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Background and Objective: The reduction of shoe heel height can increase abdominal muscles activity. This study was conducted to evaluate the effect of low shoe heel height on the trunk muscle activity in young healthy females. Materials and Methods: In this quasi- experimental (Pre-post ) study, 48 healthy females were evaluated at University of social welfare and rehabilitation at 2009-2010. Females were selected in a non probability sampling manner and divided randomly into two groups. Subjects in the first group (12 females) were used low heel height shoes(less than 3.4 cm) for six months. The second group (12 female) was used standard heel shoes height (3.5-5 cm) for six months. After the end of the first step of study, females in first group were used standard heel shoes height (3.5-5 cm) for six months. The Kinsiologic Electromyography instrument was used to test the Electromyography magnitude of rectus abdominal and external oblique activity. Data was analyzed with Paired and independent T student and Kolmogorrov-Smirnov tests. Results: Muscle activity in first and second groups at external oblique was 9.72±3.15 μν and 7.87±2.47 μν and at rectus abdominal was 11.60±3.58 μν and 9.81±3.46 μν respectively. Muscle activity before and after using standard shoe heel height was significant (p<0.05). Conclusion: It seems that using lower heel shoes height increase the trunk muscle activity.

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Background and Objective: Foot pronation could increase injury occurrence during running. This study was done to investigate the effect of shoes with spikes containing two different stiffness on frequency spectrum of muscles during running in patients with pronated feet.
Methods: This quasi-experimental study was done on15 pronated feet runners with mean age of 27.2±6.4 years. Running was done in two conditions including double density and usual spikes Track and field shoes with between rests of 5 minutes. A wireless 8 channels electromyography system (UK) with bipolar electrodes was used to record the electrical activity of the lower limb muscles. Electrodes were located on tibialis anterior, medial gastrocnemius, vastus medialis, retus femoris, vastus lateralis, biceps femoris, semitendinosus, and gluteus medius muscles in accordance with SENIAM European protocol.
Results: Frequency content of tibialis anterior and gluteus medius at loading phase were significantly greater during running with spikes double density Track and field shoes compared with usual spike shoes (P<0.05). The frequency content of muscles did not demonstrate any significant differences during running with spikes double density Track and field shoes compared with usual spike shoes at both mid-stance and push-off phases.
Conclusion: The double density spikes track and field shoes increased frequency content of tibialis anterior and gluteus medius muscles during loading phase that could be associated with shock absorption.

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Background and Objective: Genu varum is a lower limb deformity. This study was done to evaluate the effects of shoe aging on the general and directional contraction of ankle muscles during running in females with genu varum.
Methods: This case-control study was done on 30 female students (15 individuals with genu varum degree 2 and 15 healthy individuals) using new and old sneakers for 6 months in the sports biomechanics laboratory of the University of Mohaghegh Ardabili, Iran. Each subject was given a new pair of sneakers, and after the initial data collection, the subjects were asked to use them in their daily activities for at least an hour a day for 6 months. Electrical muscle activity was recorded using surface electromyography.
Results: There was no significant difference in the general and directional contractions if ankle muscles during the running phases.
Conclusion: Shoe aging has no effect on ankle joint co-contractions.