Plantar Flexor Research Articles

Effects of short-duration constant torque and constant angle stretching on the musculotendinous stiffness of ankle plantar flexors

Effects of short-duration constant torque and constant angle stretching on the musculotendinous stiffness of ankle plantar flexors

Smartphone Assessment of the Sitting Heel-Rise Test.

The study presents a new approach for assessing plantarflexor muscles' function using a smartphone. The test involves performing repeated heel raises for 60 s while seated. The seated heel-rise test offers a simple method for assessing plantarflexor muscles' function in those with severe balance impairment who are unable to complete tests performed while standing. The study aimed to showcase how gyroscopic data from a smartphone placed on the lower limb can be used to assess the test. Eight participants performed the seated heel-rise test with each limb. Gyroscope and 2D video analysis data (60 Hz) of limb motion were used to determine the number of cycles, the average rise (T-rise), lowering (T-lower), and cycle (T-total) times. The number of cycles detected matched exactly when the gyroscope and kinematic data were compared. There was good time domain agreement between gyroscopic and video data (T-rise = 0.0005 s, T-lower = 0.0013 s, and T-total = 0.0017 s). The 95% CI limits of agreement were small (T-total -0.1118, 0.1127 s, T-lower -0.1152, 0.1179 s, and T-total -0.0763, 0.0797 s). Results indicate that a smartphone placed on the thigh can successfully assess the seated heel-rise test. The seated heel-rise test offers an attractive alternative to test plantarflexor muscles' functionality in those unable to perform tests in standing positions.

Assessment of Age-Related Differences in Lower Leg Muscles Quality Using Radiomic Features of Magnetic Resonance Images.

Sarcopenia, characterised by a decline in muscle mass and strength, affects the health of the elderly, leading to increased falls, hospitalisation, and mortality rates. Muscle quality, reflecting microscopic and macroscopic muscle changes, is a critical determinant of physical function. To utilise radiomic features extracted from magnetic resonance (MR) images to assess age-related changes in muscle quality, a dataset of 24 adults, divided into older (male/female: 6/6, 66-79years) and younger (male/female: 6/6, 21-31years) groups, was used to investigate the radiomics features of the dorsiflexor and plantar flexor muscles of the lower leg that are critical for mobility. MR images were processed using MaZda software for feature extraction. Dimensionality reduction was performed using principal component analysis and recursive feature elimination, followed by classification using machine learning models, such as support vector machine, extreme gradient boosting, and naïve Bayes. A leave-one-out validation test was used to train and test the classifiers, and the area under the receiver operating characteristic curve (AUC) was used to evaluate the classification performance. The analysis revealed that significant differences in radiomic feature distributions were found between age groups, with older adults showing higher complexity and variability in muscle texture. The plantar flexors showed similar or higher AUC than the dorsiflexors in all models. When the dorsiflexor muscles were combined with the plantar flexor muscles, they tended to have a higher AUC than when they were used alone. Radiomic features in lower-leg MR images reflect ageing, especially in the plantar flexor muscles. Radiomic analysis can offer a deeper understanding of age-related muscle quality than traditional muscle mass assessments.

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

we investigated the effects of a 10week training program (i.e., minute oscillatory stretching; MOS) on the mechanical responses and walking capability in people with type 2 diabetes (T2D). 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 6kmh-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. 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. these results indicate the effectiveness of 10weeks 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.

Quantifying Active and Passive Stiffness in Plantar Flexor Muscles Following Intermittent Maximal Isometric Contractions Using Shear Wave Elastography

ObjectiveThis study aimed: (i) to investigate the impact of fatigue, triggered by maximal isometric contraction exercises, on the active and passive stiffness of plantar flexors (PF), and (ii) to examine the relationship between changes in mechanical parameters and neuromuscular alterations after fatigue. MethodsA healthy cohort (n = 12; age = 27.3 ± 5.5 y; BMI = 24.4 ± 2.35 kg/m²) was instructed to perform 60 isometric contractions, each lasting 4 s with a 1-s rest interval, using an ergometer. Several measures were taken before and after the fatigue protocol. First, the stiffness of the PF-tendon complex (PFC) was quantified during passive ankle mobilization both during and after the fatigue protocol using the ergometer. Additionally, from shear wave elastography, the active and passive stiffness of the gastrocnemius medialis (GM) were measured during passive ankle mobilization and isometric maximal voluntary contraction (MVC), respectively. Finally, the peak torque and the rate of torque development (RFD) of PF were assessed during the MVC using the ergometer. Ankle muscle activities (surface electromyograph [SEMG]) were recorded during all evaluations using electromyography. ResultsAfter the fatigue protocol, the results revealed a decline in active stiffness, peak torque of PF, RFD and SEMG activity of the GM (p < 0.001). Furthermore, significant correlation was identified between the decrease of the peak torque of PF and the active stiffness of the GM (r = 0.6; p < 0.05). A decrease in the PFC stiffness (p < 0.001) and a decrease in the shear modulus of the GM at 20° (p < 0.001) were also observed. ConclusionIsometric fatiguing exercises modify the mechanical properties of both the contractile and elastic components. Notably, decreases in both passive and active stiffness may be critical for athletes, as these changes could potentially increase the risk of injury.

Influence of foot strike pattern on co-contraction around the ankle and oxygen uptake during running at 19 km/h.

This study investigated the coactivation of plantar flexor and dorsiflexor muscles and oxygen uptake during running with forefoot and rearfoot strikes at 15 and 19 km/h. We included 16 male runners in this study. The participants ran each foot strike pattern for 5 min at 15 and 19 km/h on a treadmill. During the running, respiratory gas exchange data and surface electromyographic (EMG) activity of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus, and tibialis anterior muscles of the right lower limb were continuously recorded. The indices of oxygen uptake, energy expenditure (EE), and muscle activation were calculated during the last 2 min in each condition. During the stance phase of running at 15 and 19 km/h, activation of the tibialis anterior and MG muscles was lower and higher, respectively, with forefoot strike than with rearfoot strike. The foot strike pattern did not influence the oxygen uptake. These results suggest that the foot strike pattern has no clear effect on the oxygen uptake when running at 15 and 19 km/h. However, forefoot strike leads to plantar flexion dominance during co-contraction of the tibialis anterior and MG muscles, which are an antagonist and agonist for plantar flexion, respectively, during the stance phase.

Passive bicycle training stimulates epiphyseal bone formation and restores bone integrity independent of locomotor recovery in a rat spinal cord injury model.

It is unknown whether activity-based physical therapy (ABPT) modalities that mobilize the paralyzed limbs improve bone integrity at the highly fracture-prone epiphyseal regions of the distal femur and proximal tibia following severe spinal cord injury (SCI). In this study, 4-mo-old skeletally mature littermate-matched male Sprague-Dawley rats received either SHAM surgery or severe contusion SCI. At 1 wk postsurgery, SCI rats were stratified to undergo no-ABPT, two 20-min bouts/day of quadrupedal bodyweight-supported treadmill training (qBWSTT), or hindlimb passive isokinetic bicycle (cycle) training, 5 days/wk for another 3 wk. We assessed locomotor recovery and plantar flexor muscle mass, tracked cancellous and cortical bone microstructure at the distal femoral and proximal tibial epiphyses using in vivo microcomputed tomography (microCT), and evaluated bone turnover at the tibial epiphysis with histomorphometry. All SCI animals displayed persistent hindlimb paralysis and pervasive muscle atrophy. Over the initial 2 wk, which included 1 wk of no exercise and 1 wk of ABPT acclimation, a similar magnitude of bone loss developed in all SCI groups. Thereafter, cancellous bone loss and cortical bone decrements increased in the SCI no-ABPT group. qBWSTT attenuated this trabecular bone loss but did not prevent the ongoing cortical bone deficits. In comparison, twice-daily cycle training increased the number and activity of osteoblasts versus other SCI groups and restored all bone microstructural parameters to SHAM levels at both epiphyseal sites. These data indicate that a novel passive isokinetic cycle training regimen reversed cancellous and cortical bone deterioration at key epiphyseal sites after experimental SCI via osteoblast-mediated bone anabolic mechanisms, independent of locomotor recovery or increased muscle mass.NEW & NOTEWORTHY This study was the first to assess how quadrupedal bodyweight-supported treadmill training or passive isokinetic bicycle (cycle) training impacts bone recovery at the distal femoral and proximal tibial epiphyses in a rat model of severe contusion spinal cord injury. Our results demonstrate that passive isokinetic cycle training completely restored cancellous and cortical bone microstructural parameters at these sites via osteoblast-mediated bone anabolic actions, independent of locomotor recovery or increased plantar flexor muscle mass.

Effects of Manual Therapy on Fascial Distortion Model in Adolescent Ankle Sprain: A Pilot Study

ObjectivesThe present study aimed to assess the feasibility of investigating the effects of manual therapy on ankle functional muscle strength, static balance, and disability in adolescent patients with an ankle sprain. MethodsThe study was a nonrandomized prepost clinical feasibility trial. From September 2021 to February 2022, 31 patients with ankle sprain received manual therapy. Functional muscle strength of plantar flexor muscles and static balance were evaluated using the standing heel-rise and unipedal stance tests on the injured and healthy legs before and after the first and second sessions. Foot and Ankle Disability Index (FADI) assessed the disability at baseline, after the first and second sessions, in the third and sixth weeks. ResultsWithin-group analysis of the unipedal stance test with open and closed eyes and the standing heel-rise test showed that injured legs significantly improved after the first and second sessions, compared to uninjured legs (P < .05). Furthermore, there were significant differences among all repeated FADI measures (P < .05). ConclusionsThis study demonstrated that a study was feasible to measure ankle functional muscle strength, static balance, and disability in adolescent patients with an ankle sprain.

Comparison of the Efficacy of 2 Different Botulinum Toxin Injection Techniques in Gastrocnemius Muscle Spasticity in Hemiplegic Patients: A Randomized Double-Blind Controlled Study

ObjectiveTo compare the efficacy of the innervation zone–targeted injection technique (EUROMUSCULUS/USPRM (Ultrasound Study Group of the International Society of Physical and Rehabilitation Medicine) spasticity approach) and the injection technique along the muscle length. DesignA double-blind randomized controlled trial. SettingDepartment of rehabilitation medicine of a medical center. ParticipantsOne hundred patients with stroke experiencing ankle plantar flexor spasticity. InterventionsIn addition to conventional rehabilitation, eligible patients were randomly assigned to 2 groups. The experimental group was injected with botulinum toxin along the length of the muscle, whereas the control group was injected with the same dose and volume of botulinum toxin 25%-35% proximal to the medial head and 20%-30% proximal to the lateral aspect of the head of the gastrocnemius muscle. Main Outcome MeasuresModified Ashworth scale, modified Tardieu scale, ankle range of motion measurement, and 10-meter walk test were used before and 1 month after injection. ResultsThe study was completed by 60 participants with a mean age of 59.96±12.15 years. Both injection methods were found to be effective on range of motion, spasticity level, ambulation, and walking speed. There was no statistically significant difference between injection methods. ConclusionsBoth injection methods of botulinum toxin A produce similar clinical effects.

Effect of Dry Needling Plus Static Stretching on Plantar Flexors Spasticity in Chronic Stroke Patients.

Stroke is a leading cause of disability worldwide and is often accompanied by complications such as spasticity. Static stretching (SS) is a common physiotherapy intervention for reducing spasticity, whereas dry needling (DN) is a novel approach. However, the combined effects of DN and SS on spasticity have not been thoroughly investigated. Given the pivotal effect of spasticity on daily activities, mitigating spasticity can significantly contribute to restoring patient independence. This study will explore the impact of DN plus SS on spasticity, alpha motor neuron excitability, overall function, and quality of life in patients with chronic stroke. A double-blind, randomized, sham-controlled trial will be conducted in patients with post-stroke spasticity in the plantar flexor muscles. Twentyeight participants will be randomly assigned to either an intervention or control group. The intervention group will receive DN (60s × 3 days/week; 1 week) plus SS (20 min × 5 days/ week; 1 week). The control group will undergo sham DN (60s × 3 days/week; 1 week) and SS (20 min × 5 days/week; 1 week). DN plus SS or sham DN plus SS. Both groups will be assessed at baseline, immediately post-treatment, and after 1 week of follow-up. Outcome measures will include the Modified Modified Ashworth Scale, H-reflex latency, Hmax/Mmax ratio, active and passive ankle dorsiflexion range of motion, timed up and go test, and the EuroQol questionnaire. Results from this randomized, sham-controlled study will provide evidence for the effectiveness of DN in combination with SS for spasticity. The additional impact of DN in conjunction with SS, a widely used method for reducing muscle tone, remains unclear and warrants investigation. This study, with a high level of evidence, aims to address this knowledge gap.

Comparative Efficacy of Baclofen and Diazepam in Treating Spasticity Following Acquired Spinal Cord Injuries: A Randomized Controlled Trial

Abstract Introduction: Spasticity is a pervasive and debilitating condition. Anti-spastic medications like Baclofen and Diazepam are most commonly used for spasticity management. Objectives: The study aimed to evaluate and compare the efficacy of Baclofen with that of Diazepam in the management of spasticity following acquired spinal cord injuries. Methods: In this randomised open-label study involving 60 patients, 30 patients received 5 mg of oral Baclofen thrice daily and 30 patients received 5 mg of oral Diazepam thrice daily for the management of spasticity. The extent of spasticity was measured by Modified Ashworth Scale (MAS). The efficacy of these drugs was measured with the mean improvement in the above parameters on days 7, 14, 28, 56 and 90 from the start of pharmacotherapy. Results: Baseline muscle spasticity scores were comparable. At the endpoint, mean improvement in tone of right and left hip flexors (1.43 vs. 0.87), hip adductors (1.30 vs. 0.87), knee flexors (0.80 vs. 0.37), ankle plantar flexors (0.80 vs. 0.37) and ankle dorsiflexors (1.23 vs. 0.93) were significantly higher in Baclofen group (p&lt;0.05), while the tone of right and left hip abductors, hip and knee extensors showed no significant difference among the groups. Conclusion: Baclofen was found to be superior to Diazepam in terms of efficacy, especially for flexor spasticity of lower limbs in acquired spinal cord injuries.

Comparing the effectiveness of robotic plantarflexion resistance and biofeedback between overground and treadmill walking

Individuals with diminished walking performance caused by neuromuscular impairments often lack plantar flexion muscle activity. Robotic devices have been developed to address these issues and increase walking performance. While these devices have shown promise in their ability to increase musculature engagement of the lower limbs when used on a treadmill, most have not been developed or validated for overground walking and community use. Overground walking may limit the effectiveness of robotic devices due to differences in gait characteristics between walking terrains and reduced user engagement. The purpose of this study was to validate our multimodal robotic gait training system for overground walking in individuals with neuromuscular gait impairments. This untethered wearable robotic device can provide an ankle resistive torque proportional to the users’ biological ankle torque. The device can also provide audio biofeedback based on users’ plantar pressure intending to increase ankle power and muscle activity of the plantar flexors. Seven individuals with cerebral palsy participated. Participants walked overground and on a treadmill with our robotic gait training system in a single testing session. Results showed all seven participants to increase peak plantar flexor muscle activity, 10.3% on average, when walking with the gait trainer overground compared to treadmill. When compared to typical baseline overground walking, overground gait trainer use caused individuals to have slightly less knee joint excursion (3°) and moderately more ankle joint excursion (7°). This work supports our vision of using the wearable robotic device as a gait aid and rehabilitation tool in the home and community settings.

Gait Performance and Brain Activity Are Improved by Gait Automatization during Robot-Assisted Gait Training in Patients with Burns: A Prospective, Randomized, Single-Blinded Study.

Background: Patients with lower extremity burn injuries have decreased gait function. Gait dysfunctions are compensated by activation of executive areas such as the prefrontal cortex (PFC). Although robot-assisted gait training (RAGT) can improve gait function, the training mechanisms of RAGT are unknown. We aimed to determine the clinical effects of RAGT in patients with burns and investigate their underlying mechanisms. Methods: This single-blind, randomized controlled trial involved 54 patients with lower extremity burns. The RAGT group underwent RAGT using SUBAR® and conventional training. The control (CON) group underwent only conventional training. The primary outcome was cortical activity measured using a functional near-infrared spectroscopy device before and after 8 weeks of training to confirm the compensatory effect of gait dysfunction. The secondary outcomes were the functional ambulation category (FAC) to evaluate gait performance, 6-min walking test (6 MWT) distance to measure gait speed, isometric force and range of motion (ROM) of lower extremities to evaluate physical function, and the visual analog scale (VAS) score to evaluate subjective pain during gait. Results: PFC activation during the gait phase in the RAGT group decreased significantly compared with that of the CON. The VAS score decreased and FAC score improved after 8 weeks of training in both groups. The 6 MWT scores, isometric strengths (the left knee flexor and bilateral ankle plantar flexors), and the ROMs (the extensions of bilateral hip and bilateral knee) of the RAGT group were significantly improved compared with those of the CON. RAGT improved gait speed, lower extremity ROMs, and lower extremity muscles strengths in patients with burns. Conclusions: The improvement in gait speed and cerebral blood flow evaluation results suggests that the automatization of gait is related to the treatment mechanism during RAGT.

Age-related differences in the loss and recovery of serial sarcomere number following disuse atrophy in rats

BackgroundOlder adults exhibit a slower recovery of muscle mass following disuse atrophy than young adults. At a smaller scale, muscle fibre cross-sectional area (i.e., sarcomeres in parallel) exhibits this same pattern. Less is known, however, about age-related differences in the recovery of muscle fibre length, driven by increases in serial sarcomere number (SSN), following disuse. The purpose of this study was to investigate age-related differences in SSN adaptations and muscle mechanical function during and following muscle immobilization. We hypothesized that older adult rats would experience a similar magnitude of SSN loss during immobilization, however, take longer to recover SSN than young following cast removal, which would limit the recovery of muscle mechanical function.MethodsWe casted the plantar flexors of young (8 months) and old (32 months) male rats in a shortened position for 2 weeks, and assessed recovery during 4 weeks of voluntary ambulation. Following sacrifice, legs were fixed in formalin for measurement of soleus SSN and physiological cross-sectional area (PCSA) with the un-casted soleus acting as a control. Ultrasonographic measurements of pennation angle (PA) and muscle thickness (MT) were conducted weekly. In-vivo active and passive torque-angle relationships were constructed pre-cast, post-cast, and following 4 weeks of recovery.ResultsFrom pre- to post-cast, young and older adult rats experienced similar decreases in SSN (–20%, P < 0.001), muscle wet weight (–25%, P < 0.001), MT (–30%), PA (–15%, P < 0.001), and maximum isometric torque (–40%, P < 0.001), but there was a greater increase in passive torque in older (+ 180%, P < 0.001) compared to young adult rats (+ 68%, P = 0.006). Following cast removal, young exhibited quicker recovery of SSN and MT than old, but SSN recovered sooner than PA and MT in both young and old. PCSA nearly recovered and active torque fully recovered in young adult rats, whereas in older adult rats these remained unrecovered at ∼ 75%.ConclusionsThis study showed that older adult rats retain a better ability to recover longitudinal compared to parallel muscle morphology following cast removal, making SSN a highly adaptable target for improving muscle function in elderly populations early on during rehabilitation.

The Effect of Planovalgus on Balance and Motor Function in Children With Cerebral Palsy

Objective Lower limb deformity in children with cerebral palsy (CP) is a common musculoskeletal problem and planovalgus is the most prevalent, characterized by talus median subluxation, calcaneal valgus, and supinated forefoot. According to studies, one issue in orthopedics and pathology is the accurate diagnosis and proper treatment of planovalgus deformity in children with bilateral spastic cerebral palsy, which has attracted researchers’ attention. Accordingly, the present study investigates the effect of planovalgus deformity on the motor performance and balance of these children. Materials &amp; Methods This cross-sectional study employed a descriptive-analytical design. The convenient sampling method was used among children with bilateral spastic cerebral palsy, diagnosed with unilateral planovalgus, who were referred to the clinics of the University of Social Welfare and Rehabilitation Sciences (Nezam Mafi) and occupational therapy clinics from September 2022 to February 2023 in Tehran City, Iran. Meanwhile, all participants were willing to cooperate in this research. A total of 27 participants were evaluated by an occupational therapist based on the specified criteria and gross motor function classification system (GMFCS), which included the assessments of balance, muscle strength, range of motion, and pain. Data analysis was done using the SPSS software, version 16. Results The results revealed a statistically significant difference between the mean range of motion of ankle dorsiflexion and knee extension between the two limbs (P&lt;0.001). The mean muscle strength of the quadriceps and ankle plantar flexors indicated a statistically significant difference in the affected limb (P&lt;0.001). Additionally, the mean displacement of the center of pressure of the foot also demonstrated a statistically significant difference regarding topographical involvement (P&lt;0.001). Conclusion Planovalgus deformity is one of the most common ankle deformities, which is of great concern for children with cerebral palsy. The results obtained from the assessments of the child’s balance and motor function demonstrated the importance of assessment strategies and early interventions to achieve better rehabilitation outcomes for children with CP and planovalgus deformity.

Longitudinal Decline of Exercise Capacity in Male and Female Mice.

The population of older adults is exponentially expanding. Alongside aging comes the onset of chronic disease, decline of functional capacity, and reduced quality of life. Thus, this population increase will stress the capacity and financial viability of health and long-term care systems. Developing pre-clinical models for age-related functional decline is imperative to advancing therapies that extend healthspan and prolong independence. Previously in a cross-sectional study, we established a powerful composite scoring system we termed CFAB (comprehensive functional assessment battery). CFAB measures physical function and exercise capacity using well-validated determinants to measure overall motor function, fore-limb strength, four-limb strength/endurance, aerobic capacity, and volitional exercise/activity rate. In the current work, we used CFAB to track cohorts of male and female C57BL/6 mice over the lifespan (measuring CFAB at 6, 12, 18, 24, and 28 months of age). Overall, we found statistically significantly declining function as the mice aged, with some differences between males and females in trajectory and slope. We also determined that body mass changes presented differently between sexes, and tracked body composition (fat percentage, using magnetic resonance imagery) in females. In a subset of mice, we tracked in vivo contractile physiology noting declines in plantar flexor maximum isometric torque. In summary, our data suggest that males and females declined at different rates. We confirmed the efficacy of CFAB to track longitudinal changes in exercise capacity and physical fitness in both males and females, further validating the system to track age-related functional decline.

Impact of eccentric cycling in coronary rehabilitation program: a pragmatic randomized controlled trial versus conventional rehabilitation.

This randomized controlled trial examined the feasibility of adding eccentric exercise to a conventional cardiac rehabilitation program (CCRP) for coronary heart disease patients. Ninety-three patients were randomly assigned to either the MIX group (eccentric ergometer + CCRP) or the CON group (concentric ergometer + CCRP) for 7 weeks. Training effectiveness was assessed based on "good responders" showing improved functional capacities, such as 6-minute walk test (6MWT) distance and maximal voluntary contraction of the plantar flexors (ankle MVC). Safety was monitored with a visual analog scale for muscle soreness, perceived exertion, and heart rate during training. The proportion of good responders was similar between groups (26% in MIX, 29% in CON, P=0.744). Both groups improved in 6MWT (CON: 12.6%, MIX: 16.14%) and ankle MVC (CON: 15.5%, MIX: 11.30%), with no significant differences. Exercise tolerance did not differ significantly between the groups, but perceived effort was significantly lower in the MIX group (P<0.0001) compared to the CON group. Integrating eccentric exercise into cardiac rehabilitation is safe and well-tolerated. Nevertheless, this study did not find significant advantages over conventional programs for coronary heart disease patients. Further research should explore specific patient groups or conditions where eccentric exercise may be more beneficial, emphasizing personalized prescriptions and gradual workload progression for better cardiac rehabilitation outcomes.

Customized passive-dynamic ankle–foot orthoses can improve walking economy and speed for many individuals post-stroke

BackgroundPassive-dynamic ankle–foot orthoses (PD-AFOs) are often prescribed to address plantar flexor weakness during gait, which is commonly observed after stroke. However, limited evidence is available to inform the prescription guidelines of PD-AFO bending stiffness. This study assessed the extent to which PD-AFOs customized to match an individual’s level of plantar flexor weakness influence walking function, as compared to No AFO and their standard of care (SOC) AFO.MethodsMechanical cost-of-transport, self-selected walking speed, and key biomechanical variables were measured while individuals greater than six months post-stroke walked with No AFO, with their SOC AFO, and with a stiffness-customized PD-AFO. Outcomes were compared across these conditions using a repeated measures ANOVA or Friedman test (depending on normality) for group-level analysis and simulation modeling analysis for individual-level analysis.ResultsTwenty participants completed study activities. Mechanical cost-of-transport and self-selected walking speed improved with the stiffness-customized PD-AFOs compared to No AFO and SOC AFO. However, this did not result in a consistent improvement in other biomechanical variables toward typical values. In line with the heterogeneous nature of the post-stroke population, the response to the PD-AFO was highly variable.ConclusionsStiffness-customized PD-AFOs can improve the mechanical cost-of-transport and self-selected walking speed in many individuals post-stroke, as compared to No AFO and participants’ standard of care AFO. This work provides initial efficacy data for stiffness-customized PD-AFOs in individuals post-stroke and lays the foundation for future studies to enable consistently effective prescription of PD-AFOs for patients post-stroke in clinical practice.Trial Registration: NCT04619043.

Muscle synergy and kinematic synergy analyses during sit-to-stand motions in hallux valgus patients before and after treatment with Kinesio taping

ObjectivesTo explore the impact of hallux valgus (HV) on lower limb neuromuscular control strategies during the sit-to-stand (STS) movement, and to evaluate the effects of Kinesio taping (KT) intervention on these control strategies in HV patients.MethodsWe included 14 young healthy controls (HY), 13 patients in the HV group (HV), and 11 patients in the HV group (HVI) who underwent a Kinesio taping (KT) intervention during sit-to-stand (STS) motions. We extracted muscle and kinematic synergies from EMG and motion capture data using non-negative matrix factorization (NNMF). In addition, we calculated the center of pressure (COP) and ground reaction forces (GRF) to assess balance performance.ResultsThere were no significant differences in the numbers of muscle and kinematic synergies between groups. In the HV group, knee flexors and ankle plantar flexors were abnormally activated, and muscle synergy D was differentiated. Muscle synergy D was not differentiated in the HVI group.ConclusionAbnormal activation of knee flexors and plantar flexors led to the differentiation of module D in HV patients, which can be used as an indicator of the progress of HV rehabilitation. KT intervention improved motor control mechanisms in HV patients.

How Humans Run Faster: The Neuromechanical Contributions of Functional Muscle Groups to Running at Different Speeds.

How the neuromechanics of the lower limb functional muscle groups change with running speed remains to be fully elucidated, with implications for our understanding of human locomotion, conditioning, and injury prevention. This study compared the neuromechanics (ground reaction and joint kinetics, kinematics and muscle activity) of middle-distance athletes running on an instrumented treadmill at six wide-ranging speeds (2.78-8.33 m·s-1). Ground reaction forces and kinematics were analyzed using inverse dynamics to calculate flexor and extensor joint torques, and positive and negative work done by these torques. Contributions of each functional muscle group to the total positive and negative work done by the limb during stance, swing, and the whole stride were quantified. During stance, the ankle plantar flexors were the major energy generator and absorber (>60%) at all speeds, but their contribution to whole stride energy generation and absorption declined with speed. Positive work by the hip extensors rose superlinearly with speed during stance (3-fold) and especially during swing (12-fold), becoming the biggest energy generator across the whole stride at >5 m·s-1. Knee flexor and extensor negative work also rose superlinearly with speed during swing, with the knee flexors becoming the greatest energy absorber over the whole stride at >7.22 m·s-1. Across speeds, plantar flexor peak moment and positive work accounted for 97% and 96% of the variance in step length, and swing hip extension peak moment and positive work accounted for 98% and 99% of the variance in step frequency. There were pronounced speed, phase (stance/swing), and work (positive/negative) dependent contributions of the different functional muscle groups during running, with extensive implications for conditioning and injury prevention.