Lower Leg Muscles Research Articles

Are Lower-leg And Thigh Muscle Resistance Training Equally Effective To Adl-related Functional Fitness For Community-dwelling Elderly Females?

PURPOSE: The purpose was to compare the magnitude of lower-leg training program and thigh muscle training program to ADL-related functional fitness changes for community-dwelling elderly Japanese women. METHODS: After giving written informed consent, the subjects, unable to stand on one leg for more than 25 seconds with their eyes open, were divided into a lower-leg training group (LLG; 10 females, 72.9±4.2 yrs, BMI 22.1±1.8) and a thigh muscle training group (TMG; 10 females, 70.6±2.5 yrs, BMI 22.1±1.2). The program was 60min. two times per week for 16 weeks. Each training program consisted of three parts. At first, participants learned about management skills for their physical stiffness. Secondly, they learned each resistance program. LLG participated in the program using unstable disk and elastic band. TMG learned program was to strengthen their thigh muscles with elastic band. Finally, both groups learned a three-minute arm and leg combined exercise program with music. Participants were asked to follow their learned management skill program and resistance program every day and check it on the card. ADL-related functional fitness(sitting & standing time, zig-zag walking time, self-care working time), dynamic balance ability which measured by one-leg standing time with their eyes open and knee extension strength was evaluated. Each measurement items were assessed before and after the intervention period. Student’s t-test and two-way repeated measures ANOVA were used to test the effectiveness. RESULTS: The class participation rates were 82± 4% and 81± 8% and home participation rates were 76± 10% and 72± 15% respectively. ADL-related functional fitness of TMG improved significantly compared to LLG; Sitting & standing time (TMG: 18.6±7.4 to 13.4±6.1 sec., LLG: 16.3±7.4 to 13.8± 5.7sec., F=18.00, P=0.033), self-care working time ( TMG: 16.3±5.3 to 11.3±3.2sec., LLG: 16.1±3.2 to 14.9±4.3sec., F=17.00,P=0.026), zig-zag walking time( TMG: 15.6±7.2 to 14.2±5.5sec., LLG: 14.2±3.2 to 12.6±3.0ec., F=0.043,P=0.838). Knee extension strength improved significantly in TMG (P=0.029). One-leg standing time with their eyes open improved in LLG(P=0.038) CONCLUSIONS: Thigh-muscle training was found more effective to improve ADL-related functional fitness than lower-leg muscles for community-dwelling females.

The Acute Effects of Different Intensity Whole-Body Vibration Exposure on Muscle Tone and Strength of the Lower Legs, and Hamstring Flexibility: A Pilot Study.

The research on the change in properties of the lower leg muscles by different intensity sinusoidal vertical whole-body vibration (SV-WBV) exposures has not yet been investigated. The purpose of this study was to determine effect of a 20-minute different intensity SV-WBV application to the ankle plantar flexor and dorsiflexor muscles properties and hamstring flexibility. Prospective preintervention-postintervention design. Physiotherapy department. A total of 50 recreationally active college-aged individuals with no history of a lower leg injury volunteered. The SV-WBV was applied throughout the session with an amplitude of 2 to 4mm and a frequency of 25Hz in moderate-intensity vibration group and 40Hz in a vigorous-intensity vibration group. The gastrocnemius and tibialis anterior muscle tone was assessed with MyotonPRO, and the strength evaluation was made on the same lower leg muscles using hand-held dynamometer. The sit and reach test was used for the lower leg flexibility evaluation. The gastrocnemius muscle tone decreased on the right side (d = 0.643, P = .01) and increased on the left (d = 0.593, P = .04) when vigorous-intensity vibration was applied. Bilateral gastrocnemius muscle strength did not change in both groups (P > .05). Without differences between groups, bilateral tibialis anterior muscle strength increased in both groups (P < .01). Bilateral gastrocnemius and tibialis anterior muscle tone did not change in the moderate-intensity vibration group (P > .05). Flexibility increased in both groups (P < .01); however, there was no statistically significant difference between the groups (d = 0.169, P = .55). According to study results, if SV-WBV is to be used in hamstring flexibility or ankle dorsiflexor muscle strengthening, both vibration exposures should be preferred. Different vibration programs could be proposed to increase ankle plantar flexor muscle strength in the acute results. Vigorous-intensity vibration exposure is effective in altering ankle plantar flexor muscle tone, but it is important to be aware of the differences between the lower legs.

Alteration of muscle synergy structure while walking under increased postural constraints

It is hypothesised that specific groups of muscles aka muscle synergies (MSs) are combined by the central nervous system to control a wide repertoire of movements and also simplify motor control. Therefore, studying MSs during human locomotion is of significance, as it may reveal neuromuscular strategies for postural stability. In this study, the authors aimed to use the hypothesis of MSs to identify specific muscle co-activations during overground walking and slacklining where postural perturbations were generated by the participants rather than being externally controlled. Nine participants were asked to walk overground and on a slackline while they recorded myoelectric activity of their leg muscles. They extracted synergies from the electromyography signals in the two tasks using factor analysis. The results showed adaptation in the shared MSs structure during walking on the slackline and these shared MSs across participants were recruited flexibly to meet the demand for stability. The modulation of synergies suggests adaptive neuromuscular strategies for stability while walking on a slackline. Specifically, higher activation of quadriceps during slacklining suggests a crouched gait to facilitate balance. During overground walking, lower leg muscles revealed higher activation compared to slacklining to support a more consistent toe-off during the stance phase.

Force control during submaximal isometric contractions is associated with walking performance in persons with multiple sclerosis.

Individuals with multiple sclerosis (MS) experience progressive declines in movement capabilities, especially walking performance. The purpose of our study was to compare the amount of variance in walking performance that could be explained by the functional capabilities of lower leg muscles in persons with MS and a sex- and age-matched control group. Participants performed two walking tests (6-min walk and 25-ft walk), strength tests for the plantar flexor and dorsiflexor muscles, and steady submaximal (10% and 20% maximum) isometric contractions. High-density electromyography (EMG) was recorded during the steady contractions, and the signals were decomposed to identify the discharge times of concurrently active motor units. There were significant differences between the two groups in the force fluctuations during the steady contractions (force steadiness), the strength of the plantar flexor and dorsiflexor muscles, and the discharge characteristics during the steady contractions. Performance on the two walking tests by the MS group was moderately associated with force steadiness of the plantar flexor and dorsiflexor muscles; worse force steadiness was associated with poorer walking performance. In contrast, the performance of the control group was associated with muscle strength (25-ft test) and force steadiness of the dorsiflexors and variance in common input of motor units to the plantar flexors (6-min test). These findings indicate that a reduction in the ability to maintain a steady force during submaximal isometric contractions is moderately associated with walking performance of persons with MS.NEW & NOTEWORTHY The variance in walking endurance and walking speed was associated with force control of the lower leg muscles during submaximal isometric contractions in individuals with multiple sclerosis (MS). In contrast, the fast walking speed of a sex- and age-matched control group was associated with the strength of lower leg muscles. These findings indicate that moderate declines in the walking performance of persons with MS are more associated with impairments in force control rather than decreases in muscle strength.

The Effect of Acute Body Unloading on Somatosensory Performance, Motor Activation, and Visuomotor Tasks.

Evaluating countermeasures designed to reduce the impact of microgravity exposure on astronaut performance requires the development of effective methods of assessing changes to sensorimotor function in 1g analog systems. In this study, somatosensation at the ankle and fingers, lower leg muscle activity and visuomotor control were assessed using a full body loading and acute unloading model to simulate microgravity. It was hypothesized that the function of the hands and eyes are not constrained to ‘weight bearing’ postures for optimal function and would not differ between the loaded and acute unloaded conditions, whereas lower leg muscle activity and ankle somatosensation would be reduced in the acute unloaded condition. Somatosensation was recorded using the Active Movement Extent Discrimination Apparatus (AMEDA) protocol where participants were required to make an absolute judgment of joint position sense. A score closer to 1.0 demonstrates higher accuracy. Lower leg muscle activity was recorded using electromyography of major lower leg musculature to observe peak muscle activity and duration of contraction. The King Devick infrared eye tracking test was used to asses visuomotor control by monitoring saccade velocity and fixation time. In acute unloading, it was found that ankle somatosensation had decreased accuracy (loaded 0.68, unloaded 0.66, p = 0.045) while finger somatosensation improved (loaded 0.77, unloaded 0.79, p = 0.006). When acutely unloaded, peak lower leg muscle activation reduced ( > 27%) and total contraction time increased (2.02 × longer) compared to loading. Visuomotor assessment results did not vary between the loaded and acute unloaded postures, however the underlying techniques used by the participant to complete the task (saccade velocity and fixations time) did increase in acute unloaded conditions.SignificanceThis research provides an insight to how to the human body responds immediately to acute changes of gravitational load direction. It provides insight to the acute affects’ astronauts may encounter when in microgravity.

THE EFFECTS OF MULTIPLE MODALITIES OF COGNITIVE LOADING ON DYNAMIC POSTURAL CONTROL IN INDIVIDUALS WITH CHRONIC ANKLE INSTABILITY

BackgroundEvidence of neuroplasticity after joint injury has suggested that individuals with chronic ankle instability (CAI) may have degraded movement when facing cognitive demand. To date, research into these effects have been limited to static balance models, and typically only incorporate a single type of cognitive demands. Research questionWe aimed to determine the effects of multiple modalities of cognitive load (quantitative, verbal-memory, visuospatial) on dynamic postural control strategies in a sample of patients with CAI compared to uninjured controls. MethodsThirty-two participants (16 CAI, 16 healthy) performed a series of 20 hops-to-stabilization while either under no cognitive load (CON), or while performing Benton’s judgment of line orientation (JLO), the symbol digit modalities test (SDM), or a serial seven task (SVN). Dynamic postural stability indices and mean muscle activation from the lower leg muscles were extracted and assessed via analysis of variance. ResultsHealthy subjects demonstrated better vertical and dynamic postural stability indices under JLO (P ≤ 0.017) and SVN (P ≤ 0.010) conditions compared to CON. Postural stability was unaffected in CAI (P > 0.050). Peroneus longus and lateral gastrocnemius activation was lowest in SVN across all subjects (P ≤ 0.033). Lateral gastrocnemius activation was greatest in SDM (P ≤ 0.033). SignificanceThese results suggest improvements in postural stability under cognitive demand in healthy individuals that did not occur in CAI, suggesting less movement optimization. Quantitative tasks appear to impede stabilizing muscle activation in the leg, while verbal-memory tasks result in a more protective landing strategy.

Modulation of soleus muscle H-reflexes and ankle muscle co-contraction with surface compliance during unipedal balancing in young and older adults

This study aimed to assess modulation of lower leg muscle reflex excitability and co-contraction during unipedal balancing on compliant surfaces in young and older adults. Twenty healthy adults (ten aged 18–30 years and ten aged 65–80 years) were recruited. Soleus muscle H-reflexes were elicited by electrical stimulation of the tibial nerve, while participants stood unipedally on a robot-controlled balance platform, simulating different levels of surface compliance. In addition, electromyographic data (EMG) of soleus (SOL), tibialis anterior (TA), and peroneus longus (PL) and full-body 3D kinematic data were collected. The mean absolute center of mass velocity was determined as a measure of balance performance. Soleus H-reflex data were analyzed in terms of the amplitude related to the M wave and the background EMG activity 100 ms prior to the stimulation. The relative duration of co-contraction was calculated for soleus and tibialis anterior, as well as for peroneus longus and tibialis anterior. Center of mass velocity was significantly higher in older adults compared to young adults (p<0.001) and increased with increasing surface compliance in both groups (p<0.001). The soleus H-reflex gain decreased with surface compliance in young adults (p= 0.003), while co-contraction increased {(p}_{mathrm{S}mathrm{O}mathrm{L},mathrm{T}mathrm{A}}=0.003 mathrm{a}mathrm{n}mathrm{d} {p}_{mathrm{P}mathrm{L},mathrm{T}mathrm{A}}<0.001). Older adults did not show such modulations, but showed overall lower H-reflex gains (p<0.001) and higher co-contraction than young adults {(p}_{mathrm{S}mathrm{O}mathrm{L},mathrm{T}mathrm{A}}<0.001 mathrm{a}mathrm{n}mathrm{d} {p}_{mathrm{P}mathrm{L},mathrm{T}mathrm{A}}=0.002). These results suggest an overall shift in balance control from the spinal level to supraspinal levels in older adults, which also occurred in young adults when balancing at more compliant surfaces.

PENGARUH LATIHAN LOMPAT GAWANG DAN LATIHAN LOMPAT SAMPING TERHADAP KEMAMPUAN HEADING BOLA PADA PERMAINAN SEPAKBOLA DITINJAU DARI DAYA LEDAK OTOT TUNGKAI

This research is a field experimental study with a 2 x 2 factorial design. The population is all students of the Faculty of Sport Science, Jambi State University with SportsTraining Education samples with a sampling technique is a proportional sampling of 40 people. The data analysis technique used is Analysis of Variance (ANAVA) at a significant level of 95%. By looking at the existing problems, the results obtained from the data processing shows that: there is no significant difference in effect between hurdles and side jump exercises on the ability of heading balls in football (Fo = 0.939&gt; Ft = 4.11). There is a significant difference between the power of high limb muscle explosions with low limb muscle explosiveness to the ability of heading balls in football (Fo = 17,976&gt; Ft = 4.11). For athletes who have high leg muscle explosive power, there is a significant difference in effect between goal jump training and side lomato training on ball heading abilities in football (to = 6.034&gt; tt = 1.73). For athletes who have low leg muscle explosive power, there is a significant difference in effect between hurdles and side jump exercises on heading ball abilities in football (to = 12,357&gt; tt = 1.73).

Fatigue increases ankle sprain risk in badminton players: A biomechanical study

ABSTRACT Ankle sprains are the most common injury in regular badminton players and usually occur at the end of a match or training. The purpose of the present study was to examine the influence of fatigue produced by badminton practice on the lower limb biomechanics of badminton players. It was hypothesized that fatigue induces ankle kinematic and lower leg muscle activity changes which may increase the risk of ankle sprain. Ankle kinematics, ankle kinetics and muscles activities of 17 regular badminton players were recorded during lateral jumps before and after an intense badminton practice session. Post-fatigue, ankle inversion at foot strike and peak ankle inversion increased (+2.6°, p = 0.003 and +2.5°, p = 0.005, respectively). EMG pre-activation within 100 ms before foot landing significantly decreased after fatigue for soleus (−23.4%, p = 0.031), gastrocnemius lateralis (−12.2%, p = 0.035), gastrocnemius medialis (−23.3%, p = 0.047) and peroneus brevis (−17.4%, p = 0.036). These results demonstrate impaired biomechanics of badminton players when fatigue increases, which may cause a greater risk of experiencing an ankle sprain injury.

Estimates of Motor Neuron Excitability During Postural Sways in Lower Leg Muscles

Motor system investigations are often performed under isometric conditions, but real‐world motor behaviors are seldom isometric. During tasks where isometric force or torque measurements are not feasible (i.e. during unconstrainedconditions), EMG is often used as a surrogate of the level of muscle activity. However, the linear relationship between EMG and force generation breaks down during non‐isometric contractions. It is not clear how this affects investigators’ ability to discriminate motor units using state‐of‐the‐art high‐density surface EMG arrays. Additionally, the paired motor unit analysis technique, which generates an estimate of the intrinsic excitability of a ‘test’ motor unit by determining discharge rate hysteresis (ΔF), has not been evaluated in unconstrained conditions. Consequently, we asked if 1) visual feedback provided by the subject’s own EMG activity allow for subjects to adequately perform triangular ramp contractions in constrained conditions and 2) if the EMG visual feedback is provided in unconstrained conditions, are ΔF values in subjects similar to those in the constrained condition? We hypothesized that during voluntary isometric ramp contractions, ΔF will be similar regardless of the feedback source. We further hypothesized that standing postural adjustments using EMG feedback in unconstrained conditions will produce similar ΔF values to those calculated during the isometric ramps. We expected that although the mean values across conditions will be similar, the inter‐subject coefficient of variation of ΔF will be greater in the less constrained condition. Accordingly, surface EMG using high‐density array electrodes was collected from five subjects under three conditions: 1) seated in a dynamometer in the isometric mode with torque feedback, 2) in the isometric dynamometer with filtered EMG feedback, and 3) during postural adjustments while standing freely with EMG feedback. In agreement with our hypothesis, we found that ΔF values across all three conditions were similar. In the constrained conditions with either torque or EMG feedback ΔF was 3.10 ± 0.70 imp/s and 3.40 ± 0.75 imp/s, respectively; during the unconstrained case with EMG feedback, ΔF was 3.08 ± 0.73 imp/s (all n = 15, mean ± SE). Contrary to our expectations, the coefficient of variation was not greater in the unconstrained standing condition. These results demonstrate that real‐time EMG feedback is sufficiently similar to torque feedback during both isometric and near‐isometric, unconstrained contractions, suggesting that detailed investigations of motor unit activity may be expanded to more functional movements and used relatively easily in more clinical settings.

Cerebellar Transcranial Magnetic Stimulation Disrupts Vestibular Reflexes in Standing Balance

Despite its seemingly effortless execution, standing balance is a complex task maintained by the integration of sensory feedback from visual, somatosensory (muscle, skin, joint receptors), and vestibular (inner ear) systems. The vestibular system provides feedback about head acceleration and can be manipulated experimentally by passing an electrical current percutaneously through the mastoid processes. The cerebellum plays an important role in standing balance by integrating sensory feedback to refine activity in postural muscles. A recent study has shown that experimentally depressing cerebellar activity with repetitive transcranial magnetic stimulation can influence postural sway and muscle reflex responses following electrical vestibular stimulation. The aim of this study was to investigate the impact of acute cerebellar stimulation on vestibular muscle reflex responses in different head positions during standing balance. We applied a novel combination of stochastic electrical vestibular stimulation (SVS, ±2.5 mA, 0–20 Hz) and single‐pulse cerebellum transcranial magnetic stimulation (TMS, 60% maximum stimulator output) on fifteen healthy adults (6 males, 9 females; 21–32 years old) in two head positions: head forward and head right. Muscle reflexes were recorded bilaterally with surface electromyography (EMG) from lower leg (soleus and medial gastrocnemius) and neck (sternocleidomastoid) muscles. Time‐based cumulant density and frequency‐based coherence analyses were used to evaluate the relationship between the SVS and evoked EMG responses one second before (Pre) and one second after (Post) cerebellar TMS. 50 TMS pulses were delivered per head position. Preliminary analysis performed on left medial gastrocnemius (LMG) head right data indicated a significant reduction in the short latency (SL, P = 0.0377) and medium latency (ML, P &lt; 0.0001) reflexes following cerebellar TMS (Fig. 1). In addition, a significant drop in the coherence between the SVS and LMG Pre to Post was found using a difference of coherence test. These findings support the cerebellum to be an important center for the integration of vestibular feedback for the control of standing balance.Support or Funding InformationMount Royal University Faculty of Science and TechnologyFigure 1

Visual field motion during a body pull affects compensatory standing and stepping responses.

It is unclear whether the visual input that accompanies a perturbation of a standing person can affect whether a recovery step is taken. Visual motion speeds were manipulated during unexpected forward and backward shoulder pulls. Visual motion that appeared slower than actual body motion reduced the initial in-place resistance to the perturbation. As a result of the modulation of the in-place response, less pull force was needed to trigger a step when visual velocity appeared slower than normal. The visuomotor postural response occurred earlier and was larger when the full-field visual input was paired with a mechanical perturbation. The present study aimed to determine how visual motion evoked by an upper body perturbation during standing affects compensatory postural responses. This was investigated by rotating the visual field forwards or backwards about the ankle, time-locked to a forwards or backwards shoulder pull. Kinematic, kinetic and electromyographic responses were recorded to a range of pull forces over 160 trials in 12healthy adults (mean±SD=31±5.8years). Stepping threshold forces and in-place postural responses were compared between conditions. When the visual field moved in the same direction as the pull, so that the apparent velocity of the body was reduced (SLOW condition), the pull-force required to induce a step was less than when the visual field either rotated in the opposite direction (FAST) or was unaltered (NATURAL). For in-place responses, the body was displaced further in the direction of the pull in the SLOW condition. This was the result of a reduction in the resistive force from lower leg muscles 130ms after the visual motion onset. In trials with no pull, the visual motion induced postural responses that were later (290ms) and had smaller amplitudes compared to when visual motion is paired with an unexpected perturbation of the body. The results suggest that the apparent speed of the visual environment during a perturbation does influence whether a compensatory step is taken, not via a direct effect on the decision to step but by modulating the initial in-place response.

Effect of the use of passive body trunk exercise equipment on oxygen consumption and self-efficacy for carrying out exercise in patients with type2 diabetes.

Aims/IntroductionConsidering the difficulty in inculcating the habit of exercise among patients with type 2 diabetes, devising an easily maintained means of exercise is preferable. Passive body trunk exercise equipment (PBTE) developed for home use might solve several problems related to exercise therapy, both for patients and clinical staff involved in diabetes treatment; however, its efficacy as a therapeutic exercise device for patients with diabetes has not been ascertained. The purpose of this study was to measure the exercise intensity and self‐efficacy of PBTE, and to determine whether PBTE is a useful tool for exercise therapy.Materials and MethodsThe participants were 20 patients with type 2 diabetes, and the duration of exercise using the PBTE was set to 10 min. Oxygen consumption during exercise was measured, and self‐efficacy for continuing to exercise using the PBTE and for walking was evaluated after completion of the study.ResultsThe average exercise intensity using the PBTE was 1.7 metabolic equivalents, whereas the maximum exercise intensity was an average of 2.0 metabolic equivalents; the reported self‐efficacy for continuing to exercise using the PBTE was significantly higher than for walking.ConclusionsExercise intensity using the PBTE is similar to low‐intensity walking, and thus, it might be a useful therapeutic exercise device for patients with type 2 diabetes. Furthermore, it could be an effective exercise device for diabetes patients who do not have regular exercise habits, especially with reduced motor function or lower leg muscle strength.

The Effect of Ankle Foot Orthosis' Design and Degree of Dorsiflexion on Achilles Tendon Biomechanics-Tendon Displacement, Lower Leg Muscle Activation, and Plantar Pressure During Walking.

Background: Following an Achilles tendon rupture, ankle foot orthoses (AFO) of different designs are used to protect the healing tendon. They are generally designed to protect against re-rupture by preventing undesired dorsiflexion and to prevent elongation by achieving plantarflexion in the ankle. There is limited knowledge of the biomechanical effects of different AFO designs and ankle angles on the tendon and lower leg muscles.Hypothesis: The hypothesis was that non-uniform displacement in the Achilles tendon, lower leg muscle activity, and plantar pressure distribution would be affected differently in different designs of AFO and by varying the degree of dorsiflexion limitation.Study Design: Controlled laboratory study.Methods: Ultrasound of the Achilles tendon, EMG of the lower leg muscles and plantar pressure distribution were recorded in 16 healthy subjects during walking on a treadmill unbraced and wearing three designs of AFO. Ultrasound speckle tracking was used to estimate motion within the tendon. The tested AFO designs were a rigid AFO and a dorsal brace used together with wedges and an AFO with an adjustable ankle angle restricting dorsiflexion to various degrees.Results: There were no significant differences in non-uniform tendon displacement or muscle activity between the different designs of AFO. For the rigid AFO and the adjustable AFO there was a significant reduction in non-uniform displacement within the tendon and soleus muscle activity as restriction in dorsiflexion increased.Conclusion: The degree of dorsiflexion allowed within an AFO had greater effects on Achilles tendon displacement patterns and muscle activity in the calf than differences in AFO design. AFO settings that allowed ankle dorsiflexion to neutral resulted in displacement patterns in the Achilles tendon and muscle activity in the lower leg which were close to those observed during unbraced walking.

Peripheral motor nerve conduction abnormality, muscle strength, and muscle wasting in patients with acute stroke: A pilot study

IntroductionStroke-related muscle wasting are important therapeutic targets to reduce disability in patients with stroke. Peripheral nerve conduction impairment is one reported factor that causes muscle wasting in these patients, but muscle strength, muscle wasting, and peripheral nerve conduction abnormality have not been examined in patients with acute stroke. We therefore investigated changes in lower-leg motor nerve conduction, muscle strength, and muscle wasting in patients with acute stroke. MethodsPatients with acute stroke were recruited. Their motor conduction velocity (MCV) and compound motor action potential (CMAP) amplitude in both sides of the common peroneal nerve, and lower paretic leg muscle strength by the Motricity Index (MI) and quadriceps muscle thickness (QMT) on both sides were measured at the time of admission and again 2 weeks later. ResultsEighteen patients with acute stroke (median [interquartile range], age = 68 [14] years; female = 4 [22%]) were enrolled. The MCV and CMAP amplitude were not significantly different between limbs. The QMT was significantly reduced in paretic (P = 0.014) and non-paretic (P = 0.003) limbs, but the lower paretic leg MI was increased (P = 0.0.001). There was a significant correlation between % differences in CMAP amplitude and % differences in QMT in the paretic limb (R = 0.604, P = 0.008), but not in the non-paretic limb (R = 0.225, P = 0.369). ConclusionsLower-leg muscle wasting was associated with the change in CMAP amplitude in paretic limbs, but not in non-paretic limbs, in patients with acute stroke.

Evaluation of Lower Leg Muscle Activities During Human Walking Assisted by an Ankle Exoskeleton

Wearable robots like ankle exoskeletons have demonstrated the capability to enhance human mobility and to reduce biological efforts of human locomotion. The type of assistance provided by ankle exoskeletons could influence the lower leg muscle activities during human walking. This article aimed to systematically evaluate the lower leg muscle activities under different ankle exoskeleton assistance conditions. We measured multiple electromyography-based metrics of five lower leg muscles, while the participants walked with an ankle exoskeleton on a treadmill. Nine assistance conditions, which combined three peak times (46%, 49%, and 52% of stride time) and three peak torque levels (0.3, 0.5, and 0.7 N $\cdot$ m $\cdot$ kg $^{-1}$ ), are applied to assist plantarflexion during ankle push-off. Nine healthy subjects participated in the experiments. Of all investigated muscles, the activity level of l.SOL is influenced the most when exoskeleton assistance is applied. The root mean square of l.SOL activity reduces by 33.6 $\pm$ 14.0% under one assistance condition compared to walking without the exoskeleton. Our results can be used to guide studies on mechanical and control designs to improve neuromuscular interactions between exoskeletons and wearers.

Semi-automated volumetry of MRI serves as a biomarker in neuromuscular patients.

Muscle MRI is of increasing importance for neuromuscular patients to detect changes in muscle volume, fat-infiltration, and edema. We developed a method for semi-automated segmentation of muscle MRI datasets. An active contour-evolution algorithm implemented within the ITK-SNAP software was used to segment T1-weighted MRI, and to quantify muscle volumes of neuromuscular patients (n = 65). Semi-automated compared with manual segmentation was shown to be accurate and time-efficient. Muscle volumes and ratios of thigh/lower leg volume were lower in myopathy patients than in controls (P < .0001; P < .05). We found a decrease of lower leg muscle volume in neuropathy patients compared with controls (P < .01), which correlated with clinical parameters. In myopathy patients, muscle volume showed a positive correlation with muscle strength (rleft = 0.79, pleft < .0001). Muscle volumes were independent of body mass index and age. Our method allows for exact and time-efficient quantification of muscle volumes with possible use as a biomarker in neuromuscular patients.

An exploratory study of relationship between lower-limb muscle mass and diabetic polyneuropathy in patients with type 2 diabetes.

This exploratory study compared the lower-limb muscle mass (thigh muscle mass [TMM] and lower-leg muscle mass [LLMM]) in type 2 diabetic patients with and without diabetic polyneuropathy (DPN). A total of 130 patients with type 2 diabetes, hospitalized for glycemic control, were enrolled in this cross-sectional study. TMM and LLMM were measured using the bioelectrical impedance method. The muscle mass value was normalized by the bodyweight, and the total muscle mass was calculated by combining the muscle mass on the left and right (%TMM and %LLMM). DPN was evaluated according to the Japanese criteria. Anthropometric parameters, blood pressure, laboratory data, exercise habits, medication, related index of diabetes, and diabetic complications were analyzed. Sixty patients, comprising of 32 males (47.8%) and 28 females (44.4%) with type 2 diabetes (46.2%), had DPN. The %TTM and %LLMM were significantly lower in type 2 diabetic patients with DPN than in those without DPN. Multiple regression analysis identified DPN, age, and hemoglobin A1c (HbA1c) as the determinants of %TMM, and DPN and HbA1c were identified as the determinants of %LLMM in type 2 diabetic patients. The %TMM and %LLMM were significantly decreased in type 2 diabetic patients with DPN. DPN was found to be the strongest determinant of %TMM and %LLMM. Preventing and improving DPN, through active physical therapy, may increase the muscle mass of the lower limbs.

Physiological changes during prolonged standing and walking considering age, gender and standing work experience

Occupational standing is associated with musculoskeletal and venous disorders. The aim was to investigate whether lower leg oedema and muscle fatigue development differ between standing and walking and whether age, gender and standing work habituation are factors to consider. Sixty participants (15 young females, 15 young males, 15 older males, and 15 young males habituated to standing work) were included and required to stand/walk for 4.5 hours in three periods with two seated breaks. Waterplethysmography/bioelectrical impedance, muscle twitch force and surface electromyography were used to assess lower leg swelling (LLS) and muscle fatigue as well as gastrocnemius muscle activity, respectively. While standing led to LLS and muscle fatigue, walking did not. Low-level medial gastrocnemius activity was not continuous during standing. No significant influence of age, gender and standing habituation was observed. Walking can be an effective prevention measure to counteract the detrimental effects of quasi-static standing.Practitioner summary: Prolonged standing leads to lower leg oedema and muscle fatigue while walking does not. The primary cause of fatigue may be in other muscles than the medial gastrocnemius. Walking may be an effective prevention measure for health risks of occupational standing when included intermittently.Abbreviation: BI: bioelectrical impedance; LLS: lower leg swelling; SEMG: surface electromyography; MTF: muscle twitch force; WP: waterplethysmography; Bsl: Baseline; L: Lunch; E: Evening; MTM: method times measurement; EA: electrical activity; IQR: interquartile range; p: percentile; M: mean; SE: standard error; Adj: adjusted

Diagnostic Value of Muscle [11C] PIB-PET in Inclusion Body Myositis.

Background: The accumulation of multiple-protein aggregates within muscle fibers is a pathological hallmark of sporadic inclusion body myositis (s-IBM) with the presence of inclusion bodies. Amyloid-beta is one of the accumulated proteins in s-IBM. The aim of this study was to elucidate the utility of Pittsburgh compound B-positron emission tomography (PIB-PET) for diagnosing s-IBM.Methods: Nine patients with s-IBM and four patients with idiopathic inflammatory myopathy (IIM) were included. Patients underwent PIB-PET of body muscles. Standardized uptake values (SUVs) were measured in 16 muscles. A comparison of SUVs was made between s-IBM and IIM groups. The correlation between PIB-PET and clinical parameters was analyzed.Results: The mean SUV of all muscles in s-IBM patients was higher than in IIM patients (0.32 vs. 0.25, respectively; p = 0.031). Subgroup analysis identified a clear difference in SUVs of the forearm and lower-leg muscle groups (p = 0.021 and p = 0.045, respectively). There was no correlation between SUVs and clinical parameters in s-IBM patients.Conclusions: Muscle PIB-PET may help to make a diagnosis of s-IBM.