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Robert W. Cox, Rodrigo E. Martinez, Russell T. Baker and Lindsay Warren

stationary arm with the proximal limb, and the movement arm with the distal limb. Ankle plantar flexion is measured with the fulcrum centered over the lateral malleolus, stationary arm aligned with the fibula, and movement arm aligned with the fifth metatarsal. 1 – 3 Inclinometry, an alternative to

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Antoine Langeard, Lucile Bigot, Gilles Loggia, Nathalie Chastan, Gaëlle Quarck and Antoine Gauthier

effects of ankle flexor training by NMES on the limits of stability are less known. Mignardot et al 14 reported that 4 weeks of NMES training of ankle plantar flexors could rehabilitate the limits of stability of prefrail older adults at levels comparable with the limits of stability of nonfrail older

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Andressa Busch Rocha Pereira and Renato Moraes

reduces the action of the force of gravity), torque at the ankle joint, and the muscle tone in the extensor chain that resists gravitational force. Among the muscle groups that make up the extensor chain with an antigravity function, the plantar flexor muscles constitute the most important group because

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Stacy E. Stamm and Loren Z.F. Chiu

When the rear- and forefoot are constrained, calcaneal plantar flexion may occur, deforming the longitudinal arch. Previous research has reported calcaneal motion relative to the tibia or forefoot; these joint rotations may not accurately describe rotation of the calcaneus alone. This investigation: (1) characterized the calcaneus and leg segment and ankle joint rotations during stance in gait, and (2) described the range of calcaneal plantar flexion in different structural arch types. Men (n = 14) and women (n = 16) performed gait in a motion analysis laboratory. From heel strike to heel off, the leg rotated forward while the calcaneus plantar flexed. Before foot flat, calcaneal plantar flexion was greater than forward leg rotation, resulting in ankle plantar flexion. After foot flat, forward leg rotation was greater than calcaneal plantar flexion, resulting in ankle dorsiflexion. Structural arch type was classified using the longitudinal arch angle. The range of calcaneal plantar flexion from foot flat to heel off was small in low (−2° to −8°), moderate in high (−3° to −12°), and large in normal (−2° to −20°) structural arches. Calcaneal plantar flexion in gait during midstance may reflect functional arch characteristics, which vary depending on structural arch type.

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Annika Kruse, Christian Schranz, Martin Svehlik and Markus Tilp

examination of the most commonly affected plantar flexor muscle-tendon unit and found alterations of both the gastrocnemius medialis and the Achilles tendon when compared with typically developing children. These alterations have included reduced muscle belly length ( 4 ) and volume ( 3 ). However, reports on

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Keitaro Kubo, Toshihiro Ikebukuro, Hideaki Yata, Naoya Tsunoda and Hiroaki Kanehisa

The purpose of this study was to compare the effects of resistance training on muscle and tendon properties between knee extensors and plantar flexors in vivo. Twenty healthy young men voluntarily participated in this study. The subjects were randomly divided into two training groups: knee extension group (n = 10) and plantar flexion group (n = 10). They performed five sets of exercises with a 1-min rest between sets, which consisted of unilateral knee extension for the knee extension group and plantar flexion for the plantar flexion group at 80% of 1 repetition maximum with 10 repetitions per set (4 days/wk, 12 wk). Before and after training, muscle strength, neural activation level (by interpolated twitch), muscle volume (by magnetic resonance imaging), and tendon stiffness (by ultrasonography) were measured. There were no differences in the training-induced increases in muscle strength, activation level, muscle volume, and tendon stiffness between knee extensors and plantar flexors. These results suggested that if the used protocol of training (i.e., intensity, repetition, etc.) were the same, there were no differences in the training-induced changes in muscle and tendon properties between knee extensors and plantar flexors.

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Thomas M. Lundin, Jon W. Feuerbach and Mark D. Grabiner

The purpose of this study was to determine the effect of plantar flexor and dorsiflexor fatigue on postural sway amplitude during unilateral, or one-legged, stance. It was hypothesized that plantar flexor and dorsiflexor fatigue would increase unilateral postural sway amplitude. Eight uninjured male subjects participated in pre- and postfatigue unilateral stability tests. Selected parameters describing medial-lateral (ML) and anterior-posterior (AP) postural sway were measured on a Chattecx Balance System before and after an isokinetic fatigue protocol. The fatigue protocol resulted in a significant increase in ML postural sway amplitude (p < 0.05) and an increase in AP sway amplitude (p = 0.065). Previously, links have been established between increased postural sway amplitude and ankle joint injury. Thus, fatigue of the plantar flexors and dorsiflexors, which increased postural sway amplitude, may render the ankle joint susceptible to injury. Induced ankle muscle fatigue may represent a valid paradigm to study the causes of traumatic ankle joint injury.

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Michael D. Ross, Shelly Hooten and Darren Moore

Objective:

To determine the relationship between asymmetries in lower leg girth and standing heel-rise after anterior cruciate ligament (ACL) reconstruction.

Design:

Single-group posttest.

Participants:

15 at a mean of 30 d after ACL reconstruction.

Measurements:

Lower leg girth and number of repetitions performed on the standing heel-rise test.

Results:

A significant decrease in lower leg girth and number of repetitions performed on the standing heel-rise test for the involved leg. There was also a low correlation between asymmetries in lower leg girth and standing heel-rise test (r = .25).

Conclusion:

Ankle plantar-flexor endurance should be considered when developing rehabilitation programs for the early stages after ACL reconstruction. In this study the ankle of the involved leg attained a significantly smaller angle of maximal standing plantar flexion, suggesting that ankle range of motion should also be assessed. Caution should be used in predicting standing heel-rise asymmetries from asymmetries in lower leg girth in ACL-reconstructed patients.

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Thomas Cattagni, Clément Billet, Christophe Cornu and Marc Jubeau

Context: Prolonged tendon vibration may induce muscle fatigue, as assessed by a decrease in maximal force production. It remains unknown, however, whether the decrease in muscle strength after prolonged Achilles tendon vibration is related to the vibration frequency. Objective: To assess the maximal capacity of plantar-flexor (PF) neuromuscular function before and after prolonged Achilles tendon vibration at low and high frequencies generated using a portable device. Design: Pre- and posttest intervention with control.Setting: University laboratory. Participants: 10 healthy men age 22.6 ± 4.0 y. Intervention: Each subject participated in 3 experimental sessions that were randomly distributed and separated by 1 wk. During each experimental session, 1 of the following vibration protocols was applied for 30 min: 40-Hz vibration, 100-Hz vibration, or no vibration (control protocol). Main Outcome Measures: Maximal-voluntary-contraction torque, voluntary activation level, twitch torque, maximal electromyographic activity, and maximal M-wave of PF muscles (measured before and after each vibration or control protocol).Results: Statistical analysis exhibited no significant effect of vibration protocol on the measured variables. Conclusions: The current study demonstrates that 30 min of Achilles tendon vibration at a low or high frequency using a portable stimulator did not affect the neuromuscular performance of the PF muscles. These results emphasize the limits of tendon vibration, whatever the frequency applied, for inducing neuromuscular fatigue.

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Junpei Sasadai, Yukio Urabe, Noriaki Maeda, Hiroshi Shinohara and Eri Fujii

Context:

Posterior ankle impingement syndrome is a common disorder in soccer players and ballet dancers. In soccer players, it is caused by the repetitive stress of ankle plantar flexion due to instep kicking. Protective ankle dorsiflexion taping is recommended with the belief that it prevents posterior ankle impingement. However, the relationship between ankle taping and ball-kicking performance remains unclear.

Objective:

To demonstrate the relationship between the restrictions of ankle taping and performance of an instep kick in soccer.

Design:

Laboratory-based repeated-measures.

Setting:

University laboratory.

Participants:

11 male university soccer players.

Intervention:

The subjects’ ankle plantar flexion was limited by taping. Four angles of planter flexion (0°, 15°, 30°, and without taping) were formed by gradation limitation. The subjects performed maximal instep kicks at each angle.

Main Outcome Measures:

The movements of the kicking legs and the ball were captured using 3 high-speed cameras at 200 Hz. The direct linear-transformation method was used to obtain 3-dimensional coordinates using a digitizing system. Passive ankle plantar-flexion angle, maximal plantar-flexion angle at ball impact, ball velocity, and foot velocity were measured. The data were compared among 4 conditions using repeated-measures ANOVA, and the correlations between ball velocity and foot velocity and between ball velocity and toe velocity were calculated.

Results:

Ankle dorsiflexion taping could gradually limit both passive plantar flexion and plantar flexion at the impact. Furthermore, limitation of 0° and 15° reduced the ball velocity generated by instep kicks.

Conclusion:

Plantar-flexion-limiting taping at 30° has a potential to prevent posterior ankle impingement without decreasing the ball velocity generated by soccer instep kicks.