Effects of perfect parallel foot positions in naturally out-toeing dancers : a study examining balance and associated muscular activation of the lower limb / Evelien Maes (2017)

The parallel position hip-width apart is considered to be a safe alignment for modern, jazz and contemporary dance training. However, many dancers are naturally out-toeing, and the effectiveness of the parallel position for these dancers has not yet been researched. The aim of this study is to examine balance and muscular activity in two variations of the parallel position hip-width apart: a perfect parallel position (PP), and a parallel position with natural out-toeing (NP).

Nineteen naturally out-toeing dance students volunteered. Surface electromyography (sEMG) recorded muscular activity during a bilateral and unilateral stance, and randomized balance tests in NP and PP with eyes-open (EO) and eyes-closed (EC) conditions. Participants rated each balance experience on a scale from 1 (extremely easy) to 10 (extremely difficult).

A longer balance time for NP was observed in each test category, with a significant difference in the bilateral EC test. Lower ratings on difficulty for NP were reported, however with no significance. Surface EMG data revealed six significant differences, all of them showing a higher muscular activity in PP. In the 10-second bilateral stance, the amplitude and magnitude of the right rectus femoris was higher; the right gastrocnemius medialis showed a higher amplitude in this test as well. In the 10-seconds unilateral stance, more muscle activity in PP occurred in the biceps femoris. Similar significant higher results in PP were further observed in the bilateral EO balance test, namely in the right and left soleus. A factorial ANOVA revealed no significant interactions. However, in all unilateral tests consistent ranks were observed for the gastrocnemius medialis (first rank, highest muscle activity) and soleus (second rank).

Overall, muscular activity patterns varied among the individuals, but was consistently higher for PP during the 10-second bilateral stance. More research on the parallel position is recommended, with quantifiable tools for balance and perceived difficulty, 3D analysis, larger sample sizes, a control group, maximum voluntary isometric contractions and if possible the use of invasive EMG.