Ankle muscle activity characteristics of stroke patients with hemiplegia at gait initiation

OBJECTIVES

This study aimed to clarify the ankle muscle activity characteristics during gait initiation in stroke patients with hemiplegia.

METHODS

Gait initiation behavior was analyzed in 10 elderly controls and 30 stroke patients with hemiplegia. Activity latencies of the tibialis anterior and soleus muscles on both sides were measured using surface electromyography. The left and right conditions of the participant's leading leg were randomized and specified, and the gait initiation task was performed six times. Muscle activity latencies between the stance and stepping sides in both groups were compared. We also compared the paretic and non-paretic sides of stroke patients.

RESULTS

Muscle activity latency of the paretic leg was delayed in stroke patients compared to elderly controls. Activity latencies of the tibialis anterior and soleus muscles on the paretic side were delayed compared to those on the non-paretic side in stroke patients when leading with the paretic leg. Delayed muscle activity latency was observed only in the tibialis anterior muscle on the paretic side than on the non-paretic side when leading with the non-paretic leg.

CONCLUSION

This study showed that muscle activity in the paretic leg of stroke patients was delayed and that ankle muscle activity characteristics differed depending on the leading leg. These new results may provide a basis for training aimed at improving the latency of muscle activity in the paretic leg, as well as specific training for gait initiation by guiding the non-paretic leg, considering muscle activity patterns.

Linking brain activation to standing balance performance: A systematic review and meta analysis of functional near-infrared spectroscopy literature

BACKGROUND

Functional Near-Infrared Spectroscopy (fNIRS) holds promise for clinical applications in the field of balance impairment amelioration; however, the relationship between fNIRS metrics and balance performance remains uncertain. We aimed to quantify the correlations between fNIRS-derived brain activation and standing balance performance, and determine variables that influence these associations.

METHODS

We systematically reviewed English-language studies, published across PuBMed, PsycINFO, Embase, CINAHL, Ovid Medline, and Web of Science from inception up until July 1, 2024, that assessed standing balance tasks in adults > 18 years old with or without medical diagnosis measured with fNIRS. Pooled correlation coefficients were synthesized using a random effects restricted maximum likelihood model.

RESULTS

Overall, 17 studies were included with 420 participants. Key factors influencing the identified relationships were brain region and participant diagnosis. We identified moderate correlations between balance performance and cortical activation recorded by fNIRS in the supplementary motor area (SMA) (r = 0.52, 95 % CI = 0.39 0.64), and the prefrontal cortex (PFC) (r = 0.47, 95 % CI=0.32 - 0.60). In the PFC, increased oxygenated haemoglobin (HbO) was negatively associated with balance measures. The reverse relationship was reported in the PFC for individuals with physical and cognitive impairment. In the SMA, HbO was positively associated with balance. Few studies found associations between deoxygenated haemoglobin (HbR) and total hemoglobin (HbT) with balance performance.

SIGNIFICANCE

Current evidence supports a relationship between fNIRS measures, specifically HbO, with standing balance performance. This relationship depends on the brain region measured, age, and the diagnosis of the participants. To better understand this relationship, there is a need to report standardized balance performance metrics alongside other metrics of interest to better synthesize data across publications. Improved understanding the neural basis of standing balance with fNIRS will lead to more informed interventions for balance rehabilitation.

Effects of a reactive task on gait initiation in elderly individuals with mild cognitive impairment

BACKGROUND

Older adults with mild cognitive impairment (MCI) exhibit deficits in motor control alongside cognitive decline. Gait initiation, a complex motor task, involves dynamic postural adjustments, fall risk, and cognitive demands. Reaction time tasks increase attentional and cognitive requirements. This study examined whether gait initiation differs between individuals with MCI and cognitively healthy adults and whether a reaction time task influences performance.

METHODS

A total of 30 participants were recruited, including 11 individuals with MCI and 19 cognitively healthy controls. Gait initiation was assessed under two conditions: self-initiated and light-triggered reactive gait initiation. Biomechanical parameters were collected using high-speed motion capture cameras and force plates, measuring center of pressure (COP) and center of mass (COM) movement time, displacement, and velocity, as well as gait parameters such as step length, step width, and landing angle. A two-way mixed ANOVA was conducted to examine the effects of cognitive function and task condition on gait initiation performance.

RESULTS

Older adults with MCI exhibited shorter movement time, shorter COP displacement, and faster COP velocity when performing gait initiation under the reaction time task. Under the reactive time task condition, both groups demonstrated shorter total gait initiation time, greater COP displacement, faster COP velocity, shorter COM displacement, slower COM velocity, and shorter step length.

CONCLUSIONS

Gait assessment in older adults with MCI should include gait initiation analysis, preferably incorporating reactive time tasks. Particular attention should be given to COP parameters in result interpretation.

A comparison of anticipatory processes between gait and step initiation: The role of the final state

BACKGROUND

Whole-body movement initiation with change of base of support is a common paradigm used to assess balance-movement coordination. During clinical evaluation, two transitions are commonly used: gait or step initiation. During their respective anticipatory periods, two mechanisms regulate the whole-body centre of mass acceleration: a shift in the centre of pressure (CoP); and modulation of internal whole-body angular momentum (HM). These transitions have different final states, and we do not know whether the two mechanisms are used similarly during the anticipatory period.

RESEARCH QUESTION

Is the final state already taken into account during the anticipatory period of a whole-body movement initiation?

METHODS

We compared the time evolution of the CoP and HM in the sagittal plane during the anticipatory period of both gait and step initiation in 13 young, healthy participants.

RESULTS

During gait initiation, we observed a larger backward CoP shift (31-56 % and 75-100 % of the anticipatory period), a larger forward-directed HM (45-68 %), and a lower backward-directed HM (84-100 %) compared to step initiation.

SIGNIFICANCE

Our results show that mechanical instability is larger during gait initiation, while HM modulation is larger during step initiation. These findings suggest that the final state of a transition is taken into account during the anticipatory period. Based on our results, we suggest future research should use gait and step initiation to evaluate the generation of mechanical instability, and the use of free segments, respectively, in populations with balance deficits.

Assessing the measurement characteristics of cervical joint repositioning error in individuals with and without forward head posture

BACKGROUND

The current study aimed to examine the joint repositioning error (JRE) in three groups of Forward head posture (FHP) with chronic neck pain (CNP), FHP without CNP, and a healthy control.

METHOD

This cross-sectional study involved 30 participants from each group, selected via convenience sampling. Neck pain intensity was quantified using the Visual Analogue Scale (VAS), neck function was examined using the Neck Disability Index (NDI), and FHP was estimated by measuring the craniovertebral angle. The primary outcome measures were the absolute error (AE) and constant error (CE) of joint repositioning during different cervical movements, evaluated using a laser pointer.

RESULTS

ANOVA results showed that the AE of joint repositioning during right and left neck rotation and lateral bending, along with CE in all neck movements except for left rotation (P = 0.235), was significantly greater in FHP group with CNP compared to the healthy group (P < 0.05). The one-sample t-test showed a significant overshoot for flexion (P = 0.02), extension (P = 0.01) and right rotation (P = 0.03) repositioning (P = 0.06) in the FHP with CNP group and for right rotation repositioning (P = 0.009) in the FHP without CNP group. Also, a significant overshoot tendency for right (P = 0.01) and left (P = 0.002) lateral flexion was observed in the asymptomatic group.

CONCLUSIONS

The research found that the AE and CE of joint repositioning were higher in the FHP group with CNP compared to the healthy group. Furthermore, there was no significant strong correlation between VAS and NDI with the indices of JRE across different cervical movements.

Assessment and Correlates of Different Phenotypical Characteristics of Psychological Flexibility in Adapting to Chronic Pain: A Feasibility Study

OBJECTIVES

This study examined the feasibility of a research protocol for assessing psychological flexibility in patients with chronic pain to gain insight into the uniqueness of different phenotypes of psychological flexibility and to tentatively test whether psychological flexibility is associated with effective adaptation to chronic pain.

METHODS

In a cross-sectional study, in twenty patients with chronic pain, different phenotypes of psychological flexibility and a variety of positive and negative health indicators were assessed. Correlations were explored to determine the unicity of the different phenotypes of psychological flexibility and to test their associations with chronic pain.

RESULTS

All phenotypes of psychological flexibility could be assessed reliably in this patient group. Preliminary findings suggest that all phenotypes assess unique flexibility aspects (79% of the intercorrelations were less than moderate; > -0.30, < 0.30). Higher levels of different psychological flexibility phenotypes were generally associated with higher positive health indicators and lower negative health indicators (70% of the moderate correlations; ≤ -0.30 or ≥ 0.30 were in the expected direction).

CONCLUSIONS

Results confirm that the protocol is feasible for large-scale research in patients with chronic pain and that it is useful to further investigate the different phenotypes of psychological flexibility in relation to optimal adaptation to chronic pain in a longitudinal study.

PRACTICE IMPLICATIONS

Psychological flexibility is a potentially important future target in the treatment (e.g., biofeedback, cognitive behavioral therapy, mindfulness) of patients with chronic pain.

Effects of Core Stability Training on Balance, Standing, and Gait in Children with Mild Cerebral Palsy: A Randomized Controlled Trial

Background/Objectives: Children with diplegic spastic cerebral palsy (CP) often present with impaired postural control, poor balance, and gait abnormalities that negatively affect their functional mobility and independence. Core stability, which is the ability to control the position and movement of the trunk, is considered a critical component in maintaining postural alignment and improving gross motor function. This study aimed to investigate the impact of a structured core stability exercise program on the standing ability, functional balance, and gait parameters of children diagnosed with diplegic spastic CP. Methods: Forty children (28 males, 12 females) aged 4-10 years with a clinical diagnosis of diplegic spastic cerebral palsy were randomly allocated into two groups (n = 20 each). The study group underwent a 12-week core stability exercise program in addition to a standardized physiotherapy regimen, which was conducted three times per week. The control group received the physiotherapy program alone. Functional outcomes were assessed pre- and post-intervention using the Gross Motor Function Classification System (GMFCS), Pediatric Balance Scale, and Kinovea software for gait analysis. Results: Both groups demonstrated statistically significant improvements in all measured variables after the intervention. However, the study group showed significantly greater improvements in standing ability (9%), balance (9%), and gait parameters (p < 0.05), particularly in knee flexion, ankle dorsiflexion, and plantar flexion, during gait cycles. Conclusions: Core stability training resulted in superior enhancements in balance, standing, and gait performance compared with physiotherapy alone in children with diplegic spastic cerebral palsy.

Cortical dynamics underlying initiation of rapid steps with contrasting postural demands

Our ability to flexibly initiate rapid visually-guided stepping movements can be measured in the form of express visuomotor responses (EVRs), which are short-latency (∼100 ms), goal-directed bursts of lower-limb muscle activity. Interestingly, we previously demonstrated that recruitment of anticipatory postural adjustments (APAs) interacted with the subcortically-generated EVRs in the lower limb, suggesting context-dependent top-down modulation. We investigated the associated cortical dynamics prior to and during rapid step initiation towards a salient visual target in twenty-one young, healthy individuals while stepping under varying postural demands. We recorded high-density EEG, surface electromyography from gluteus medius and ground-reaction forces. Independent component analysis and time-frequency statistics revealed significant, yet relatively modest differences between conditions in preparatory cortical dynamics, most evidently in primary motor areas. Following target presentation, we observed stronger theta and alpha power enhancement in the supplementary motor area, and stronger alpha and beta power decrease in primary motor, parietal and occipital clusters during APA recruitment that preceded steps under high postural demands. Side-specific changes in motor cortex lagged the timing of EVR expression, supporting the EVR's purportedly subcortical origin. Together, our findings point towards greater cortical involvement in step initiation under high postural demands as compared to more reflexive, stimulus-driven steps. These findings may be particularly relevant for populations where postural control is impaired by age or disease, as more cortical resources may need to be allocated during stepping.

Functional Electrical Stimulation of the Plantarflexor Muscle During Walking Leads to a Proximal-to-Distal Redistribution of Lower Limb Joint Work

OBJECTIVE

This study aimed to compare the effects of different conditions of functional electrical stimulation (FES) applied to the ankle plantarflexor muscles (gastrocnemius, soleus, or both combined) during push-off on lower limb joint biomechanics at controlled walking speeds in healthy young adults.

METHODS

Fifteen healthy young adults walked along a 7-meter walkway at controlled speeds under six conditions: bilateral stimulation of the soleus, gastrocnemius, both muscles combined, and matched-speed trials without stimulation. Stimulation was applied below the discomfort threshold during push-off (heel-off to toe-off of the trailing leg). Two force plates and a motion capture system measured lower limb joint biomechanics.

RESULTS

All FES conditions increased positive (+8%) and total mechanical work (+5%) at the ankle. FES reduced positive knee work (- 10%) and negative hip work (- 5%), although this was significant only for gastrocnemius stimulation alone or combined with soleus. The ankle's contribution to both positive and total lower limb work increased with FES, while the contributions of the knee and hip decreased regardless of the stimulation condition. Additionally, FES increased ankle plantarflexion angle (13%) and velocity peaks (6%), without affecting spatiotemporal gait parameters at comparable speeds.

CONCLUSION

FES applied to the plantarflexor muscles during push-off leads to a proximal-to-distal redistribution of lower limb joint work during walking at controlled speeds in healthy young adults, with subtle differences depending on the stimulation condition. These findings underscore the potential of FES as a solution to redistribute lower limb joint work during walking.

Influence of trunk muscle fatigue on lower limb asymmetries in novice runners

Running is generally considered a symmetrical activity that involves harmonized functions of upper and lower limbs. However, asymmetry can occur under certain conditions, such as fatigue, as lower limbs perform distinct functional tasks. While running, trunk muscles play a crucial role in transmitting loads between the upper and lower limbs, yet the impact of trunk muscle fatigue on the dominant and nondominant legs has not been well addressed. This study investigated the effects of trunk muscle fatigue on ground reaction force characteristics on dominant and nondominant legs in novice runners. Thirty participants were asked to run along a runway at 3.3 m · s-1 before and after a trunk muscle fatigue protocol. Ground reaction force data were collected bilaterally, and subsequent asymmetries were calculated. Trunk muscle fatigue had different effects on the dominant and nondominant legs. In the dominant leg peak medial force increased, while the nondominant leg showed reduced peak lateral force, peak braking force and peak negative free moment and increased medio-lateral impulse. Trunk muscle fatigue increased asymmetries in peak lateral force, peak braking force and decreased asymmetry in peak negative free moment. These findings suggest that trunk muscle fatigue, due to its different effects on dominant and nondominant legs, deteriorates running asymmetry and may increase injury risk in novice runners. Strengthening and improving the endurance of trunk muscles is recommended for novice runners to prevent strength reduction-related changes in running mechanics and mitigate injury risk.

Transtibial limb loss influences muscle excitation, 3D dynamic balance and their cross-sectional correlation in older individuals during walking

BACKGROUND

Two-thirds of individuals with amputations in large cities are older. Our study identifies how lower-limb amputation alters dynamic balance, muscle excitation and their relationship across samples of older individuals at multiple walking speeds. We hypothesized that individuals with amputation would express different relationships between their muscle excitation and 3D dynamic balance, which would depend on speed.

METHODS

Angular momenta of the body and individual segments, as well as bilateral electromyography signals of five muscles were compared between individuals with (n = 13) and without (n = 10) below-knee amputation at self-selected normal and fast speeds, using Statistical Parametric Mapping. We also related balance and muscle excitation through Pearson correlations of angular momenta and electromyography (α = 0.05).

FINDINGS

There were multiple increases (and few decreases) in whole-body and segmental angular momenta for individuals with amputation during early, mid and late stance as well as terminal swing, especially in the sagittal plane. Excitation of the medial hamstring of the residual leg in late swing was decreased at both speeds in individuals with amputations. Generally, both groups had positive correlations between muscle excitation and angular momenta. However, interesting exceptions occurred for the group with amputation such as a negative relationship between the medial hamstring of the residual limb and whole-body angular momentum in the transverse plane at normal walking speeds, where increased muscle activity was associated with more balanced individuals.

INTERPRETATION

Use of prostheses during walking by older individuals influences dynamic balance, muscle coordination, and their correlation. Observability of these differences depends on speed and anatomical plane.

Associations of physical activity and sleep with mental health during and post-COVID-19 pandemic in chinese college students: a longitudinal cohort study

BACKGROUND

The COVID-19 pandemic seriously impacted people's lifestyles, leading to changes in physical activity, sleep and mental health. This study aimed to assess the recovery of these indicators in Chinese university students post-COVID-19 pandemic, and explore the association between lifestyle changes and psychological problems.

METHODS

A two-wave longitudinal study was conducted with 2,748 college students in Hebei, China. Self-report questionnaires measured physical activity, sleep and psychological variables (depression symptoms, anxiety symptoms, and perceived stress) in 2022 and 2024. McNemar chi-square test compared differences between the two waves. Additionally, univariate and multivariate logistic regression analyses were performed to examine the independent and joint associations between changes in lifestyle behaviors and psychological problems across this period.

RESULTS

Proportion of physical inactivity decreased from 22.5% to 16.2%, and poor sleep quality reduced from 18.3% to 16.2% after the pandemic (P < 0.05). Depression symptoms and anxiety symptoms also improved (P < 0.05), while perceived stress remained high (64.5%). Compared to consistently inactive students, those becoming physically active (depression OR = 0.40, anxiety OR = 0.34, stress 0.56) and those persistently active (depression OR = 0.43, anxiety OR = 0.38, stress 0.47) had reduced psychological symptoms. However, after adjusting for confounders, the association between improved physical activity and mental health problems was insignificant (P > 0.05). Improved sleep (depression OR = 0.42, anxiety OR = 0.24, stress 0.42) and consistently good sleep (depression OR = 0.20, anxiety OR = 0.20, stress 0.37) also demonstrated a protective effect after fully adjusting for demographics and socioeconomic status.

CONCLUSIONS

This study found that high perceived stress persisted. Although physical activity improved across this period, its change was not significantly associated with mental health after adjustments. However, improved sleep quality was significantly associated with reductions in depression levels, anxiety levels, and perceived stress. These findings highlight the importance of sleep and physical activity in mental health recovery post-pandemic and the need for targeted interventions.

Anticipatory muscle activations to coordinate balance and movement during motor transitions: A narrative review

BACKGROUND

Maintaining balance while moving is vital for day-to-day activities. A key challenge in the comprehension of human movement is to determine how muscles contribute to balance-movement coordination. Motor transitions, defined as movements executed between two steady balance states, are particularly interesting phases to study balance-movement coordination because a large, discrete change in whole-body momentum may disturb balance. During voluntarily-initiated motor transitions, anticipatory muscle patterns provide the biomechanical conditions that are favourable to both maintaining balance and executing the movement.

RESEARCH QUESTION

What are the mechanical consequences of anticipatory muscle activations for balance-movement coordination during voluntarily-initiated motor transitions?

METHODS

We review the biomechanical contributions of the anticipatory muscle activations identified in the literature during four types of voluntarily-initiated motor transitions, through the prism of three balance mechanisms ('moving the centre of pressure (CoP)', 'counter-rotating segments', and 'applying new external force(s)'). In particular, we investigate how anticipatory muscle activations modulate whole-body centre of mass acceleration.

RESULTS

We show that the mechanical consequences of anticipatory muscle activations have been extensively described, but mainly using the 'moving the CoP' mechanism. Unlike their role during steady balance states, both 'moving the CoP' and 'applying new external force(s)' mechanisms create a required mechanical instability during the anticipatory phase of motor transitions. The 'counter-rotating' mechanism may act as a stabiliser during motor transitions, but additional research is needed to clarify this assumption.

SIGNIFICANCE

This review establishes that muscle activation processes have different mechanical consequences for balance-movement coordination during the anticipatory phases of motor transitions, compared to steady balance states. Because the mechanical instability that is created can lead to falls, a better understanding of the mechanisms underlying motor transitions is needed to enable the design of more effective fall prevention programs and/or devices for population with balance deficits.

Physical activity and sedentariness levels in patients with post-exertional malaise resulting from post-COVID-19 syndrome

BackgroundPost-exertional malaise (PEM) is a complex phenomenon characterized by extreme fatigue, reduced endurance, and muscular and joint pains. Physical activity (PA) has recognized health benefits, including reducing the risks of chronic diseases and mortality. During the pandemic, a general decline in PA was measured, but the profile of the various components of PA and sedentariness in patients with PEM resulting from post-COVID-19 syndrome (PCS-19) remains scarce. It is relevant to observe the impact of these discomforts on PQ after their occurrence.ObjectiveThis study examines the detailed PA and sedentary profile of individuals affected by PEM associated with PCS-19.MethodsAn online questionnaire disseminated via social media platform evaluated PA and sedentariness before and after COVID-19 diagnostic.ResultsIndividuals with PEM (n = 154) became more sedentary and inactive post-COVID-19. Specifically, PA at work decreased in women and those whose last infection occurred over a year ago. Walk decreased for women but increased for men. Bike journeys generally decreased after COVID-19. The severity of PEM, the pace of recovery, and fear of malaise influenced PA changes.ConclusionsThe PCS-19 leads to increased sedentary behavior and a decline in PA, particularly at work, and is more pronounced among women and those more severely affected by PEM. These findings are critical for post-COVID PA resumption, including for workers who go back to work and who regain normal duties while being potentially deconditioned.

Interoception after frontal brain injury: A systematic review

OBJECTIVE

Interoception is crucial for emotional processing. It relies on the bidirectional connections between the insula, a crucial structure in interoception, and the frontal lobe, which is implicated in emotional experiences. Acquired frontal brain injury often leads to emotional disorders. Our goal was to explore the interoceptive profiles of patients with frontal lesions with or without insular involvement.

METHOD

Given the neuroanatomical links between interoception and emotions, we conducted a systematic Preferred Reporting Items for Systematic Reviews and Meta-analyses guided review of studies assessing at least one dimension of interoception in adults with acquired frontal injuries, with or without associated insular lesions.

RESULTS

Seven articles were included. The review indicated that interoceptive accuracy declines after frontal injuries. The two studies that investigated interoceptive sensitivity found lower scores in patient groups. Finally, inconsistent results were found for interoceptive metacognition after frontal damage.

CONCLUSIONS

This review is the first to explore interoceptive disorders after acquired frontal brain injury. The findings reveal deficits in cardiac interoceptive accuracy and interoceptive sensitivity following frontal damage. Inconsistent results were observed for interoceptive metacognition. Further research is needed to confirm the presence of interoceptive deficits following a frontal lesion. Additionally, the relationship between interoceptive deficits and emotional disorders, often reported after frontal brain injury, should be investigated.

Sex-specific Mendelian randomization phenome-wide association study of basal metabolic rate

Observationally, higher basal metabolic rate (BMR) is associated with metabolism-related disorders, cancer, aging, and mortality. In this Mendelian randomization (MR) phenome-wide association study, using two-sample MR methods, we systematically and comprehensively investigated the health effects of genetically predicted BMR across the phenome sex-specifically. We obtained sex-specific genetic variants strongly (p < 5 × 10- 8) and independently (r2 < 0.001) predicting BMR from the UK Biobank and applied them to over 1,000 phenotypes within the same study. We combined genetic variant-specific Wald estimates using inverse-variance weighting, supplemented by sensitivity analysis. We used a false-discovery rate correction to allow for multiple comparisons as well as multivariable MR adjusted for body mass index and testosterone to investigate the independent effects of BMR on phenotypes with significant univariable associations. We obtained 217/219 genetic variants predicting BMR and applied them to 1,150/1,242 phenotypes in men/women, respectively. BMR was associated with 190/270 phenotypes in univariable analysis and 122/123 phenotypes in multivariable analysis in men/women. Examples of robust associations in multivariable analysis included those with neoplasms, diseases of the circulatory system, and growth and reproductive investment. In conclusion, BMR might affect a wide range of health-related outcomes. The underlying mechanisms and interactions between phenotypes warrant further study, as BMR is modifiable.

Combined Proxies for Heart Rate Variability as a Global Tool to Assess and Monitor Autonomic Dysregulation in Fibromyalgia and Disease-Related Impairments

BACKGROUND

Heart rate variability (HRV) provides both linear and nonlinear autonomic proxies that can be informative of health status in fibromyalgia (FM), where sympatho-vagal abnormalities are common. This retrospective observational study aims to: 1. detect differences in correlation dimension (D2) between FM patients and healthy controls (HCs); 2. correlate D2 with standard HRV parameters; 3. correlate the degree of HRV changes using a global composite parameter called HRV grade, derived from three linear indices (SDNN = intervals between normal sinus beats; RMSSD = mean square of successive differences; total power), with FM clinical outcomes; 4. correlate all linear and nonlinear HRV parameters with clinical variables in patients.

METHODS

N = 85 patients were considered for the analysis and compared to 35 healthy subjects. According to standard diagnostic protocol, they underwent a systematic HRV protocol with a 5-min paced breathing task. Disease duration, pain intensity, mood, sleep, fatigue, and quality of life were assessed. Non-parametric tests for independent samples and pairwise correlations were performed using JMP (all p < 0.001).

RESULTS

Mann-Whitney U found a significant difference in D2 values between FM patients and HCs (p < 0.001). In patients, D2 was associated with all HRV standard indices (all p < 0.001) and FM impairment (FIQ = -0.4567; p < 0.001). HRV grade was also associated with FM impairment (FIQ = 0.5058; p < 0.001).

CONCLUSION

Combining different HRV measurements may help understand the correlates of autonomic dysregulation in FM. Specifically, clinical protocols could benefit from the inclusion and validation of D2 and HRV parameters to target FM severity and related dysautonomia.

The Physiological Component of the BOLD Signal: Impact of Age and Heart Rate Variability Biofeedback Training

Aging is associated with declines in autonomic nervous system (ANS) function, including reduced heart rate variability (HRV), impaired neurovascular coupling, and diminished cerebrovascular responsiveness-factors that may contribute to cognitive decline and neurodegenerative diseases. Understanding how aging alters physiological signal integration in the brain is crucial for identifying potential interventions to promote brain health. This study examines age-related differences in how cardiac and respiratory fluctuations influence the blood oxygenation level-dependent (BOLD) signal, using two independent resting-state fMRI datasets with concurrent physiological recordings from younger and older adults. Our findings reveal significant age-related reductions in the percent variance of the BOLD signal explained by heart rate (HR), respiratory variation (RV), and end-tidal CO 2 , particularly in regions involved in autonomic regulation, including the orbitofrontal cortex, anterior cingulate cortex, insula, basal ganglia, and white matter. Cross-correlation analysis also revealed that younger adults exhibited stronger HR-BOLD coupling in white matter, as well as a more rapid BOLD response to RV and CO 2 in gray matter. Additionally, we investigated the effects of heart rate variability biofeedback (HRV-BF) training, a non-invasive intervention designed to modulate heart rate oscillations. The intervention altered physiological-BOLD coupling in an age- and training-dependent manner: older adults who underwent HRV-BF to enhance HR oscillations exhibited a shift toward younger-like HR-BOLD coupling patterns, while younger adults who trained to suppress HR oscillations showed increased CO 2 -BOLD coupling. These findings suggest that HRV-BF may help mitigate age-related declines in autonomic or cerebrovascular function. Overall, this study underscores the role of physiological dynamics in brain aging and highlights the importance of considering autonomic function when interpreting BOLD signals. By demonstrating that HRV-BF can modulate physiological-BOLD interactions, our findings suggest a potential pathway for enhancing cerebrovascular function and preserving brain health across the lifespan.

Dynamic balance of persons with unilateral upper limb absence when responding to a walking disturbance

BACKGROUND

A high prevalence of falls has been reported in individuals with upper limb absence (ULA). This prevalence is increased in upper limb prosthesis users. It is possible that ULA and prosthesis use may alter recovery mechanisms in response to a perturbation.

RESEARCH QUESTION

The purpose of this study was to investigate the reactive response of individuals with unilateral transradial ULA to perturbations during walking compared to control participants, and to determine the effect of prosthesis use on perturbation response strategies and resultant dynamics.

METHODS

10 upper limb prosthesis users and 10 matched able-bodied control participants completed two walking treadmill tasks: 1) a steady-state walking baseline trial at 1.0 m/s, and 2) 12 perturbation trials containing an unexpected, rapid treadmill belt acceleration and deceleration while walking. Six perturbations were delivered to each leg during single limb stance. Prosthesis users completed both tasks with and without their customary prosthesis. Whole-body angular momentum ranges (Lrange) in each plane during baseline and perturbation response were compared between prosthesis users and controls using one-sided independent t-tests. A two-way repeated measures ANCOVA, with years of prosthesis use modeled as a covariate, assessed the main and interaction effects of prosthesis use and perturbation side of Lrange in three planes, and shoulder add-abduction and flexion-extension ranges in prosthesis users.

RESULTS AND SIGNIFICANCE

Prosthesis users exhibited greater Lrange than controls during baseline and perturbation response, in the sagittal-plane only. Lrange during perturbation response was significantly greater when the prosthesis was not worn, also in the sagittal-plane only. Perturbations may present a greater recovery challenge to people with transradial ULA partially due to a mass and inertia imbalance between the sound and impaired limbs when not wearing a prosthesis. Holistic rehabilitation regimes including both prosthesis and balance training should be considered for ULA populations.

How Does Push-Off Distance Influence Force-Velocity Profile and Performance During Vertical Jumping?

In many sports, practitioners must reach their maximal jump height (hmax) under time constraints. This requires a reduction of the countermovement depth and so of the push-off distance (hPO). The purpose of this study was to investigate how hPO influences force-velocity (F-v) profiles (F¯0, v¯0, P¯max, and SFv) and performance. Eleven participants (age: 26 [5] y, height: 175.6 [11.2] cm, mass: 76 [15] kg; squat 1RM: 129 [34] kg) performed maximal countermovement jumps. Kinetic and kinematic measurements were used to assess individual F-v profiles for 3 different hPO conditions (hPO-SMALL, hPO-MEDIUM, hPO-LARGE) from countermovement jumps performed under different load conditions (bodyweight [BW], BW + 8 kg, BW + 17 kg, BW + 40%1RM, BW + 70%1RM). Results indicated that F¯0 and P¯max changed across hPO conditions, while v¯0 remained constant. A lower hPO led to a significantly higher F¯0 and P¯max. These changes resulted in a steeper SFv leading to a more force-oriented profile, a lower optimal SFv and a greater F-v imbalance. Reducing hPO and modifying F-v profile led, to some extent, to a reduction in hmax. Performance is a compromise between hPO, P¯max, and F-v imbalance, all influenced by countermovement depth. This explains why reducing countermovement depth to meet time constraint may lower performance.

Mobile phone tasks impair frontal dynamic stability and increase fall risk during obstacle crossing in young men

Falls, a major cause of accidental deaths, are often caused by obstacles, particularly among young people who may trip in over half of cases. Although mobile phone use has been linked to impaired gait and balance, its effect on dynamic stability during obstacle crossing is not well understood. This study investigates the impact of mobile phone usage on dynamic stability and fall risk during obstacle-crossing movements and compares the effects of various mobile phone tasks on obstacle-crossing performance. Seventeen healthy young men performed four obstacle-crossing tasks in random order: no mobile phone use, video browsing, text editing, or numerical computation. A motion capture system and two three-dimensional force plates recorded kinematic data and ground reaction forces. Gait spatiotemporal parameters and whole-body angular momentum were analyzed using one-way repeated-measures analysis of variance. Mobile phone use significantly reduced step width and stride speed while increasing obstacle-crossing time and leg-raising height (P < 0.05). Video browsing and numerical computation caused larger frontal-plane angular momentum ranges during the first single-support and second double-support phases than text editing (P < 0.05). Additionally, all mobile phone tasks increased in mean frontal plane external moments and free moments relative to the no-phone condition (P < 0.05). Mobile phone use impairs dynamic stability and elevates lateral fall risk during obstacle crossing, with numerical computation having the most detrimental impact.

Maintaining Mobility and Balance in Multiple Sclerosis: A Systematic Review Examining Potential Impact of Symptomatic Pharmacotherapy

BACKGROUND

Mobility disability (MD) manifests as walking dysfunction and postural instability in more than 90% of people with multiple sclerosis (MS) within 10 years of disease onset. Disease-modifying pharmacotherapies reduce rates of relapses and new lesions and slow disease progression, but ongoing decline in MD can persist or result from secondary, symptomatic pharmacotherapies. This systematic review focuses on symptomatic pharmacotherapies that potentially impact markers of MD in MS.

METHODS

PubMed/Medline, Google Scholar, and Scopus were searched between January 1990 and December 2024. Eligible studies were included on the basis of the following criteria: (1) randomized, placebo-controlled trials (RCTs); (2) confirmed MS diagnosis; (3) one MD-related outcome; and (4) one symptomatic pharmacotherapy; OR (5) multiple doses of a symptomatic pharmacotherapy. Results were uploaded to Rayyan: Intelligent Systematic Review software and screened by two blinded reviewers for eligibility. Risk of bias was assessed using the PEDRo Scale for quality assessment.

RESULTS

This review included 23 RCTs (all RCTs scored good-to-excellent on PEDRo Scale); 13 RCTs examined fampridine (4-aminopyridine) for its direct effects on MD, and 10 RCTs assessed indirect effects of symptomatic pharmacotherapies, including cannabinoids (n = 9), and baclofen (n = 1) on MD. The MD outcomes included gait (25-foot walk [T25FW], kinetics, and kinematics), community mobility (12-item MS Walking Scale [MSWS-12]), endurance (6-min walk [6MW]), balance (Berg Balance Scale [BBS], Dynamic Gait Index [DGI], Six-Spot Step Test, posturography, and falls), and functional mobility (Timed Up and Go [TUG] and 5 Times Sit-to-Stand [5STS]). Fampridine significantly improved gait (T25FW, MSWS-12), endurance (6MW), and functional mobility (5STS, TUG), with the largest effect on gait speed; changes in balance were inconclusive. Indirect pharmacotherapies, specifically cannabinoids mainly reduced spasticity (Modified Ashworth Scale, nine out of nine studies), but rarely improved pain (Numerical Rating Scale, two out of nine studies) or MD outcomes (two out of nine studies). Both direct and indirect pharmacotherapies resulted in adverse effects, notably dizziness (n = 366), urinary tract infection (n = 216), and nausea (n = 150), potentially impacting MD in MS.

CONCLUSIONS

Fampridine may improve gait and functional mobility in MS, but its effect on balance requires further investigation in RCTs. Cannabinoids and baclofen may alleviate spasticity and pain, but seemingly have limited secondary effect on markers of MD, such as gait and postural stability. Clinicians should consider the impact of symptomatic pharmacotherapies on MD in MS, including potential side effects. Future research should explore integrating rehabilitation (e.g., balance training) with symptomatic pharmacotherapies, as this might enhance positive effects or combat deleterious effects on markers of MD.

A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults

OBJECTIVE

To analyse the relationship between traditional stiffness and muscle antagonist coactivation in both stroke and healthy participants, using linear and non-linear measures of coactivation and COP during standing, stand-to-sit, and gait initiation.

METHODS

Participants were evaluated through a cross-sectional design. Electromyography, isokinetic dynamometer, and force plate were used to calculate coactivation, intrinsic and functional stiffness, and COP displacement, with both linear and non-linear metrics. Spearman's correlations and Mann-Whitney tests were applied (p < 0.05).

RESULTS

Post-stroke participants showed higher contralesional intrinsic stiffness (p = 0.041) and higher functional stiffness (p = 0.047). Coactivation was higher on the ipsilesional side during standing (p = 0.012) and reduced on the contralesional side during standing and transitions (p < 0.01). Moderate correlations were found between intrinsic and functional stiffness (p = 0.030) and between coactivation and intrinsic stiffness (standing and stand-to-sit: p = 0.048) and functional stiffness (gait initiation: p = 0.045). COP displacement was reduced in post-stroke participants during standing (p < 0.001) and increased during gait initiation (p = 0.001). Post-stroke participants exhibited increased gastrocnemius/tibialis anterior coactivation during gait initiation (p = 0.038) and higher entropy and stability across tasks (p < 0.001).

CONCLUSION

Post-stroke participants showed higher contralesional intrinsic and functional stiffness, reduced coactivation in static tasks, and increased coactivation in dynamic tasks. COP and coactivation analyses revealed impaired stability and random control, highlighting the importance of multidimensional evaluations of postural tone.

Autonomic dysfunction after stroke: an overview of recent clinical evidence and perspectives on therapeutic management

PURPOSE

Central autonomic dysfunction is common in acute stroke and is associated with cardiovascular complications and increased mortality. The aim of this review is to present novel diagnostic and therapeutic approaches to the management of this disorder and the latest data on its impact on the clinical outcome after stroke.

METHODS

We performed a narrative review of recent literature, with a particular focus on articles related to underlying pathophysiological mechanisms of cardiac autonomic dysregulation, the role of cardiac autonomic dysregulation in the activation of neuroinflammatory response and the development of cardiovascular, respiratory and metabolic complications in patients with ischemic and hemorrhagic stroke.

RESULTS

The assessment of central autonomic dysfunction by non-invasive diagnostic techniques, including heart rate variability and baroreflex sensitivity, has gained wide practical application in recent years, and they may have a predictive role for evaluating disease prognosis. The emerging evidence derived from recent trials demonstrates that the presence of autonomic imbalance may lead to increased mortality and have an adverse effect on post-stroke rehabilitation.

CONCLUSION

The early detection and treatment of central autonomic system dysfunction may lead to improved survival of patients with stroke. Among the available therapeutic approaches, neuromodulatory techniques and pharmacological interventions are promising strategies which may be implemented as part of standard acute stroke care to improve patient recovery. Future studies are warranted to address the long-term effects of potential therapeutic agents on the modulation of cardiovascular autonomic function in stroke survivors.

Balancing postural control and motor inhibition during gait initiation

This study examines the relationship between stopping a planned gait initiation due to sudden environmental changes and maintaining body stability. Using a gait initiation version of the Stop Signal Task (SST), we studied changes in anticipatory postural adjustments (APAs) during gait initiation and suppression. We found that trial-level variables, such as the time to start or stop stepping, interacted with biomechanical factors like the center of mass displacement relative to the base of support affecting performance. A critical biomechanical threshold was identified, beyond which stopping movement was unlikely. These findings highlight the strong link between limb action control and body equilibrium, offering a framework within a motor control paradigm. By integrating biomechanical elements, the model effectively simulates real-life scenarios, identifying key variables for studying neural correlations between action and postural control, and aiding in the development of injury prevention and rehabilitation tools for individuals with movement and posture impairments.

Impact of Visual Input and Kinesiophobia on Postural Control and Quality of Life in Older Adults During One-Leg Standing Tasks

Visual conditions significantly influence fear of movement (FOM), which is a condition that impairs postural control and quality of life (QOL). This study examined how visual conditions influence sway velocity during repeated one-leg standing tasks and explored the potential relationship between postural control, FOM, and QOL in older adults with and without FOM. Thirty-seven older adults with FOM and 37 controls participated in the study. Postural sway velocity was measured across three repeated trials under visual conditions in both anteroposterior (AP) and mediolateral (ML) directions. The groups demonstrated significant interaction under visual conditions (F = 7.43, p = 0.01). In the eyes-closed condition, the FOM group exhibited faster ML sway velocity than the control group, with significant differences across all three trials. There was a significant interaction between sway direction and vision (F = 27.41, p = 0.001). In addition, the FOM demonstrated strong negative correlations with several QOL measures on social functioning (r = -0.69, p = 0.001) and role limitations due to emotional problems (r = -0.58, p = 0.001) in the FOM group. While FOM influenced sway velocity during balance tasks, visual input emerged as a key determinant of postural control. The FOM group demonstrated a heightened reliance on vision, suggesting an increased need for vision-dependent strategies to maintain balance.

Impact of body image on the kinematics of gait initiation

In daily life, we walk naturally by considering our physical characteristics and formulating appropriate motor plans. However, the impact of changes in body image on walking movements during motor planning remains poorly understood. Therefore, in this study, we examined changes in walking behavior under different conditions where body image was altered. We included 26 participants (13 men and 13 women, aged 18.27 ± 0.52) who performed walking movements under five conditions: eyes open, eyes covered, eyes covered while imagining their bodies becoming larger, eyes covered without imagining altered body size, and eyes open again. As a result, under the condition where participants imagined their bodies becoming larger, their step length, step completion time, and foot lift height increased. To generate a torque larger than the actual body size, the participants made a motor planning with a larger body image, resulting in an increase in step length. Since these results are attributed to the disparity between actual body size and body image, which affects motor planning, our findings have potential applications in rehabilitation and sports coaching settings.

The effects of paced breathing on psychological distress vulnerability and heart rate variability in adults sustaining traumatic injury

BACKGROUND

Traumatic physical injuries can lead to psychological distress and increased risk of psychiatric disorders, often reflected in dysregulated autonomic responses measurable through heart rate variability (HRV). Slow-paced breathing has shown potential in enhancing HRV, but its effectiveness in injured survivors remains unexplored. This study investigates the effect of slow-paced breathing on HRV among injured survivors compared to non-injured individuals and explores the influence of psychological distress and spontaneous respiratory rate on this effect.

METHODS

The study involved 120 injured individuals and 112 non-injured controls with similar age, sex, and education levels. Injured participants with minor-to-moderate injuries from traffic crashes were assessed 3-6 weeks post-injury. Psychological distress was defined as the risk of post-traumatic stress disorder and/or major depression. Physiological assessment (HRV) included a 2-min resting baseline and a 2-min slow-paced breathing session (6 breaths/min). Repeated measure MANCOVA assessed HRV changes between groups, while correlation analyses examined the relationship between these changes.

RESULTS

Injured survivors had significantly lower HRV than non-injured controls. Both groups showed notable HRV increases during slow-paced breathing. Among injured individuals, those with higher psychological distress exhibited greater HRV increases, particularly in parasympathetic activity and overall variability. Higher spontaneous respiratory rates were associated with greater HRV changes, especially in non-injured individuals.

CONCLUSION

Slow-paced breathing demonstrated significant physiological effects for injured survivors, particularly those with higher psychological distress, and supports its potential in improving stress regulation post-injury. Future research should examine the long-term effects of sustained breathing practice and clinical applicability in reducing psychological distress and disability post-injury.

Heart Rate Variability Biofeedback Training Can Improve Menopausal Symptoms and Psychological Well-Being in Women with a Diagnosis of Primary Breast Cancer: A Longitudinal Randomized Controlled Trial

Breast cancer survivors experience numerous chronic symptoms linked to autonomic dysfunction including anxiety, stress, insomnia, menopausal symptoms, and cognitive impairment. Effective non-pharmacological solutions to address these are currently lacking.

METHODS

Our three-armed longitudinal randomized controlled trial assessed the effectiveness of a 4-week remote smartphone-based heart rate variability biofeedback intervention which involved daily paced breathing at 6 breaths p/min; active (12 breaths p/min) and waitlist controls were included. Heart rate variability and self-reported cancer-related symptoms were assessed at baseline, post-, and 6 months-post intervention. Participants were 60 UK-based women with primary breast cancer history (6 to 60 months post-active treatment).

RESULTS

The intervention group showed significant increases in low-frequency heart rate variability over time (F (4, 103.89) = 2.862, p = 0.027, d = 0.33), long-lasting improvement in sleep quality (F (4, 88.04) = 4.87, p = 0.001, d = 0.43) and cessations in night sweats (X2 (2, N = 59) = 6.44, p = 0.04, Cramer's V = 0.33), and reduced anxiety post-intervention compared to the active and waitlist controls (F (4, 82.51) = 2.99, p = 0.023, d = 0.44). Other findings indicated that the intervention and active control participants reported lasting improvements in cognitive function, fatigue, and stress-related symptoms (all ps < 0.05). The waitlist group reported no symptom changes across time.

CONCLUSION

Heart rate variability biofeedback is a feasible intervention for addressing diverse chronic symptoms commonly reported by breast cancer survivors.

Deep, posterior muscles of the neck. A proposal for injection procedures

The emergence of the col-cap concept in the 2010s led to a focus on previously neglected muscles, hoping to improve the benefit of botulinum toxin injections in patients with movements disorders of the head and neck. The deep posterior cervical muscles are part of this. They include sub-occipital muscles, the semi-spinalis cervicis muscle and even deeper muscles such as the multifidus. Injecting them requires the use of ultrasound. This article will take up the anatomical notions necessary to perform these injections in an accurate and safe manner. We will also describe how to find these muscles using ultrasound.

Assessing dynamic stability in children with idiopathic toe walking during overground walking

BACKGROUND

Children with idiopathic toe walking present with reduced ankle mobility, impaired balance, and difficulties in motor control. There is a need to diagnose idiopathic toe walking in a holistic manner and improve the monitoring of interventions. The aim is to assess dynamic stability with measures of margin of stability and whole-body angular momentum and evaluate their clinical relevance.

METHODS

A retrospective cross-sectional study with 35 idiopathic toe walkers (23 male, mean age (SD) 10.0 (2.9) years) and 20 typically developing controls (10 male, 11.4 (2.8) years). All participants had a clinical gait analysis at the local hospital. Dynamic stability was assessed with margin of stability, whole-body angular momentum, GaitSD, and spatiotemporal gait parameters. Student t-tests with adjustments for multiple comparisons were performed.

FINDINGS

Margin of stability in anterior direction was significantly shorter (ES = 1.29) and whole-body angular momentum in the coronal plane was significantly larger (ES = 0.90) in idiopathic toe walkers compared to typically developing children. No other results were below the set threshold for significance.

INTERPRETATION

Children with idiopathic toe walking continue to use an immature, falling forward movement strategy to maintain forward momentum. It is probable that those children adopted toe walking behavior to support increased energy absorption during the initial fall. Furthermore, the addition of dynamic stability measures not only provides insight into their ability to balance, these measures also allow an understanding of the plausible strategies adopted during walking and could potentially improve diagnosis and quantification of therapeutic outcomes.

Effects of Visual Input on Postural Stability and Compensatory Strategies in Adults with Chronic Low Back Pain

Chronic low back pain (LBP) impairs balance control due to deficits in sensory integration, yet limited research examines postural sway under varying visual conditions. This study assessed the effects of visual input on postural stability using the normalized stability index, sway excursions, and contralateral toe-touch durations during repeated one-leg standing tasks. Thirty-two adults with LBP and 40 control subjects performed dominant limb standing on a force plate. Outcome measures included the Oswestry disability index, visual analog scale, normalized stability index, sway excursions (anteroposterior [AP], mediolateral [ML]), and contralateral toe-touch duration. The LBP group showed a significant interaction for the normalized stability index under visual conditions (F = 4.95, p = 0.03) with reduced stability in the second trial of the eyes-open condition (t = 1.71, p = 0.04). Sway excursions increased in the AP direction during the first trial (t = -2.43, p = 0.01) and in the ML (t = -2.09, p = 0.02) and AP (t = -1.84, p = 0.03) directions during the third trial. Contralateral toe-touch duration increased in the second trial (t = -2.06, p = 0.02). Individuals with LBP exhibited balance deficits, particularly under eyes-open conditions, relying on compensatory strategies. Optimizing neuromuscular control and sensory integration may improve postural stability.

Intrasession and Intersession Reliability of Neck Retraction Strength Using a Strain Gauge Device

Neck pain ranks among the most prevalent musculoskeletal conditions and is commonly accompanied by altered physical function. With 10.8% of sports-related injuries affecting the head and neck, evaluating neck strength is vital for detecting muscle weakness and monitoring rehabilitation progress. The purpose of this study was to determine the intrasession and intersession reliability of a strain gauge for measuring neck retraction strength in healthy adult men. Ten male participants (age, 22.7 [2.6] y; body mass, 90.8 [13.3] kg; height, 184.2 [7.1] cm) completed a neck retraction isometric test across 3 testing occasions separated by 7 days. Contraction duration, peak and mean force, impulse, and peak rate of force development were quantified within and between sessions. Contraction duration, peak force, and impulse demonstrated moderate to excellent intra- (intraclass correlation coefficient [ICC] [3,1] = .72-.98, coefficient of variation [CV] = 2.7%-2.1%) and intersession reliability (ICC [3,k] = .66-.89, CV = 4.8%-7.1%); however, only acceptable intrasession reliability was found for peak rate of force development and mean force (ICC = .71-.99, CV = 3.4%-22.7%). It appears that a portable fixed strain gauge can be used to reliably measure neck retraction strength in a healthy male population.

Designing and developing a prescription digital therapeutic for at-home heart rate variability biofeedback to support and enhance patient outcomes in post-traumatic stress disorder treatment

Post-traumatic stress disorder (PTSD) is a psychiatric condition producing considerable distress, dysfunction, and impairment in affected individuals. While various forms of psychotherapy are commonly utilized in PTSD treatment, the known neurological pathologies associated with PTSD are insufficiently addressed by these conventional approaches. Heart rate variability biofeedback (HRV-BFB) is a promising tool for correcting autonomic dysfunction in PTSD, with subsequent changes in clinically significant outcome measures. This paper outlines a systematic approach for the development, distribution, and implementation of a prescription at-home HRV-BFB digital therapeutic. We provide recommendations for evidence-generation strategies and propose appropriate regulatory pathways within existing frameworks. Widespread access to HRV-BFB could potentially reduce the distress, disability, and healthcare burden associated with PTSD. Promoting HRV-BFB as a primary intervention could also serve to reduce the stigma associated with "mental" illness and increase health literacy regarding the neuroimmune impacts of psychosocial factors. These processes might in turn improve treatment-seeking, adherence, and supported self-management of these conditions.

Genetically predicted basal metabolic rate and infectious diseases: a Mendelian randomization study

BACKGROUND

The causal relationship between basal metabolic rate (BMR) and infectious diseases remains elusive. This study aims to clarify this association.

METHODS

This study analyzed genome-wide association studies (GWASs) data from the UK Biobank and FinnGen cohorts to investigate the association between BMR and infectious diseases in European populations. Mendelian randomization (MR) analysis was initially employed, followed by multivariable Mendelian randomization (MVMR) to account for potential confounders. Mediation analysis further confirmed significant relationships. Sensitivity analyses were conducted to validate the study findings.

RESULTS

Using two sample MR, genetically predicted BMR was positively linked to skin and soft tissue infections (SSTIs) (OR: 1.31, 95% CI: 1.18-1.47, P < .001), osteomyelitis (OR: 1.95, 95% CI: 1.36-2.80, P < .001) (1.36 ± 2.80), all-cause infections (OR: 1.36, 95% CI: 1.26-1.48, P < .001) and sepsis (OR: 1.36, 95% CI: 1.23-1.51, P < .001). MVMR analysis confirmed BMR's direct causal effect on SSTIs, osteomyelitis, all-cause infections, and sepsis, except for BMI and other factors affecting osteomyelitis. Mediation analysis revealed VAT as a mediator in the linkage between BMR and SSTIs and all-cause infections. HbA1c mediated the path from BMR to osteomyelitis, while CRP and BMI exhibited mediation effects in the BMR-all-cause infections relationship.

CONCLUSION

The study revealed a significant link between increased BMR and elevated risks of SSTIs, osteomyelitis, and bacterial infections, highlighting the intricate BMR-immune connection and its implications for disease control. Key message What is already known on this topic:  High BMR is positively correlated with COVID-19 and associated with proinflammatory and immunological activation, but the relationship between BMR and other infectious diseases remains largely unexplored. What this study adds:  Higher BMR significantly raises the risk of SSTIs, osteomyelitis, all-cause infections, and sepsis. VAT, HbA1c, CRP, and BMI may mediate the BMR-infection relationship. How this study might affect research, practice, or policy:  A higher BMR may be a valuable indicator associated with an increased risk for SSTIs, osteomyelitis, and sepsis. Modulating BMR might hold promise as a clinically relevant intervention to prevent specific infectious diseases.

Bilateral Asymmetries of Plantar Pressure and Foot Balance During Walking, Running, and Turning Gait in Typically Developing Children

Biomechanical asymmetries between children's left and right feet can affect stability and coordination, especially during dynamic movements. This study aimed to examine plantar pressure distribution, foot balance, and center of pressure (COP) trajectories in children during walking, running, and turning activities to understand how different movements influence these asymmetries. Fifteen children participated in the study, using a FootScan plantar pressure plate to capture detailed pressure and balance data. The parameters, including time-varying forces, COP, and Foot Balance Index (FBI), were analyzed through a one-dimensional Statistical Parametric Mapping (SPM1d) package. Results showed that asymmetries in COP and FBI became more pronounced, particularly during the tasks of running and directional turns. Regional plantar pressure analysis also revealed a more significant load on specific foot areas during these dynamic movements, indicating an increased reliance on one foot for stability and control. These findings suggest that early identification of asymmetrical loading patterns may be vital in promoting a balanced gait and preventing potential foot health issues in children. This study contributes to understanding pediatric foot biomechanics and provides insights for developing targeted interventions to support healthy physical development in children.

Comparing autonomic nervous system function in patients with functional somatic syndromes, stress-related syndromes and healthy controls

BACKGROUND

The goal of this study was to examine autonomic nervous system function by measuring heart rate (HR), heart rate variability (HRV), skin conductance levels (SCL), and peripheral skin temperature (ST) in response to and during recovery from psychosocial stressors in patients with functional somatic syndromes (FSS; fibromyalgia and/or chronic fatigue syndrome), stress-related syndromes (SRS; overstrain or burn-out), and healthy controls (HC).

METHODS

Patients with FSS (n = 26), patients with SRS (n = 59), and HC (n = 30) went through a standardized psychosocial stress test consisting of a resting phase (120 s), the STROOP color word task (120 s), a mental arithmetic task (120 s) and a stress talk (120 s), each followed by a 120 s recovery period. HR, HRV, SCL, and ST were monitored continuously.

RESULTS

Average HR and SCL were higher, and HRV was lower, in both patient groups compared to HC during rest (0.50 < Cohen's d < 0.97). A larger SC response to psychosocial stress was found in FSS compared to HC (d = 0.71). However, HR increased less during psychosocial stress and showed a smaller reduction during recovery in both patient groups compared to HC (0.68 < d < 0.98). HRV was lower in both patient groups compared to HC during recovery (0.91 < d < 0.98). There were no differences in ST levels or responses between groups.

CONCLUSIONS

Our results indicate a dominance of the sympathetic nervous system in both patient groups compared to controls, suggesting that autonomic nervous system dysfunction is a transdiagnostic feature for stress-related and functional somatic syndromes.

Patients with multiple sclerosis and low disability display cautious rotational behavior during gait initiation

BACKGROUND

Multiple sclerosis induces locomotor impairments. The objective was to characterize the effects of Multiple Sclerosis on whole-body angular momentum control during gait initiation.

METHODS

Fifteen patients with Multiple Sclerosis with Expanded Disability status scale of 2.5 and 16 healthy participants were instructed to perform gait initiation. Spatiotemporal parameters, whole-body angular momentum, net external moment about the body's center of mass and its components were calculated by using a 3D motion capture system and two force plates.

FINDINGS

Patients with Multiple Sclerosis had a significantly smaller whole-body angular momentum range during the double support phase of gait initiation in the transversal plane (p = 0.011), and smaller net external moment at the transition between the initial double support phase and the execution phase in the sagittal plane (p = 0.013). In the transversal plane, patients with Multiple Sclerosis had a smaller net external moment during the double support phase (p = 0.024) and between the double support phase and the execution phase (p < 0.001).

INTERPRETATION

Despite preserved spatiotemporal parameters during gait initiation, patients with Multiple Sclerosis with low disability had reduced net external moments in the transversal and sagittal planes during the critical transitional period of this functional task, which appeared as a compensatory modality to preserve global postural stability. This finding highlights the cautious rotational behaviors in these planes to prevent the risk of falling and preserve dynamic stability. Whole-body angular momentum and net external moment are relevant parameters for functional and disease progression follow-up of the disease.

Effects of an external load on anticipatory mechanisms of handstand walking initiation in experienced gymnasts

Anticipatory postural adjustments (APAs) are responsible for a successful first step execution in handstand walking. This study evaluates gymnasts' ability to adapt their APAs and stepping parameters in response to adding/removing an external load over repeated handstand walking initiation trials. Eighteen gymnasts performed five handstand walking initiation trials without load (PRE), eight trials with an external load (LOAD) and five trials with removed load (POST). Force platforms and a motion capture system were used to quantify mechanical parameters from the anticipatory phase and the stepping phase. During the first LOAD trial, APAs did not change, however, the step height decreased by 0.56 cm compared to PRE (p = 0.007). During the second and third LOAD trials, the mediolateral center of pressure APAs increased by 2.0 cm (p = 0.01) and 2.3 cm (p = 0.01) compared to the first LOAD trial, while the step parameters returned to baseline. The removed load did not change APAs, while the step parameters were initially altered and then returned to baseline. Results show gymnasts' ability to modify their APAs over repeated trials to adapt to an external load, enabling them to initiate accurate forward steps. Training exercises should target handstand walking preparatory mechanisms for a smooth transition between handstand and stepping.

Implementation of Wearable Technology for Remote Heart Rate Variability Biofeedback in Cardiac Rehabilitation

Cardiovascular diseases pose a significant threat to global health, and cardiac rehabilitation (CR) has become a critical component of patient care. Heart Rate Variability Biofeedback (HRVB) is a non-invasive approach that helps modulate the Autonomic Nervous System (ANS) through Resonance Frequency (RF) breathing, supporting CR for cardiovascular patients. However, traditional HRVB techniques rely heavily on manual RF selection and face-to-face guidance, limiting their widespread application, particularly in home-based CR. To address these limitations, we propose a remote human-computer collaborative HRVB system, "FreeResp", which features autonomous RF adjustment through a simplified cognitive computational model, eliminating the reliance on therapists. Furthermore, the system integrates wearable technology and the Internet of Things (IoT) to support remote monitoring and personalized interventions. By incorporating tactile guidance technology with an airbag, the system assists patients in performing diaphragmatic breathing more effectively. FreeResp demonstrated high consistency with conventional HRVB methods in determining RF values (22/24) from 24 valid training samples. Moreover, a one-month home-based RF breathing training using FreeResp showed significant improvements in Heart Rate Variability (HRV) (p < 0.05). These findings suggest that FreeResp is a promising solution for home-based CR, offering timely and precise interventions and providing a new approach to long-term cardiovascular health management.

The mediating role of body surface area-adjusted basal metabolic rate: effects of low muscle mass and central obesity on cognitive impairment in Chinese patients with type 2 diabetes mellitus

Background

This study investigates the relationship between basal metabolic rate (BMR), body composition, obesity indices, and cognitive impairment (CI) in middle-aged and older type 2 diabetes mellitus (T2DM) patients, assessing their potential role in CI screening.

Methods

A cross-sectional study included 1243 T2DM patients over 45 years old. CI was assessed using the Montreal Cognitive Assessment. BMR and body composition indices were measured through bioelectrical impedance analysis. The associations and predictions related to CI were explored using multivariable-adjusted logistic regression, restricted cubic spline (RCS) models, and receiver operating characteristic (ROC) curve analyses. Mediation analysis explored the role of BMR adjusted by body surface area (BMR/BSA) in CI risk.

Results

Patients with CI showed significantly lower BMR, BMR adjusted for height squared (BMR/Height²), BMR/BSA, appendicular skeletal muscle mass (ASM), and fat-free mass (FFM), alongside higher waist circumference (WC) and percentage of body fat. Logistic regression showed that participants in the fourth quartile of BMR, BMR/Height2, and BMR/BSA had approximately a 54% reduced risk of CI (odds ratio range 0.457 to 0.463). RCS analysis indicated a linear decrease in CI risk with increasing BMR metrics. ROC analysis indicated high predictive efficacy for CI with combined indicators, particularly BMR and FFM (area under the curve 0.645). Mediation analysis suggested that BMR/BSA played a significant mediating role in WC, ASM and FFM on CI risk, with a mediation proportion ranging from 45.73% to 50.87%.

Conclusion

Low energy expenditure assessed by BMR/BSA is an independent risk factor for increased CI risk in middle-aged and elderly T2DM patients. Central obesity, low muscle mass, and low energy expenditure significantly elevate CI risk in this population.

Impact of muscle fatigue on anticipatory postural adjustments during gait initiation

Introduction

Prolonged or strenuous exercise leads to a temporary decrease in muscle function and performance, which interferes with activity of both prime movers and postural muscles. This effect of fatigue has been reported both for single segment movements and for locomotion. However, little is known regarding the effects of fatigue on anticipatory postural adjustments (APAs) during gait initiation, a task in which the control of focal movement should be strictly coupled to a feedforward control of posture.

Methods

We studied APAs during gait initiation in 16 healthy well-trained adult males, searching for muscle activities that precede the backward shift of the Center of Pressure (CoP). Participants stood on a force plate for about 10 s and then started walking at their natural speed. APAs were evaluated before and after a 1 min exhausting sequence of countermovement jumps. An optoelectronic system captured the heel-off events while a force plate measured the CoP position and vertical ground reaction force. Wireless probes recorded the electromyogram of trunk and leg muscles from both sides.

Results

It was observed that muscle fatigue delayed excitatory and inhibitory APAs, of about 40 and 80 ms, respectively, and a parallel delay was induced on prime movers; moreover, velocity and amplitude of backward CoP shift were reduced. Regarding APAs sign and occurrence, most of the participants showed bilateral inhibition in dorsal muscles and excitation in the ventral ones, displaying a forward "diving" strategy that was almost unaffected by fatigue. However, after fatigue, three of the "diving" participants switched to a "turning" strategy, i.e., they displayed a reciprocal activation/inhibition pattern in the dorsal muscles, compatible with a trunk rotation.

Discussion

The "turning" strategy has been previously described in untrained individuals and in a toes-amputee mountain climber, who showed a "diving" approach to gait initiation when wearing his prosthetic shoes and switched to the "turning" approach when barefoot. Altogether, these results support the idea that one and the same person may develop a repertoire of postural strategies among which the central nervous system will choose, according to the personal fitness and the constraints in which the action is performed.

Application of machine learning for detecting high fall risk in middle-aged workers using video-based analysis of the first 3 steps

OBJECTIVES

Falls are among the most prevalent workplace accidents, necessitating thorough screening for susceptibility to falls and customization of individualized fall prevention programs. The aim of this study was to develop and validate a high fall risk prediction model using machine learning (ML) and video-based first 3 steps in middle-aged workers.

METHODS

Participants to provide training data (n = 190, mean [SD] age = 54.5 [7.7] years, 48.9% male) and validation data (n = 28, age = 52.3 [6.0] years, 53.6% male) were enrolled in this study. Pose estimation was performed using a marker-free deep pose estimation method called MediaPipe Pose. The first 3 steps, including the movements of the arms, legs, trunk, and pelvis, were recorded using an RGB camera, and the gait features were identified. Using these gait features and fall histories, a stratified k-fold cross-validation method was used to ensure balanced training and test data, and the area under the curve (AUC) and 95% CI were calculated.

RESULTS

Of 77 gait features in the first 3 steps, we found 3 gait features in men with an AUC of 0.909 (95% CI, 0.879-0.939) for fall risk, indicating an "excellent" (0.9-1.0) classification, whereas we determined 5 gait features in women with an AUC of 0.670 (95% CI, 0.621-0.719), indicating a "sufficient" (0.6-0.7) classification.

CONCLUSIONS

These findings suggest that fall risk prediction can be developed based on ML and the first 3 steps in men; however, the accuracy was only "sufficient" in women. Further development of the formula for women is required to improve its accuracy in the middle-aged working population.

Effects of minute oscillation stretching training on muscle and tendon stiffness and walking capability in people with type 2 diabetes

AIM

we investigated the effects of a 10 week training program (i.e., minute oscillatory stretching; MOS) on the mechanical responses and walking capability in people with type 2 diabetes (T2D).

METHODS

seventeen T2D patients performed maximum voluntary contractions of the plantar flexor muscles during which Achilles tendon stiffness (kT) and muscle-tendon stiffness (kM) were evaluated at different percentages of the maximum voluntary force (MVC). In addition, each participant was requested to walk at different walking speeds (i.e. 2, 3, 4, 5, and 6 kmh-1) while their net energy cost of walking (Cnet), cumulative EMG activity per distance travelled (CMAPD) and kinematic parameters (step length, step frequency, the ankle/knee range of motion) were evaluated.

RESULTS

maximum tendon elongation increased after MOS training, and kT significantly decreased (between 0 and 20% of MVC). No differences were observed for muscle elongation or kM after training. Cnet decreased after training (at the slowest tested speeds) while no changes in CMAPD were observed. Step length and ankle ROM during walking increased after training at the slowest tested speeds, while step frequency decreased; no significant effects were observed for knee ROM.

CONCLUSION

these results indicate the effectiveness of 10 weeks of MOS training in reducing tendon stiffness and the energy cost during walking in people with T2D. This training protocol requires no specific instrumentation, can be easily performed at home, and has a high adherence (92 ± 9%). It could, thus, be useful to mitigate mechanical tendon deterioration and improve physical behaviour in this population.

Balance recovery schemes following mediolateral gyroscopic moment perturbations during walking

Maintaining balance during human walking hinges on the exquisite orchestration of whole-body angular momentum (WBAM). This study delves into the regulation of WBAM during gait by examining balance strategies in response to upper-body moment perturbations in the frontal plane. A portable Angular Momentum Perturbator (AMP) was utilized in this work, capable of generating perturbation torques on the upper body while minimizing the impact on the center of mass (CoM) excursions. Ten participants underwent upper-body perturbations during either the mid-stance or touch-down moment in both ipsilateral and contralateral directions in the frontal plane. Our findings emphasize the predominant role of the hip strategy and foot placement as primary mechanisms for recovering from WBAM perturbations, regardless of the perturbation's timing or direction. Specifically, hip add/abduction torque and step width were significantly modulated following perturbations during the stance and swing phases, respectively, to reject frontal-plane balance threats. The knee and ankle torque modulation were not found to be effective in the recovery process. Additionally, we observed that recovery from WBAM perturbations occurs promptly within the same stride in which the perturbation occurs, unlike other perturbation scenarios, such as platform translation. These insights have the potential to enhance the development of assistive devices and more robust controllers for bipedal robots.

The Impact of Autonomic Nervous System Modulation on Heart Rate Variability and Musculoskeletal Manifestations in Chronic Neck Pain: A Double-Blind Randomized Clinical Trial

Background: The role of autonomic nervous system (ANS) modulation in chronic neck pain remains elusive. Transcutaneous vagus nerve stimulation (t-VNS) provides a novel, non-invasive means of potentially mitigating chronic neck pain. This study aimed to assess the effects of ANS modulation on heart rate variability (HRV), pain perception, and neck disability. Methods: In this double-blind randomized clinical trial, 102 participants with chronic neck pain were randomly allocated to one of three groups: t-VNS plus standard-care physiotherapy (SC-PT), heart rate variability biofeedback (HRV-BF) with SC-PT, or SC-PT alone. Interventions were administered three times weekly for 6 weeks. The following outcome measures were assessed at baseline and after 6 weeks: HRV, the visual analog scale (VAS), the pressure pain threshold (PPT), and the neck disability index (NDI). Results: The t-VNS group exhibited significant improvements compared to the HRV-BF and SC-PT groups. Specifically, t-VNS increased the RR interval (mean difference [MD] = 35.0 ms; p = 0.037) and decreased the average heart rate (MD = -5.4 bpm; p = 0.039). Additionally, t-VNS reduced the VAS scores (versus HRV-BF: MD = -0.8 cm, p = 0.044; SC-PT: MD = -0.9 cm, p = 0.018), increased the PPT (versus HRV-BF: MD = 94.4 kPa, p < 0.001; SC-PT (MD = 56.2 kPa, p = 0.001)), and lowered the NDI scores (versus HRV-BF: MD = -4.0, p = 0.015; SC-PT: MD = -5.9, p < 0.001). Conclusions: t-VNS demonstrated superior effectiveness compared to HRV-BF and SC-PT in regulating HRV, alleviating pain, and enhancing functional capabilities in individuals with chronic neck pain.

Environmental constraints for improving motor flexibility during obstacle crossing in older adults

BACKGROUND

An age-related decline in motor flexibility, which is the ability to synergistically control the degrees of freedom of the body to ensure stable performance of a task, is a factor that contributes to falls. We investigated whether providing environmental constraints to increase the movement repertoire (i.e., the motor solution that works to achieve one's goal), in combination with aiming at precise control of the performance, would be effective for improving motor flexibility, and whether the effect on the leading limb would extend to the trailing limb.

METHODS

Fifteen older adults (75.1 ± 6.2 years and 14 younger adults (34.6 ± 5.0 years) performed under three walking conditions: walking normally and crossing the obstacle (normal), walking and crossing the obstacle with constraints of foot placement after stepping over it (constrained), and walking and crossing the obstacle with constraints as in the constrained condition, in addition to aiming for maintaining a constant clearance height at the moment of obstacle crossing (precision). An uncontrolled manifold analysis was used to quantify motor flexibility as the synergy index. The foot height at the moment of obstacle crossing was used as the performance variable and seven segmental angles were used as the elemental variables. A higher synergy index indicates greater motor flexibility.

RESULTS

For the leading limb, the synergy index was significantly higher under the precision condition than those under the other conditions. This suggests that not only providing environmental constraints but also keeping constant the performance variable is critical to improving motor flexibility. Moreover, the effects of an increase in the synergy index in the leading limb extended to the trailing limb.

CONCLUSIONS

Providing environmental constraints to increase the movement repertoire while also aiming for precision in the performance variable was an effective method of improving motor flexibility during obstacle crossing for older adults.