The posterior muscles in the lower leg are responsible for generating the forces that support walking, running, and jumping in humans. The Flexor Hallucis Longus (FHL), one of the main toe flexor muscles, originates from the lower posterior fibula, crosses over the posterior side of the ankle joint, and inserts into the sole of the foot at the base of the distal phalanx of the hallux [1]. By flexing the big toe, the FHL produces the final push that lifts the foot from the ground during the toe-off phase of the gait cycle and supports approximately 52% of an individual’s body weight at this instant [2]. Due to its role in flexing multiple joints associated with the foot, as well as stabilizing the foot, the FHL is commonly injured in people who frequently run and jump, such as ballet dancers. Using sEMG, muscle activity was acquired and analyzed from the FHL and Gastrocnemius to detect differences in activation between dancers and non-dancers.
Participants were designated as a dancer if a minimum of five years of formal dance training was reported through a participant questionnaire (N = 2) and non-dancer if no such training exists in their athletic history (N = 2). EMG Sensors were used to record raw sEMG data of the FHL and Gastrocnemius muscles. Participants began by completing a toe flexion hold to activate their FHL muscle, followed by a calf raise to activate their Gastrocnemius, in order to define the maximum voluntary contraction (MVC) of each muscle. Participants were then asked to complete a two minute relevé, a common ballet movement. EMG data was acquired twice during the balance, once in the initial seconds and once at the end of the two minutes to detect muscular fatigue in the FHL and Gastrocnemius.
For participants in the dancer group (N = 2), the FHL muscle was shown to fatigue a mean value of 7.2% during the relevé. For participants in the non-dancer group (N = 2), the FHL showed no signs of muscular fatigue during the two minutes. This difference in fatigue of the FHL between the participant groups highlights a difference in the muscle activation of the lower leg in people with dance training versus without while completing the relevé. This preliminary validation study showcases the potential that differences exist in the activation profiles of lower leg muscles between dancers and non-dancers.