scholarly journals Ankle joint mechanics and foot proportions differ between human sprinters and non-sprinters

2011 ◽  
Vol 279 (1735) ◽  
pp. 2018-2024 ◽  
Author(s):  
Josh R. Baxter ◽  
Thomas A. Novack ◽  
Herman Van Werkhoven ◽  
David R. Pennell ◽  
Stephen J. Piazza
Keyword(s):  
Ankle Joint ◽  
Bone Geometry ◽  
Running Economy ◽  
Joint Mechanics ◽  
Moment Arm ◽  
Joint Rotation ◽  
Human Foot ◽  
Moment Arms ◽  
Muscle Work ◽  
Centre Of Rotation

Recent studies of sprinters and distance runners have suggested that variations in human foot proportions and plantarflexor muscle moment arm correspond to the level of sprint performance or running economy. Less clear, however, is whether differences in muscle moment arm are mediated by altered tendon paths or by variation in the centre of ankle joint rotation. Previous measurements of these differences have relied upon assumed joint centres and measurements of bone geometry made externally, such that they would be affected by the thickness of the overlying soft tissue. Using magnetic resonance imaging, we found that trained sprinters have shorter plantarflexor moment arms ( p = 0.011) and longer forefoot bones ( p = 0.019) than non-sprinters. The shorter moment arms of sprinters are attributable to differences in the location of the centre of rotation ( p < 0.001) rather than to differences in the path of the Achilles tendon. A simple computer model suggests that increasing the ratio of forefoot to rearfoot length permits more plantarflexor muscle work during plantarflexion that occurs at rates expected during the acceleration phase following the sprint start.

scholarly journals Plantar flexor moment arm and muscle volume predict torque-generating capacity in young men

2014 ◽  
Vol 116 (5) ◽  
pp. 538-544 ◽  
Author(s):  
Josh R. Baxter ◽  
Stephen J. Piazza
Keyword(s):  
Plantar Flexion ◽  
Young Men ◽  
Knee Extensor ◽  
Muscle Volume ◽  
Joint Torque ◽  
Muscle Size ◽  
Plantar Flexor ◽  
Moment Arm ◽  
Joint Rotation ◽  
Moment Arms

Muscle volume is known to correlate with maximal joint torque in humans, but the role of muscle moment arm in determining maximal torque is less clear. Moderate correlations have been reported between maximal isometric knee extensor torque and knee extensor moment arm, but no such observations have been made for the ankle joint. It has been suggested that smaller muscle moment arms may enhance force generation at high rates of joint rotation, but this has not yet been observed for ankle muscles in vivo. The purpose of the present study was to correlate plantar flexor moment arm and plantar flexor muscle volume with maximal plantar flexor torque measured at different rates of plantar flexion. Magnetic resonance imaging was used to quantify the plantar flexor moment arm and muscle volume of the posterior compartment in 20 healthy young men. Maximal plantar flexor torque was measured isometrically and at three plantar flexion speeds using an isokinetic dynamometer. Plantar flexor torque was significantly correlated with muscle volume (0.222 < R2 < 0.322) and with muscle moment arm at each speed (0.323 < R2 < 0.494). While muscle volume was strongly correlated with body mass and stature, moment arm was not. The slope of the torque-moment arm regression line decreased as the rate of joint rotation increased, indicating that subjects with small moment arms experienced smaller reductions in torque at high speeds. The findings of this study suggest that plantar flexor moment arm is a determinant of joint strength that is at least as important as muscle size.

scholarly journals Achilles tendon moment arm in humans is not affected by inversion/eversion of the foot: a short report

2018 ◽  
Vol 5 (1) ◽  
pp. 171358 ◽  
Author(s):  
Susann Wolfram ◽  
Christopher I. Morse ◽  
Keith L. Winwood ◽  
Emma Hodson-Tole ◽  
Islay M. McEwan
Keyword(s):  
Achilles Tendon ◽  
Magnetic Resonance Images ◽  
Triceps Surae ◽  
Short Report ◽  
Moment Arm ◽  
Moment Arms ◽  
Musculoskeletal Models ◽  
Rotation Method ◽  
Centre Of Rotation ◽  
Foot Position

The triceps surae primarily acts as plantarflexor of the ankle joint. However, the group also causes inversion and eversion at the subtalar joint. Despite this, the Achilles tendon moment arm is generally measured without considering the potential influence of inversion/eversion of the foot during plantarflexion. This study investigated the effect of foot inversion and eversion on the plantarflexion Achilles tendon moment arm. Achilles tendon moment arms were determined using the centre-of-rotation method in magnetic resonance images of the left ankle of 11 participants. The foot was positioned at 15° dorsiflexion, 0° or 15° plantarflexion using a Styrofoam wedge. In each of these positions, the foot was either 10° inverted, neutral or 10° everted using an additional Styrofoam wedge. Achilles tendon moment arm in neutral foot position was 47.93 ± 4.54 mm and did not differ significantly when the foot was positioned in 10° inversion and 10° eversion. Hence, inversion/eversion position of the foot may not considerably affect the length of the Achilles tendon moment arm. This information could be useful in musculoskeletal models of the human lower leg and foot and when estimating Achilles tendon forces during plantarflexion with the foot positioned in inversion or eversion.

scholarly journals Shorter heels are linked with greater elastic energy storage in the Achilles tendon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. D. Foster ◽  
B. Block ◽  
F. Capobianco ◽  
J. T. Peabody ◽  
N. A. Puleo ◽  
...  
Keyword(s):  
Energy Storage ◽  
Achilles Tendon ◽  
Elastic Energy ◽  
Mechanical Energy ◽  
Running Economy ◽  
Triceps Surae ◽  
Morphological Data ◽  
Energetic Cost ◽  
Moment Arm ◽  
Moment Arms

AbstractPrevious research suggests that the moment arm of the m. triceps surae tendon (i.e., Achilles tendon), is positively correlated with the energetic cost of running. This relationship is derived from a model which predicts that shorter ankle moment arms place larger loads on the Achilles tendon, which should result in a greater amount of elastic energy storage and return. However, previous research has not empirically tested this assumed relationship. We test this hypothesis using an inverse dynamics approach in human subjects (n = 24) at speeds ranging from walking to sprinting. The spring function of the Achilles tendon was evaluated using specific net work, a metric of mechanical energy production versus absorption at a limb joint. We also combined kinematic and morphological data to directly estimate tendon stress and elastic energy storage. We find that moment arm length significantly determines the spring-like behavior of the Achilles tendon, as well as estimates of mass-specific tendon stress and elastic energy storage at running and sprinting speeds. Our results provide support for the relationship between short Achilles tendon moment arms and increased elastic energy storage, providing an empirical mechanical rationale for previous studies demonstrating a relationship between calcaneal length and running economy. We also demonstrate that speed and kinematics moderate tendon performance, suggesting a complex relationship between lower limb geometry and foot strike pattern.

Estimates of Achilles Tendon Moment Arm Length at Different Ankle Joint Angles: Effect of Passive Moment

2018 ◽  
pp. 1-22 ◽  
Author(s):  
Jared R. Fletcher ◽  
Brian R. MacIntosh
Keyword(s):  
Achilles Tendon ◽  
Passive Force ◽  
Moment Arm ◽  
Joint Angles ◽  
Joint Rotation ◽  
Male And Female ◽  
Moment Arms ◽  
Passive Rotation ◽  
Ankle Angle ◽  
Tendon Excursion

The length of a muscle’s moment arm can be estimated non-invasively using ultrasound, and the tendon excursion method. The main assumption with the tendon excursion method, however, is that the force acting on the tendon during passive rotation is constant. However, passive force changes through the range of motion, and moment arm is underestimated. We attempted to account for passive force on the measurement of Achilles tendon moment arm using the tendon excursion method in 8 male and female runners. Tendon excursion was measured using ultrasound while the ankle was passively rotated at 0.17 rad•s-1. Moment arm was calculated at 5° intervals as the ratio of tendon displacement to joint rotation from 70° to 115°. Passive moment (MP) was measured by a dynamometer. The displacement attributable to MP was calculated by monitoring tendon displacement during a ramp isometric maximum contraction. MP was 5.7±2.1 Nm at 70° and decreased exponentially from 70°-90°. °. This resulted in MP-corrected moment arms that were significantly larger than uncorrected moment arms at joint angles where MP was present. Further, MP-corrected moment arms did not change with ankle angle, which was not the case for uncorrected moment arms.

Estimates of Achilles Tendon Moment Arm Length at Different Ankle Joint Angles: Effect of Passive Moment

2018 ◽  
Vol 34 (3) ◽  
pp. 220-225 ◽  
Author(s):  
Jared R. Fletcher ◽  
Brian R. MacIntosh
Keyword(s):  
Achilles Tendon ◽  
Passive Force ◽  
Moment Arm ◽  
Joint Angles ◽  
Joint Rotation ◽  
Male And Female ◽  
Moment Arms ◽  
Passive Rotation ◽  
Ankle Angle ◽  
Tendon Excursion

The length of a muscle’s moment arm can be estimated noninvasively using ultrasound and the tendon excursion method. The main assumption with the tendon excursion method is that the force acting on the tendon during passive rotation is constant. However, passive force changes through the range of motion, and thus moment arm is underestimated. The authors attempted to account for passive force on the measurement of Achilles tendon moment arm using the tendon excursion method in 8 male and female runners. Tendon excursion was measured using ultrasound while the ankle was passively rotated at 0.17 rad·s−1. Moment arm was calculated at 5° intervals as the ratio of tendon displacement to joint rotation from 70° to 115°. Passive moment (MP) was measured using a dynamometer. The displacement attributable to MP was calculated by monitoring tendon displacement during a ramp isometric maximum contraction. MP was 5.7 (2.1) N·m at 70° and decreased exponentially from 70° to 90°. This resulted in MP-corrected moment arms that were significantly larger than uncorrected moment arms at joint angles where MP was present. Furthermore, MP-corrected moment arms did not change with ankle angle, which was not the case for uncorrected moment arms.

scholarly journals Characterization and clinical implications of ankle impedance during walking in chronic stroke

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Amanda L. Shorter ◽  
James K. Richardson ◽  
Suzanne B. Finucane ◽  
Varun Joshi ◽  
Keith Gordon ◽  
...  
Keyword(s):  
Ankle Joint ◽  
Stance Phase ◽  
Clinical Care ◽  
Joint Stiffness ◽  
Mechanical Impedance ◽  
Chronic Stroke ◽  
Joint Mechanics ◽  
Clinical Assessments ◽  
Post Stroke ◽  
Joint Damping

AbstractIndividuals post-stroke experience persisting gait deficits due to altered joint mechanics, known clinically as spasticity, hypertonia, and paresis. In engineering, these concepts are described as stiffness and damping, or collectively as joint mechanical impedance, when considered with limb inertia. Typical clinical assessments of these properties are obtained while the patient is at rest using qualitative measures, and the link between the assessments and functional outcomes and mobility is unclear. In this study we quantify ankle mechanical impedance dynamically during walking in individuals post-stroke and in age-speed matched control subjects, and examine the relationships between mechanical impedance and clinical measures of mobility and impairment. Perturbations were applied to the ankle joint during the stance phase of walking, and least-squares system identification techniques were used to estimate mechanical impedance. Stiffness of the paretic ankle was decreased during mid-stance when compared to the non-paretic side; a change independent of muscle activity. Inter-limb differences in ankle joint damping, but not joint stiffness or passive clinical assessments, strongly predicted walking speed and distance. This work provides the first insights into how stroke alters joint mechanical impedance during walking, as well as how these changes relate to existing outcome measures. Our results inform clinical care, suggesting a focus on correcting stance phase mechanics could potentially improve mobility of chronic stroke survivors.

Analysis of the mero-carpopodite joint of the American lobster and snow crab. II. Kinematics, morphometrics and moment arms

2003 ◽  
Vol 83 (6) ◽  
pp. 1249-1259 ◽  
Author(s):  
S.C. Mitchell ◽  
M.E. DeMont
Keyword(s):  
Joint Angle ◽  
Snow Crab ◽  
Moment Arm ◽  
Scaling Effects ◽  
Joint Angles ◽  
Positive Allometry ◽  
Moment Arms ◽  
Arm Reaching ◽  
Flexion Extension ◽  
The Moment

This research reports on the kinematics of lobster and snow crab walking, documents changes in the moment arms of the mero-carpopodite joint during rotation, and examines scaling effects of morphological and mechanical variables in these crustacean species. Forward walking lobsters and lateral walking crabs were recorded and images analysed to describe the kinematics of these animals, and subsequently morphometric and moment arm measurements made. During forward walking the lobster maintains fixed mero-carpopodite joint angles during both the power and recovery strokes, though each of the walking legs maintains different joint angles. Legs 3 and 5 are maintained at angles which appear to equalize the flexor and extensor moment arms, and leg 4 joint angle appears to maximize the extensor moment arm. The snow crab has a joint excursion angle of between approximately 50° to 150° and, during flat bed walking, the leading and trailing legs move through similar excursion angles. The length of the meropodite for both species are longer for the anterior two leg pairs relative to the posterior two pairs and the rate of growth of the meropodite is largely isometric for the lobster while consistently increases with positive allometry in the crab. The flexor and extensor moment arms generated as the joint undergoes flexion/extension show two distinct patterns with the extensor moment arm being maximized at relatively low joint angles (55°–115°) and the flexor moment arm reaching a plateau at joint extension with angles between 95° and 155°. The flexor apodeme possesses the largest moment arms in all legs for both species, suggesting the flexors are able to generate greater torques. It appears that, mechanically, these laterally moving animals may be ‘pulling’ with the leading legs to a greater extent than ‘pushing’ with the trailing legs.

scholarly journals Ankle morphology amplifies calcaneus movement relative to triceps surae muscle shortening

2013 ◽  
Vol 115 (4) ◽  
pp. 468-473 ◽  
Author(s):  
R. Csapo ◽  
J. Hodgson ◽  
R. Kinugasa ◽  
V. R. Edgerton ◽  
S. Sinha
Keyword(s):  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Sagittal Plane ◽  
Triceps Surae ◽  
Myotendinous Junction ◽  
Joint Movement ◽  
Center Of Rotation ◽  
Moment Arms ◽  
Plantarflexor Muscles

The present study investigated the mechanical role of the dorsoventral curvature of the Achilles tendon in the conversion of the shortening of the plantarflexor muscles into ankle joint rotation. Dynamic, sagittal-plane magnetic resonance spin-tagged images of the ankle joint were acquired in six healthy subjects during both passive and active plantarflexion movements driven by a magnetic resonance compatible servomotor-controlled foot-pedal device. Several points on these images were tracked to determine the 1) path and deformation of the Achilles tendon, 2) ankle's center of rotation, and 3) tendon moment arms. The degree of mechanical amplification of joint movement was calculated as the ratio of the displacements of the calcaneus and myotendinous junction. In plantarflexion, significant deflection of the Achilles tendon was evident in both the passive (165.7 ± 7.4°; 180° representing a straight tendon) and active trials (166.9 ± 8.8°). This bend in the dorsoventral direction acts to move the Achilles tendon closer to the ankle's center of rotation, resulting in an ∼5% reduction of moment arm length. Over the entire range of movement, the overall displacement of the calcaneus exceeded the displacement of the myotendinous junction by ∼37%, with the mechanical gains being smaller in dorsi- and larger in plantarflexed joint positions. This is the first study to assess noninvasively and in vivo using MRI the curvature of the Achilles tendon during both passive and active plantarflexion movements. The dorsoventral tendon curvature amplifies the shortening of the plantarflexor muscles, resulting in a greater displacement of the tendon's insertion into the calcaneus compared with its origin.

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