Effects of Single Compared to Dual Task Practice on Learning a Dynamic Balance Task in Young Adults

The Effect of Upright Stance and Vision on a Cognitive Task in Elderly Subjects and Patients with Parkinson's Disease

Standing compared to sitting enhances cognitive performance in healthy subjects. The effect of stance on cognitive performance has been addressed here in patients with Parkinson's disease (PwPD). We hypothesized that a simple cognitive task would be less enhanced in PwPD by standing with respect to sitting, because of a larger cognitive effort for maintenance of standing posture than in healthy subjects. We recruited 40 subjects (20 PwPD and 20 age-matched healthy subjects, HE). Each participant performed an arithmetic task (backward counting aloud by 7) in two postural states, sitting and standing, with eyes open (EO) and with eyes closed (EC). All trials lasted 60 s and were randomized across subjects and conditions. The number of correct subtractions per trial was an index of counting efficiency and the ratio of correct subtractions to total subtractions was an index of accuracy. All conditions collapsed, the efficiency of the cognitive task was significantly lower in PwPD than HE, whilst accuracy was affected to a lower extent. Efficiency significantly improved from sitting to standing in HE under both visual conditions whilst only with EO in PwPD. Accuracy was not affected by posture or vision in either group. We suggest that standing, compared to sitting, increases arousal, thus improving the cognitive performance in HE. Conversely, in PwPD this improvement was present only with vision, possibly due to their greater balance impairment with EC consuming an excess of attentional resources. These findings have implications for balance control and the risk of falling in PwPD in the absence of visual cues.

Persisting effects of jaw clenching on dynamic steady-state balance

The effects of jaw clenching on balance has been shown under static steady-state conditions but the effects on dynamic steady-state balance have not yet been investigated. On this basis, the research questions were: 1) if jaw clenching improves dynamic steady-state balance; 2) if the effects persist when the jaw clenching task loses its novelty and the increased attention associated with it; 3) if the improved dynamic steady-state balance performance is associated with decreased muscle activity. A total of 48 physically active healthy adults were assigned to three groups differing in intervention (Jaw clenching and balance training (JBT), only balance training (OBT) or the no-training control group (CON)) and attending two measurement points separated by two weeks. A stabilometer was used to assess the dynamic steady-state balance performance in a jaw clenching and non-clenching condition. Dynamic steady-state balance performance was measured by the time at equilibrium (TAE). The activities of tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF), biceps femoris (BF) and masseter (MA) muscles were recorded by a wireless EMG system. Integrated EMG (iEMG) was calculated to quantify the muscle activities. All groups had better dynamic steady-state balance performance in the jaw clenching condition than non-clenching at T1, and the positive effects persisted at T2 even though the jaw clenching task lost its novelty and attention associated with it after balance training with simultaneous jaw clenching. Independent of the intervention, all groups had better dynamic steady-state balance performances at T2. Moreover, reductions in muscle activities were observed at T2 parallel to the dynamic steady-state balance performance improvement. Previous studies showed that jaw clenching alters balance during upright standing, predictable perturbations when standing on the ground and unpredictable perturbations when standing on an oscillating platform. This study complemented the previous findings by showing positive effects of jaw clenching on dynamic steady-state balance performance.

Bibliometric and visualized analysis of dynamic balance and brain function using web of science and CiteSpace from 1995 to 2022

Purpose

This study aims to explore the dynamic balance of human beings and investigate the relationship between functional structure as well as functional connectivity. Through a comprehensive bibliometric and visual analysis of the research literature from 1995 to 2022, we quantitatively display the development of the dynamic balance and brain structure as well as functional connection. Our objective is to present new trends and frontiers in the study of dynamic balance and brain function through bibliometrics software, providing valuable insights for future research in this domain.

Methods

The literature on dynamic balance, brain structure and functional connectivity between 1995 and 2022 was retrieved from the Web of Science database. We employed CiteSpace software to analyze various aspects, including the year of publication, journal, authors, keywords, institutions, countries, and references. Based on the analysis results, a co-reference map was generated to visually observe research hotspots and knowledge structures.

Results

A total of 1533 records were retrieved during the survey period (1995-2022), with a gradually increase in the number of annual publications. Notably, the data suggests a notable increase in publications between 2020 and 2021. The number of publications increased by 20 % from 2020 to 2021. The journal "Proceedings of the National Academy of Sciences (PNAS)" emerged as the most prolific journal. Among the cited authors, Deco and Gustavo ranked at the top. Key research terms in this field include "neural network", "functional connectivity", "dynamic", "model" and "brain". Particularly, the keyword "neural network" exhibited the strongest growth. The analysis of keywords cluster revealed the top 10 clusters of research themes. Oxford University stood out as the most productive institution, while the United States held the greatest influence with the highest number of publications and centrality. The reference cluster analysis further demonstrated the top 10 clusters in the literature.

Conclusion

Through the use of CiteSpace software, this study performed a comprehensive bibliometric and visual analysis of the Web of Science research literature on human dynamic balance and brain structural as well as functional connectivity over the past few decades. This may help researchers identify new perspectives on potential collaborators as well as collaborating institutions, hot topics, and research frontiers in the research field. The results provided an intuitive displayed overview of research trends, hotspots and frontiers in this field, facilitating a general understanding of its progression. Through unremitting efforts, it provides valuable guidance and reference for future research work.

Rapid Dual-Task Decrements After a Brief Period of Manual Tracking in Simulated Weightlessness by Water Submersion

OBJECTIVE

Investigating dual-task (DT) performance during simulated weightlessness by water submersion, using a manual tracking and a choice reaction task. In contrast to previous work, we focus on performance changes over time.

BACKGROUND

Previous research showed motor tracking and choice reaction impairments under DT and single-task (ST) conditions in shallow water submersion. Recent research analyzed performance as average across task time, neglecting potential time-related changes or fluctuations of task-performance.

METHOD

An unstable tracking and a choice reaction task was performed for one minute under ST and DT conditions in 5 m water submersion and on dry land in 43 participants. Tracking and choice reaction time performance for both tasks were analyzed in blocks of 10 seconds.

RESULTS

Tracking performance deteriorated underwater compared to dry land conditions during the second half while performing one minute in DT conditions. Choice reaction time increased underwater as well, but independent of task time and type.

CONCLUSION

Tracking error increased over time when performing unstable tracking and choice reaction together. Potentially, physiological and psychological alterations under shallow submersion further strain the human system during DT operations, exceeding available recourse capacities such that DT performance deteriorated over time.

APPLICATION

Humans operating in simulated weightlessness underwater should be aware of substantial performance declines that can occur within a short amount of time during DT situations that include continuous tracking.

Quick on Your Feet: Modifying the Star Excursion Balance Test with a Cognitive Motor Response Time Task

The Star Excursion Balance Test (SEBT) is a common assessment used across clinical and research settings to test dynamic standing balance. The primary measure of this test is maximal reaching distance performed by the non-stance limb. Response time (RT) is a critical cognitive component of dynamic balance control and the faster the RT, the better the postural control and recovery from a postural perturbation. However, the measure of RT has not been done in conjunction with SEBT, especially with musculoskeletal fatigue. The purpose of this study is to examine RT during a SEBT, creating a modified SEBT (mSEBT), with a secondary goal to examine the effects of muscular fatigue on RT during SEBT. Sixteen healthy young male and female adults [age: 20 ± 1 years; height: 169.48 ± 8.2 cm; weight: 67.93 ± 12.7 kg] performed the mSEBT in five directions for three trials, after which the same was repeated with a response time task using Blazepod™ with a random stimulus. Participants then performed a low-intensity musculoskeletal fatigue task and completed the above measures again. A 2 × 2 × 3 repeated measures ANOVA was performed to test for differences in mean response time across trials, fatigue states, and leg reach as within-subjects factors. All statistical analyses were conducted in JASP at an alpha level of 0.05. RT was significantly faster over the course of testing regardless of reach leg or fatigue state (p = 0.023). Trial 3 demonstrated significantly lower RT compared to Trial 1 (p = 0.021). No significant differences were found between fatigue states or leg reach. These results indicate that response times during the mSEBT with RT is a learned skill that can improve over time. Future research should include an extended familiarization period to remove learning effects and a greater fatigue state to test for differences in RT during the mSEBT.

Test-retest reliability of the single leg stance on a Lafayette stability platform

The validity and reliability of the Lafayette stability platform are well-established for double leg testing. However, no evaluation of single leg (SL) stance on the platform was discovered yet. Therefore, this study aimed to investigate the reliability of conducting the SL stance on the Lafayette platform. Thirty-six healthy and active university students (age 23.2 ± 3.2 years; BMI 21.1 ± 3.1 kg/m2) were tested twice, one week apart (week 1; W1, week 2; W2). They stood on their dominant leg with eyes-open (EO) and eyes-closed (EC) in random order. Three successful trials of 20 seconds each were recorded. The duration during which the platform was maintained within 0° of tilt was referred to as time in balance (TIB). At all-time points, TIB was consistently longer in EO (EOW1: 17.02 ± 1.04s; EOW2: 17.32 ± 1.03s) compared to EC (ECW1: 11.55 ± 1.73s; ECW2: 13.08 ± 1.82s). A ±10 seconds difference was demonstrated in the Bland-Altman analysis in both EO and EC. Lower standard error of measurement (SEM) and coefficient of variation (CV) indicated consistent output. High intraclass correlation coefficient (ICC) values were seen between weeks (EO = 0.74; EC = 0.76) and within weeks (EOW1 = 0.79; EOW2 = 0.86; ECW1 = 0.71; ECW2 = 0.71). Although statistical measures (i.e., SEM, CV, and ICC) indicated good reliability of Lafayette for SL tasks, the wide agreement interval is yet to be clinically meaningful. Factors underlying the wide variation need to be identified before Lafayette is used for TIB assessment.

Effects of fixed versus variable task prioritization during short-term dual task practice on motor and cognitive task performance in young adults

OBJECTIVE

It has been shown that variable compared to fixed task prioritization during dual task practice more effectively improves motor (i.e., postural control) and cognitive (i.e., memory) performance in older adults. However, it is unclear whether this finding is also valid in young adults. Thus, the present study examined the effect of fixed (allocate equal priority on both tasks) versus variable (vary priority between both tasks) priority during short-term motor-cognitive dual task practice on single and dual task performance in healthy young adults (age range: 20-30 years).

RESULTS

During two days of practice, significant improvements of motor (i.e., balance task: reduced root mean square error; p < 001, η_p² = .72) and cognitive (i.e., arithmetic task: increased serial three subtractions; p < .001, η_p² = .78) task performance were observed and that was irrespective of group ("fixed priority" and "variable priority"). Further, the statistical analysis of post-practice single and dual task performance revealed no significant differences between groups, irrespective of task (i.e., motor or cognitive). This indicates that in young as opposed to old adults, single and dual task performance improvements are independent of task prioritization (i.e., fixed or variable priority) during short-term motor-cognitive dual task practice.

Effects of cognitive-motor dual task training on cognitive and physical performance in healthy children and adolescents: A scoping review

Simultaneous dual- or multitasking training has been used in manifold ways to improve cognitive-motor performance in different age groups. Dual task (DT) training is assumed to improve both, single task (ST) motor and cognitive performance, but particularly, performance under dual tasking conditions. Further, DT interventions have been shown to be beneficial for motor skill learning and cognitive performance as well as academic achievements in children and adolescents. The aim of this scoping review was to summarize current evidence on different cognitive-motor interventions that practice motor and cognitive performance simultaneously in children and adolescents and to identify training regimes that are most effective to improve cognitive or motor performance in this target group.

METHODS

Four electronic databases were searched (Pubmed, MEDLINE, Web of Science and APA Psycinfo) until May 2021. Following the PRISMA guidelines, title, abstract, and full-text screening as well as quality assessment was done by two independent reviewers. Studies were eligible if they (1) were published in English or German language, (2) accessible as a full-text version, (3) included at least one group of children or adolescents with a mean age of 4 to 21 years, (4) used dual-tasks as part of the intervention, (5) conducted one or more training sessions, and (6) reported at least one cognitive or motor outcome. The main outcome measures were cognitive and motor as well as cognitive-motor DT performance. Due to the heterogeneity in the characteristics of the included studies, we designed this review as a scoping review.

RESULTS

Seven studies met the inclusion criteria (n = 543, age four to 14 years, 47.1% female). One study reported two intervention experiments. Studies differed in sample size (20-189) as well as in type of training (specific or general DT training) and dose (frequency: one session/week to 110 sessions within 22 weeks). Overall, task-specific improvements in physical and cognitive functions were found, but not consistently across all interventions. Two interventions out of five interventions that measured motor performance demonstrated improvement in that domain, especially in balance. Three out of five interventions that measured cognitive functions found improved cognition. Only one study examined DT performance post training but failed to gain significant improvements in comparison to a control group. Studies only occasionally integrated training principles like individualization or progression in the design of their intervention.

DISCUSSION

The results indicate that DT training interventions may improve physical and/or cognitive functions in children and adolescents. Best practice recommendations for training regimes cannot be derived as outcomes differed a lot and were not systematically assessed across studies. Future studies should integrate more principles of training monitoring and aspects like individualization and progression to provide ideal training control and achieve better DT training results. Further, more high-quality trials are needed that adhere to the previous concepts.

PSYCINFO CLASSIFICATION

2340 Cognitive Processes 2820 Cognitive & Perceptual Development. 3720 Sports.

Effects of balance exercises during daily tooth brushing on balance performance in healthy children

BACKGROUND

It has been shown that supervised balance training is effective in improving balance performance in children but relatively costly in terms of personnel, materials, and time. Integrating balance exercises into daily routines such as tooth brushing reduces these needs, but its effectiveness is unknown.

OBJECTIVE

This study investigated the impact of balance exercises performed during daily tooth brushing on measures of static and dynamic balance in healthy children.

METHODS

Fifty-five healthy children were assigned to either an intervention (n = 32, age: 9.5 ± 0.7 years) or a control (n = 23, age: 9.2 ± 0.5 years) group. Participants of the intervention group performed progressive balance exercises while tooth brushing on a daily basis (2 sessions per day × 3 min per session) for eight weeks. Static (i.e., timed one-legged stance test [OLS]) and dynamic (i.e., Lower Quarter Y Balance test [YBT-LQ]) balance were tested before and after the intervention period.

RESULTS

The adherence rate to exercise was 98% for the participants of the intervention group. Significant test × group interactions in favor of the intervention group were detected in three out of four OLS stance conditions and for all YBT-LQ reach directions.

CONCLUSIONS

Eight weeks of balance exercises while tooth brushing proved to be feasible (i.e., high adherence rate) and effective (i.e., enhanced static and dynamic balance performance) and is thus recommended to improve postural control in healthy children.

Specific Posture-Stabilising Effects of Vision and Touch Are Revealed by Distinct Changes of Body Oscillation Frequencies

We addressed postural instability during stance with eyes closed (EC) on a compliant surface in healthy young people. Spectral analysis of the centre of foot pressure oscillations was used to identify the effects of haptic information (light-touch, EC-LT), or vision (eyes open, EO), or both (EO-LT). Spectral median frequency was strongly reduced by EO and EO-LT, while spectral amplitude was reduced by all "stabilising" sensory conditions. Reduction in spectrum level by EO mainly appeared in the high-frequency range. Reduction by LT was much larger than that induced by the vision in the low-frequency range, less so in the high-frequency range. Touch and vision together produced a fall in spectral amplitude across all windows, more so in anteroposterior (AP) direction. Lowermost frequencies contributed poorly to geometric measures (sway path and area) for all sensory conditions. The same subjects participated in control experiments on a solid base of support. Median frequency and amplitude of the spectrum and geometric measures were largely smaller when standing on solid than on foam base but poorly affected by the sensory conditions. Frequency analysis but not geometric measures allowed to disclose unique tuning of the postural control mode by haptic and visual information. During standing on foam, the vision did not reduce low-frequency oscillations, while touch diminished the entire spectrum, except for the medium-high frequencies, as if sway reduction by touch would rely on rapid balance corrections. The combination of frequency analysis with sensory conditions is a promising approach to explore altered postural mechanisms and prospective interventions in subjects with central or peripheral nervous system disorders.

Investigation of balance performance under different sensory and dual-task conditions in patients with chronic neck pain

BACKGROUND

Most studies suggest that people with chronic neck pain (CNP) have decreased balance abilities. However, balance performance during performing concurrent tasks is not clarified.

OBJECTIVES

To investigate balance performance under different sensory and dual-task conditions in people with and without CNP.

METHOD

Twenty-two women with CNP and twenty-two asymptomatic women were tested using the Biodex Stability System. Overall stability index (OSI), anterior/posterior stability index (APSI), medial/lateral stability index (MLSI) were obtained in two sessions: eyes-open and eyes-closed. Both sessions consisted of four conditions: quiet standing, rotating head, counting backward, standing on foam. Higher index scores mean poorer balance.

DESIGN

Case-Control study.

RESULTS

A mixed factorial ANOVA (2 × 8 design) showed that there was a main effect of CNP on OSI, APSI, and MLSI (p < 0.001), which indicates that CNP causes poor balance. Further, there was an interaction between CNP and test conditions for only OSI (p < 0.05). Simple effects tests showed that patients with CNP had higher OSI in all conditions except standing on foam with eyes-open, and quiet standing and counting backward with eyes-closed (p < 0.05). The largest effect size was obtained during rotating head with eyes-open (η²:0.301), followed by counting backward with eyes-open and quiet standing with eyes-open (η²:0.267 and 0.245). Performing a concurrent task, closing eyes, or standing on foam mostly increased OSI in both groups (p < 0.05).

CONCLUSIONS

Patients with CNP have poorer balance under different sensory and dual-task conditions. Addressing balance assessment while performing concurrent tasks, especially head rotations, may offer new insights into the management of CNP.

Cognitive and motor task performance under single- and dual-task conditions: effects of consecutive versus concurrent practice

The concurrent execution of two or more tasks simultaneously results in performance decrements in one or both conducted tasks. The practice of dual-task (DT) situations has been shown to decrease performance decrements. The purpose of this study was to investigate the effects of consecutive versus concurrent practice on cognitive and motor task performance under single-task (ST) and DT conditions. Forty-five young adults (21 females, 24 males) were randomly assigned to either a consecutive practice (INT consecutive) group, a concurrent practice (INT concurrent) group or a control (CON) group (i.e., no practice). Both INT groups performed 2 days of acquisition, i.e., practicing a cognitive and a motor task either consecutively or concurrently. The cognitive task required participants to perform an auditory stroop task and the number of correct responses was used as outcome measure. In the motor task, participants were asked to stand on a stabilometer and to keep the platform as close to horizontal as possible. The time in balance was calculated for further analysis. Pre- and post-practice testing included performance assessment under ST (i.e., cognitive task only, motor task only) and DT (i.e., cognitive and motor task simultaneously) test conditions. Pre-practice testing revealed no significant group differences under ST and DT test conditions neither for the cognitive nor the motor task measure. During acquisition, both INT groups improved their cognitive and motor task performance. The post-practice testing showed significantly better cognitive and motor task values under ST and DT test conditions for the two INT groups compared to the CON group. Further comparisons between the two INT groups revealed better motor but not cognitive task values in favor of the INT consecutive practice group (ST: p = 0.022; DT: p = 0.002). We conclude that consecutive and concurrent practice resulted in better cognitive (ST condition) and motor (ST and DT test conditions) task performance than no practice. In addition, consecutive practice resulted in superior motor task performance (ST and DT test conditions) compared to concurrent practice and is, therefore, recommended when executing DT practice schedules.

Effects of task difficulty during practice on learning a dynamic balance task in healthy young adults: An intervention study

OBJECTIVE

Cross-sectional studies reported increased postural sway during balance tasks with a high (e.g., unipedal stance on foam ground) compared to a low (e.g., unipedal stance on firm ground) level of task difficulty. Therefore, practicing/training balance tasks using high compared to low stimuli seems to be beneficial as it addresses larger adaptive reserves. Thus, the present study was performed to investigate the role of task difficulty during practice on learning a dynamic balance task in healthy young adults.

RESULTS

During acquisition, both practice groups ("Easy" or "Difficult" task condition) significantly improved their performance (i.e., time in balance). Further, the statistical analysis of post-practice performance revealed a significant main effect of test (i.e., better performance under easy compared to difficult test conditions, irrespective of group) but not of group. Additionally, the Group × Test interaction did not reach the level of significance, indicating that learning a dynamic balance task did not depend on the practiced task condition.

Effects of Cognitive Over Postural Demands on Upright Standing Among Young Adults

A growing body of research has shown that static stance control (e.g., body sway) is influenced by cognitive demands (CD), an effect that may be related to competition for limited central resources. Measures of stance control have also been impacted by postural demands (PD) (e.g., stable vs. unstable stances). However, less is known of any possible interactions between PD and CD on static stance control in populations with intact balance control and ample cognitive resources, like young healthy adults. In this study, among the same participants, we factorially compared the impact of PD with and without CD on static stance control. Thirty-four healthy young adults wore inertial measurement units (IMU) while completing static stance tasks for 30 seconds in three different PD positions: feet apart, feet together, and tandem feet. After completing these tasks alone, participants performed these tasks with CD by concurrently completing verbal serial seven subtractions from a randomly selected three-digit number. For two dependent measures, path length and jerk, there were main effects of CD and PD but no interaction effect between these factors. For all other stance control parameters, there was only a PD main effect. Thus, adding a cognitive demand to postural demands, while standing upright, may have an independent impact on stance control, but CD does not seem to interact with PD. These results suggest that young healthy adults may be less sensitive to simple PD and CD due to their greater inherent balance control and available cognitive resources. Future work might explore more complex PD and CD combinations to determine the boundaries under which young adults' resources are taxed.

Effects of Motor Versus Cognitive Task Prioritization During Dual-Task Practice on Dual-Task Performance in Young Adults

Background: Previous studies have reported positive effects of concurrent motor and cognitive task practice compared to motor or cognitive task practice only on dual-task performance in young adults. Knowledge about the effect of motor vs. cognitive task prioritization during practice on dual-task performance remains unclear and has not been investigated in depth so far. Thus, we examined the effects of motor task compared to cognitive task prioritization during dual-task practice on motor-cognitive performance in healthy young adults.

Methods: Healthy young adults were randomly assigned to dual-task (DT; i.e., concurrent motor and cognitive practice) or single-task (ST; i.e., motor or cognitive task practice only) practice groups. In DT practice, subjects were instructed to either prioritize the motor or the cognitive task. The motor task required subjects to keep a stabilometer in a horizontal position. The cognitive task involved serial three subtractions. Outcome variables were the root-mean-square error (RMSE) for the motor task and the total number of correct calculations for the cognitive task. All participants practiced for 2 consecutive days under their respective treatment condition and were tested under DT condition 24 h later (i.e., retention on day 3) without providing instructions on task prioritization.

Results: Irrespective of prioritization (i.e., prioritize the motor task or the cognitive task), the DT practice groups similarly improved their DT motor and cognitive task performance. The ST groups also improved motor or cognitive performance depending on their respective training contents (i.e., motor practice improved RMSE and cognitive practice improved number of correct calculations but not vice versa).

Conclusion: We conclude that DT compared to ST practice is well-suited to improve DT performance, irrespective of task-prioritization. DT but not ST practice resulted in an improved modulation of both domains (i.e., motor and cognitive) during DT performance. Our findings might be explained by freeing up central resources following DT practice that can be used to effectively perform the concurrent execution of motor and cognitive processing demands. However, this process is not further enhanced by the prioritized task domain.

The Acute Effects of Cognitive-Based Neuromuscular Training and Game-Based Training on the Dynamic Balance and Speed Performance of Healthy Young Soccer Players: A Randomized Controlled Trial

Objective: The aim of this study was to investigate the acute effects of cognitive and game-based trainings (GBT) on dynamic balance (DB) and speed performance (SP) in healthy young soccer players. Materials and Methods: Forty-nine male soccer players were divided into three groups: cognitive-based neuromuscular training (CBNT; n = 16; age = 16.93 ± 1.18 years; body mass index [BMI] = 21.37 ± 1.57 kg/m²) group, GBT (n = 17; age = 17.05 ± 1.39 years; BMI = 21.10 ± 0.97 kg/m²) group, and control group (n = 16; age = 16.75 ± 1.12 years; BMI = 21.95 ± 1.36 kg/m²). The athletes in CBNT and GBT groups took part in one session lasting 1 hour. The Star Excursion Balance Test and the Speed Dribbling Test were used to evaluate DB and SP, respectively. The measurements were taken just before and after the trainings. Statistical analysis of the study was performed using SPSS 22.0 software (Statistical Package for Social Sciences, Inc., Chicago, IL). The Paired Student's t-test and Wilcoxon test were used. For in-group evaluation the ANOVA test was used for comparisons between the three groups. The Tukey's test was used for post hoc analysis. Results: DB significantly improved in all directions in the GBT group (P < 0.05). Also, significant improvements were observed in DB in all directions except anterior, anterolateral, and anteromedial in the CBNT group, and except anterior, medial, and anteromedial directons in the control group (P < 0.05). SP significantly developed just in the CBNT and GBT groups (P = 0.001, P = 0.003, respectively). CBNT and GBT improved the DB of soccer players by 9.6% and 9.5%, respectively. Also, trainings improved the SP by 3.1% and 2.6%, respectively. Conclusion: CBNT and GBT are promising trainings that can improve DB and SP of healthy young soccer players. Trial number: NCT03739658 (ClinicalTrials.gov Identifier).

Role of physique and physical fitness in the balance of Korean national snowboard athletes

Background

The objective of this study is to understand the relationship between physique, physical fitness, and balance performance for snowboard athletes.

Methods

We considered all Korean national snowboard athletes (n = 9 with 6 males and 3 females, age = 17.44 ± 4.42), who have an experience of competition at continental cup level, to measure their physique, physical fitness, and (both static and dynamic) balance. Static balance was evaluated based on one-legged standing, while dynamic balance was estimated using a stability platform.

Results

Static balance is strongly correlated (p < 0.05) with circumference of the left lower leg (34.49 ± 2.42 cm; ρ = 0.68), sit-up (57.56 ± 8.8; ρ = 0.72), sargent jump (50.22 ± 11.78 cm; ρ = 0.67), strength of bench press (39.11 ± 17.73 kg; ρ = 0.67), angle of left ankle dorsiflexion (73.78 ± 7.86°; ρ = 0.77), average extension strength at 180° for left knee (321 ± 63.95 %BW; ρ = 0.77) and right knee (337 ± 60.32 %BW; ρ = 0.77), and right knee peak flexion strength at 60° (148 ± 25.61 %BW; ρ = 0.73). Center dynamic balance is negatively correlated with circumference of the right lower leg (34.63 ± 2.38 cm; ρ = −0.67, p < 0.05), while right dynamic balance is positively correlated with left ankle flexion (148.44 ± 5.20°; ρ = 0.78, p < 0.05).

Conclusion

Static balance is related to core muscle endurance and power, ankle flexibility, and knee stability, while dynamic balance is negatively correlated with circumference of the most frequently used lower leg (i.e., the leg dominating the snowboarding stance). The relationship between physique, physical fitness, and balance provides an insight into improving the balance performance of elite snowboard athletes through a training program that can affect the physique and physical fitness factors related to balance.

State-space intermittent feedback stabilization of a dual balancing task

Balancing the body in upright standing and balancing a stick on the fingertip are two examples of unstable tasks that, in spite of strong motor and sensory differences, appear to share a similar motor control paradigm, namely a state-space intermittent feedback stabilization mechanism. In this study subjects were required to perform the two tasks simultaneously, with the purpose of highlighting both the coordination between the two skills and the underlying interaction between the corresponding controllers. The experimental results reveal, in particular, that upright standing (the less critical task) is modified in an adaptive way, in order to facilitate the more critical task (stick balancing), but keeping the overall spatio-temporal signature well known in regular upright standing. We were then faced with the following question: to which extent the physical/biomechanical interaction between the two independent intermittent controllers is capable to explain the dual task coordination patterns, without the need to introduce an additional, supervisory layer/module? By comparing the experimental data with the output of a simulation study we support the former hypothesis, suggesting that it is made possible by the intrinsic robustness of both state-space intermittent feedback stabilization mechanisms.

A Single Bout of Aerobic Exercise Improves Motor Skill Consolidation in Parkinson's Disease

Background: Motor learning is impaired in Parkinson’s disease (PD), with patients demonstrating deficits in skill acquisition (online learning) and consolidation (offline learning) compared to healthy adults of similar age. Recent studies in young adults suggest that single bouts of aerobic exercise (AEX), performed in close temporal proximity to practicing a new motor task, may facilitate motor skill learning. Thus, we aimed at investigating the effects of a single bout of aerobic cycling on online and offline learning in PD patients.

Methods: 17 PD patients (Hoehn and Yahr 1 – 2.5, age: 64.4 ± 6.2) participated in this crossover study. Immediately prior to practicing a novel balance task, patients either performed 30 min of (i) moderate intensity (60–70% VO_2max) aerobic cycling, or (ii) seated rest (order counterbalanced). The task required patients to stabilize a balance platform (stabilometer) in a horizontal position for 30 s. For each experimental condition, patients performed 15 acquisition trials, followed by a retention test 24 h later. We calculated time in balance (platform within ± 5° from horizontal) for each trial, and analyzed within- and between-subjects differences in skill acquisition (online learning) and skill retention (offline learning) using mixed repeated-measures ANOVA.

Results: We found that the exercise bout had no effect on performance level or online gains during acquisition, despite affecting the time course of skill improvements (larger initial and reduced late skill gains). Aerobic cycling significantly improved offline learning, as reflected by larger 24-h skill retention compared to the rest condition.

Conclusion: Our results suggest that a single bout of moderate-intensity AEX is effective in improving motor skill consolidation in PD patients. Thus, acute exercise may represent an effective strategy to enhance motor memory formation in this population. More work is necessary to understand the underlying mechanisms, the optimal scheduling of exercise, and the applicability to other motor tasks. Further, the potential for patients in later disease stages need to be investigated. The study was a priori registered at ClinicalTrials.gov (NCT03245216).