Different montages of transcranial direct current stimulation on postural stability in chronic low back pain patients: A randomized sham-controlled study.

BACKGROUND: Impairment in both the motor and cognitive aspects of postural control is a critical issue in patients with chronic low back pain (CLBP) who experience high pain anxiety (HPA). OBJECTIVE: This study aimed to compare the effects of cathodal and anodal transcranial direct current stimulation (c-tDCS and a-tDCS) over the dorsolateral prefrontal cortex (DLPFC) on postural control during cognitive postural tasks in CLBP patients with HPA. METHODS: This study included 66 patients randomly assigned to three groups: DLPFC a-tDCS, DLPFC c-tDCS, and sham tDCS. All groups received 20 minutes of tDCS, but the stimulation was gradually turned off in the sham group. Postural stability indices were assessed using the Biodex Balance System. RESULTS: Both the a-tDCS and c-tDCS groups showed a significant reduction in most postural stability indices at static and dynamic levels after the interventions (immediately, 24 hours, and one-week follow-up) during the cognitive postural task (P< 0.01). Additionally, there was a significant improvement in postural balance in the a-tDCS and c-tDCS groups compared to the sham tDCS group (P< 0.01). Furthermore, the a-tDCS group showed significantly greater improvement than the c-tDCS group (P< 0.01). CONCLUSION: Based on the results, both a-tDCS and c-tDCS over the DLPFC had positive effects on postural control during cognitive postural tasks in CLBP patients with HPA.

Transcranial pulsed current stimulation: A scoping review of the current literature on scope, nature, underlying mechanisms, and gaps.

Transcranial pulsed current stimulation (tPCS) is a noninvasive brain stimulation technique that has aroused considerable attention in recent years. This review aims to provide an overview of the existing literature on tPCS, examine the scope and nature of previous research, investigate its underlying mechanisms, and identify gaps in the literature. Searching online databases resulted in 36 published tPCS studies from inception until May 2023. These studies were categorized into three groups: human studies on healthy individuals, human studies on clinical conditions, and animal studies. The findings suggest that tPCS has the potential to modulate brain excitability by entraining neural oscillations and utilizing stochastic resonance. However, the underlying mechanisms of tPCS are not yet fully understood and require further investigation. Furthermore, the included studies indicate that tPCS may have therapeutic potential for neurological diseases. However, before tPCS can be applied in clinical settings, a better understanding of its mechanisms is crucial. Hence, the tPCS studies were categorized into four types of research: basic, strategic, applied, and experimental research, to identify the nature of the literature and gaps. Analysis of these categories revealed that tPCS, with its diverse parameters, effects, and mechanisms, presents a wide range of research opportunities for future investigations.

The effect of transcranial direct current stimulation on rating of perceived exertion: A systematic review of the literature.

The rating of perceived exertion (RPE) is a widely used method for monitoring the load during training, as it provides insight into the subjective intensity of effort experienced during exercises. Considering the role of brain in monitoring and perception of the effort, several studies explored the effect of transcranial direct current stimulation (tDCS) on RPE in different populations. The aim of current study is to review the studies that investigated the effect of tDCS on RPE in three groups including healthy untrained people, physically active persons, and athletes. Nine databases were searched for papers assessing the effect of tDCS on RPE. The data from the included studies were extracted and methodological quality was examined using the risk of bias 2 (ROB2) tool. Thirty-three studies met the inclusion criteria. According to the meta-analysis, active a-tDCS significantly decreased the RPE compared to the sham stimulation. The a-tDCS could decrease the RPE when it was applied over M1 or DLPF. Regarding the measurement tool, Borg's scale 6-20 and OMNI scale could show an improvement in RPE scale. A-tDCS is a promising technique that can decrease the RPE. M1 and DLPFC are suggested as the target area of stimulation. From the tools that measure the RPE, Borg's RPE 6-20 and OMNI scale could better show the effect of a-tDCS.

Age and Type of Task-Based Impact of Mental Fatigue on Balance: Systematic Review and Meta-Analysis.

The role of cognition in balance control suggests that mental fatigue may negatively affect balance. However, cognitive involvement in balance control varies with the type or difficulty of the balance task and age. Steady-state balance tasks, such as quiet standing, are well-learned tasks executed automatically through reflex activities controlled by the brainstem and spinal cord. In contrast, novel, and challenging balance tasks, such as proactively controlling balance while walking over rugged terrain or reacting to unexpected external perturbations, may require cognitive processing. Furthermore, individuals with preexisting balance impairments due to aging or pathology may rely on cognitive processes to control balance in most circumstances. This systematic review and meta-analysis investigated the effect of mental fatigue on different types of balance control tasks in young and older adults. A literature search was conducted in seven electronic databases and 12 studies met eligibility criteria. The results indicated that mental fatigue had a negative impact on both proactive (under increased cognitive load) and reactive balance in young adults. In older adults, mental fatigue affected steady-state and proactive balance. Therefore, mentally fatigued older individuals may be at increased risk of a loss of balance during steady-state balance task compared to their younger counterparts.

Exploring sensory, motor, and pain responses as potential side or therapeutic effects of sub-2 mA, 400 Hz transcranial pulsed current stimulation.

BACKGROUND: Various brain stimulation devices capable of generating high-frequency currents are readily available. However, our comprehension of the potential side or therapeutic effects associated with high-frequency transcranial pulsed current stimulation (tPCS), particularly concerning the new 400 Hz tPCS device, AscenZ-IV Stimulator, developed by AscenZion Neuromodulation Co. Pte. Ltd. in Singapore, remains incomplete. OBJECTIVE: This study examines preliminary parameters for the safe and comfortable application of 400 Hz tPCS at intensities below 2 mA. METHODS: In a cross-sectional study, 45 healthy participants underwent sub-2 mA 400 Hz tPCS to assess sensory, motor, and pain thresholds on the dominant side. Study 1 (N = 15) targeted the primary motor cortex of the right-hand area, while study 2 (N = 30) focused on the back of the right forearm. RESULTS: Study one showed that increasing the current intensity gradually resulted in no responses at sub-0.3 mA levels, but higher intensities (p < 0.001) induced sensory perception and pain responses. Study two replicated these findings and additionally induced motor responses along with the sensory and pain responses. CONCLUSION: Despite the theoretical classification of tPCS as a subsensory level of stimulation, and the expectation that individuals receiving this type of current should not typically feel its application on the body, this high-frequency tPCS device generates different levels of stimulation due to the physiological phenomenon known as temporal summation. These novel levels of stimulation could be viewed as either potential "side-effects" of high frequency tPCS or as additional "therapeutic benefits". This dual capacity may position the device as one that generates both neuromodulatory and neurostimulatory currents. Comprehensive comprehension of this is vital for the development of therapeutic protocols that incorporate high-frequency tPCS.

The effects of anodal tDCS on pain reduction in people with knee osteoarthritis: A systematic review and meta-analysis.

OBJECTIVES: To synthesise the literature on the efficacy of primary motor cortex anodal transcranial direct current stimulation (M1-a-tDCS), as a standalone or priming technique, for pain reduction in people with knee osteoarthritis (KOA). METHODS: The systematic literature search was conducted in MEDLINE, CINAHL, Embase and CENTRAL according to PRISMA statement. RESULTS: Fourteen studies involving 740 people with KOA were included. In the meta-analysis, six studies compared a-tDCS alone with sham stimulation, and five studies compared a-tDCS combined with other methods with sham stimulation. We found positive effect of a-tDCS alone on pain in KOA (standard mean difference (SMD) -0.52; 95% CI, -0.78 to -0.25; P=0.001; I2 = 69%). Further, a-tDCS with other treatments showed positive effect (SMD -1.23; 95% CI, -1.59 to -0.88; P<0.001; I2 = 48%) on pain in people with KOA. This evidence showed low certainty due to a high risk of bias and imprecision. DISCUSSION AND CONCLUSION: A-tDCS could be considered as standalone and an adjunct treatment for pain reduction in people with KOA. Future randomised studies should address quality issues, including small sample size, to enhance the overall certainty of the findings. SIGNIFICANCE: A-tDCS can be used as a standalone and adjunct treatment for KOA. STUDY REGISTRATION: PROSPERO number CRD42021255114.

Does Multisession Cathodal Transcranial Direct Current Stimulation of the Left Dorsolateral Prefrontal Cortex Prime the Effects of Cognitive Behavioral Therapy on Fear of Pain, Fear of Movement, and Disability in Patients with Nonspecific Low Back Pain? A Randomized Clinical Trial Study.

Many studies have shown that low back pain (LBP) is associated with psychosomatic symptoms which may lead to brain changes. This study aimed to investigate the effect of the concurrent application of cognitive behavioral therapy (CBT) and transcranial direct electrical stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) on fear of pain, fear of movement, and disability in patients with nonspecific LBP. This study was performed on 45 LBP patients (23 women, 22 men; mean age 33.00 ± 1.77 years) in three groups: experimental (2 mA cathodal tDCS (c-tDCS)), sham (c-tDCS turned off after 30 s), and control (only received CBT). In all groups, CBT was conducted for 20 min per session, with two sessions per week for four weeks. Fear of pain, fear of movement, and disability were evaluated using questionnaires at baseline, immediately after, and one month after completion of interventions. Results indicated that all three different types of intervention could significantly reduce fear and disability immediately after intervention (p > 0.05). However, improvement in the experimental group was significantly higher than in the other groups immediately after and at the one-month follow-up after interventions (p < 0.05). DLPFC c-tDCS can prime the immediate effects of CBT and also the lasting effects on the reduction in the fear of pain, fear of movement, and disability in LBP patients.

The Association Between Cognitive Domains and Postural Balance among Healthy Older Adults: A Systematic Review of Literature and Meta-Analysis.

PURPOSE OF REVIEW: This review aims to explore which cognitive domain is more closely associated with which type of balance (static or dynamic). RESENT FINDING: Based on recent reviews, inhibitory control, a part of cognition, plays a crucial role in balance performance. Previous reviews report significant links between cognition, mobility, and physical function in older adults. However, evidence regarding the relationship between cognition and balance scores remains inconclusive. The strength of association between cognition and balance appears to be domain-specific and task-specific. Executive function exhibits the strongest correlation with balance, while episodic memory shows a small link with dynamic balance. Processing speed and global cognition demonstrate moderate correlations. Additionally, there is a slight association between cognitive domains and static balance. Further research is needed to elucidate the underlying mechanisms and develop targeted interventions for managing balance-related concerns that are domain-specific and task-specific.

The Effect of Uni-Hemispheric Dual-Site Anodal tDCS on Brain Metabolic Changes in Stroke Patients: A Randomized Clinical Trial.

Uni-hemispheric concurrent dual-site anodal transcranial direct current stimulation (UHCDS a-tDCS) of the primary motor cortex (M1) and the dorsolateral prefrontal cortex (DLPFC) may enhance the efficacy of a-tDCS after stroke. However, the cellular and molecular mechanisms underlying its beneficial effects have not been defined. We aimed to investigate the effect of a-tDCSM1-DLPFC on brain metabolite concentrations (N-acetyl aspartate (NAA), choline (Cho)) in stroke patients using magnetic resonance spectroscopy (MRS). In this double-blind, sham-controlled, randomized clinical trial (RCT), 18 patients with a first chronic stroke in the territory of the middle cerebral artery trunk were recruited. Patients were allocated to one of the following two groups: (1) Experimental 1, who received five consecutive sessions of a-tDCSM1-DLPFC M1 (active)-DLPFC (active). (2) Experimental 2, who received five consecutive sessions of a-tDCSM1-DLPFC M1 (active)-DLPFC (sham). MRS assessments were performed before and 24 h after the last intervention. Results showed that after five sessions of a-tDCSM1-DLPFC, there were no significant changes in NAA and Cho levels between groups (Cohen's d = 1.4, Cohen's d = 0.93). Thus, dual site a-tDCSM1-DLPFC did not affect brain metabolites compared to single site a-tDCS M1.

Transcranial direct current stimulation over dorsolateral prefrontal cortex improves postural stability in non-specific chronic low back pain patients with high fear of pain: A randomized sham-controlled trial.

Deficits in postural stability in response to environmental challenges are seen in chronic low back pain (CLBP) patients with high fear of pain (HFP). Hence, it is essential to follow effective approaches to treat postural stability deficits and improve the health status of these patients. The current study aimed to compare the effects of cathodal and anodal transcranial direct current stimulation (c-tDCS and a-tDCS) over the left dorsolateral prefrontal cortex (DLPFC) on postural stability in non-specific CLBP patients with HFP. In this randomized clinical trial study, 75 patients were randomly assigned to left DLPFC a-tDCS, left DLPFC c-tDCS and sham stimulation groups (n = 25 in each group). All groups received a single-session 2 mA tDCS for 20 min, but the stimulation was slowly turned off after 30 s in the sham group. Before, immediately, 24 h and 1 week after the interventions, postural stability indices were assessed using a Biodex Balance System. A significant reduction in most indices was shown in both a-tDCS and c-tDCS groups after interventions (immediately, 24 h and 1 week follow-up) during static and dynamic postural tasks compared with the sham tDCS group (p < .01). In addition, some tests showed a significant difference between a-tDCS and c-tDCS (p < .05). The findings indicated positive effects of both a-tDCS and c-tDCS on the left DLPFC, with more efficacy of a-tDCS on postural stability in LBP patients with HFP.

A step toward restoring hand functions in patients with multiple sclerosis-a study protocol.

Multiple sclerosis (MS) is a chronic autoimmune disease characterized by inflammation, demyelination of axons, and oligodendrocyte loss in the central nervous system. This leads to neurological dysfunction, including hand impairment, which is prevalent among patients with MS. However, hand impairment is the least targeted area for neurorehabilitation studies. Therefore, this study proposes a novel approach to improve hand functions compared to current strategies. Studies have shown that learning new skills in the motor cortex (M1) can trigger the production of oligodendrocytes and myelin, which is a critical mechanism for neuroplasticity. Transcranial direct current stimulation (tDCS) has been used to enhance motor learning and function in human subjects. However, tDCS induces non-specific effects, and concurrent behavioral training has been found to optimize its benefits. Recent research indicates that applying tDCS during motor learning can have priming effects on the long-term potentiation mechanism and prolong the effects of motor training in health and disease. Therefore, this study aims to assess whether applying repeated tDCS during the learning of a new motor skill in M1 can be more effective in improving hand functions in patients with MS than current neurorehabilitation strategies. If this approach proves successful in improving hand functions in patients with MS, it could be adopted as a new approach to restore hand functions. Additionally, if the application of tDCS demonstrates an accumulative effect in improving hand functions in patients with MS, it could provide an adjunct intervention during rehabilitation for these patients. This study will contribute to the growing body of literature on the use of tDCS in neurorehabilitation and could have a significant impact on the quality of life of patients with MS.

Mental fatigue does not affect static balance under both single and dual task conditions in young adults.

The ability to control balance and prevent falls while carrying out daily life activities may require a predominantly controlled (cognitive) or automatic processing depending on the balance challenge, age, or other factors. Consequently, this process may be affected by mental fatigue which has been shown to impair cognitive abilities. Controlling static balance in young adults is a relatively easy task that may proceed automatically with minimal cognitive input making it insusceptible to mental fatigue. To investigate this hypothesis, static single and dual task (while concurrently counting backward by seven) balance was assessed in 60 young adults (25.2 ± 2.4 years) before and after 45 min of Stroop task (mental fatigue condition) and watching documentary (control), presented in a randomized counterbalanced order on separate days. Moreover, because mental fatigue can occur due to task underload or overload, participants carried out two different Stroop tasks (i.e., all congruent, and mainly incongruent trials) on separate days in the mental fatigue condition. Results of the study revealed a significantly higher feeling of mental fatigue after the mental fatigue conditions compared to control (p < 0.001). Similarly, the performance on congruent Stroop trials decreases with time indicating objective mental fatigue (p < 0.01). However, there was no difference in balance or concurrent task performance under both single and dual task assessments between the three conditions (p > 0.05) indicating lack of effect of mental fatigue on static balance in this population. Therefore, future studies investigating this phenomenon in occupational or sport settings in similar population should consider using more challenging balance tasks.

Priming Effects of Anodal Transcranial Direct Current Stimulation on the Effects of Conventional Physiotherapy on Balance and Muscle Performance in Athletes With Anterior Cruciate Ligament Injury.

CONTEXT: In athletes, postural control impairment and knee muscle dysfunction are the most common disorders following anterior cruciate ligament (ACL) injury. Because of functional changes in the motor cortex following ACL injury, physiotherapy (PT) is not enough for treatment and using neuromodulators, such as trans-cranial direct current stimulation (tDCS) may be necessary. The present study focused on the effects of anodal tDCS (a-tDCS) over the primary motor cortex (M1) concurrent with PT on postural control and muscular performance in the athletes with ACL injury. DESIGN: In this study, 34 athletes with ACL injury were randomly assigned in 2 groups of intervention group (active M1 a-tDCS concurrent with PT, n = 16) and control group (sham M1 a-tDCS concurrent with PT, n = 16). METHODS: The participants of all groups received 20-minute 2 mA M1 a-tDCS with PT during 10 sessions, while tDCS was turned off after 30 seconds in the sham group. Before, immediately following, and 1 month after the interventions, the center of pressure and the average of power of flexor and extensor muscles at 2 velocities of 30°/s and 60°/s were measured by force plate and isokinetic devices, respectively. RESULTS: One month after treatment, the displacement of center of pressure was decreased in the intervention group (P < .05), while there were no changes in the control group. Y-axis of center of pressure decreased in the intervention group relative to the control group, although average of power of flexor and extensor muscles increased immediately in both groups, but the rise in the intervention group was larger than that in the control group (P < .05). CONCLUSION: The findings indicated that M1 a-tDCS can induce the efficacy of PT, which has a lasting effect on the improvement of the postural control in athletes with ACL injury.

Concurrent multi-session anodal trans-cranial direct current stimulation enhances pelvic floor muscle training effectiveness for female patients with multiple sclerosis suffering from urinary incontinence and pelvic floor dysfunction: a randomized clinical trial study.

INTRODUCTION AND HYPOTHESIS: Urinary incontinence following a pelvic floor muscle (PFM) dysfunction is a common disorder in women with multiple sclerosis (MS). Concurrent anodal transcranial direct current stimulation (a-tDCS) of the primary motor cortex (M1) may prime the effects of PFM training (PFMT) in MS patients. This study was aimed at investigating the effects of M1 a-tDCS on the effectiveness of PFMT in the treatment of female MS patients with urinary incontinence and PFM dysfunctions. METHODS: In a randomized double-blinded, control trial study, 30 women with MS were divided into two groups (experimental group: concurrent active M1 a-tDCS and PFMT; control group: concurrent sham M1 a-tDCS and PFMT). Over the course of 8 weeks, these patients received 20-min interventions three times a week. As an indication of PFM function, the bladder base displacement was measured by ultrasonography before, during the 4th week, immediately, and 1 month after the intervention ended. Urinary incontinence was also measured by Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UISF) before, immediately, and 1 month after the intervention ended. RESULTS: A significant improvement in PFM function occurred in the 4th week of intervention and remained 1 month after the intervention in the experimental group when compared with the control group (p<0.05). Compared with baseline, both groups reported significant improvements in PFM function at 8 weeks (p<0.05). Also, both groups were found to have decreased ICIQ-UIS scores after the intervention and at 1-month follow-up (p<0.05). CONCLUSIONS: In MS patients, M1 a-tDCS can significantly enhance the effects of PFMT on the PFM function and urinary incontinence.

Mental Fatigue Impairs Postural Stability in Older Adults.

Purpose: Postural instability can increase the risk of a fall in older adults. In this study, the impact of mental fatigue on postural stability among healthy older adults was investigated. Method: Participants were randomly divided into two groups: experimental and control groups. Postural stability of all participants was tested using the Biodex Balance System (BBS) before and immediately after watching a 30-min documentary program (control group) or completing a 30-min Stroop task (experimental group). Subjective ratings of mental fatigue were measured before and after the Stroop task or watching documentary program. Results: The results indicated that experimental group revealed higher stability scores in the posttest compared to pretest (P ≤ 0.001). However, there were no significant differences for BBS scores between pre and posttest in control group (P = .688). In addition, posttest of subjective ratings of mental fatigue was significantly different between experimental and control groups. Finally, there was also evidence of an association between Visual analog scale and BBS scores in the experimental group (rs = 0.712, P = .002). Conclusions: Mental fatigue caused by Stroop task had a negative impact on postural stability in older adults. This may be due to reduction in attentional resources that was caused by mental fatigue. Thus, mental fatigue could be considered as a risk factor for increased risk of falls in older adults.

Digitalized transcranial electrical stimulation: A consensus statement.

OBJECTIVE: Although relatively costly and non-scalable, non-invasive neuromodulation interventions are treatment alternatives for neuropsychiatric disorders. The recent developments of highly-deployable transcranial electric stimulation (tES) systems, combined with mobile-Health technologies, could be incorporated in digital trials to overcome methodological barriers and increase equity of access. The study aims are to discuss the implementation of tES digital trials by performing a systematic scoping review and strategic process mapping, evaluate methodological aspects of tES digital trial designs, and provide Delphi-based recommendations for implementing digital trials using tES. METHODS: We convened 61 highly-productive specialists and contacted 8 tES companies to assess 71 issues related to tES digitalization readiness, and processes, barriers, advantages, and opportunities for implementing tES digital trials. Delphi-based recommendations (>60% agreement) were provided. RESULTS: The main strengths/opportunities of tES were: (i) non-pharmacological nature (92% of agreement), safety of these techniques (80%), affordability (88%), and potential scalability (78%). As for weaknesses/threats, we listed insufficient supervision (76%) and unclear regulatory status (69%). Many issues related to methodological biases did not reach consensus. Device appraisal showed moderate digitalization readiness, with high safety and potential for trial implementation, but low connectivity. CONCLUSIONS: Panelists recognized the potential of tES for scalability, generalizability, and leverage of digital trials processes; with no consensus about aspects regarding methodological biases. SIGNIFICANCE: We further propose and discuss a conceptual framework for exploiting shared aspects between mobile-Health tES technologies with digital trials methodology to drive future efforts for digitizing tES trials.

The effects of concurrent bilateral anodal tDCS of primary motor cortex and cerebellum on corticospinal excitability: a randomized, double-blind sham-controlled study.

Transcranial direct current stimulation (tDCS) applied to the primary motor cortex (M1), and cerebellum (CB) can change the level of M1 corticospinal excitability (CSE). A randomized double-blinded crossover, the sham-controlled study design was used to investigate the effects of concurrent bilateral anodal tDCS of M1 and CB (concurrent bilateral a-tDCSM1+CB) on the CSE. Twenty-one healthy participants were recruited in this study. Each participant received anodal-tDCS (a-tDCS) of 2 mA, 20 min in four pseudo-randomized, counterbalanced sessions, separated by at least 7 days (7.11 days ± 0.65). These sessions were bilateral M1 stimulation (bilateral a-tDCSM1), bilateral cerebellar stimulation (bilateral a-tDCSCB), concurrent bilateral a-tDCSM1+CB, and sham stimulation (bilateral a-tDCSSham). Transcranial magnetic stimulation (TMS) was delivered over the left M1, and motor evoked potentials (MEPs) of a contralateral hand muscle were recorded before and immediately after the intervention to measure CSE changes. Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and long interval intracortical inhibition (LICI) were assessed with paired-pulse TMS protocols. Anodal-tDCS significantly increased CSE after concurrent bilateral a-tDCSM1+CB and bilateral a-tDCSCB. Interestingly, CSE was decreased after bilateral a-tDCSM1. Respective alterations in SICI, LICI, and ICF were seen, including increased SICI and decreased ICF, which indicate the involvement of glutamatergic and GABAergic systems in these effects. These results confirm that the concurrent bilateral a-tDCSM1+CB have a facilitatory effect on CSE, whereas bilateral a-tDCSM1 exert some inhibitory effects. Moreover, the effects of the 2 mA, 20 min a-tDCS on the CB were consistent with its effects on the M1.

Feasibility of the A-STEP for the assessment of exercise capacity in people with cystic fibrosis.

OBJECTIVES: To evaluate feasibility of the Alfred Step Test Exercise Protocol (A-STEP) for the assessment of exercise capacity in adults and children with cystic fibrosis (CF); in adults to test whether demographics and/or lung function correlated with exercise capacity. METHODS: Adults and children with stable CF from two centres completed the A-STEP (a recently developed incremental maximal-effort step test). Feasibility was evaluated by: usefulness for exercise capacity assessment (measures of exercise capacity were: level reached, exercise-induced desaturation, and achievement of at least one maximal effort criteria); safety; operational factors; time to complete; floor and/or ceiling effects. We used multiple linear regression to test whether demographics and/or lung function correlated with exercise capacity. RESULTS: A total of 49 participants: 38 adults (18 male), percent predicted (pp) forced expiration in one second (FEV1 ) 29-109, aged 22-48 years and 11 children (6 male), ppFEV1 68-107, aged 10-15 years were included. Levels reached (mean (SD) [range]) were 10.2 (2.4) [6-15] (adults), 10.1 (2.5) [7-14] (children); desaturation (change between baseline and peak-exercise SpO2 ): was 8.4 (3.8 [0-15]% (adults), 2.0 (2.0) [0-7]% (children). A total of 8 (21%) adults and no children desaturated <90% SpO2 . At least one criterion for maximal effort was reached by 33 (84%) adults and 10 (91%) children. There were no adverse events. The A-STEP was straightforward to use and carried out by one operator. A total of 26 (68.4%) adults and 7 (63.6%) children completed the test within the recommended 8-12 min. All participants completed a minimum of 6 levels, and completed the test before the final 16th level. In adults, ppFEV1 and ppFVC correlated with the level reached (r = 0.55; p = <0.001 and r = 0.66, p = <0.0001) and desaturation (r = 0.55, p = <0.001 and r = 0.45, p = <0.005). CONCLUSION: In adults and children with stable CF, the A-STEP was feasible, safe, and operationally easy to use for the assessment of exercise capacity, without floor or ceiling effects. In adults, lung function correlated with exercise capacity.

Neural mechanisms underlying state mental fatigue: a systematic review and activation likelihood estimation meta-analysis.

Sustained performance of cognitive tasks could lead to the development of state mental fatigue characterized by subjective sensation of mental weariness and decrease in cognitive performance. In addition to the occupational hazards associated with mental fatigue, it can also affect physical performance reducing endurance, balance, and sport-specific technical skills. Similarly, mental fatigue is a common symptom in certain chronic health conditions such as multiple sclerosis affecting quality of life of the patients. Despite its widely acknowledged negative impact, the neural mechanisms underlining this phenomenon are still not fully understood. We conducted a systematic review and activation likelihood estimation (ALE) meta-analysis of functional neuroimaging studies investigating the effect of mental fatigue due to time-on-task (TOT) on brain activity to elucidate the possible underlying mechanisms. Studies were included if they examined change in brain activity induced by experimental mental fatigue (TOT effect) or investigated the relationship between brain activity and subjective mental fatigue due to TOT. A total of 33 studies met the review's inclusion criteria, 13 of which were included in meta-analyses. Results of the meta-analyses revealed a decrease in activity with TOT in brain areas that constitute the cognitive control network. Additionally, an increased activity with TOT, as well as negative relationship with subjective mental fatigue was found in parts of the default mode network of the brain. The changes in cognitive control and the default mode networks of the brain due to state mental fatigue observed in this study were discussed in relation to the existing theories of mental fatigue.

Effects of static stretching and strengthening exercises on flexion relaxation ratio in patients with LBP: A randomized clinical trial.

INTRODUCTION: Stretching and strengthening exercises are commonly used to improve muscle shortness. Consequently, the aim of this trial was to compare the flexion-relaxation response (electromyography activities of shortened hamstring and back muscles) in chronic nonspecific LBP patients. METHODS: In this randomized controlled clinical trial, forty-five eligible patients were randomly categorized into three groups; static stretching (n = 15), strengthening exercise in lengthened hamstring position (n = 15) and control (n = 15). All groups received conventional physical therapy for LBP and the two intervention groups received special exercise programs as well. Each group performed three treatment sessions for a week, a total of 12 sessions. The flexion-relaxation ratio (FRR) for knee and back muscles were assessed as the primary outcome measure. Pain and functional disability for participants were also assessed. RESULTS: The results indicated non-significant differences between the three groups regarding the changes of FRR (mean between-group differences ranged over 0.69 to 39.1; p > 0.05), pain and disability (mean between-group differences ranged over 0.15 to 5.96; p > 0.05). Within-group analysis for each group, revealed statistically significant improvement in the patients' score of either pain (mean within-group differences ranged over -27.20 to -35.76; p < 0.001) or disability (mean within-group differences ranged over -16.17 to 24.95; p < 0.001) as secondary outcomes. In other words, the scores of pain and disability decreased in all treatment groups as compared to the baseline. CONCLUSION: Neither static stretching nor strengthening exercises in lengthened hamstring position affected FRR more than the control group.