Lower Extremity Muscle Activity Research Articles

A Comparison of the Transient Effect of Complex and Core Stability Exercises on Static Balance Ability and Muscle Activation during Static Standing in Healthy Male Adults.

Balance ability is a necessary exercise factor required for the activities of daily living. This study investigated the effects of short-term complex exercise (CE) and core stability exercise (CSE) on balance ability and trunk and lower-extremity muscle activation on healthy male adults. Twenty-nine healthy male adults were included. All performed CE and CSE for 1 min each; the exercise order was randomized. The primary and secondary outcomes were balance ability and muscle activation, respectively. In balance ability, CE showed a significant difference in all variables in both eye-opened and eye-closed conditions compared with the baseline (p < 0.05). In comparisons among exercises, the path length and average velocity variables showed a significant decrease in the eye-opened condition, and the path length variable showed a significant decrease in the eye-closed condition (p < 0.05). In muscle activation, CE showed a significant increase in the gluteus medius (Gmed) and decrease in the rectus femoris (RF), tibialis anterior (TA), and RF/biceps femoris (BF) ratio in the eye-opened condition compared to the baseline and a significant decrease in RF and RF/BF ratio in the eye-closed condition (p < 0.05). Both CE and CSE improved the static balance ability. Furthermore, muscle activation significantly increases in Gmed and decreases in the RF, TA, and RF/BF ratio. Therefore, we recommend including CE in an exercise program that has the purpose of improving static balance ability.

The effect of road-bike damping on neuromuscular short-term performance

ABSTRACT The aim of this study was to understand if and how surface-induced vibrations and road bike damping affect short-term neuromuscular performance in cycling. Thirty cyclists (mass 75.9 ± 8.9 kg, height 1.82 ± 0.05 m, Vo2max 63.0 ± 6.8 ml/min/kg) performed steady-state and maximum effort tests with and without vibration exposure (front dropout: 44 Hz, 4.1 mm; rear dropout: 38 Hz, 3.5 mm) on a damped and a nondamped bike. Transmitted accelerations to the musculoskeletal system, activation of lower extremity muscles (gast. med., soleus, vast. med., rec. fem.) and upper body muscles (erec. spinae, deltoideus, tric. brachii), oxygen uptake, heart rate and crank power output were measured. The main findings indicate a transmission of vibration to the whole body, but since no major propulsive muscles increase their activation with vibration, the systemic energy demand increases only marginally with vibration. Damping reduces vibrations at the upper body, which indicates an increase in comfort, but has no effect on the vibration transfer to the lower extremities. Therefore, road bike damping does not affect neuromuscular response of the propulsive muscle groups and energy demand. Consequently, short-term power output does not increase with damping.

Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability.

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and perturbation. CDP is based on the inverted pendulum model that traces the interrelationship between the center of pressure and the center of gravity. CDP can be used to analyze the proportions of vision, proprioception, and vestibular sensation to maintain postural stability. The following characters define chronic ankle instability (CAI): persistent ankle pain, swelling, the feeling of "giving way," and self-reported disability. Postural stability and fibular muscle activation level in individuals with CAI decreased due to lateral ankle ligament complex injuries. Few studies have used CDP to explore the postural stability of individuals with CAI. Studies that investigate postural stability and related muscle activation by using synchronized CDP with surface electromyography are lacking. This CDP protocol includes a sensory organization test (SOT), a motor control test (MCT), and an adaption test (ADT), as well as tests that measure unilateral stance (US) and limit of stability (LOS). The surface electromyography system is synchronized with CDP to collect data on lower limb muscle activation during measurement. This protocol presents a novel approach for evaluating the coordination of the visual, somatosensory, and vestibular systems and related muscle activation to maintain postural stability. Moreover, it provides new insights into the neuromuscular control of individuals with CAI when coping with real complex environments.

Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability

Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability

Ankle kinematics, center of pressure progression, and lower extremity muscle activity during a side-cutting task in participants with and without chronic ankle instability

This study assessed ankle kinematics, surface electromyography, and center-of-pressure (COP) progression relative to the medial border of the foot during a side-cutting task in individuals with and without chronic ankle instability (CAI). Thirty participants (CAI = 15; Controls = 15) performed a side-cutting task on a force platform while 3-dimentional ankle kinematics, COP position, and surface electromyography from the tibialis anterior, medial gastrocnemius, fibularis longus, fibularis brevis, vastus medialis, and semitendinosus were recorded on the testing leg. Ankle kinematics, root-mean-square muscle activity and COP position relative to the medial boarder of the foot were compared between CAI and healthy controls (p < 0.05). Significantly greater ankle internal rotation from 35–54% of the stance phase (p = 0.032) was found for the CAI group compared to controls. Furthermore, significantly greater tibialis anterior muscle activity from 86–94% of the stance phase (p = 0.022) and a more medial COP position from 81–100% (p < 0.05) and of the stance phase was also observed in the CAI group. Less lateral COP progression and increased tibialis anterior activation in the CAI group could reflect a protective movement strategy during anticipated side-cutting to avoid recurrent injury. However, greater ankle internal rotation during mid-stance highlights a potential ‘giving way’ mechanism in individuals with CAI.

Ankle bracing’s effects during a modified agility task: analysis of sEMG, impulse, and time to complete using a crossover, repeated measures design

ABSTRACT This study explored the effects of no braces, softshell (AE), and semi-rigid (T1) ankle braces on time to complete a modified agility task, as well as lower extremity muscle activity and impulse during the change of direction component of the task. Thirty-nine healthy, active individuals completed a modified agility task under the three brace conditions. Time to complete the modified agility task, along with mean surface electromyographic activity (sEMG) and impulse during the deceleration and propulsive phases of the task were measured. There were no significant differences across conditions with respect to sEMG or impulse measures during the deceleration or propulsive phases. There was a significant change in time to complete the modified agility task, F(2,76) = 17.242, p< 0.001, ηp2 = 0.312. Post-hoc analysis revealed a significant increase in time to complete the modified agility task when wearing the AE (0.16 (95% CI, 0.062 to 0.265) seconds, p< 0.001) and T1 (0.20 (95% CI, 0.113 to 0.286) seconds, p< 0.001) ankle braces compared to no braces. It appears that performance on a modified agility task may be diminished when wearing ankle braces, although sEMG activity and impulse are unaffected.

Lower extremity kinetics and muscle activation during gait are significantly different during and after pregnancy compared to nulliparous females

BackgroundLow back, pelvic, and lower extremity pain are common during and after pregnancy. Understanding differences in mechanics between pregnant and non-pregnant females is a first step toward identifying potential pathological mechanisms. The primary purpose of this study was to compare joint kinetics and muscle activation during gait between females during and after pregnancy to nulliparous females. MethodsTwenty pregnant females completed testing on three occasions (second trimester, third trimester, and post-partum), while 20 matched, nulliparous controls were tested once. Motion capture, force data, and surface electromyography were averaged across seven trials during gait. Lower extremity kinematics, lower extremity moments and work normalized to pre-pregnancy body mass, work distribution, and peak and average muscle activation amplitude were calculated. Independent t-tests were conducted between pregnant and nulliparous females at each time point. ResultsCompared to controls, peak hip abductor moments were greater throughout and after pregnancy. Females in second trimester also demonstrated greater sagittal negative ankle work and greater percent contribution of the ankle and smaller percent contribution of the hip to negative work. Compared to controls, during third trimester there were greater knee abductor, ankle plantarflexor, and ankle dorsiflexor moments and greater work at the ankle and total work. Several moment and work variables continued to be elevated post-partum compared to controls. Gluteus maximus muscle activation amplitude was smaller in second trimester and post-partum compared to controls. SignificanceWhile overall joint demands were greater during and after pregnancy, there was a smaller relative sagittal utilization of the hip early in pregnancy and smaller gluteus maximus muscle amplitude during second trimester and post-partum. Because the gluteus maximus muscle contributes to force closure and dynamic stability of the low back and pelvis, relative gluteus maximus disuse, concurrent with increased joint loads, could potentially contribute to pain during and after pregnancy.

Muscle Activity during Postural Stability Tasks: Role of Military Footwear and Load Carriage

Decrements to postural control manifest as an increase in muscle activity, indicating continuous attempts to maintain body equilibrium and postural stability. Extrinsic factors such as footwear, and intrinsic factors such as muscle fatigue, can affect postural stability. The purpose of this study was to analyze the impact of two types of military footwear and a military-type load-carrying task on lower extremity muscle activity during various postural stability tasks. Sixteen males’ (age: 26.63 ± 3.93 years; mass: 87 ± 12.4 kg; height: 178.04 ± 6.2 cm) muscle activity from knee flexors, extensors, ankle dorsiflexors, and plantar flexors were measured using electromyography in standard (STD) and minimalist (MIN) military footwear, before (PRE) and after (POST) a simulated workload during sensory organization and motor control tests on the Neurocom EquitestTM. Mean muscle activity was analyzed using 2 (footwear) × 2 (time) repeated measures ANOVA with an alpha level of 0.05. Results revealed a requirement of significantly greater muscle activity in POST and STD. MIN demonstrated lesser balance decrements POST workload, which could be attributed to its design characteristics. Results will help in suggesting footwear design characteristics to minimize muscular exertion while eliciting better postural control, and to prevent postural instability due to overexertion in military personnel.

Task-specificity Of Corticospinal Excitability: The Influence Of Contractile Properties

Transcranial magnetic stimulation (TMS) is increasingly applied to investigate neurophysiological function during exercise interventions. Although often assessed in testing modalities that are different than the intervention, neurophysiological function may be task-specific. PURPOSE: To compare neurophysiological function between an isometric squat (SQT) and knee extension (KE). METHODS: Twenty-two young adults (2 women, 20 right-footed, age: 25±5yrs, BMI: 25.9±3.1, VO2: 46.2±8.8 ml·kg-1·min-1) performed isometric SQT (N=7) or KE (N=15), with hip-, knee- and ankle-joints fixed at 90° as part of a larger study, exposing participants to operational stress for a 5-day period. Lower extremity strength and muscle activity (RMS) were recorded during maximum voluntary contractions (MVCs), using a linear force transducer and electromyography (EMG) sensors placed over the vastus lateralis, respectively. Motor-evoked-potential (MEP)-based stimulus response curves (SRC) were derived using TMS and a double cone coil placed over the dominant motor cortex leg hotspot during intermittent isometric contractions at 15% MVC. Forty stimuli were applied for two rounds of SRC, with stimulator output (SO) ranging from 5-100% in 5% increments and random order. Since neurophysiological function did not differ across days, grand averaged responses were compared using multivariate ANOVAs or Mann-Whitney U. RESULTS: Greater force and muscle activity were evident for KE compared to SQT (Force: 1303.9±407.0 vs. 812.8±189.5N, p=0.01; EMGRMS: 0.04±0.003 vs. 0.06±0.01, p=0.03). KE corticospinal excitability was twice as high compared to SQT (1.4±0.7 vs. 0.7±0.4mV, p=0.04), but similar when normalized to muscle activity (KE: 25.3±13.9 vs. SQT: 17.4±10.7 mV·EMGRMS-1, p=0.21). No difference was evident in SRCV50 and SRCSLOPE (54±9 vs. 62±14%, p=0.12 and 5.0±1.9 vs. 4.2±1.1, p=0.35). CONCLUSION: Contractile and corticospinal excitability appear to be task-specific, discouraging the assessment of neurophysiological function in modalities that are different from the intervention. Contractile function further seems to influence corticospinal excitability, which may reflect the underlying differences in neuromechanics between the two movements. Supported by the Department of Defense W81XWH-16-PHTBIRP-CR3A.

한발서기 동안 동측 반대측 방향의 , 상지부하가 다리근육의 근활성도에 미치는 영향

한발서기 동안 동측 반대측 방향의 , 상지부하가 다리근육의 근활성도에 미치는 영향

Military-Type Workload and Footwear Alter Lower Extremity Muscle Activity During Unilateral Static Balance: Implications for Tactical Athletic Footwear Design.

Maintaining upright standing balance is critical for military personal. The impact of military footwear and occupation-related fatigue on muscle activity during balance performance has been previously documented. However, the current literature has not provided a muscle activation profile of the lower extremity during challenging conditions such as unilateral balance trials. Twenty-two recreationally active male participants (age: 22.2 ± 2.7 years; height: 177 ± 6.8 cm; mass: 79.8 ± 9.7 kg) donned two styles of military footwear (minimalist and standard) and performed a military style workload. Unilateral static balance was accessed before (PRE) and after (POST) the workload as surface electromyography was recorded on the right lower extremity. This study found that the minimalist footwear increased muscle activation prior to the workload compared to the standard footwear (co-contraction index mean difference: 0.149), whereas the standard footwear increased muscle activity after the workload (co-contraction index mean difference: 0.097). These findings suggest that footwear design characteristics affect lower extremity muscle activity differently depending on the workload condition. These findings intend to aid in the design of military footwear to maximize balance performance in a military population.

Gender Differences in the Activation and Co-activation of Lower Extremity Muscles During the Stair-to-Ground Descent Transition

The movement pattern during stair descent differs by gender, and this difference may be associated with gender differences in muscle strength or activation. The purpose of this study was to determine whether a gender difference in muscle activation exists by comparing the muscle activation amplitude and co-activation of lower extremity muscles during the stair-to-ground descent transition. Fifteen men and thirteen women descended stairs and the muscle activation was measured. Women showed a significantly lower peak normalized electromyography amplitude of the vastus lateralis (women: 171.7% peak EMG activation amplitude for level walking (PEALW), men: 297.0%PEALW, p < 0.05). Additionally, women showed significantly elevated co-activation of the vastus lateralis and biceps femoris compared to men (p < 0.05). The lower amplitude of the vastus lateralis in women indicates lower recruitment of knee extensor. In conclusion, the significantly higher co-activation of the vastus lateralis and biceps femoris in women may be a women’s stair descent strategy to safely descend stairs by increasing knee joint stability and stiffness through less recruitment of knee extensor muscle during stair-to-ground descent transition.

Effect of changing water depth on muscle activity and motion kinematics during sit-to-stand motion

BackgroundSit-to-stand (STS) movement is a fundamental activity in daily life. Studies have examined the effect of water depth during aquatic exercise; however, no investigation has examined the effect of water depth on STS movements. Research questionThis study examined whether changing water depth affected muscle activity and motion kinematics during the STS movement. MethodsEleven participants performed the STS movement on the ground (land) and at different water depths (1.0-m [deep] and 0.6-m [shallow]) at a self-determined pace. Lower extremity and trunk muscle activity, lower extremity joint angle, and trunk segment inclination angle were measured. Mean muscle activity during STS movement, initial and final postures, and range of motion of each angle was evaluated. Correlations of a normalised time-series pattern of electromyography and motion kinematics measures between land and shallow (land-shallow) and between land and deep (land-deep) were investigated. ResultsThe rectus femoris was more active in shallow than in deep water STS movement but less than that in land STS. Other muscles showed no significant differences between shallow and land STS movement. Correlation of the time series pattern in the tibialis anterior, rectus femoris, and erector spinae muscles was higher in the land-shallow than the land-deep STS. The trunk showed more forward inclination in the shallow STS than the land but less than the deep. Correlation of the time series pattern in the hip joint and trunk inclination angles was higher in the land-shallow STS than in the land-deep STS. SignificanceSTS exercise in the shallow water depth reduced muscle load for the knee extensor but not for other muscles. The muscle activity pattern showed a higher correlation between the land STS and shallow water than deep. Sitting posture becomes upright when the water depth decreases, but a similar motion pattern could be attained regardless of water depth.

Change in Lower Extremity Muscle Activity with Visual and Noises During Walking

Background/Objectives: In this study, four conditions of visual and noises were examined to determine the inferior limb muscle activity after walking for 10 minutes on a treadmill.Method/Statistical Analysis: Nine males and nine females, who agreed to participate in the study, were recruited. Participants were asked to walk on a treadmill for 10 minutes on each of the four conditions (a), (b), (c), and (d) depending on visual acuity and noise. Electromyograph was used to measure and compare muscle activity.Findings: There was no significant difference in biceps femoris muscle(p>.05). The comparison of the tibialis anterior muscle resulted in a significant difference between the conditions a-c, a-d, b-c and b-d (p c>b>a, followed by de-conditioned vision and dB was the highest when it was higher 90. The comparison of the lateral gastrocnemius muscle resulted in a significant difference between the a-c, b-c and b-d conditions (p c>b>a, followed by de-conditioned vision and dB was the highest when it was > 90. The comparison of the medial gastrocnemius muscle showed that not all four conditions differed significantly (p>.05).Improvements/Applications: There was significant difference in muscle activity between TA, LGM than when vision was blocked, that the muscle activity has improved when walking over 90 dB than 60 dB.

High day-to-day repeatability of lower extremity muscle activation patterns and joint biomechanics of dual-belt treadmill gait: A reliability study in healthy young adults

PurposeThe reliability of lower extremity muscle activation patterns has not been clearly studied in a dual-belt instrumented treadmill environment. The primary study objective was to quantify the day-to-day reliability of quadriceps, hamstrings, gastrocnemius and gluteus medius activation patterns in healthy young adult gait. Secondarily, the reliability of spatiotemporal, and knee/hip motion and moment-based gait outcomes was assessed.Scope: 20 young adults were recruited and tested on two separate days. Using standardized procedures, participants were prepared for surface electromyography and lower extremity motion capture. All individuals walked on a dual-belt instrumented treadmill while muscle activation, segment motions and ground reaction forces were recorded. Sagittal plane motion and net external sagittal and frontal plane moments were calculated. Discrete biomechanical and muscle activation measures were calculated, and non-negative matrix factorization extracted amplitude and temporal muscle activation features. Intraclass Correlation Coefficients, Standard Error of Measurement and Minimum Detectable Change were calculated. ConclusionsHigh to excellent Intraclass correlation coefficients were found between visits for most primary and secondary outcomes. The absolute and relative reliability, including Minimum Detectable Change values, provided in this study support the use of dual-belt instrumented treadmill walking as an acceptable medium to collect biomechanical and lower extremity EMG outcomes for future studies.

The Effect of Basketball Shoe Collar on Ankle Stability: A Systematic Review and Meta-Analysis

Purpose: This review is to systematically estimate if there is any relationship between the shoe collar characteristic and the risk of ankle sprain by reviewing the literature. Methods: Relevant papers were collected through PubMed, ScienceDirect, Google Scholar, and Scopus focused on ankle stability comparison in basketball shoes between high-top and low-top. Articles were involved if they: 1) compared subjects between high-top shoes and low-top shoes, 2) only focused on basketball shoes, 3) utilized kinematics and electromyogram as the primary outcome, 4) published in English. Results: 6 studies were collected in this systematic review, the selecting studies were divided into two different groups based on different motions of test, one of group is a side step cutting task for testing ROM of ankle in coronal plane, another one is conducting a jump task and the peak ankle inversion data at the landing after jump was extracted. Through the meta-analysis combined with a random effect, the model indicated that the type of shoe has no effect on the ankle inversion (p = 0.08) and ROM (p = 0.85). Conclusion: The results showed that there no significant difference in the shoe collar was found. Thus, the more parameters of ankle changes and muscle activity of lower extremity should be assessed in the future to improve our comprehensive understanding for shoe collar effect of ankle stability.

Comparison of lower limb muscle activity during the dynamic balance test between baseball pitchers and healthy young adults

BACKGROUND: Dynamic balance is an essential factor for efficient pitching by baseball pitchers. OBJECTIVE: To compare distances reached and lower-extremity muscle activity during the star excursion balance test (SEBT) in baseball pitchers and healthy young adults. METHODS: Nineteen baseball pitchers (BPG) and 20 healthy adults (HAG) were recruited. Surface EMG was used to measure the activity of vastus medialis (VM), vastus lateralis (VL), tibialis anterior, and lateral gastrocnemius. RESULTS: The BPG exhibited greater dynamic balance than in the HAG (p&lt; 0.05) in the posteromedial (PM) and posterolateral (PL) directions. For the PM and PL directions, significantly greater muscle activity of VM and VL was found in the BPG than in the HAG (p&lt; 0.05). CONCLUSION: SEBT performance is characterized by high-level VM and VL muscle activities. Neuromuscular control of knee extensors, such as the VM and VL of pitchers, might affect the dynamic balance measured by the SEBT.

Analysis of the lower extremity muscle activity depending on the use of a knee aid in elderly people with osteoarthritis

This study analysed the lower extremity muscle activity depending on the use of the Power Leg, a wearable knee aid, in elderly people with osteoarthritis. Eight participants who had osteoarthritis were asked to repeat sit-to-stand from a chair first without the knee aid, following which they were asked to repeat the same movement with the knee aid. Surface electromyography (EMG) was used to analyse muscle activities of the vastus medialis, rectus femoris, and vastus lateralis on the quadriceps femoris of the right leg while performing sit-to-stand motion. The result showed an 11.25% decrease in muscle activity of the vastus medialis, from 50.43% without the knee aid to 39.18% with the knee aid, which was significant (p < .05). Muscle activity of the rectus femoris decreased by 5.17%, from 29.49% without the knee aid down to 24.32% with the knee aid. However, the difference was not significant. The vastus lateralis had reduced muscle activity by 16.22%, from 57.15% without the knee aid to 40.93% with the knee aid, which was significant (p < .05). The results of this study showed that the Power Leg knee aid may decrease muscle activity by assisting lower extremity muscles during the sit-to-stand motion and effectively support the knee extensor during knee extension. Given these findings, as well as the ease of wearing and using the Power Leg knee aid, it is concluded that the wearable knee aid is very useful for the elderly with knee osteoarthritis.

Kinematics and muscle activity when running in partial minimalist, traditional, and maximalist shoes

While several studies have examined kinematic and kinetic differences between maximalist (MAX), traditional (TRAD), or partial minimalist (PMIN) shoes, to date it is unknown how MAX shoes influence muscle activity. This study compared lower extremity kinematics and muscle activity when running in PMIN, TRAD, and MAX shoes. Thirteen participants ran in each shoe while whole body kinematics were recorded using motion capture and electromyography was recorded from seven leg muscles. Differences in kinematics and root mean square amplitudes (RMS) were compared between shoe conditions. There were small differences in sagittal and frontal plane ankle kinematics between shoe conditions, with the MAX shoes resulting in less dorsiflexion at foot strike (p = .002) and less peak dorsiflexion (p < .001), and the PMIN shoes resulting in greater peak eversion (p = .012). Gluteus medius (p.006) and peroneus longus (p = .007) RMS amplitudes were greater in the MAX shoe then the TRAD or PMIN shoes while tibialis anterior RMS amplitudes were higher in the PMIN shoes (p = .005) than either the TRAD or MAX shoes. Consistent with previous findings, these results suggest there are small differences in kinematics when running in these three shoe types. This may partly be explained by the changes in muscle activity, which may be a response in order to maintain a preferred or habitual movement path. Implications for these difference in muscle activity in terms of fatigue or injury remain to be determined.

Real-time MR elastography for viscoelasticity quantification in skeletal muscle during dynamic exercises.

To develop and test real-time MR elastography for viscoelastic parameter quantification in skeletal muscle during dynamic exercises. In 15 healthy participants, 6 groups of lower-leg muscles (tibialis anterior, tibialis posterior, peroneus, extensor digitorum longus, soleus, gastrocnemius) were investigated by real-time MR elastography using a single-shot, steady-state spiral gradient-echo pulse sequence and stroboscopic undersampling of harmonic vibrations at 40 Hz frequency. One hundred and eighty consecutive maps of shear-wave speed and loss angle (φ) covering 30.6 s of total acquisition time at 5.9-Hz frame rate were reconstructed from 360 wave images encoding 2 in-plane wave components in an interleaved manner. The experiment was carried out twice to investigate 2 exercises-isometric plantar flexion and isometric dorsiflexion-each performed over 10 s between 2 resting periods. Activation of lower-extremity muscles was associated with increasing viscoelastic parameters shear-wave speed and φ, both reflecting properties related to the transverse direction relative to fiber orientation. Major viscoelastic changes were observed in soleus muscle during plantar flexion (shear-wave speed: 20.0% ± 3.6%, φ: 41.3% ± 12.0%) and in the tibialis anterior muscle during dorsiflexion (41.8% ± 10.2%, φ: 27.9% ± 2.8%; all P < .0001). Two of the muscles analyzed were significantly activated by plantar flexion and 4 by dorsiflexion based on shear-wave speed, whereas φ changed significantly in 5 muscles during both exercises. Real-time MR elastography allows mapping of dynamic, nonperiodic viscoelasticity changes in soft tissues such as voluntary muscle with high spatial and temporal resolution. Real-time MR elastography thus opens new horizons for the in vivo study of physiological processes in soft tissues toward functional elastography.