JEB desktop wallpaper calendar 2016

JEB desktop wallpaper calendar 2016

SUMMARY

Wearing high heels (HH) places the calf muscle–tendon unit (MTU) in a shortened position. As muscles and tendons are highly malleable tissues, chronic use of HH might induce structural and functional changes in the calf MTU. To test this hypothesis, 11 women regularly wearing HH and a control group of 9 women were recruited. Gastrocnemius medialis (GM) fascicle length, pennation angle and physiological cross-sectional area (PCSA), the Achilles' tendon (AT) length, cross-sectional area (CSA) and mechanical properties, and the plantarflexion torque–angle and torque–velocity relationships were assessed in both groups. Shorter GM fascicle lengths were observed in the HH group (49.6±5.7 mm vs 56.0±7.7 mm), resulting in greater tendon-to-fascicle length ratios. Also, because of greater AT CSA, AT stiffness was higher in the HH group (136.2±26.5 N mm–1 vs 111.3±20.2 N mm–1). However, no differences in the GM PCSA to AT CSA ratio, torque–angle and torque–velocity relationships were found. We conclude that long-term use of high-heeled shoes induces shortening of the GM muscle fascicles and increases AT stiffness, reducing the ankle's active range of motion. Functionally, these two phenomena seem to counteract each other since no significant differences in static or dynamic torques were observed.

  • LIST OF SYMBOLS AND ABBREVIATIONS

    AT
    Achilles' tendon
    CSA
    cross-sectional area
    CTRL
    control
    E
    Young's modulus
    GL
    gastrocnemius lateralis muscle
    GM
    gastrocnemius medialis muscle
    HH
    high heels
    K
    tendon stiffness
    Lf
    fascicle length
    Ltend
    tendon length
    MA
    moment arm
    MRI
    magnetic resonance imaging
    MTU
    muscle–tendon unit
    MVC
    maximum voluntary contraction
    PCSA
    physiological cross-sectional area
    SOL
    soleus muscle
    TA
    tibialis anterior muscle
    vmax
    maximum contraction velocity
    vopt
    optimal contraction velocity
    θ
    pennation angle
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