scholarly journals Applying Stretch to Evoke Hyperreflexia in Spasticity Testing: Velocity vs. Acceleration

2021 ◽  
Vol 8 ◽  
Author(s):  
Lizeth H. Sloot ◽  
Guido Weide ◽  
Marjolein M. van der Krogt ◽  
Kaat Desloovere ◽  
Jaap Harlaar ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Peak Velocity ◽  
Neurological Diseases ◽  
Maximum Velocity ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Reflex Response ◽  
Movement Initiation ◽  
Maximum Acceleration ◽  
Triceps Surae Muscle

In neurological diseases, muscles often become hyper-resistant to stretch due to hyperreflexia, an exaggerated stretch reflex response that is considered to primarily depend on the muscle's stretch velocity. However, there is still limited understanding of how different biomechanical triggers applied during clinical tests evoke these reflex responses. We examined the effect of imposing a rotation with increasing velocity vs. increasing acceleration on triceps surae muscle repsonse in children with spastic paresis (SP) and compared the responses to those measured in typically developing (TD) children. A motor-operated ankle manipulator was used to apply different bell-shaped movement profiles, with three levels of maximum velocity (70, 110, and 150°/s) and three levels of maximum acceleration (500, 750, and 1,000°/s2). For each profile and both groups, we evaluated the amount of evoked triceps surae muscle activation. In SP, we evaluated two additional characteristics: the intensity of the response (peak EMG burst) and the time from movement initiation to onset of the EMG burst. As expected, the amount of evoked muscle activation was larger in SP compared to TD (all muscles: p < 0.001) and only sensitive to biomechanical triggers in SP. Further investigation of the responses in SP showed that peak EMG bursts increased in profiles with higher peak velocity (lateral gastrocnemius: p = 0.04), which was emphasized by fair correlations with increased velocity at EMG burst onset (all muscles: r > 0.33–0.36, p ≤ 0.008), but showed no significant effect for acceleration. However, the EMG burst was evoked faster with higher peak acceleration (all muscles p < 0.001) whereas it was delayed in profiles with higher peak velocity (medial gastrocnemius and soleus: p < 0.006). We conclude that while exaggerated response intensity (peak EMG burst) seems linked to stretch velocity, higher accelerations seem to evoke faster responses (time to EMG burst onset) in triceps surae muscles in SP. Understanding and controlling for the distinct effects of different biological triggers, including velocity, acceleration but also length and force of the applied movement, will contribute to the development of more precise clinical measurement tools. This is especially important when aiming to understand the role of hyperreflexia during functional movements where the biomechanical inputs are multiple and changing.

scholarly journals The effects of triceps surae muscle stimulation on localized achilles subtendon tissue displacements

2021 ◽  
Author(s):  
Nathan L. Lehr ◽  
William H. Clark ◽  
Michael D. Lewek ◽  
Jason R. Franz
Keyword(s):  
Achilles Tendon ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Muscle Stimulation ◽  
Triceps Surae Muscle ◽  
Ankle Angle ◽  
In Series ◽  
Fixed End

The triceps surae muscle tendon unit is comprised of the lateral and medial gastrocnemius (MG) and soleus (SOL) muscles and three in series elastic “subtendons” that form the Achilles tendon. Comparative literature and our own in vivo evidence suggests that sliding between adjacent subtendons may facilitate independent muscle actuation. We aim to more clearly define the relation between individual muscle activation and subtendon tissue displacements. Here, during fixed-end contractions, electrical muscle stimulation controlled the magnitude of force transmitted via individual triceps surae muscles while ultrasound imaging recorded resultant subtendon tissue displacements. We hypothesized that MG and SOL stimulation would elicit larger displacements in their associated subtendon. 10 young adults completed 4 experimental activations at 3 ankle angles (-20°, 0°, 20°) with knee flexed to approximately 20°: MG stimulation (STIMMG), SOL stimulation (STIMSOL), combined stimulation, and volitional contraction. At 20° plantarflexion, STIMSOL elicited 49% larger tendon non-uniformity (SOL – MG subtendon tissue displacement) than that of STIMMG (p=0.004). For STIMSOL, a one-way post-hoc ANOVA revealed a significant main effect of ankle angle (p=0.009) on Achilles tendon non-uniformity. However, peak tendon non-uniformity decreased by an average of 61% from plantarflexion to dorsiflexion, likely due to an increase in passive tension. Our results suggest that localized tissue displacements within the Achilles tendon respond in anatomically consistent ways to differential patterns of triceps surae muscle activation, but these relations are highly susceptible to ankle angle. This in vivo evidence points to at least some mechanical independence in actuation between the human triceps surae muscle-subtendon units.

scholarly journals Older Adults Overcome Reduced Triceps Surae Structural Stiffness to Preserve Ankle Joint Quasi-Stiffness During Walking

2020 ◽  
Vol 36 (4) ◽  
pp. 209-216
Author(s):  
Rebecca L. Krupenevich ◽  
William H. Clark ◽  
Gregory S. Sawicki ◽  
Jason R. Franz
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Muscle Activation ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Triceps Surae Muscle ◽  
Age Related ◽  
Lower Ankle Joint

Ankle joint quasi-stiffness is an aggregate measure of the interaction between triceps surae muscle stiffness and Achilles tendon stiffness. This interaction may be altered due to age-related changes in the structural properties and functional behavior of the Achilles tendon and triceps surae muscles. The authors hypothesized that, due to a more compliant of Achilles’ tendon, older adults would exhibit lower ankle joint quasi-stiffness than young adults during walking and during isolated contractions at matched triceps surae muscle activations. The authors also hypothesized that, independent of age, triceps surae muscle stiffness and ankle joint quasi-stiffness would increase with triceps surae muscle activation. The authors used conventional gait analysis in one experiment and, in another, electromyographic biofeedback and in vivo ultrasound imaging applied during isolated contractions. The authors found no difference in ankle joint quasi-stiffness between young and older adults during walking. Conversely, this study found that (1) young and older adults modulated ankle joint quasi-stiffness via activation-dependent changes in triceps surae muscle length–tension behavior and (2) at matched activation, older adults exhibited lower ankle joint quasi-stiffness than young adults. Despite age-related reductions during isolated contractions, ankle joint quasi-stiffness was maintained in older adults during walking, which may be governed via activation-mediated increases in muscle stiffness.

Muscle activation and its distribution within human triceps surae muscles

2005 ◽  
Vol 99 (3) ◽  
pp. 1149-1156 ◽  
Author(s):  
Ryuta Kinugasa ◽  
Yasuo Kawakami ◽  
Tetsuo Fukunaga
Keyword(s):  
Muscle Activation ◽  
Spin Echo ◽  
Region Of Interest ◽  
Transverse Relaxation Time ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Active Muscle ◽  
Percentage Area ◽  
The Mean ◽  
Triceps Surae Muscles

The purposes of this study were 1) to quantify the volume of activated parts within a whole muscle and 2) to examine activated area distributions along the length of muscle. Seven male subjects performed five sets of 10 repetitions of a single-leg calf-raise exercise with the knee fully extended. Transverse relaxation time (T2)-weighted spin echo images were acquired before and immediately after the exercise. A range of pixels with a T2 greater than the mean +1 SD of the region of interest (ROI) from the preexercise image and pixels with a T2 lower than the mean + SD of the ROI from the postexercise image were defined as “active” muscle. The active muscle images were three dimensionally reconstructed, from which the volume of the activated muscle was determined for individual triceps surae (TS) muscles. Our data indicate that ∼46% of the medial gastrocnemius (MG) muscle was activated during the exercise, with activation of the lateral gastrocnemius (LG) and soleus (Sol) muscles being ∼35%. In the MG, distal portions had a greater percentage area of activated muscle than the proximal portions ( P < 0.05), which was consistent with the results regarding electromyogram activity. In contrast, regional activation differences were not observed in the LG and Sol. These findings suggest that the amounts of activated muscle and its distribution would be different among TS muscles.

Neural Compensation Within the Human Triceps Surae During Prolonged Walking

2011 ◽  
Vol 105 (2) ◽  
pp. 548-553 ◽  
Author(s):  
Neil J. Cronin ◽  
Jussi Peltonen ◽  
Thomas Sinkjaer ◽  
Janne Avela
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Neural Activation ◽  
Fascicle Length ◽  
Muscle Fascicle ◽  
Compound Action Potentials ◽  
Triceps Surae Muscles ◽  
Short Time

During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded every 5 min, and fascicle lengths were estimated at the beginning and end of the protocol using ultrasound. After 1 h of walking, soleus activity increased by 9.3 ± 0.2% ( P < 0.05) and medial gastrocnemius activity decreased by 9.3 ± 0.3% ( P < 0.01). Gastrocnemius fascicle length at ground contact shortened by 4.45 ± 0.99% ( P < 0.001), whereas soleus fascicle length was unchanged ( P = 0.988). Throughout the stance phase, medial gastrocnemius fascicle lengthening decreased by 44 ± 13% ( P < 0.001), whereas soleus fascicle lengthening amplitude was unchanged ( P = 0.650). The data suggest that a compensatory neural strategy exists between triceps surae muscles and that changes in muscle activation are generally mirrored by changes in muscle fascicle length. These findings also support the notion of muscle-specific changes in TT compliance after prolonged walking and highlight the ability of the CNS to maintain relatively constant movement patterns in spite of neuromechanical changes in individual muscles.

Recruitment of triceps surae motor units in the decerebrate cat. I. Independence of type S units in soleus and medial gastrocnemius muscles

1996 ◽  
Vol 75 (5) ◽  
pp. 1997-2004 ◽  
Author(s):  
S. M. Dacko ◽  
A. J. Sokoloff ◽  
T. C. Cope
Keyword(s):  
Firing Rate ◽  
Soleus Muscle ◽  
Motor Units ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Reflex Response ◽  
Reflex Inhibition ◽  
Decerebrate Cat ◽  
Firing Behavior ◽  
Slow Twitch

1. We tested the hypothesis that reflex inhibition of soleus motor units reflects selective inhibition of slow-twitch (type S) motor units throughout the triceps surae. Physiological properties including type, together with firing behavior, were measured from single motor units in the medial gastrocnemius (MG) muscle of decerebrate cats with the use of intra-axonal recording and stimulation. MG unit firing was contrasted during net inhibition or excitation of the slow-twitch soleus muscle produced by ramp-hold-release stretches of MG. 2. Stretch of the MG muscle increased the firing of type S motor units in the MG regardless of the reflex response of the soleus muscle. When stretch inhibited soleus, each of the 14 type S units sampled from MG either was newly recruited or exhibited increases in the rate of ongoing firing. Increased firing was observed in 320 of 321 stretch trials. For 8 of these 14 units, a total of 155 stretch trials evoked reflex excitation of soleus, and unit firing increased in all trials. 3. For the eight MG type S motor units studied during both reflex inhibition and excitation of soleus, firing rate tended to be higher during inhibition. The higher rates were also associated with the higher MG forces required to elicit soleus inhibition. For one MG type S unit it was possible to compare firing rates during soleus inhibition and excitation for trials of overlapping levels of MG force. For this unit, firing rate was similar, but still appreciably higher, during inhibition. 4. Soleus inhibition was also produced by stretch of the plantaris (PL) or lateral gastrocnemius (LG) muscles. Type S units in PL (n = 2) or in LG (n = 1) were recruited or increased firing rate even when stretch of these muscles produced soleus inhibition. 5. The firing behavior of 12 fast-twitch (type F) units was studied (11 from MG, 1 from PL). All type F units either were recruited or accelerated the rate of firing during soleus inhibition, as well as during soleus excitation. 6. These findings give evidence that reflex inhibition of type S motor units in the soleus muscle does not necessarily reflect an organizational scheme in which there is inactivation of type S units in other active muscles. In the DISCUSSION we point out the absence of direct evidence for selective inactivation of units on the basis of their type classification.

Limiting mechanisms of force production after repetitive dynamic contractions in human triceps surae

2004 ◽  
Vol 96 (4) ◽  
pp. 1516-1521 ◽  
Author(s):  
M. Klass ◽  
N. Guissard ◽  
J. Duchateau
Keyword(s):  
Maximal Voluntary Contraction ◽  
Muscle Activation ◽  
Voluntary Contraction ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Neutral Position ◽  
M Wave ◽  
Human Triceps Surae ◽  
Fatiguing Contractions

The influence of repetitive dynamic fatiguing contractions on the neuromuscular characteristics of the human triceps surae was investigated in 10 subjects. The load was 50% of the torque produced during a maximal voluntary contraction, and the exercise ended when the ankle range of motion declined to 50% of control. The maximal torque of the triceps surae and the electromyographic (EMG) activities of the soleus and medial gastrocnemius were studied in response to voluntary and electrically induced contractions before and after the fatiguing task and after 5 min of recovery. Reflex activities were also tested by recording the Hoffmann reflex (H reflex) and tendon reflex (T reflex) in the soleus muscle. The results indicated that whereas the maximal voluntary contraction torque, tested in isometric conditions, was reduced to a greater extent ( P < 0.05) at 20° of plantar flexion (-33%) compared with the neutral position (-23%) of the ankle joint, the EMG activity of both muscles was not significantly reduced after fatigue. Muscle activation, tested by the interpolated-twitch method or the ratio of the voluntary EMG to the amplitude of the muscle action potential (M-wave), as well as the neuromuscular transmission and sarcolemmal excitation, tested by the M-wave amplitude, did not change significantly after the fatiguing exercise. Although the H and T reflexes declined slightly (10-13%; P < 0.05) after fatigue, these adjustments did not appear to have a direct deleterious effect on muscle activation. In contrast, alterations in the mechanical twitch time course and postactivation potentiation indicated that intracellular Ca2+-controlled excitation-contraction coupling processes most likely played a major role in the force decrease after dynamic fatiguing contractions performed for short duration.

Long-term use of high-heeled shoes alters the neuromechanics of human walking

2012 ◽  
Vol 112 (6) ◽  
pp. 1054-1058 ◽  
Author(s):  
Neil J. Cronin ◽  
Rod S. Barrett ◽  
Christopher P. Carty
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Fascicle Length ◽  
High Heel ◽  
Muscle Fascicle

Human movement requires an ongoing, finely tuned interaction between muscular and tendinous tissues, so changes in the properties of either tissue could have important functional consequences. One condition that alters the functional demands placed on lower limb muscle-tendon units is the use of high-heeled shoes (HH), which force the foot into a plantarflexed position. Long-term HH use has been found to shorten medial gastrocnemius muscle fascicles and increase Achilles tendon stiffness, but the consequences of these changes for locomotor muscle-tendon function are unknown. This study examined the effects of habitual HH use on the neuromechanical behavior of triceps surae muscles during walking. The study population consisted of 9 habitual high heel wearers who had worn shoes with a minimum heel height of 5 cm at least 40 h/wk for a minimum of 2 yr, and 10 control participants who habitually wore heels for less than 10 h/wk. Participants walked at a self-selected speed over level ground while ground reaction forces, ankle and knee joint kinematics, lower limb muscle activity, and gastrocnemius fascicle length data were acquired. In long-term HH wearers, walking in HH resulted in substantial increases in muscle fascicle strains and muscle activation during the stance phase compared with barefoot walking. The results suggest that long-term high heel use may compromise muscle efficiency in walking and are consistent with reports that HH wearers often experience discomfort and muscle fatigue. Long-term HH use may also increase the risk of strain injuries.

scholarly journals Multi- and Single-Joint Resistance Exercises Promote Similar Plantar Flexor Activation in Resistance Trained Men

2020 ◽  
Vol 17 (24) ◽  
pp. 9487
Author(s):  
Paulo Gentil ◽  
Daniel Souza ◽  
Murillo Santana ◽  
Rafael Ribeiro Alves ◽  
Mário Hebling Campos ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Negative Impact ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Plantar Flexors ◽  
Lateral Gastrocnemius ◽  
Leg Press ◽  
Electromyographic Signal ◽  
Triceps Surae Muscles ◽  
Gastrocnemius Muscles

The present study aimed to compare soleus, lateral, and medial gastrocnemius muscles activation during leg press and calf raise exercises in trained men. The study involved 22 trained men (27.1 ± 3.6 years, 82.7 ± 6.6 kg, 177.5 ± 5.2 cm, 3.6 ± 1.4 experience years) who performed one set of each exercise using a 10-repetition maximum (10RM) load in a counterbalanced randomized order and separated by 10 min of rest. The electromyographic signal was measured for the three major plantar flexors: soleus, medial, and lateral gastrocnemius. A comparison between exercises showed that the mean adjusted by peak values during the leg press were 49.20% for the gastrocnemius lateralis, 51.31% for the gastrocnemius medialis, and 50.76% for the soleus. Values for calf raise were 50.70%, 52.19%, and 51.34% for the lateral, medial gastrocnemius, and soleus, respectively. There were no significant differences between exercises for any muscle (lateral gastrocnemius (p = 0.230), medial gastrocnemius (p = 0.668), and soleus (p = 0.535)). The present findings suggest that both leg press and calf raises can be used with the purpose to recruit triceps surae muscles. This bring the suggestion that one can chose between exercises based on personal preferences and practical aspects, without any negative impact on muscle activation.

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