Abstract
Extreme postures and imbalances in neuromuscular activity may place classical ballet dancers at higher risk of injury. Dance studio mirrors provide visual feedback by which a dancer can self-correct their body position and alignment, but have been suggested to negatively impact kinesthetic abilities and decrease performance capabilities. Thus, we investigated the effects of a mirror on muscle activity of the quadriceps, heart rate (HR), rating of perceived exertion (RPE), and qualitative performance. A lack of visual feedback would increase muscle activity of the quadriceps, HR, and RPE, and decrease self-reported perception of technical quality. 10 female participants completed a single leg balance, an adagio, and a jump task twice - once in each condition. Muscle activity of the vastus lateralis (VL) and vastus medialis oblique (VMO), as well as HR and RPE were assessed during each combination. Qualitative performance was assessed with an exit survey. No significant differences were found between conditions for RPE or HR in all three tasks (RPE: Balance p = 0.468, Adagio p = 0.191, Jumps p = 0.769; HR: Balance p = 0.409, Adagio p = 0.424, Jumps p = 0.244). No significant differences were found between conditions/tasks for peak, mean, and RMS sEMG. Dancers significantly ranked their artistic expression lower in a non-mirror condition (p = 0.018, Cohen's d = 0.775). No differences in muscle activity of the VMO and VL or vital signs of fatigue were found. Psychological implications of visual feedback, including dancer's perceived decrease in artistic expression without a mirror present, should be further explored in future studies.