Treadmill Walking Research Articles

The underestimation of speed perception while walking in virtual reality with bodyweight unloading

As space agencies prepare for long-duration missions, such as establishing a permanent moon base, maintaining astronauts’ physical and mental health becomes crucial. Exercise is known to counteract the adverse effects of space travel, and virtual reality (VR) has the potential to enhance the psychological well-being of crew members. This study aimed to investigate the impact of bodyweight unloading on speed perception during treadmill walking in a VR environment. Eighteen participants walked on an AlterG treadmill while wearing a VR headset that displayed a moving virtual outdoor environment. The treadmill simulated different bodyweight conditions (100%, 60%, and 20%) to represent Earth’s gravity, intermediate, and lunar gravity, respectively. A staircase method was used to determine participants’ estimated threshold speed for perceiving visual speed equivalence. The results revealed that in all conditions, participants consistently underestimated their walking speed compared to the visual scene speed. No significant differences were found in estimated threshold speeds between the unloading conditions. Individual responses varied, possibly due to biomechanical differences and personal preferences. Participants reported no motion sickness symptoms, likely attributed to the short duration of speed mismatches and the use of high-resolution and high-refresh-rate VR equipment. This study provides insights into the combination of VR and treadmill walking, suggesting the importance of individual customization to enhance user experience and prevent motion sickness.

Saving Legs & Lives: the efficacy of a community-based cardiovascular rehabilitation programme versus usual care on exercise capacity and quality of life in patients who have undergone lower limb revascularisation for peripheral arterial disease—protocol for a single-centre randomised-controlled trial

IntroductionPeripheral artery disease (PAD) is an atherosclerotic condition characterised by stenosis or occlusion of the arteries in the lower limbs. Patients with PAD commonly report intermittent claudication (leg pain/discomfort) during...

The association between foot morphology and foot loading during gait

The perceived association between foot type and injury risk has inspired the development of many foot typing methods. The purpose of this study was to determine how well different foot typing methods explained variations in regional foot loading in asymptomatic adults during gait, while considering age, sex, and walking speed as covariates. Six methods were used to determine foot type in 92 asymptomatic adults. An insole pressure sensor system measured peak force and force-time integral during treadmill walking at a self-selected pace. The foot was divided into nine regions and the association between foot type and foot loading was analyzed using generalized estimating equations (GEE) while accounting for the covariates. Over an average of 250 steps per individual, the results demonstrated variability in the association between regional foot loading and foot type. Specifically, Arch Index and X-Ray Arch Type correlated with hindfoot and midfoot loading, while Foot Posture Index correlated with medial midfoot, forefoot, and toe loading. Calcaneal Pitch and Meary’s Angle correlated with medial hindfoot, midfoot, and forefoot loading, while Varus/valgus angle correlated with loading in the forefoot and toes. The location and direction of associations were generally similar for Calcaneal Pitch, Meary’s Angle, and X-Ray Arch Type, and opposite of Arch Index. The analyses demonstrated that walking speed, age, and sex were all important factors that affected the relationship between plantar loading and foot type. Specific foot type methods correlate better with loading in specific foot regions, potentially making them better to evaluate injury risk in those regions.

Maximal oxygen uptake, pulmonary function and walking economy are not impaired in patients diagnosed with long COVID.

SARS-CoV-2 may result in the development of new symptoms, known aslong COVID, a few months after the original infection. It is elusive to what extent physical capacity in patients diagnosed with long COVID is impacted. We compared maximal oxygen uptake (V̇O2max), one of the single most important factors for cardiovascular health and mortality, expired lung volumes and air flow, oxygen cost of walking and 6-min-walking-test (6MWT), in 20 patients diagnosed with long COVID (11 males and 9 females; 44 ± 16years (SD); 26.7 ± 3.8BMI, duration of acute phase 1.7 ± 1.2weeks, tested 4 ± 3months after long COVID diagnosis) with 20 healthy age and sex matched controls (11males and 9females; 44 ± 16years; 25.9 ± 4.0BMI). Long COVID patients had a V̇O2max of 41.4 ± 16.2mL∙kg-1∙min-1(men) and 38.2 ± 7.5 (women) and this was not different from controls. Similarly, mean spirometry measures in the patient group (VC; FVC; FEV1; FEV1/FVC) were also not different (85-106%) from predicted healthy values. Finally, inclined treadmill (5%, 4km∙h-1) walking economy was not different between the groups (long COVID: 15.2 ± 1.1mL∙kg-1∙min-1; controls: 15.2 ± 1.2mL∙kg-1∙min-1), while the 6MWT revealed a difference (long COVID: 606 ± 118m; controls: 685 ± 85m; p = 0.036). V̇O2max, oxygen cost of walking, and spirometry measurements did not appear to be impaired in patients diagnosed with long COVID with a prior mild to moderate SARS-CoV-2 infection. The typical outcomes in these essential factors for health and longevity implies that while long COVID can present with a range of symptoms, caution should be made when attributing these symptoms directly to compromised pulmonary function or V̇O2max.

Changes in interlimb coordination induced by within-stride changes in treadmill speed.

During walking, interlimb coordination involves the right and left legs working together to achieve a desired movement. Previously, dynamic treadmill walking has been shown to drive asymmetric gait changes in healthy young adults through selectively changing the speed of the whole treadmill. Currently, the coordination demands of this novel walking environment are unknown and must be understood prior to assessing dynamic treadmill walking in clinical populations. We investigated the interlimb coordination requirements of dynamic treadmill walking in ten healthy young adults. We quantified interlimb coordination changes as phase shift (timing of maximum cross-correlation between limb angle trajectories of the left and right legs), center of oscillation (limb angle at midstance), and center of oscillation difference (oscillation angle difference between legs). We found that phase shift in the Fast trial (i.e., 1.0m/s treadmill speed in first 50% of gait cycle, 0.5m/s in latter 50%) was significantly more positive (i.e., the right leg oscillates ahead of the left leg in time) than in the Slow, Accelerate, and Decelerate trials (all p<0.01). The Fast trial produced significantly positive center of oscillation values on the right leg, indicating that the right leg is oscillating about a more flexed axis than the left. Center of oscillation difference was similarly more positive during the Fast trial than in the Decelerate (p<0.01) and Slow (p<0.01) trials. These results exemplify that some forms of dynamic treadmill walking change interlimb coordination to a greater extent than others. After several minutes of dynamic treadmill walking, interlimb coordination is changed relative to baseline walking in the spatial domain (Fast and Decelerate conditions) and the temporal domain (Fast and Slow). Therefore, dynamic treadmill walking is tunable in both biomechanical and interlimb coordination parameters, creating a variety of options for restoring gait symmetry in asymmetric populations.

Minimum Electromyography Sensor Set Needed to Identify Age-Related Impairments in the Neuromuscular Control of Walking Using the Dynamic Motor Control Index.

The dynamic motor control index is an emerging biomarker of age-related neuromuscular impairment. To date, it has been computed by quantifying the co-activity of eleven lower limb muscles. Because clinics that routinely employ electromyography typically collect from fewer muscles, a reduced muscle sensor set may improve the clinical usability of this metric of motor control. This study aimed to test if commonly used eight- and five-muscle electromyography (EMG) sensor sets produce similar dynamic motor control indices as the previously examined eleven-muscle sensor set and similarly differentiate across age subgroups. EMG data were collected during treadmill walking from 36 adults separated into young (N = 18, <35 yrs.), young-old (N = 13, 65-74 yrs.), and old-old (N = 5, ≥75 yrs.) subgroups. Dynamic motor control indices generated using the sensor set with eleven muscles correlated with the eight-muscle set (R2 = 0.70) but not the five-muscle set (R2 = 0.30). Regression models using the eleven-muscle (χ2(4) = 10.62, p = 0.031, Nagelkerke R2 = 0.297) and eight-muscle (χ2(4) = 9.418, p = 0.051, Nagelkerke R2 = 0.267) sets were significant and approaching significance, respectively, whereas the model for the five-muscle set was not significant (p = 0.663, Nagelkerke R2 = 0.073). In both the eleven-muscle (Wald χ2 = 5.16, p = 0.023, OR = 1.26) and eight-muscle models (Wald χ2 = 4.20, p = 0.04, OR = 1.19), a higher index significantly predicted being in the young group compared to the old-old group. Age-related differences in the neuromuscular control of walking can be detected using dynamic motor control indices generated using eleven- and eight-muscle sensor sets, increasing clinical usability of the dynamic motor control index.

Cardiovascular effects of exercise training in pregnant people with a high body mass index: secondary results from a randomised controlled trial (ETIP)

ObjectivesWe aimed to determine the effectiveness of exercise training during pregnancy on peak oxygen uptake (V̇O2peak), cardiac function and flow-mediated dilatation (FMD) of the brachial artery throughout pregnancy and post...

The human plasma lipidome response to exertional heat tolerance testing

BackgroundThe year of 2023 displayed the highest average global temperatures since it has been recorded—the duration and severity of extreme heat are projected to increase. Rising global temperatures represent a major public health threat, especially to occupations exposed to hot environments, such as construction and agricultural workers, and first responders. Despite efforts of the scientific community, there is still a need to characterize the pathophysiological processes leading to heat related illness and develop biomarkers that can predict its onset.MethodsLiquid chromatography-tandem mass spectrometry (LC–MS/MS)-based lipidomics analysis was performed on plasma from male and female subjects who underwent exertional heat tolerance testing (HTT), consisting of a 2-h treadmill walk at 5 km/h with 2.0% incline at a controlled temperature of 40ºC. From HTT, heat tolerance was calculated using the physiological strain index (PSI).ResultsNearly half of all 995 detected lipids from 27 classes were responsive to HTT. Lipid classes related to substrate utilization were predominantly affected by HTT, with a downregulation of triacylglycerols and upregulation of free fatty acids and acyl-carnitines (CARs). Even chain CAR 4:0, 14:0 and 16:1, suggested by-products of incomplete beta oxidation, and diacylglycerols displayed the highest correlation to PSI. PSI did not correlate with plasma lactate levels, suggesting that correlations between even chain CARs and PSI are related to metabolic efficiency versus physical exertion.ConclusionsOverall, HTT displays a strong impact on the human plasma lipidome and lipid metabolic inefficiencies may underlie reduced heat tolerance.

A Biomechanical Dataset of 1,798 Healthy and Injured Subjects During Treadmill Walking and Running

Quantitative biomechanical gait analysis is an important clinical and research tool for injury and disease diagnosis and treatment. However, one major criticism is that gait analysis laboratories largely operate in isolation and there is a lack of benchmark datasets, which can be used to advance research and statistical methodologies. To address this, we present an open biomechanics dataset of n = 1798 healthy and injured, young and older adults during treadmill walking and/or running at a range of gait speeds. The full dataset is available on Figshare+ and data files are contained within a series of zipped folders with folder names representing the subject ID. Each subject ID folder contains walking and/or running data containing raw marker trajectory data along with metadata for each participant. Five tutorials are also provided, demonstrating aspects such as loading data files, sample analyses of discrete variables, and calculating joint angles from code along with covering more complex topics such as principal component analysis for dimensionality reduction, statistical parametric mapping, and conducting unsupervised clustering.

Differences in landing biomechanics in the presence of delayed onset muscle soreness following or not active recovery

ObjectiveDelayed onset muscle soreness (DOMS) can reduce joint range of motion and strength, cause edema, and increase joint stiffness. Here we set out to determine whether quadriceps DOMS followed by an active recovery low-intensity exercise alters jump landing biomechanics. Methods3D landing kinematics, kinetics, and DOMS were evaluated in 26 healthy adults (15 women) performing drop and vertical jump landings before and after a squat protocol to induce quadriceps DOMS. In the presence of DOMS, half of the participants (n = 13) performed a low-intensity exercise for active recovery (10-minute treadmill walking), while the other half (n = 13) did not. Descriptive statistics and generalized estimative equations were applied to determine the effects of DOMS and active recovery on landing kinematics and kinetics. ResultsDOMS decreased knee and ankle flexion angles and increased knee and ankle frontal plane angles during vertical jumps. DOMS elicited a longer time to reach peak ground reaction force during drop jumps. Low-intensity exercise for active recovery reduced DOMS perception but did not alter the biomechanics of landing. ConclusionDOMS changes landing strategy. However, including a low-intensity exercise for active recovery before landing practice did not change the kinematics and kinetics of landing.

Walking economy and exercise efficiency in successful weight loss maintainers

PurposeFollowing short-term weight loss, the energetic cost of transport decreases and exercise efficiency increases. Whether changes persist during long-term weight maintenance is unknown. MethodsWe compared walking economy and exercise efficiency in weight loss maintainers (WLM, maintaining ≥13.6 kg weight loss for ≥1 year), controls without obesity (NC, BMI similar to current BMI of WLM), and controls with overweight/obesity (OC, BMI similar to pre-weight loss BMI of WLM). Energy expenditure (EE) and respiratory quotient were measured using indirect calorimetry at rest, while standing, and during treadmill walking. Gross and net energetic cost of transport (J/kg/m) was measured during level treadmill walking at 0.75, 1.12, and 1.52 m/s. Gross, net, and delta efficiency (%) were measured during inclined treadmill walking (2 %, 4 %, and 6 % grade) and a constant speed (1.12 m/s). ResultsWLM (n = 32, BMI: 23.8 ± 2.3 kg/m2) and NC (n = 28, BMI: 22.7 ± 1.6 kg/m2) had significantly lower EE (kJ/min) compared to OC (n = 26, BMI: 33.0 ± 4.5 kg/m2) during rest, standing, and walking (p < 0.01). Net energetic cost of transport was significantly lower in WLM compared to OC at 1.12 and 1.52 m/s (p < 0.05). Net efficiency was significantly greater in WLM compared to OC while walking (p ≤ 0.05). There were no significant differences between WLM and NC for any measures of economy or efficiency. ConclusionWLM had lower walking economy and greater walking efficiency compared to OC, but there were no differences between WLM and NC. Thus, individuals maintaining significant weight loss may be successful with long-term weight loss, in part, due to resistance against adaptive reductions in walking energetics.

Self-selected speed provides more accurate human gait kinematics and spatiotemporal parameters than overground simulated speed on a treadmill: a cross-sectional study

BackgroundWalking speed, a key element of gait analysis, is essential for evaluating the biomechanics of the musculoskeletal system and is typically assessed on flat surfaces, such as walkways or treadmills. While many authors have compared the differences and similarities between treadmill and overground walking, no studies have yet investigated the differences between treadmill gait analysis at self-selected speed (SS) and overground simulated speed (OS). The hypothesis is that accurate kinematic measurements depend on selecting the correct gait speed; however, a mismatch between the perceived comfortable treadmill speed and actual overground speed may affect the accuracy of treadmill gait analyses. This study aimed to assess treadmill gait in healthy young adults by comparing the SS with the OS. The objectives were to determine whether participants could match SS with OS on a treadmill, examine sex differences in gait kinematics and spatiotemporal parameters (KSP) at different speeds, and identify which speed better reflects natural gait kinematics.MethodsA total of 60 healthy men and 70 healthy women, aged 22–35 years, participated in this cross-sectional study to investigate the gait kinematics and spatiotemporal differences between the SS and OS. Student’s t-test, Bonferroni adjustment, Cohen’s effect size, and quadratic regression were employed to analyse differences across walking speeds and groups.ResultsA discrepancy between OS and SS was observed in 66.4% of the participants. Our findings revealed that the adjusted R² values for KSP at SS were consistently greater than those at OS, suggesting that SS offers a more robust and accurate representation of gait kinematics, whereas OS is less reliable.ConclusionsThese findings underscore the importance of individualized speed selection in gait analysis, as it significantly impacts the accuracy of kinematic and spatiotemporal measurements. This insight is pivotal for clinicians and researchers to develop more effective rehabilitation strategies and comprehensively understand gait dynamics.

Associations Between Body Mass Index, Gait Biomechanics, and In Vivo Cartilage Function After Exercise in Those With Anterior Cruciate Ligament Reconstruction

Background: Both high body mass index (BMI) and anterior cruciate ligament reconstruction (ACLR) independently influence knee osteoarthritis risk. Preliminary evidence shows the combination of these risk factors leads to poorer recovery and altered biomechanical outcomes after ACLR, but few studies have directly evaluated early changes in cartilage health between normal-BMI and high-BMI groups in this population. Purpose: To evaluate ultrasound-based measures of cartilage strain and compositional changes (via echo-intensity [EI]) in response to an incline walking stress test between normal-BMI and high-BMI individuals with ACLR. A secondary evaluation was conducted of associations between habitual walking biomechanics (ie, ground-reaction forces, sagittal knee kinetics and kinematics) and cartilage strain and EI outcomes. Study Design: Controlled laboratory study. Methods: Gait biomechanics and femoral trochlear ultrasound analyses were evaluated in 64 participants with ACLR who had normal BMI (BMI < 27.0; n = 40) and high BMI (BMI ≥ 27.0; n = 24). Ultrasound images were collected bilaterally before and after an incline treadmill walk, and medial and lateral trochlear strain and EI changes pre-post exercise were used to compare BMI groups and limbs. Gait outcomes included ground-reaction forces, peak sagittal plane knee moments, angles, and excursions and were used to determine associations with cartilage outcomes in the entire cohort. Results: High-BMI individuals with ACLR exhibited greater medial trochlear cartilage strain in the ACLR limb compared with normal-BMI individuals (approximately 6%; P < .01). In those with high BMI, the ACLR limb exhibited greater medial trochlear strain relative to non-ACLR limbs (approximately 4%; P < .05), but between-limb differences were not observed in the normal-BMI group (P > .05). Medial trochlear EI changes were greater bilaterally in those with high BMI compared with normal-BMI ACLR counterparts (approximately 10%; P < .01). Last, individuals who walked with greater peak knee flexion angles exhibited less medial cartilage strain (ΔR2 = 0.06; P = .025). Conclusion: The data suggested that high BMI affects cartilage functional properties after ACLR, whereas smaller knee flexion angles were associated with larger medial cartilage strain. Clinical Relevance: High-BMI individuals with ACLR may represent a subset of patients exhibiting earlier declines in cartilage functional integrity in response to loading, necessitating additional or more targeted interventions to mitigate disease development.

Study of the Brain Functional Connectivity Processes During Multi-Movement States of the Lower Limbs.

Studies using source localization results have shown that cortical involvement increased in treadmill walking with brain-computer interface (BCI) control. However, the reorganization of cortical functional connectivity in treadmill walking with BCI control is largely unknown. To investigate this, a public dataset, a mobile brain-body imaging dataset recorded during treadmill walking with a brain-computer interface, was used. The electroencephalography (EEG)-coupling strength of the between-region and within-region during the continuous self-determinant movements of lower limbs were analyzed. The time-frequency cross-mutual information (TFCMI) method was used to calculate the coupling strength. The results showed the frontal-occipital connection increased in the gamma and delta bands (the threshold of the edge was >0.05) during walking with BCI, which may be related to the effective communication when subjects adjust their gaits to control the avatar. In walking with BCI control, the results showed theta oscillation within the left-frontal, which may be related to error processing and decision making. We also found that between-region connectivity was suppressed in walking with and without BCI control compared with in standing states. These findings suggest that walking with BCI may accelerate the rehabilitation process for lower limb stroke.

Identification of distinct subtypes of post-stroke and neurotypical gait behaviors using neural network analysis of kinematic time series data.

Heterogeneous types of gait impairment are common post-stroke. Studies used supervised and unsupervised machine learning on discrete biomechanical features to summarize the gait cycle and identify common patterns of gait behaviors. However, discrete features cannot account for temporal variations that occur during gait. Here, we propose a novel machine-learning pipeline to identify subgroups of gait behaviors post-stroke using kinematic time series data. We analyzed ankle and knee kinematic data during treadmill walking data in 39 individuals post- stroke and 28 neurotypical controls. The data were first input into a supervised dual-stage Convolutional Neural Network-Temporal Convolutional Network, trained to extract temporal and spatial gait features. Then, we used these features to find clusters of different gait behaviors using unsupervised time series k-means. We repeated the clustering process using 10,000 bootstrap training data samples and a Gaussian Mixture Model to identify stable clusters representative of our dataset. Finally, we assessed the kinematic differences between the identified clusters using 1D statistical parametric mapping ANOVA. We then compared gait spatiotemporal and clinical characteristics between clusters using one-way ANOVA. We obtained five clusters: two clusters of neurotypical individuals (C1 and C2) and three clusters of individuals post-stroke (S1, S2, S3). C1 had kinematics that resembled the normative gait pattern. Individuals in C2 had a shorter stride time than C1. Individuals in S1 had mild impairment and walked with increased bilateral knee flexion during the loading response. Individuals in S2 had moderate impairment, were the slowest among the clusters, took shorter steps, had increased knee flexion during stance bilaterally and reduced paretic knee flexion during swing. Individuals in S3 had mild impairment, asymmetric swing time, had increased ankle abduction during the gait cycle and reduced dorsiflexion bilaterally during loading response and stance. Every individual was assigned to a cluster with a cluster membership likelihood above 93%. Our results indicate that joint kinematics in individuals post-stroke are distinct from controls, even in those individuals with mild impairment. The three subgroups post-stroke showed distinct kinematic impairments during specific phases in the gait cycle, providing additional information to clinicians for gait retraining interventions.

Heel Raises and Calf Stretches Exercises Versus Medication Only in Ischemic Intermittent Claudication: A Randomized Controlled Trial.

Intermittent claudication is a primary symptom of peripheral artery disease (PAD). a chronic progressive disease caused primarily by atherosclerosis. It is usually characterized by leg pain, aches, cramps, or fatigue when walking, which improves with rest. Physical therapy, including a supervised exercise program, is often recommended as the first treatment for sprains. This study aims to evaluate the short-term effects of incorporating heel raise and calf stretch exercises with standard medical therapy compared to medical therapy alone in managing intermittent claudication. From May 2022 to November 2023, 160 patients with Stage II Fontaine PAD were randomly assigned to two equal groups. Group A (80 patients) received heel raise and calf stretch exercises in addition to medical treatment, while Group B (80 patients) received only medical treatment. Both groups underwent treadmill walking tests before and after three months to measure absolute walking distance (ACD), peak walking time (PWT), and Walking Impairment Questionnaire (WIQ) scores, including distance, speed, and symptom severity. At baseline, there were no significant differences between the groups in terms of ACD, peak walking time, ankle-brachial index, distance, speed, and symptoms. At follow-up, Group A showed significantly greater improvements in ACD (312.00 ± 45.43 m), peak walking time (8.54 ± 1.55 min), distance (29.46 ± 4.63 km), speed (20.01 ± 3.13 kph), and WIQ symptoms (22.10 ± 1.02) compared to Group B, which had ACD (276.55 ± 29.07 m), peak walking time (6.72 ± 1.70 min), distance (23.68 ± 3.89 km), speed (15.71 ± 2.71 kph), and WIQ symptoms (20.80 ± 1.47) (P < .001). The ankle-brachial index remained similar between the groups (P > .05). We concluded that integrating standard physical therapy exercises, such as calf raises and leg stretches, with medical therapy significantly enhances walking function in patients with ischemic intermittent claudication.

Exploring age-related differences in the relationship between spatial and temporal contributions to step length asymmetry during split-belt adaptation

Gait adaptability is crucial for meeting environmental demands, and impaired gait adaptation increases fall risk, particularly in older adults. While prior research exists on older adults’ gait adaptation, particularly in perturbation studies, the specific contributions of temporal and spatial adaptation strategies to step length asymmetry (SLA) during split-belt treadmill walking require further examination. This study fills this gap by evaluating how distinct adaptation strategies contribute to SLA in healthy young and older adults. 19 healthy young adults (20.4 ± 1.1 years) and 19 healthy older adults (68.3 ± 8.1 years) walked on a split-belt treadmill requiring their non-dominant leg to move twice as fast as their dominant leg. Repeated measures ANOVA investigated (1) spatial and temporal contributions to SLA, (2) SLA across gait adaptation epochs, and (3) rates of adaptation and deadaptation. Older adults displayed reduced temporal contributions to SLA compared to younger adults (F1,36 = 6.42, p = .02, ŋ2 = .15), but no group differences were observed in spatial contributions to SLA (F1,36 = 3.23, p = .08, ŋ2 = .082). SLA during adaptation and deadaptation did not differ by age group, nor did the rate of adaptation (F1,34.7 = 0.594, p = .45) or deadaptation F1,33.6 = 2.886, p = .09). These findings suggest that while older adults rely less on temporal strategies for gait adaptation, but maintain overall adaptability comparable to younger adults. Findings enhance our understanding of age-related changes in gait adaptation mechanisms and may inform targeted interventions to improve gait adaptability in older populations.

Combined exercise Intervention protocol validation in sedentary workers health risk with Nonspecific Chronic low back pain People

Background: Most chronic low back pain is nonspecific as the cause of the pain is unknown. Hence exercise protocol focussing on one area of fitness is not appropriate. A general exercise programme that combines muscular strength, flexibility and aerobic fitness would benefit the rehabilitation of Nonspecific Chronic Low Back Pain and its health risk. The present study aimed to validate the content of the combined exercise intervention protocol. Methods: The development and expert judgement stages are part of the content validation process. The development of the exercise protocol was based on a comprehensive literature review. The protocol was created in a step-by-step progressive manner. Exercises for flexibility (20 minutes), stabilisation and strengthening (20 minutes), and aerobic (20 minutes) make up the three main parts of the exercise protocol. 12 independent professionals with a minimum of 10 years of experience were invited. Ten of the twelve specialists consented to take part in the study. In India, all of the professionals were engaged in orthopaedic and musculoskeletal physical therapy. There are two professors, three associate professors, and five senior physiotherapists among the experts. Responses were gathered by mail. During the validation phase, The Exercise protocol was graded by the experts on relevance and ease of performance using a 5-point scale. After collecting the responses content validity index and kappa values were calculated. Results: 37 out of 39 items in the combined exercise intervention protocol showed good agreement. Treadmill walking with 60-75% and 80% and above target heart rate showed a kappa value of 0.66 for relevance and 0.50 for ease of performance. Conclusions: The designed exercise protocol exhibited good content validity.

Sex differences in the association between skeletal muscle energetics and perceived physical fatigability: the Study of Muscle, Mobility and Aging (SOMMA).

Greater perceived physical fatigability and lower skeletal muscle energetics are bothpredictors of mobility decline. Characterizing associations between muscle energetics and perceived fatigability may provide insight into potential targets to prevent mobility decline. We examined associations of in vivo (maximal ATP production, ATPmax) and ex vivo (maximal carbohydrate supported oxidative phosphorylation [max OXPHOS] and maximal fatty acid supported OXPHOS [max FAO OXPHOS]) measures of mitochondrial energetics with two measures of perceived physical fatigability, Pittsburgh Fatigability Scale (PFS, 0-50, higher = greater) and Rating of Perceived Exertion (RPE Fatigability, 6-20, higher = greater) after a slow treadmill walk. Participants from the Study of Muscle, Mobility and Aging (N = 873) were 76.3±5.0 years old, 59.2% women, and 85.3% White. Higher muscle energetics (both in vivo and ex vivo) were associated with lower perceived physical fatigability, all p < 0.03. When stratified by sex, higher ATPmax was associated with lower PFS Physical for men only; higher max OXPHOS and max FAO OXPHOS were associated with lower RPE Fatigability for both sexes. Higher skeletal muscle energetics were associated with 40-55% lower odds of being in the most (PFS≥25, RPE Fatigability ≥12) vs least (PFS 0-4, RPE Fatigability 6-7) severe fatigability strata, all p < 0.03. Being a woman was associated with 2-3 times higher odds of being in the most severe fatigability strata when controlling for ATPmax but not the ex vivomeasures (p < 0.05). Better mitochondrial energetics were linked to lower fatigability and less severe fatigability in older adults. Findings imply that improving skeletal muscle energetics may mitigate perceived physical fatigability and prolong healthy aging.

Adapting spatiotemporal gait symmetry to functional electrical stimulation during treadmill walking.

Individuals with neurological impairments often exhibit asymmetrical gait patterns. This study explored the potential of using functional electrical stimulation (FES) as a perturbation method during treadmill walking to promote gait symmetry adaptation by investigating whether the FES perturbation could induce gait adaptation concerning spatial and temporal gait symmetry in healthy subjects. In the FES perturbation, both legs received electrical pulses at the same period as the subjects' initial stride duration, and the temporal gap between the two pulses for each leg was manipulated over a 7-min period. Following this, subjects continued to walk for another 5 minutes without FES. Subjects participated in two trials: implicit and explicit. In the implicit trial, they walked comfortably during FES perturbation without consciously adjusting their gait. In the explicit trial, they voluntarily synchronized their toe-off phase to the stimulation timing. To examine the effects of the FES perturbation, we measured step length and stance time and then analyzed changes in step length and stance time symmetries alongside their subsequent aftereffects. During the explicit trial, subjects adapted their gait patterns to the electrical pulses, resulting in a directional change in stance time (temporal) symmetry, with the left stance becoming shorter than the right. The stance time asymmetry induced by FES perturbation showed a slight residual effect. In the implicit trial, the directional change trend was slightly observed but not statistically significant. No consistent trend in step length (spatial) symmetry changes was observed in either condition, indicating that subjects may adapt their spatial gait patterns independently of their temporal patterns. Our findings suggest that the applied FES perturbation strategy under explicit condition can induce adaptations in subjects' temporal gait asymmetry, particularly in stance. The implicit condition showed a similar slight trend but was not statistically significant. Further experiments would provide deeper understanding into the mechanism behind subjects' response to FES perturbations, as well as the long-term effects of these perturbations on the spatial and temporal aspects of gait symmetry.