Identification of Individual Muscle Length Parameters from Measurements of Passive Joint Moment Around the Ankle Joint

The neuromuscular adaptations in response to muscle stretch training have not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity, and spinal motoneuron excitability were examined during standardized plantar flexor stretches after 3 wk of twice daily stretch training (4 × 30 s). No changes were observed in a nonexercising control group ( n = 9), however stretch training elicited a 19.9% increase in dorsiflexion range of motion (ROM) and a 28% increase in passive joint moment at end ROM ( n = 12). Only a trend toward a decrease in passive plantar flexor moment during stretch (−9.9%; P = 0.15) was observed, and no changes in electromyographic amplitudes during ROM or at end ROM were detected. Decreases in Hmax:Mmax(tibial nerve stimulation) were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed. Muscle and fascicle strain increased (12 vs. 23%) along with a decrease in muscle stiffness (−18%) during stretch to a constant target joint angle. Muscle length at end ROM increased (13%) without a change in fascicle length, fascicle rotation, tendon elongation, or tendon stiffness following training. A lack of change in maximum voluntary contraction moment and rate of force development at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. Thus, increases in end ROM were underpinned by increases in maximum tolerable passive joint moment (stretch tolerance) and both muscle and fascicle elongation rather than changes in volitional muscle activation or motoneuron pool excitability.

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Estimation of Passive Ankle Joint Moment during Standing and Walking

Journal of Applied Biomechanics ◽

10.1123/jab.21.1.72 ◽

2005 ◽

Vol 21 (1) ◽

pp. 72-84 ◽

Cited By ~ 8

Author(s):

Tetsuro Muraoka ◽

Tadashi Muramatsu ◽

Daisuke Takeshita ◽

Hiroaki Kanehisa ◽

Tetsuo Fukunaga

Keyword(s):

Muscle Contraction ◽

Ankle Joint ◽

Joint Moment ◽

Medial Gastrocnemius ◽

Joint Motion ◽

Fascicle Length ◽

Passive Joint ◽

Muscle Fascicle ◽

Ankle Joint Moment ◽

Ankle Joint Motion

This study estimated the passive ankle joint moment during standing and walking initiation and its contribution to total ankle joint moment during that time. The decrement of passive joint moment due to muscle fascicle shortening upon contraction was taken into account. Muscle fascicle length in the medial gastrocnemius, which was assumed to represent muscle fascicle length in plantarflexors, was measured using ultrasonography during standing, walking initiation, and cyclical slow passive ankle joint motion. Total ankle joint moment during standing and walking initiation was calculated from ground reaction forces and joint kinematics. Passive ankle joint moment during the cyclical ankle joint motion was measured via a dynamometer. Passive ankle joint moment during standing and at the time (Tp) when the MG muscle-tendon complex length was longest in the stance phase during walking initiation were 2.3 and 5.4 Nm, respectively. The muscle fascicle shortened by 2.9 mm during standing compared with the length at rest, which decreased the contribution of passive joint moment from 19.9% to 17.4%. The muscle fascicle shortened by 4.3 mm at Tp compared with the length at rest, which decreased the contribution of passive joint moment from 8.0% to 5.8%. These findings suggest that (a) passive ankle joint moment plays an important role during standing and walking initiation even in view of the decrement of passive joint moment due to muscle fascicle shortening upon muscle contraction, and (b) muscle fascicle shortening upon muscle contraction must be taken into account when estimating passive joint moment during movements.

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Changes in the collagen fibre orientation and stiffness of the connective tissues surrounding individual muscle fibres with muscle length

Journal of Biomechanics ◽

10.1016/0021-9290(94)90925-3 ◽

1994 ◽

Vol 27 (6) ◽

pp. 646

Author(s):

Peter P. Purslow ◽

John A. Trotter

Keyword(s):

Fibre Orientation ◽

Collagen Fibre ◽

Muscle Length ◽

Muscle Fibres ◽

Connective Tissues ◽

Individual Muscle

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Measurement of muscle length-related electromyography activity of the hip flexor muscles to determine individual muscle contributions to the hip flexion torque

SpringerPlus ◽

10.1186/2193-1801-3-624 ◽

2014 ◽

Vol 3 (1) ◽

pp. 624 ◽

Cited By ~ 8

Author(s):

Takumi Jiroumaru ◽

Toshiyuki Kurihara ◽

Tadao Isaka

Keyword(s):

Muscle Length ◽

Individual Muscle ◽

Flexor Muscles ◽

Hip Flexion ◽

Hip Flexor

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Mechanism of thixotropic behavior at relaxed joints in the rat

Journal of Applied Physiology ◽

10.1152/jappl.1987.62.4.1615 ◽

1987 ◽

Vol 62 (4) ◽

pp. 1615-1621 ◽

Cited By ~ 16

Author(s):

A. W. Wiegner

Keyword(s):

Ankle Joint ◽

Soleus Muscle ◽

Short Range ◽

Time Course ◽

Muscle Length ◽

Muscle Preparation ◽

Pentobarbital Sodium ◽

Stiffness Properties ◽

Thixotropic Behavior ◽

Human Joints

When a relaxed joint is subjected to a small sinusoidal torque, the amplitude of the steady-state displacement response is increased up to severalfold by a transient larger perturbation. The original state, in which the relaxed joint is unexpectedly stiff, is restored by several seconds of inactivity. This thixotropic phenomenon has previously been observed in a variety of human joints. We have now investigated the mechanism of thixotropic behavior at relaxed joints in rats anesthetized with pentobarbital sodium, by using a series of preparations including the intact ankle joint, a blood-perfused soleus muscle preparation, an isolated soleus muscle, and ankle joint isolated by severing all muscular attachments. Thixotropic behavior was observed in all intact, isolated muscle, and isolated joint preparations. The contribution of the joint to thixotropic behavior was comparable to, and at times exceeded, the contribution of muscle. We also analyzed the short-range stiffness properties of relaxed, blood-perfused soleus muscles and found them to be similar to thixotropy with respect to range of action (0.2–0.3% of muscle length), elastic modulus (approximately 4 kg/cm2), and time course for redevelopment (time constant = 2.5 s at 34 degrees C). Thus thixotropic behavior at a relaxed joint may be attributed both to the joint structures and to short-range stiffness of muscles acting at the joint.

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