Maximal Plantar Flexion Research Articles

Comparative and reliability studies of neuromechanical leg muscle performances of volleyball athletes in different divisions

This study compared neural profiles of the leg muscles of volleyball athletes playing in different divisions of Taiwan's national league to analyse the reliability and correlations between their profiles and biomechanical performances. Twenty-nine athletes including 12 and 17 from the first and second divisions of the league, respectively, were recruited. The outcome measures were compared between the divisions, including soleus H-reflex, first volitional (V) wave, normalised rate of electromyography (EMG) rise (RER) in the triceps surae muscles, and RER ratio for the tibialis anterior and soleus muscles, normalised root mean square (RMS) EMG in the triceps surae muscles, antagonist co-activation of the tibialis anterior muscle, rate of force development (RFD), and maximal plantar flexion torque and jump height. Compared to the results of the second division, the neural profiles of the first division showed greater normalised V waves, normalised RER in the lateral gastrocnemius, and normalised RMS EMG of the soleus and lateral gastrocnemius muscles with less antagonist co-activation of the tibialis anterior. First division volleyball athletes showed greater maximal torque, jump height, absolute RFD at 0-30, 0-100, and 0-200ms, and less in the normalised RFD at 0-200ms of plantar flexion when compared to the results of those in the second division. Neural profiles correlated to fast or maximal muscle strength or jump height. There are differences in the descending neural drive and activation strategies in leg muscles during contractions between volleyball athletes competing at different levels. These measures are reliable and correlate to biomechanical performances.

Combined Arthroscopic and Fluoroscopic Guidance in the Atraumatic Treatment of Posterior Ankle Impingement Syndrome

Posterior ankle impingement syndrome can result from chronic overuse or acute trauma. When coupled with the presence of an anatomic bony anomaly, the patient can present with significant pain with maximal plantarflexion. Treatment involves resection of the site of bony impingement (e.g., os trigonum or fractured Steida's process) and circumferential fibrosis and inflammation. The presented technique involves a stepwise approach incorporating focused arthroscopic release of the surrounding fibrosis and atraumatic fluoroscopic resection of the bony source of impingement. Thus, a minimal amount of trauma is incurred to the patient, and fragment resection is performed in an efficient manner.

Relação entre modificações cinemáticas da corrida e o tempo limite na vVO2máx

Exhaustive running at maximal oxygen uptake velocity (vVO2max) can alter running kinematic parameters and increase energy cost along the time. The aims of the present study were to compare characteristics of ankle and knee kinematics during running at vVO2max and to verify the relationship between changes in kinematic variables and time limit (Tlim). Eleven male volunteers, recreational players of team sports, performed an incremental running test until volitional exhaustion to determine vVO2max and a constant velocity test at vVO2max. Subjects were filmed continuously from the left sagittal plane at 210 Hz for further kinematic analysis. The maximal plantar flexion during swing (p<0.01) was the only variable that increased significantly from beginning to end of the run. Increase in ankle angle at contact was the only variable related to Tlim (r=0.64; p=0.035) and explained 34% of the performance in the test. These findings suggest that the individuals under study maintained a stable running style at vVO2max and that increase in plantar flexion explained the performance in this test when it was applied in non-runners.

Neurorehabilitation with versus without resistance training after botulinum toxin treatment in children with cerebral palsy: A randomized pilot study

To compare the effects of physical rehabilitation with (PRT) and without (CON) progressive resistance training following treatment of spastic plantarflexors with botulinum toxin type A (BoNT) in children with cerebral palsy (CP). Fourteen children with CP performed supervised PRT (n=7) or CON (n=7) two times per week for 12 weeks, following the BoNT-treatment. Outcome measurements were performed at baseline (pre BoNT), and 4 and 12 weeks post BoNT. They consisted of: ankle muscle function (maximal torque and submaximal torque steadiness of isometric ankle dorsi- and plantarflexion and associated ankle muscle [EMG] activity), gait function (3-dimensional gait analysis), balance function (sway analysis), gross motor function (GMFM-66), and spasticity (modified Ashworth). Submaximal torque control (torque steadiness) of isometric dorsiflexion improved similarly in the two groups, and the improvement was related to the reduction in antagonist (soleus) co-activity (P< 0.05). Maximal plantarflexion torque increased after PRT, whereas a reduction was seen after CON (P< 0.05). No changes in function were observed. Both types of physical rehabilitation in combination with BoNT-treatment improved antagonist (ankle dorsiflexion) torque-control to the same extent - which was related to the reduction in antagonist co-activity - but only rehabilitation with PRT increased maximal plantarflexion torque.

Four-dimensional ultrasound calf muscle imaging in patients with genetic types of distal myopathy

PurposeTo demonstrate the capabilities of 4D ultrasound calf muscle imaging in patients with genetic types of distal myopathies (DMs). MethodsThree patients with DM were studied: a 58-year-old man with Vocal Cord and Pharyngeal Weakness Distal Myopathy (VCPDM), a 36-year-old woman with Tibial Muscular Dystrophy (TMD) and a 27-year-old woman with Hereditary Inclusion Body Myopathy Type 2 (HIBM2). Their calf muscles were evaluated in rest and during maximal plantar flexion using 3D/4D ultrasound imaging. The results were compared to myosonograms of healthy controls. ResultsAll patients had myopathic syndrome due to advanced muscular dystrophy. In comparison to controls abnormal calf muscle architectonics, reduced muscle contractility and a combination of spot-like hypo- and hyperechoic areas were established on 4D ultrasound imaging. The changes were associated with the degree of muscle atrophy, fat and fibrous tissue infiltration. ConclusionsFour-dimensional myosonology gives additional information for muscle architectonics in patients with genetic types of DM. Further studies are needed to evaluate if the described findings are typical for specific genetic types of myopathy.

Imaging of muscle blood volume changes during exercise with Vascular Space Occupancy (VASO) MRI

Large, rapid changes in perfusion accompany exercise, mediated in part by a local vasodilatory response. Impaired vasodilation occurs in diabetes, obesity, and other conditions. VASO MRI was developed to measure blood volume changes in the brain by nulling the signal of blood; vasodilation thus causes a loss of MRI signal intensity. The purpose of this work was to implement VASO for skeletal muscle. Eighteen subjects participated in the optimization of this method. Subjects were placed supine in a Philips 3.0T scanner with their foot on a force transducer, a knee coil around the calf, and an occlusion cuff around the thigh. Anatomical and VASO images were acquired (Fig 1).Maximal plantarflexion contractions were performed for 1–20 seconds, six minutes apart. The cuff was inflated to 240 mm Hg for five minutes, occluding arterial flow; VASO response was monitored for up to fifteen minutes after cuff release. NIRS spectroscopy was also performed to relate observed VASO signal changes to blood oxygenation and volume changes. VASO signal follows a similar time course to NIRS post occlusion.The decrease in VASO signal following a series of three ten second maximal plantarflexion contractions, as shown in Fig 2, should be proportional to increased blood volume demonstrating the promise of this new imaging paradigm to study blood volume changes in exercising muscle. This work was supported by NIH/NIAMS R01 AR050101.

Computed Tomography of the Ankle in Full Plantar Flexion: A Reliable Method for Preoperative Planning of Arthroscopic Access to Osteochondral Defects of the Talus

The purpose of this study was to determine whether preoperative computed tomography (CT) of the ankle joint in full plantar flexion is a reliable and accurate tool to determine the anterior arthroscopic accessibility of talar osteochondral defects (OCDs). Twenty consecutive patients were prospectively studied. All patients had an OCD of the talar dome and had a preoperative CT scan of the affected ankle in maximum plantar flexion. Accessibility of the OCD was defined by the distance between the anterior border of the OCD and the anterior distal tibial rim. This distance was measured on sagittal CT reconstructions by 2 investigators. The reference standard was the distance between the same landmarks measured during anterior ankle arthroscopy by an orthopaedic surgeon blinded to the CT scans. Intraobserver and interobserver reliability of CT, as well as the correlation and agreement between CT and arthroscopy, were calculated. The measured distance between the anterior border of the OCD and the anterior distal tibial rim ranged from -3.1 to 9.1 mm on CT and from -3.0 to 8.5 mm on arthroscopy. The intraobserver and interobserver reliability of the measurements made on CT scans (intraclass correlation coefficients >0.99, P < .001), as well as the correlation between CT and arthroscopy, were excellent (r = 0.98, P < .001). Measurements on CT scans of the ankle in full plantar flexion are a reliable and accurate preoperative method to determine the in situ arthroscopic location of talar OCDs.

아킬레스 건염 환자의 보행 시 고관절, 슬관절 및 족관절 모멘트의 변화에 대한 연구

본 연구는 아킬레스 건염 환자들과 정상인들을 대상으로 보행 선형지표와 고관절, 슬관절, 그리고 족관절의 모멘트 변화를 조사하여 아킬레스 건염에 의한 보행의 역학적 변화를 구명하고 아킬레스 건염을 예방하기 위한 예측인자들을 찾고자 실시되었다. 연구의 대상자는 아킬레스 건염 환자 20명과 비슷한 신체조건을 가진 건강한 정상인 20명이며, 대상자가 맨발 상태에서 힘판의 중앙 부분을 밟고 지나가도록 13 m의 거리를 편안한 속도로 5회 왕복하도록 하였다. 또한 대상자가 보행하는 동안 3차원 동작분석 장비를 이용하여 고관절, 슬관절, 그리고 족관절 모멘트를 산출하였다. 수집된 자료들을 SPSS 12.0 소프트웨어를 사용하여 분석하였다. 연구의 결과 아킬레스 건염 환자들의 고관절은 입각기 초기에 신전 모멘트가 감소하였고, 중후반에는 굴곡 모멘트가 감소하였다. 또한 슬관절에서는 입각기 초기부터 지속적인 굴곡 모멘트의 감소가 나타났으며 후기에는 신전 모멘트의 감소를 보였다. 그리고 족관절은 입각기 중반에 저측굴곡 모멘트가 감소하였으며 말기에는 배측 굴곡 모멘트가 감소하였다. 정상인과 비교해 아킬레스 건염 환자들에게서 보행의 역학적인 변화가 두드러지게 나타났으며, 임상에서는 아킬레스 건염 환자의 보행에 대한 변화를 세밀하게 파악하여 치료적 접근을 시도해야 할 것으로 보인다. 그리고 앞으로의 연구에서는 아킬레스 건염 환자에게서 나타나는 역학적인 변화에 대한 조사가 더 이루어져야 할 것이다. This study was to investigate the change of gait temporal parameter and ankle joint moment between patients with achilles tendinitis and healthy people. Thus, the purpose of this study is to clarify biomechanical change of gait in patients with achilles tendinitis and to find risk factor for prevention of achilles tendinitis. We recruited 20 patients with an achilles tendinitis and 20 healthy people. While subjects shuttled 5 times on 13 m distance with comfortable pace, we examined gait function marker with three-dimensional gait analysis system. All subject outstepped center of forceplate during gait and calculated ankle joint moment using software. Obtained data was analyzed using SPSS 12.0 software. In results, we confirmed that patients with achilles tendinitis showed reduction of extension moment in early initial phase and reduction of flexion moment in mid-stance on hip joint. and reduction of flexion moment in early initial phase and reduction of extension moment in late phase on knee joint. And we identified that patients with achilles tendinitis showed reduction of dorsiflexion moment in early stance phase, maximal plantarflexion moment in mid stance phase, and dorsiflexion moment in late stance phase. Thus, there are biomechanical changes on gait in patients with achilles tendinitis compared to healthy people. And, in clinical settings, they should focus on changes of gait in patients with achilles tendinitis. Further study will be undertaken for the biomechanical changes of patietns with achilles tendinitis.

Aging-Related Cocontraction Effects During Ankle Strategy Balance Recovery Following Tether Release in Women

ABSTRACT Increased antagonistic muscle activation during balance recovery has been documented during proprioceptive reliant responses in older adults. The authors examined ankle muscle cocontraction levels in young and older adults during balance recovery from a tether-release-induced, vestibular-input-reliant perturbation. Nine healthy young adult and 9 older women without history of falls performed maximum isometric plantar flexion and dorsiflexion trials followed by balance recovery trials using the ankle strategy. Surface electromyography data normalized to isometric conditions were analyzed during the 100 ms prior to release, the 50 ms immediately after release, and the 100-ms epochs from 100–400 ms following release. No differences existed in gastrocnemius and soleus activity levels (p > .05), though antagonistic tibialis anterior activity was greater in the older adults during the 300–400 ms epoch (young: 23.5 ± 5.8%, older: 38.7 ± 9.4%; p = .001). Vestibular-dominated perturbations may increase antagonistic activity during the recovery phase in older adults, inhibiting efficient balance recovery during proprioceptive and vestibular reliant perturbations.

December 2011 Letters to the Editor-in-Chief

Letters to the Editor-in-Chief of JOSPT as follows: ‘Early Prognostic Factors in Patients With Whiplash’ and Author's Response ‘Staying Current in the Use of Ultrasound Imaging’ and Author's Response ‘Differentiating the Soleus From the Gastrocnemius With the Heel Raise Test’ and Author's Response J Orthop Sports Phys Ther 2011;41(12):983–987. doi:10.2519/jospt.2011.0202

Simulation of unilateral equinus using an adjustable orthosis in children

In order to increase understanding of the biomechanical consequences of equinus foot on gait, we developed an orthosis to induce an adjustable degree of unilateral equinus. The aim of this study was to evaluate its feasibility and consequences on 3D ankle kinematics and kinetics. 3D gait analysis was carried out in 10 healthy children without the orthosis, with the non-adjusted orthosis and with the orthosis adjusted to +10°, 0°, -10°, -20° of ankle dorsiflexion and maximum plantarflexion (MP). The amount of dorsiflexion at initial contact was close to the goniometric measurement. Significant kinematic and kinetic changes occurred at -10°, -20° and MP. The mean maximum equinus at initial contact -21.65° ± 4.17 and during stance -11.61° ± 4.82 were larger than those obtained with previous described devices. Our device was easy-to-use and induced an adjustable, well tolerated equinus. It provides a new way to simulate equinus and its biomechanical consequences on gait.

The jump shot – A biomechanical analysis focused on lateral ankle ligaments

Handball is one of the top four athletic games with highest injury risks. The jump shot is the most accomplished goal shot technique and the lower extremities are mostly injured. As a basis for ankle sprain simulation, the aim of this study was to extend the ankle region of an existing musculoskeletal full-body model through incorporation of three prominent lateral ankle ligaments: ligamentum fibulotalare anterius (LFTA), ligamentum fibulotalare posterius (LFTP), ligamentum fibulocalcaneare (LFC). The specific objective was to calculate and visualise ligament force scenarios during the jumping and landing phases of controlled jump shots. Recorded kinematic data of performed jump shots and the corresponding ground reaction forces were used to perform inverse dynamics. The calculated peak force of the LFTA (107N) was found at maximum plantarflexion and of the LFTP (150N) at maximum dorsiflexion. The peak force of the LFC (190N) was observed at maximum dorsiflexion combined with maximum eversion. Within the performed jump shots, the LFTA showed a peak force (59N to 69N) during maximum plantarflexion in the final moment of the lift off. During landing, the force developed by the LFTA reached its peak value (61N to 70N) at the first contact with the floor. After that, the LFTP developed a peak force (70N to 118N). This model allows the calculation of forces in lateral ankle ligaments. The information obtained in this study can serve as a basis for future research on ankle sprain and ankle sprain simulation.

Evaluating Foot Kinematics Using Magnetic Resonance Imaging: From Maximum Plantar Flexion, Inversion, and Internal Rotation to Maximum Dorsiflexion, Eversion, and External Rotation

The foot consists of many small bones with complicated joints that guide and limit motion. A variety of invasive and noninvasive means [mechanical, X-ray stereophotogrammetry, electromagnetic sensors, retro-reflective motion analysis, computer tomography (CT), and magnetic resonance imaging (MRI)] have been used to quantify foot bone motion. In the current study we used a foot plate with an electromagnetic sensor to determine an individual subject's foot end range of motion (ROM) from maximum plantar flexion, internal rotation, and inversion to maximum plantar flexion, inversion, and internal rotation to maximum dorsiflexion, eversion, and external rotation. We then used a custom built MRI-compatible device to hold each subject's foot during scanning in eight unique positions determined from the end ROM data. The scan data were processed using software that allowed the bones to be segmented with the foot in the neutral position and the bones in the other seven positions to be registered to their base positions with minimal user intervention. Bone to bone motion was quantified using finite helical axes (FHA). FHA for the talocrural, talocalcaneal, and talonavicular joints compared well to published studies, which used a variety of technologies and input motions. This study describes a method for quantifying foot bone motion from maximum plantar flexion, inversion, and internal rotation to maximum dorsiflexion, eversion, and external rotation with relatively little user processing time.

Multi-Rigid Image Segmentation and Registration for the Analysis of Joint Motion From Three-Dimensional Magnetic Resonance Imaging

We report an image segmentation and registration method for studying joint morphology and kinematics from in vivo magnetic resonance imaging (MRI) scans and its application to the analysis of foot and ankle joint motion. Using an MRI-compatible positioning device, a foot was scanned in a single neutral and seven other positions ranging from maximum plantar flexion, inversion, and internal rotation to maximum dorsiflexion, eversion, and external rotation. A segmentation method combining graph cuts and level set was developed. In the subsequent registration step, a separate rigid body transformation for each bone was obtained by registering the neutral position dataset to each of the other ones, which produced an accurate description of the motion between them. The segmentation algorithm allowed a user to interactively delineate 14 foot bones in the neutral position volume in less than 30 min total (user and computer processing unit [CPU]) time. Registration to the seven other positions took approximately 10 additional minutes of user time and 5.25 h of CPU time. For validation, our results were compared with those obtained from 3DViewnix, a semiautomatic segmentation program. We achieved excellent agreement, with volume overlap ratios greater than 88% for all bones excluding the intermediate cuneiform and the lesser metatarsals. For the registration of the neutral scan to the seven other positions, the average overlap ratio is 94.25%, while the minimum overlap ratio is 89.49% for the tibia between the neutral position and position 1, which might be due to different fields of view (FOV). To process a single foot in eight positions, our tool requires only minimal user interaction time (less than 30 min total), a level of improvement that has the potential to make joint motion analysis from MRI practical in research and clinical applications.

Effects of 12-week Tai Chi training on soleus H-reflex and muscle strength in older adults: a pilot study

The purpose of this study was to determine the effects of 12-week Tai Chi (TC) training on the soleus (SOL) H-reflex modulation and plantarflexion muscle strength in older adults. Twenty volunteers were assigned into training (N = 14; 72.2 ± 3.7 years of age) and control (N = 6; 74.2 ± 6.1 years of age) groups. The participants in the TC group practiced Yang style TC 1 h per session, 3 sessions per week, for 12 weeks, guided by a qualified TC instructor. The ratio of the maximal peak-to-peak amplitude of SOL H-reflex (H (max)) to M-wave (M (max)) was determined during bipedal standing under four sensory conditions: stable surface and eyes open (SO), stable surface and eyes closed (SC), unstable surface and eyes open (UO), and unstable surface and eyes closed (UC). The maximal isometric plantarflexion muscle strength was also assessed by using a dynamometer. The results showed that the SOL H (max)/M (max) ratio increased significantly after the 12 weeks of TC training under the SC (37.0%), UO (33.3%) and UC (36.0%) conditions (P < 0.05). The maximal plantarflexion strength also improved significantly after training (19.8%; P < 0.05). In contrast, the control group showed no significant changes in all measurements after the 12 weeks.

Evoked Spinal Reflexes and Force Development in Elite Athletes With Middle-Portion Achilles Tendinopathy

Controlled laboratory study. To compare the neuromuscular function of the triceps surae muscle bilaterally in elite athletes with unilateral chronic Achilles tendinopathy. Previous studies suggest that tendinopathies or chronic pain may lead to a spinal/supraspinal level modulation of the excitability or voluntary activation of ipsilateral motor units. However, this has not been studied in Achilles tendinopathy. Fourteen college athletes (mean ± SD age, 24.2 ± 1.7 years) who had unilateral chronic middle-portion tendinopathy in their Achilles tendons were recruited. Bilateral measurements of soleus reflex tests, including H-reflex and V wave, and rate of force development (RFD), as well as corresponding electromyography of the tibialis anterior and triceps surae muscles, were performed. Statistical within-subject and between-leg comparisons were made. In the leg with tendinopathy, the V wave of the soleus muscle was significantly increased (P<.001). The side with tendinopathy also had a reduced normalized RFD (0-30, 0-50, and 0-100 ms) in plantar flexion, and concomitant higher electromyography ratios between the tibialis anterior and soleus (0-30 and 0-50 milliseconds) during the early stage of explosive contractions (P<.05). No significant differences were found for H-reflex, maximal plantar flexion and dorsiflexion torque, and absolute RFD. Higher volitional supraspinal reflexes and lower maximal-strength independent force development occur in the triceps surae of elite athletes with unilateral middle-portion Achilles tendinopathy. These changes potentially indicate an acquired compensatory mechanism for maximal force production and deficits in explosive strength. The RFD is also suggested as a sensitive parameter to depict neuromuscular changes during treatment of chronic tendinopathies.

Position of the prosthesis components in total ankle replacement and the effect on motion at the replaced joint

In some cases of total ankle replacement, perfect alignment of the prosthetic components is not achieved. This study analyses the extent to which component positioning is critical for the final range of motion. Fourteen patients undergoing total ankle replacement were assessed preoperatively and postoperatively at seven and 13 months follow-up. X-ray pictures of the ankle were taken in static double leg stance, i.e. at neutral joint position, and in maximum plantarflexion and dorsiflexion. Measurements were obtained by a specially devised computer program based on anatomical reference points digitised on the radiograms. These allowed calculation of the position and orientation of the components in the sagittal and coronal planes, together with the joint range of motion. The mean range of motion was about 34 degrees at the first follow-up and maintained at the second. Tibial and talar components were more anterior than the mid-tibial shaft in 11 and nine patients, respectively. Mean inclination was about four degrees posterior for the tibial component and nearly one degree anterior for the talar component. A significantly larger range of motion was found in ankles both with the talar component located and inclined more anteriorly than the tibial. Correlation, though weak, was found between motion at the replaced ankle and possible residual subluxation and inclination of the components. However, a satisfactory range of motion was also achieved in those patients where recommended locations for the components could not be reached because of the size of the original joint deformity.

Similarities and Differences of the Soleus and Gastrocnemius H-reflexes during Varied Body Postures, Foot Positions, and Muscle Function: Multifactor Designs for Repeated Measures

BackgroundAlthough the soleus (Sol), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles differ in function, composition, and innervations, it is a common practice is to investigate them as single H-reflex recording. The purpose of this study was to compare H-reflex recordings between these three sections of the triceps surae muscle group of healthy participants while lying and standing during three different ankle positions.MethodsThe Sol, MG and LG muscles' H-reflexes were recorded from ten participants during prone lying and standing with the ankle in neutral, maximum dorsiflexion, and maximum plantarflexion positions. Four traces were averaged for each combination of conditions. Three-way ANOVAs (posture X ankle position X muscle) with planned comparisons were used for statistical comparisons.ResultsAlthough the H-reflex in the three muscle sections differed in latency and amplitude, its dependency on posture and ankle position was similar. The H-reflex amplitudes and maximum H-reflex to M-response (H/M) ratios were significantly 1) lower during standing compared to lying with the ankle in neutral, 2) greater during standing with the ankle in plantarflexion compared to neutral, and 3) less with the ankle in dorsiflexion compared to neutral during lying and standing for all muscles (p ≤ .05).ConclusionVarying demands are required for muscles activated during distinctly different postures and ankle movement tasks.

Isometric fatigue patterns in time and time–frequency domains of triceps surae muscle in different knee positions

The occurrence of fatigue in triceps surae (TS) muscles during sustained plantar flexion contraction is investigated by means of the RMS electromyogram (EMG) and the instantaneous median frequency (IMF) of the short time Fourier transform (STFT). Six male subjects realized a 40% maximal plantar flexion isometric voluntary contraction until fatigue in two knee positions. Electrodes were positioned on gastrocnemius medialis, gastrocnemius lateralis and soleus muscles. The torque (TO) and EMG signals were synchronized. The RMS and the median of the IMF values were obtained, respectively, for each 250 ms and 1 s windows of signal. Each signal was segmented into 10 epochs, from which the mean values of IMF, RMS and TO were obtained and submitted to linear regressions to determine parameter trends. Friedman test with the Dunn’s post hoc were used to test for differences among muscles activation for each knee position and among slopes of regression curves, as well as to observe changes in TS RMS values over time. The results indicate different activation strategies with the knee extended (KE) in contrast to knee flexed (KF). With the KE, the gastrocnemii showed typical fatigue behavior with significant ( p < 0.05) IMF reductions and RMS increases over time, while soleus showed concomitant RMS and IMF increases ( p < 0.05) suggesting an increased soleus contribution to the torque production. With KF, the gastrocnemii were under activated, increasing the role of soleus. Thus, time–frequency analysis represented an important tool for TS muscular fatigue evaluation, allowing differentiates the role of soleus muscle.

Medial gastrocnemius muscle volume and fascicle length in children aged 2 to 5 years with cerebral palsy

The aim of this article was to compare medial gastrocnemius muscle volume, physiological cross-sectional area (PCSA), muscle length, fascicle length, and pennation angle in children aged 2 to 5 years with spastic cerebral palsy (CP) and in typically developing children. method: Fifteen children with spastic CP (11 males, four females; mean age 45 mo [SD 15 mo]; five with hemiplega; 10 with diplega; 10 classified at Gross Motor Function Classification System (GMFCS) level I, five at GMFCS level II) and 20 typically developing children (11 males, nine females; mean age 48 mo [SD 14 mo]) participated in the study. Individuals with spastic CP were included if they had a minimum range of motion of 0° ankle dorsiflexion with the knee extended and were excluded if they had had previous botulinum toxin treatment to the calf muscles or previous calf surgery. Typically developing children were included if they were able to walk independently and were excluded if there was a history of previous lower leg injury or other developmental disorder affecting the lower limb. Freehand two-dimensional and three-dimensional ultrasound was used to assess muscle properties of the relaxed medial gastrocnemius muscle at three ankle joint angles: maximum dorsiflexion, neutral and maximum plantarflexion. PCSA was calculated as a function of muscle volume and muscle fascicle length and pennation angle was recorded at the neutral ankle joint angle. Medial gastrocnemius muscle volume was 22% lower in the group with spastic CP than in the typically developing group, which in the absence of significant group differences in neutral fascicle length gave rise to an equivalent reduction in PCSA for the group with spastic CP. Significant positive correlations were found between muscle volume and age (r=0.63-0.65) and between muscle length and age (r=0.72-0.81) in both groups. Maximum ankle dorsiflexion angle was also reduced in the group with spastic CP (8°) compared with the typically developing group (26°). The observed reduction in muscle PCSA in the group with spastic CP would be expected to contribute to the clinically observed muscle weakness in spastic CP and suggests the need for early intervention in order to minimize loss of muscle PCSA in spastic CP.