independently. Following the eligibility criteria, we included 18 articles in the review: 13 on the acute effects, and five on the chronic effects. This review showed that the acute effect of dual-tasks impairs the motor and cognitive performances of athletes (dual-task cost). However, training with dual-tasks (chronic effect) improved working memory skills and attentional control. We conclude that dual-tasks acutely and chronically impacts motor and cognitive performance.

Association between the level of attention and dual-task costs on postural sway and cognitive yield in children, adolescents, and young adults

BACKGROUND

Postural stability requires attentional resources. Dual-task paradigms are used to investigate the attentional demand of the studied tasks. However, no studies have been conducted on the subjects' level of attention, analyzing its association with dual-task costs (DTC).

RESEARCH QUESTION

To evaluate the attentional level and DTC on postural sway and cognitive yield in children, adolescents, and young adults, investigating age-related differences, and to analyze if the participants' attention level is associated with DTC.

METHODS

Postural sway and cognitive-yield of 30 children, 24 adolescents, and 32 young adults were assessed in a dual-task paradigm. We calculated DTC on postural sway and cognitive yield. Attention level was tested using Psychological Battery for Attention Assessment. We tested the association between DTC and attention level.

RESULTS

Young adults showed higher DTC on area and velocity of postural sway than children and adolescents. No differences in DTC on cognitive yield were found between the groups. Children showed lower attention levels than adolescents and young adults. Attention level was negatively associated with DTC on cognitive yield in young adults. Focused Attention is responsible for 24.4% of the variance in DTC on cognitive yield.

CONCLUSION

Age impacts DTC on postural stability, but not on cognitive performance. The smaller changes in sway found in children/adolescents when dual-tasking, potentially reflect less developed attentional levels and postural control, which make them performing postural tasks closed to their stability boundaries, and, therefore, make them prioritize stability protection more than adults. Similar DTC on cognition between groups may reflect an equalization of the chosen cognitive task at everyone's difficulty level. The lower attention levels of children may reflect an attentional system in development, with prioritization o postural tasks when dual-tasking to maintain stability. Although attention level increases throughout age, attention only predicted DTC on cognition. Better Focused Attention's levels predicted lower DTC on cognitive yield for young adults.

Dual-task effects in children with neuromotor dysfunction: a systematic review

INTRODUCTION

Based on the assumption that motor actions result from the interaction between cognitive, perceptual, mechanical and neurological mechanisms, neuromotor dysfunctions are expected to impair central coordination processes required to perform dual-tasks. The aim of the present work was to systematically review the literature concerning the effects of dual-task in the activities performed by children with neuromotor dysfunctions.

EVIDENCE ACQUISITION

A tailored search strategy in relevant databases was conducted by two independent reviewers in August 2018 seeking for online articles published in English evaluating dual-task (motor-motor, cognitive-cognitive or cognitive-motor) effects on activities in subjects with neuromotor dysfunctions younger than 18 years. The following data were extracted: category of dual-task paradigm (motor-motor; cognitive-cognitive; cognitive-motor), primary and secondary tasks, study methods, methodological quality of the studies, and research gaps in the literature.

EVIDENCE SYNTHESIS

We identified 13 full-text reports that fulfilled the predefined inclusion and exclusion criteria.

CONCLUSIONS

There are a few high-quality studies addressing dual-task effects on activities performed by children with neuromotor dysfunctions. These children show greater susceptibility to dual-task costs than typical ones. There is a lack of studies addressing children with CP and Down Syndrome, which are highly prevalent and commonly seen in clinical settings. Thus, dual-task effects in children with neuromotor dysfunctions remain a wide research field, with need for further studies to fill in the existing gaps.

Tapping the Full Potential? Jumping Performance of Volleyball Athletes in Game-Like Situations

Background: One key issue in elite interactive team sports is the simultaneous execution of motor actions (e.g., dribbling a ball) and perceptual-cognitive tasks (e.g., visually scanning the environment for action choices). In volleyball, one typical situation is to prepare and execute maximal block jumps after multiple-options decision-making and concurrent visual tracking of the ongoing game dynamics to find an optimal blocking location. Based on resource-related dual- and multi-tasking theories simultaneous execution of visual-cognitive and motor tasks may interfere with each other. Therefore, the aim of this study was to investigate whether volleyball-specific perceptual-cognitive demands (i.e., divided attention, decision making) affect blocking performance (i.e., jumping performance and length of the first step after the ready-block-position) compared to relatively isolated jumping performance.

Methods: Twenty-two elite volleyball players (1st – 3rd German league) performed block jumps in front of a net construction in a single-task condition (ST) and in two perceptual (-cognitive) dual-task conditions including a dual-task low (DT_L; presenting a picture of an opponent attack on a screen) and a dual-task high condition (DT_H; presenting videos of an offensive volleyball set play with a two-alternative choice).

Results: The results of repeated-measures ANOVAs showed a significant effect of conditions on jumping performance [F(2,42) = 33.64, p < 0.001, η_p² = 0.62] and on the length of the first step after the ready-block-position [F(2,42) = 7.90, p = 0.001, η_p² = 0.27). Post hoc comparisons showed that jumping performance in DT_H (p < 0.001) and DT_L (p < 0.001) was significantly lower than in ST. Also, length of the first step after the ready-block-position in DT_H (p = 0.005) and DT_L (p = 0.028) was significantly shorter than in ST.

Conclusion: Our findings suggest that blocking performance (i.e., jumping height, length of the first step) decreases in elite volleyball players when a perceptual (-cognitive) load is added. Based on the theory of Wickens (2002), this suggests a resource overlap between visual-processing demands for motor performance and for tracking the dynamics of the game. Interference with the consequence of dual-task related performance costs can therefore also be found in elite athletes in their specific motor expert domain.

Profiles of Cognitive-Motor Interference During Walking in Children: Does the Motor or the Cognitive Task Matter?

The evidence supporting the effects of age on the ability to coordinate a motor and a cognitive task show inconsistent results in children and adolescents, where the Dual-Task Effects (DTE) – if computed at all – range from either being lower or comparable or higher in younger children than in older children, adolescents and adults. A feasible reason for the variability in such findings is the wide range of cognitive tasks (and to some extend of motor tasks) used to study Cognitive-Motor Interference (CMI). Our study aims at determining the differences in CMI when performing cognitive tasks targeting different cognitive functions at varying walking pathways. 69 children and adolescents (boys, n = 45; girls, n = 24; mean age, 11.5 ± 1.50 years) completed higher-level executive function tasks (2-Back, Serial Subtraction, Auditory Stroop, Clock Task, TMT-B) in comparison to non-executive distracter tasks [Motor Response Task (MRT), TMT-A] to assess relative effects on gait during straight vs. repeated Change of Direction (COD) walking. DT during COD walking was assessed using the Trail-Walking-Test (TWT). The motor and cognitive DTE were calculated for each task. There were significant differences between 5th and 8th graders on single gait speed on the straight (p = 0.016) and the COD pathway (p = 0.023), but not on any of the DT conditions. The calculation of DTEs revealed that motor DTEs were lowest for the MRT and highest for the TWT in the numbers/letters condition (p < 0.05 for all comparisons). In contrast, there were cognitive benefits for the higher-order cognitive tasks on the straight pathways, but cognitive costs for both DT conditions on the COD pathway (p < 0.01 for all comparisons). Our findings demonstrate that DT changes in walking when completing a secondary task that involve higher-level cognition are attributable to more than low-level divided attention or motor response processes. These results specifically show the direct competition for higher-level executive function resources important for walking, and are in agreement with previous studies supporting the cognitive-motor link in relation to gait in children. This might be in line with the idea that younger children may not have adequate cognitive resources.

Single- and Dual-Task Balance Training Are Equally Effective in Youth

Due to maturation of the postural control system and secular declines in motor performance, adolescents experience deficits in postural control during standing and walking while concurrently performing cognitive interference tasks. Thus, adequately designed balance training programs may help to counteract these deficits. While the general effectiveness of youth balance training is well-documented, there is hardly any information available on the specific effects of single-task (ST) versus dual-task (DT) balance training. Therefore, the objectives of this study were (i) to examine static/dynamic balance performance under ST and DT conditions in adolescents and (ii) to study the effects of ST versus DT balance training on static/dynamic balance under ST and DT conditions in adolescents. Twenty-eight healthy girls and boys aged 12-13 years were randomly assigned to either 8 weeks of ST or DT balance training. Before and after training, postural sway and spatio-temporal gait parameters were registered under ST (standing/walking only) and DT conditions (standing/walking while concurrently performing an arithmetic task). At baseline, significantly slower gait speed (p < 0.001, d = 5.1), shorter stride length (p < 0.001, d = 4.8), and longer stride time (p < 0.001, d = 3.8) were found for DT compared to ST walking but not standing. Training resulted in significant pre-post decreases in DT costs for gait velocity (p < 0.001, d = 3.1), stride length (-45%, p < 0.001, d = 2.4), and stride time (-44%, p < 0.01, d = 1.9). Training did not induce any significant changes (p > 0.05, d = 0-0.1) in DT costs for all parameters of secondary task performance during standing and walking. Training produced significant pre-post increases (p = 0.001; d = 1.47) in secondary task performance while sitting. The observed increase was significantly greater for the ST training group (p = 0.04; d = 0.81). For standing, no significant changes were found over time irrespective of the experimental group. We conclude that adolescents showed impaired DT compared to ST walking but not standing. ST and DT balance training resulted in significant and similar changes in DT costs during walking. Thus, there appears to be no preference for either ST or DT balance training in adolescents.