Resistance band training with functional electrical stimulation improves force control capabilities in older adults: a preliminary study.

Resistance band training (RBT) with functional electrical stimulation (FES) may be an effective exercise regimen for improving age-related motor impairments. This preliminary study investigated the potential effects of bimanual RBT with FES on upper limb motor functions in older adults. This study randomly assigned 22 elderly people to the bimanual RBT with FES (Bi-RBT+FES) group and the RBT without FES (Bi-RBT) group. All participants performed isometric hand-grip force control tasks in unimanual (dominant and non-dominant) and bimanual conditions before and after four weeks of exercise for each group. We quantified the mean force, force accuracy, force variability, and force regularity at two targeted force levels (i.e., 10 % and 40 % of maximum voluntary contraction; MVC) to estimate changes in force control capabilities. The results revealed that the Bi-RBT+FES group demonstrated a greater force accuracy in the dominant hand at 10 % of MVC after training. Non-dominant hands in the Bi-RBT+FES group increased force accuracy at 40 % of MVC and reduced force variability collapsed across two targeted force levels. Both groups showed a decrease in force regularity after training. These preliminary results indicate that Bi-RBT+FES may be a viable option to facilitate functional recovery of the upper limbs in older adults.

Effects of visual feedback and force level on bilateral ankle-dorsiflexion force control.

This study investigated the potential effects of visual feedback and force level on bilateral force control capabilities in the lower limbs. Thirty-nine healthy young adults performed bilateral ankle-dorsiflexion isometric force control tasks for different visual feedback conditions, including continuous visual feedback (CVF) and withdrawal of visual feedback (WVF), indicating the removal of visual feedback on force outputs during the task and force level conditions (i.e., 10 % and 40 % of the maximum voluntary contraction). Bilateral force control capabilities were estimated using force accuracy, variability, regularity, and absolute power in 0-4 Hz and interlimb coordination by cross-correlation with time lag and uncontrolled manifold (UCM) variables. Correlation analyses determined the relationship between changes in bilateral force control capabilities and interlimb coordination from the CVF to WVF conditions. The findings revealed better bilateral force control capabilities in the CVF condition as indicated by less force error, variability, regularity, absolute power in 0-4 Hz, and advanced interlimb force coordination. From CVF to WVF conditions, increased bad variability correlated with greater force control deficits. These findings suggest that visuomotor processing is an important resource for successful fine motor control in the lower limbs.

Advanced Force Coordination of Lower Extremities During Visuomotor Control Task in Soccer Players.

Purpose: This study is aimed to determine specific bilateral lower extremity motor performances and coordination patterns in soccer players with healthy controls using the bilateral force control paradigm. We hypothesized that soccer players would show more advanced bilateral force control performances than untrained controls. Methods: Participants were 13 university soccer players and 13 healthy controls. Each group performed bilateral ankle dorsiflexion force control tasks across two vision conditions (i.e., vision and no-vision) and two targeted force levels (i.e., 10% and 40% maximum voluntary contraction). We calculated force accuracy, variability, and symmetry to assess force control performances. To estimate bilateral force coordination, we calculated Pearson's correlation coefficients between feet-within a single trial and considered uncontrolled manifold variables across multiple trials. In the no-vision condition, we performed secondary analyses for initial force control patters after removal of visual feedback. Results: There were no significant group differences in bilateral force accuracy and variability but, compared to the control group, soccer players showed higher force symmetry between left and right ankle dorsiflexion forces. For force coordination between feet, soccer players revealed more negative values of the correlation coefficient and greater good variability from the uncontrolled manifold analysis than those for the control group. The secondary analysis revealed no significant group differences in the time until force drift and amount of force adjustments. Conclusions: Soccer players have more compensatory and flexible interlimb force coordination strategies between feet.

Effects of physical exercise interventions on cognitive function in Parkinson's disease: An updated systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: To determine whether physical exercise interventions can improve cognitive function, including overall performance and specific domains, in patients with Parkinson's disease (PD) and to provide potential evidence on how cognitive benefits can be optimized by exercise prescriptions. METHODS: Using PubMed, Web of Science, and Cochrane Library (from inception to August 2022), four independent reviewers screened the search results and extracted data from randomized controlled trials of physical exercise interventions in patients with PD with an outcome measure of cognitive function. Random-effects meta-analysis models were used to report standardized mean differences (SMDs) with 95 % confidence intervals (CIs). RESULTS: Twenty-one randomized controlled trials including 761 patients with PD were eligible for inclusion. Physical exercise interventions led to significant improvements in global cognitive function (SMD = 0.69; 95 % CI = 0.31 to 1.06; P < 0.001). With respect to cognitive domains, the significant effect of exercise was found on executive function (SMD = 0.94; 95 % CI = 0.05 to 1.83; P = 0.039), but not on attention/working memory, language, memory, and visuospatial function. In moderator variable analyses, the effect on global cognition was observed in combined exercise programs (SMD = 0.79; 95 % CI = 0.46 to 1.12; P < 0.001), whereas there were no significant positive effects in aerobic exercise programs, strength exercise programs, and flexibility exercise programs. In addition, exercise interventions of light-to-moderate intensity with at least 60 min in duration, and of any frequency or period, were beneficial to the global cognitive function. CONCLUSION: This updated systematic review and meta-analysis suggests that physical exercise interventions are effective in improving global cognitive function and, to a lesser extent, executive function in patients with PD. At least 60 min a day of combined exercise programs on as many days of the week as feasible may be recommended as the non-pharmacological therapeutic option to improve cognitive function.

Associations of Orthostatic Hypotension and Orthostatic Intolerance with Domain-Specific Cognitive Decline in Patients with Early Parkinson Disease: An 8-Year Follow-up.

OBJECTIVE: Although orthostatic hypotension (OH) and orthostatic intolerance (OI) are prevalent in patients with Parkinson disease (PD), it remains unclear how these conditions primarily affect the trajectory of decline in specific cognitive domains. This study aimed to explore the effects of OH and OI on longitudinal domain-specific cognitive changes in patients with PD. DESIGN: An 8-year follow-up of the Parkinson Progression Markers Initiative cohort study. SETTING AND PARTICIPANTS: A total of 403 patients with early, untreated PD and 195 matched healthy controls were included. They were classified into OH, OI, and normal groups. OH was defined according to the international consensus, and OI was defined as the presence of orthostatic symptoms without meeting the criteria for OH. METHODS: The patients underwent detailed neuropsychological testing annually for up to 8 years of follow-up. Linear mixed effects models were used to investigate the associations between OH, OI, and longitudinal cognitive changes. RESULTS: The prevalence of both OH and OI in patients with PD was significantly higher than that in controls (13.4% vs 7.2%, P = .002, for OH, and 29.3% vs 14.4%, P < .001, for OI). The OH group in patients with PD showed a faster decline in Letter-Number Sequencing (LNS) (ß = -0.11, 95% CI -0.20 to -0.02, t = -2.44, P = .015) and Semantic Fluency Test (SFT) (ß = -0.44, 95% CI -0.81 to -0.08, t = -2.42, P = .016) scores than the normal group. Similarly, the OI group showed a steeper decline in LNS (ß = -0.08, 95% CI -0.14 to -0.01, t = -2.20, P = .028) and SFT (ß = -0.36, 95% CI -0.63 to -0.08, t = -2.55, P = .011) scores compared to the normal group. There were no significant longitudinal changes in the other neuropsychological test scores between the groups. CONCLUSIONS AND IMPLICATIONS: Both OH and OI may be associated with a faster decline in executive function among cognitive domains of patients with PD. These findings may highlight the potential importance of orthostatic blood pressure control in PD patients with OH and even those with orthostatic symptoms without OH.

Effects of high-intensity interval training and moderate-intensity continuous training on sarcopenia-related parameters in participants with Parkinson's disease: A 24-week randomized pilot trial substudy.

OBJECTIVE: To evaluate the potential efficacy of two different supervised exercise regimens, namely high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT), on sarcopenia-related parameters in participants with Parkinson's disease (PD). METHODS: We analyzed data from a randomized controlled pilot trial (CRIS identifier: KCT0007130). An aerobic exercise intervention using a cycle ergometer (40-60 min) in combination with calisthenics (5 min) was performed in three sessions/week for 24 weeks for HIIT (60% maximum aerobic power for 30-50 s with 1-min rest intervals) and MICT (50% peak oxygen consumption) groups. Changes in sarcopenia-related parameters, including appendicular skeletal muscle mass (ASM), ASM index (ASM/height2), handgrip strength, 6-min walking distance, and 30-s chair-stand test (30CST) score, were compared among the HIIT (n = 9), MICT (n = 10), and usual care (n = 11) groups. RESULTS: The HIIT group showed greater increases in leg lean mass (p = 0.011), ASM (p = 0.035), and ASM index (p = 0.025), and greater improvements in 6-min walking distance (p = 0.024) and 30CST scores (p = 0.026) compared with the usual care group. However, among these parameters, only the 30CST score significantly improved in the MICT group compared to the usual care group (p = 0.002). Three of the four (75%) sarcopenic patients who underwent HIIT showed improved sarcopenia after the 24-week exercise intervention, whereas it did not improve in the sarcopenic patients included in the MICT (n = 2) and usual care (n = 2) groups. CONCLUSION: This study suggests that HIIT may be superior to MICT in improving sarcopenia in patients with PD. Further large-scale investigations are required to confirm our findings.

Dual-hemisphere anodal transcranial direct current stimulation improves bilateral motor synergies.

Transcranial direct current stimulation (tDCS) is one of the non-invasive brain stimulation techniques that can improve motor functions. As bimanual motor actions require high motor cortical activations between hemispheres, applying bilateral anodal stimulation on left and right sides of primary motor cortex (M1) can improve for improvements in bimanual motor tasks. This study investigated which bilateral tDCS protocol effectively improves bimanual hand-grip force control capabilities in healthy young adults. We used three different bilateral tDCS protocols: (a) dual-anodal stimulation on the M1 of bilateral hemispheres (Bi-AA), (b) anodal-cathodal stimulation on the M1 of dominant and nondominant hemispheres (Bi-AC), and (c) sham stimulation (Sham). The results indicated that applying the Bi-AA significantly improved bilateral motor synergies estimated by uncontrolled manifold analysis relative to Sham. However, these differences were not observed in the comparison between Bi-AA and Bi-AC as well as between Bi-AC and Sham. These findings suggest that facilitating motor cortical activations between both hemispheres may be an additional option for advancing interlimb motor coordination patterns.

Repetitive transcranial magnetic stimulation improves cardiovascular autonomic nervous system control: A meta-analysis.

BACKGROUND: Cardiovascular autonomic system (ANS) may be affected by altered neural activations in the brain. This systematic review and meta-analysis investigated potential effects of repetitive transcranial magnetic stimulation (rTMS) protocols on cardiovascular ANS control. METHODS: Through 19 qualified studies, we acquired 70 comparisons for data synthesis. Individual effect sizes were estimated by comparing changes in following cardiovascular ANS control variables between active and sham stimulation conditions: (a) blood pressure (BP), (b) heart rate (HR), and (c) heart rate variability (HRV). Moreover, two moderator variable analyses determined whether changes in cardiovascular ANS control were different based on (a) rTMS protocols (excitatory rTMS versus inhibitory rTMS) and (b) specific targeted cortical regions, respectively. RESULTS: The random-effects model meta-analysis revealed significant improvements in cardiovascular ANS control after the rTMS protocols. Specifically, applying excitatory and inhibitory rTMS protocols significantly decreased values of BP and HR variables. For HRV variables, excitatory rTMS protocols showed significant positive effects. These improvements in cardiovascular ANS control were observed while applying either excitatory rTMS protocols to the left dorsolateral prefrontal cortex or inhibitory rTMS protocols to the right dorsolateral prefrontal cortex. LIMITATIONS: Relatively small number of studies for inhibitory rTMS on the right dorsolateral prefrontal cortex were included in this meta-analysis. CONCLUSION: These findings suggest that applying excitatory and inhibitory rTMS protocols on prefrontal cortical regions may be effective to improve cardiovascular ANS control.

Prognostic significance of peripheral neutrophils and lymphocytes in early untreated Parkinson's disease: an 8-year follow-up study.

BACKGROUND: To explore whether peripheral blood neutrophils and lymphocytes are associated with longitudinal motor and cognitive decline in patients with early Parkinson's disease (PD) and, to uncover the disease-specific mechanisms underlying these associations. METHODS: Data were obtained from the Parkinson's Progression Markers Initiative cohort. We included 376 patients with recently diagnosed, drug-naïve PD and 178 matched healthy controls. The patients underwent annual assessments, including the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part 3 test to measure motor function and the Montreal Cognitive Assessment (MoCA) to measure cognitive function, for up to 8 years of follow-up. Dopamine transporter (DAT) imaging was performed at baseline and the 1-year, 2-year and 4-year follow-up visits. RESULTS: At baseline, patients with PD showed higher neutrophil and lower lymphocyte counts, resulting in a higher neutrophil-to-lymphocyte ratio (NLR) than that in healthy controls. Higher neutrophil counts were associated with a greater increase in MDS-UPDRS part 3 scores in patients with PD (estimate: 0.25, 95% CI: 0.12 to 0.37, p<0.001). Correspondingly, higher neutrophil levels were related to a greater reduction in DAT activity in the caudate (estimate: -0.007, 95% CI: -0.014 to -0.001, p=0.046) and putamen (estimate: -0.0039, 95% CI: -0.0077 to -0.0002, p=0.042). However, there were no significant effects of lymphocyte count and NLR on changes in the MDS-UPDRS part 3 and MoCA scores and striatal DAT uptake over time. CONCLUSION: Among the blood biomarkers, only a higher neutrophil count was associated with faster motor progression along with accelerated nigrostriatal dopaminergic degeneration in patients with PD. The impact of neutrophils and lymphocytes on longitudinal cognitive changes remains unclear. TRIAL REGISTRATION NUMBER: NCT01141023.

Altered Bimanual Kinetic and Kinematic Motor Control Capabilities in Older Women.

Older women may experience critical neuromuscular impairments interfering with controlling successful bimanual motor actions. Our study aimed to investigate altered bimanual motor performances in older women compared with younger women by focusing on kinetic and kinematic motor properties. Twenty-two older women and 22 younger women performed bimanual kinetic and kinematic motor tasks. To estimate bimanual kinetic functions, we calculated bimanual maximal voluntary contractions (i.e., MVC) and force control capabilities (i.e., mean force, accuracy, variability, and regularity of the total force produced by two hands) during bimanual hand-grip submaximal force control tasks. For bimanual kinematic performances, we assessed the scores of the Purdue Pegboard Test (i.e., PPT) in both hands and assembly tasks, respectively. For the bimanual MVC and PPT, we conducted an independent t-test between two groups. The bimanual force control capabilities were analyzed using two-way mixed ANOVAs (Group × Force Level; 2 × 2). Our findings revealed that the older women showed less bimanual MVC (p = 0.046) and submaximal force outputs (p = 0.036) and greater changes in bimanual force control capabilities as indicated by a greater force variability (p = 0.017) and regularity (p = 0.014). Further, the older women revealed lower scores of PPT in both the hands condition (p < 0.001) and assembly task condition (p < 0.001). The additional correlation analyses for the older women showed that lower levels of skeletal muscle mass were related to less bimanual MVC (r = 0.591; p = 0.004). Furthermore, a higher age was related to lower scores in the bimanual PPT assembly task (r = -0.427; p = 0.048). These findings suggested that older women experience greater changes in bimanual motor functions compared with younger women.

A meta-analysis showing improved cognitive performance in healthy young adults with transcranial alternating current stimulation.

Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation used for improving cognitive functions via delivering weak electrical stimulation with a certain frequency. This systematic review and meta-analysis investigated the effects of tACS protocols on cognitive functions in healthy young adults. We identified 56 qualified studies that compared cognitive functions between tACS and sham control groups, as indicated by cognitive performances and cognition-related reaction time. Moderator variable analyses specified effect size according to (a) timing of tACS, (b) frequency band of simulation, (c) targeted brain region, and (b) cognitive domain, respectively. Random-effects model meta-analysis revealed small positive effects of tACS protocols on cognitive performances. The moderator variable analyses found significant effects for online-tACS with theta frequency band, online-tACS with gamma frequency band, and offline-tACS with theta frequency band. Moreover, cognitive performances were improved in online- and offline-tACS with theta frequency band on either prefrontal and posterior parietal cortical regions, and further both online- and offline-tACS with theta frequency band enhanced executive function. Online-tACS with gamma frequency band on posterior parietal cortex was effective for improving cognitive performances, and the cognitive improvements appeared in executive function and perceptual-motor function. These findings suggested that tACS protocols with specific timing and frequency band may effectively improve cognitive performances.

Increased Cerebellar Gray Matter Volume in Athletes: A Voxel-Wise Coordinate-Based Meta-Analysis.

Purpose: The purpose of this systematic review and meta-analysis study was to investigate distinct brain structural characteristics in athletes as compared with those in non-athletes by quantifying regional gray matter (GM) volume changes using voxel-based morphometry analysis based on a whole-brain approach. Methods: The systematic literature search was conducted from November 1, 2020 to October 18, 2021 via the two search engines including the PubMed and Web of Science. We included 13 studies that reported GM volume data in 229 athletes as compared 219 non-athletes based on the whole-brain analysis with specific three-dimensional coordinates in a standard stereotactic space. Thus, we performed a coordinate-based meta-analysis using the seed-based d mapping via permutation of subject images methods. Result: The coordinate-based meta-analysis reported that the athletes significantly reveal greater regional GM volume across right cerebellar lobules IV-V and Brodmann area 37 regions than those in the non-athletes with minimal levels of heterogeneity and publication bias between the included studies. The subgroup analyses show that greater GM volume for athletes in closed-skill sports appeared across the right cerebellar hemispheric lobules VIII and the right cingulum than those for non-athletes. Conclusion: These cumulative findings from multiple brain imaging studies suggest potential brain plasticity evidence in the athletes who experienced extensive motor training.

Transcranial direct current stimulation influences repetitive bimanual force control and interlimb force coordination.

This study aimed to investigate the potential effect of bilateral transcranial direct current stimulation (tDCS) on repetitive bimanual force control and force coordination in healthy young adults. In this sham-controlled crossover study, 18 right-handed young adults were enrolled. Repetitive bimanual handgrip force control trials were performed by the participants at 40% of maximum voluntary contraction until task failure. We randomly provided bilateral active and sham tDCS to the primary motor cortex (M1) of each participant before conducting the repetitive bimanual force control task. We quantified the number of successful trials to assess the ability to maintain bimanual force control across multiple trials. Moreover, we estimated bimanual force control and force coordination by quantifying force accuracy, variability, regularity, and correlation coefficient in maximal and adjusted successful trials. Force asymmetry was calculated to examine potential changes in motor dependency on each hand during the task. Bilateral tDCS significantly increased the number of successful trials compared with sham tDCS. The adjusted successful trial revealed that participants who received bilateral tDCS maintained better bimanual force control and coordination, as indicated by decreased force variability and regularity as well as more negative correlation coefficient values in comparison with sham condition. Moreover, participants who received bilateral tDCS produced more force from the dominant hand than from the nondominant hand in both maximal and adjusted successful trials. These findings suggest that bilateral tDCS on M1 successfully maintains bimanual force control with better force coordination by modulating motor dependency.

Association of Early Weight Change With Cognitive Decline in Patients With Parkinson Disease.

BACKGROUND AND OBJECTIVE: To examine whether early weight change is associated with subsequent deterioration in cognitive function, including overall performance and specific domains, in Parkinson disease (PD). METHODS: This observational study used data from the Parkinson Progression Markers Initiative cohort. The patients underwent annual nonmotor assessments covering neuropsychiatric, sleep-related, and autonomic symptoms for up to 8 years of follow-up. Cognitive function was measured using the Montreal Cognitive Assessment (MoCA) and detailed neuropsychological testing. Linear mixed-effects models were applied to investigate the association of early weight change with longitudinal evolution of cognitive and other nonmotor symptoms. RESULTS: A total of 358 patients with early PD were classified into weight loss (decrease of >3% body weight during the first year; n = 98), weight maintenance (within ±3%; n = 201), and weight gain (increase of >3%; n = 59) groups. The weight loss group showed a significantly faster decline in MoCA scores than the weight maintenance group (ß = -0.19, 95% CI -0.28 to -0.10). With respect to specific cognitive domains, the weight loss group showed a steeper decline in sematic fluency test scores (ß = -0.37, 95% CI -0.66 to -0.08) and MoCA phonemic fluency scores (ß = -0.18, 95% CI -0.31 to -0.05) and, to a lesser extent, Letter-Number Sequencing scores (ß = -0.07, 95% CI -0.14 to 0.01) compared with the weight maintenance group. Conversely, the weight gain group showed a slower decline in the Symbol Digit Modalities Test scores (ß = 0.34, 95% CI 0.05 to 0.63), although no association was found with longitudinal changes in MoCA scores. We did not find any significant effects of weight change on the progression of other nonmotor symptoms. DISCUSSION: Early weight loss was associated with a faster progression of decline in global cognitive function and executive function in patients with PD, whereas early weight gain was associated with a slower progression of decline in processing speed and attention. The impact of early weight change on nonmotor symptoms seemed to be specific to cognition.

Effects of Exercise on Depressive Symptoms in Patients With Parkinson Disease: A Meta-analysis.

BACKGROUND AND OBJECTIVE: The purpose of this study was to provide clear evidence in support of the use of exercise to improve depressive symptoms in patients with Parkinson disease (PD) and to investigate whether this effect differs by exercise type and intensity. METHODS: Three independent reviewers searched for randomized controlled trials (RCTs) that applied exercise interventions with depressive symptoms as an outcome measure for patients with PD on PubMed and Web of Science up to February 28, 2022. Random-effects meta-analyses were performed, in which standardized mean differences (SMDs) between the effects of exercise and control interventions on depressive symptoms with 95% CIs were calculated. RESULTS: A total of 19 RCTs including 1,302 patients with PD were eligible for meta-analysis, and we obtained 23 comparisons from the included studies for data synthesis. Physical exercise interventions showed significant effects on the reduction in depressive symptoms in patients with PD (SMD = 0.829; 95% CI = 0.516-1.142; p < 0.001). Moderator analyses on exercise type revealed significant positive effects for combined exercise interventions (SMD = 1.111; 95% CI = 0.635-1.587; p < 0.001), whereas aerobic training alone failed to show significant effects (SMD = 0.202; 95% CI = -0.045 to 0.449; p = 0.108). Both light-to-moderate intensity exercises (SMD = 0.971; 95% CI = 0.521-1.421; p < 0.001) and moderate-to-vigorous intensity exercises (SMD = 0.779; 95% CI = 0.407-1.152; p < 0.001) significantly improved depressive symptoms with a small difference between the exercise intensities. DISCUSSION: Our results suggest that physical exercise has significant antidepressant effects in patients with PD. These effects seemed to be more closely associated with exercise type than intensity. Different types of exercise interventions may result in greater benefit and require further investigation.

Unilateral hand force control impairments in older women.

Older women may experience deficits in sensorimotor control at their upper limb because of aging progress compromising the motor system. This study aimed to investigate whether younger and older women differ in sensorimotor capabilities assessed by unilateral force control performances at a lower targeted force level. Twenty-one older and 21 younger women performed isometric unilateral force control tasks at 10 % of maximum voluntary contraction for each hand, respectively. Purdue Pegboard Test (PPT) was used to measure unilateral hand dexterity. Five force control variables (i.e., maximal and submaximal force, force error, variability, and regularity) and PPT scores were analyzed in two-way mixed ANOVAs (Group × Hand Condition), respectively. The absolute force power was analyzed in three-way mixed ANOVA (Group × Hand Condition × Frequency Band). The findings revealed that older women produced less maximal and submaximal unilateral forces than in younger women. Greater variability, regularity, and force frequency oscillations below 4 Hz were observed in older women as compared with those in younger women. Force error in the dominant hand was greater in older women than those in younger women. Finally, older women showed lower PPT scores than younger women. These findings suggested that older women may have deficits in unilateral force control capabilities as well as motor dexterity.

Bimanual motor impairments in older adults: an updated systematic review and meta-analysis.

This updated systematic review and meta-analysis further examined potential effects of aging on bimanual movements. Forty-seven qualified studies that compared bimanual motor performances between elderly and younger adults were included in this meta-analysis. Moderator variable analyses additionally determined whether altered bimanual motor performances in older adults were different based on the task types (i.e., symmetry vs. asymmetry vs. complex) or outcome measures (i.e., accuracy vs. variability vs. movement time). The random effects model meta-analysis on 80 comparisons from 47 included studies revealed significant negative overall effects indicating more bimanual movement impairments in the elderly adults than younger adults. Moderator variable analyses found that older adults showed more deficits in asymmetrical bimanual movement tasks than symmetrical and complex tasks, and the bimanual movement impairments in the elderly adults included less accurate, more variable, and greater movement execution time than younger adults. These findings suggest that rehabilitation programs for improving motor actions in older adults are necessary to focus on functional recovery of interlimb motor control including advanced motor performances as well coordination.

Higher visual gain contributions to bilateral motor synergies and force control.

This study investigated the effects of altered visual gain levels on bilateral motor synergies determined by the uncontrolled manifold (UCM) hypothesis and force control. Twelve healthy participants performed bimanual index finger abduction force control tasks at 20% of their maximal voluntary contraction across four different visual gain conditions: 8, 80, 256, and 512 pixels/N. Quantifying force accuracy and variability within a trial provided a bimanual force control outcome. The UCM analysis measured bilateral motor synergies, a proportion of good variance to bad variance across multiple trials. Correlation analyses determined whether changes in the UCM variables were related to changes in force control variables from the lowest to highest visual gain conditions, respectively. Multiple analyses indicated that the three highest visual gain conditions in comparison to the lowest visual gain increased values of bilateral motor synergies and target force accuracy. The correlation findings showed that a reduction of bad variance from the lowest to three highest visual gain conditions was related to increased force accuracy. These findings reveal that visual gain greater than 8 pixels/N facilitates bimanual force control.

A Review and Meta-Analysis of Interactive Metronome Training: Positive Effects for Motor Functioning.

Interactive metronome training may be effective for improving motor performances through timing. In this systematic review and meta-analysis, 18 prospective studies met our eligibility criteria, and we summarized the effects of interactive metronome training protocols on motor functioning. We estimated effect sizes by quantifying differences in altered motor functions between participants in interactive metronome training and control groups. Two additional subgroup analyses determined whether the positive effects on motor function improvements were different among (a) three types of participants (i.e., athletes, healthy individuals, and patients with neurological disorders) and (b) two different training protocols (i.e., interactive metronome training only and interactive metronome training combined with an additional motor program). Random-effects model meta-analysis revealed moderate positive effects of interactive metronome training on motor function, with interactive metronome treatment effects significant across athletes, healthy individuals, and patients with neurological disorders. Interactive metronome training combined with additional motor programs showed comparable effects to those obtained after interactive metronome training alone. These findings suggest motor improvement benefits to strengthening or capitalizing on an individual's motor timing.