Victoria Conn1, Sara Pecina1, David Elmer1, Jessica Washington2. 1Berry College, Mount Berry, GA. 2Florida Southern College, Lakeland, FL.

BACKGROUND: Ballet dancers are prone to fatigue-related hip injuries. They complete most of their training following a strenuous 30-minute barre warm-up. A lack of literature exists in evaluating the effects of the barre’s fatigue and changes in peak muscle activation patterns in movements that increase pressure within the hip joint. METHODS: Five participants (20.2±1.3 yrs; 165.4±7.3 cm; 58.8±7.9 kg) with prior ballet training were recruited through a collegiate dance company, with exclusion criteria being any other prior hip injury or surgery. Muscle activation was measured bilaterally on gluteus maximus, gluteus medius, sartorius, and biceps femoris via surface electromyography (EMG). A percentage of voluntary muscle contraction (%MVIC) on both the dominant and nondominant sides during two ballet movements, a grand ronde jambe en l'air (RJ) and a grand battement en croix (GB) were recorded both before and following a standardized 30-minute barre. Video recording was used to identify the phases of each movement. RESULTS: The movements were analyzed using a repeated measures factorial ANOVA with Tukey post hoc analysis of statistically significant results. Muscle activation was significantly greater pre- vs. post-testing in the GB (F(1,2519)=5.69, p=0.02), but not in the RJ (F(1,623)=0.83, p=0.36). Muscle activation of the gluteus medius was significantly greater than gluteus maximus in both the RJ (t= -9.20, p<0.001) and the GB (t= -16.31, p<0.001). Planned comparisons in muscle activation between similar phases in the GB were not statistically significant (t= -0.80-0.13, all p=1.00). CONCLUSIONS: There was an increase in muscle activation in GB movements before the barre but not in the RJ movement regardless of being before or after the barre. Repetitive external rotation of the leg within movements performed may account for the differences in the activation of gluteus medius and maximus. A lack of statistical significance within phases of nearly identical movement in the GB supports the theory that internal cues and coaching for completing the movement are different depending on the phase. There is no difference in the resulting peak muscle activation experienced thus, this would support current practices in how the instruction of this movement occurs. Further research with a larger participant count and including other similar movements can further evaluate how fatigue impacts these movements.

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