Interactions between the human gastrocnemius muscle and the Achilles tendon during incline, level and decline locomotion

Lichtwark, Glen A.; Wilson, Alan M.

doi:10.1242/jeb.02434

Cited by 281 publications

(327 citation statements)

References 26 publications

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“…This could aid more confident determination of force distribution between the plantar flexors. The current approach based on physiological cross-sectional area (PCSA) has often been used (34)(35)(36), but relies upon the assumption that relative muscle activation level is similar in each of the plantar flexors (e.g., MG, LG, and soleus are all activated at 70% of their maximum). In the present study, it is assumed that this holds across speeds (e.g., if MG relative activation increases by 10% from one speed to the next, so does soleus and LG relative activation).…”

Section: Discussionmentioning

confidence: 99%

“…To estimate the force in the muscle fascicles of MG (F MG ), F SEE was divided by the cosine of the MG pennation angle (equation 2 in ref. 35). This approach to calculating muscle force does not account for any contribution of antagonistic dorsiflexors to the net ankle moment, although this was assumed not to be significant during the stance phase, when tibialis anterior is minimally active (23), and the key variables in this study were determined.…”

Section: Methodsmentioning

confidence: 99%

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Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

Farris

Sawicki

2012

Proc. Natl. Acad. Sci. U.S.A.

203

256

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Humans walk and run over a wide range of speeds with remarkable efficiency. For steady locomotion, moving at different speeds requires the muscle-tendon units of the leg to modulate the amount of mechanical power the limb absorbs and outputs in each step. How individual muscles adapt their behavior to modulate limb power output has been examined using computer simulation and animal models, but has not been studied in vivo in humans. In this study, we used a combination of ultrasound imaging and motion analysis to examine how medial gastrocnemius (MG) muscletendon unit behavior is adjusted to meet the varying mechanical demands of different locomotor speeds during walking and running in humans. The results highlighted key differences in MG fascicle-shortening velocity with both locomotor speed and gait. Fascicle-shortening velocity at the time of peak muscle force production increased with walking speed, impairing the ability of the muscle to produce high peak forces. Switching to a running gait at 2.0 m·s −1 caused fascicle shortening at the time of peak force production to shift to much slower velocities. This velocity shift facilitated a large increase in peak muscle force and an increase in MG power output. MG fascicle velocity may be a key factor that limits the speeds humans choose to walk at, and may explain the transition from walking to running. This finding is consistent with previous modeling studies.muscle mechanics | biomechanics | preferred transition speed A nkle plantar-flexor muscles are a vital source of mechanical power for human locomotion (1, 2). During walking, plantar-flexor muscles provide body weight support, contribute to propulsion, and accelerate the limb into swing (3). In running, the ankle acts in a spring-like manner, absorbing energy in plantarflexor muscle-tendon units during early stance and providing energy to accelerate the body in late stance (1). The mechanical work required to produce whole-body movement during walking and running varies between gaits and across speeds (4, 5). Thus, the plantar-flexors may need to adjust their mechanical work output with gait and speed to meet the changing demands on their contribution to total mechanical work.A recent experimental study in humans used an inverse-dynamics approach to examine how the mechanical power outputs of muscles acting at the hip, knee, and ankle joint were modulated for walking and running at a range of speeds (6). It was found that positive power output at the ankle, in conjunction with the knee and hip, increased with walking speed. Also, Hansen et al. (7) showed that at walking speeds above those preferred, the net positive work done at the ankle increased. When switching from walking to running gait, the relative contribution of ankle positive power output to total positive power output also increased (6). It was inferred from these data that plantar-flexor muscle mechanics were adjusted to accommodate faster walking speeds and then again with the switch to running gait. If this is truly the case, then it may hav...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

Farris

Sawicki

2012

Proc. Natl. Acad. Sci. U.S.A.

203

256

View full text Add to dashboard Cite

show abstract

“…When combined with the findings of increased stiffness during the hopping task, it might be suggested that whilst increasing stiffness as a strategy to limit exposure to ground contact, individuals with AT lack the structural apparatus to achieve this in the most effective manner. During SSC tasks, elongation of the TA occurs in the presence of a 'quasi-isometric' plantarflexion contraction 18 . However, it has been reported that AT is associated with reduced tendon stiffness 19,20 , so the increased stretch amplitude may be viewed as an indicator of reduced tendon stiffness.…”

Section: Discussionmentioning

confidence: 99%

Achilles tendinopathy alters stretch shortening cycle behaviour during a sub-maximal hopping task

Debenham

Travers

Gibson

et al. 2016

Journal of Science and Medicine in Sport

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ObjectivesTo describe stretch shortening cycle behaviour of the ankle and lower limb in patients with Achilles tendinopathy (AT) and establish differences with healthy volunteers. DesignBetween-subjects case-controlled MethodsFifteen patients with AT (mean age 41.2 ± 12.7 years) and eleven healthy volunteers (CON) (mean age 23.2 ± 6.7 years) performed sub-maximal single-limb hopping on a custom built sledge-jump system. Using 3D motion analysis and surface EMG, temporal kinematic (lower limb stiffness, ankle angle at 80 ms pre-contact, ankle angle at contact, peak ankle angle, ankle stretch amplitude) and EMG measures (onset, offset and peak times relative to contact) were captured. Data between AT and CON were compared statistically using a linear mixed model. ResultsPatients with AT exhibited significantly increased lower limb stiffness when compared to healthy volunteers (p<0.001) and their hopping range was shifted towards a more dorsiflexed position (p<0.001). Furthermore, ankle stretch amplitude was greater in AT compared with healthy volunteers (p<.001). A delay in muscle activity was also observed; soleus onset (p<.001), tibialis anterior peak (p=0.026) and tibialis anterior offset (p<.001) were all delayed in AT compared with CON. ConclusionsThese findings indicate that patients with AT exhibit altered stretch-shortening cycle behaviour during sub-maximal hopping when compared with healthy volunteers. Patients with AT hop with greater lower limb stiffness, in a greater degree of ankle dorsiflexion and have a greater stretch amplitude.Likewise, delayed muscle activity is evident. These findings have implications in terms of informing the understanding of the pathoaetiology and management of AT.3

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“…28 However, there was no difference in medial gastrocnemius fascicle length between incline and decline walking or running. 19 It must be noted that the length change of the medial gastrocnemius fascicles is dependent upon the movement of both the knee and ankle, while the VL fascicles are only affected by movement of the knee. Therefore, muscle-specific length changes during functional movements may be due to such factors as the length and compliance of the tendon, whether the muscle is biarticular or uniarticular, the amount of muscle force, and the relative joint angle changes required for the movement.…”

Section: Methodsmentioning

confidence: 99%

Vastus Lateralis Fascicle Length Changes During Stair Ascent and Descent

Chleboun

Harrigal²,

J³

et al. 2008

J Orthop Sports Phys Ther

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Interactions between the human gastrocnemius muscle and the Achilles tendon during incline, level and decline locomotion

Cited by 281 publications

References 26 publications

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

Achilles tendinopathy alters stretch shortening cycle behaviour during a sub-maximal hopping task

Vastus Lateralis Fascicle Length Changes During Stair Ascent and Descent

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