Jamie L Leonard

University of Toledo, Toledo, Ohio, United States

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Publications (2)3.66 Total impact

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    ABSTRACT: Our purpose was to assess the effect of foot intrinsic muscle fatigue on pronation, as assessed with navicular drop, during static stance. Twenty-one healthy young adults participated. Navicular drop was measured before and after fatiguing exercise of the plantar foot intrinsic muscles. Surface electromyography of the abductor hallucis muscle was recorded during maximum voluntary isometric contractions (MVIC) in order to find the baseline median frequency (MedF). Subjects then performed sets of 75 repetitions of isotonic flexion contractions of the intrinsic foot muscles against a 4.55 kg weight on a custom pulley system. After each set an MVIC was performed to track shifts in MedF. After a MedF shift of at least 10%, navicular drop measurements were repeated. Subjects exhibited 10.0+/-3.8mm of navicular drop at baseline and 11.8+/-3.8mm after fatigue (p<0.0005). The change in navicular drop was significantly correlated with change in MedF (r=.47, p=.03). The intrinsic foot muscles play a role in support of the medial longitudinal arch in static stance. Disrupting the function of these muscles through fatigue resulted in an increase in pronation as assessed by navicular drop.
    Journal of Electromyography and Kinesiology 07/2008; 18(3):420-5. DOI:10.1016/j.jelekin.2006.11.004 · 1.65 Impact Factor
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    ABSTRACT: Exposure of the human body to cold is perceived as a stressor and results in a sympathetic response geared at maintaining core temperature. Application of ice to the periphery may lead to a decrease in core temperature, which may counteract the therapeutic effects of cryotherapy. To determine if core temperature is lowered by the application of an ice bag to the ankle joint complex. A within-subjects, repeated-measures design. The University of Virginia General Clinical Research Center. Twenty-three healthy adults aged 19 to 39 years. Subjects were admitted to the hospital on 2 separate occasions. During one admission, subjects had a 20-minute ice treatment applied to their ankles; in the other admission, a bag of marbles was applied. Temperature measurements were recorded at 6 time intervals: baseline (before ice application), immediately after ice application, 10 and 20 minutes after ice application, and 10 and 20 minutes after ice removal. We measured core temperature and ankle and soleus muscle surface temperatures. A mixed-effects model analysis of variance with repeated measures was used to determine if differences existed in core temperature and ankle and soleus surface temperatures between conditions (cryotherapy and control) and over time. Core temperature did not change after ice application or ice removal (P > 0.05). The average core temperatures during the cryotherapy and control conditions were 36.72 degrees C +/- 0.42 degrees C and 36.45 degrees C +/- 1.23 degrees C, respectively. A 20-minute cryotherapy treatment applied to the ankle did not alter core temperature.
    Journal of athletic training 04/2006; 41(2):185-8. · 2.02 Impact Factor