Fatigue effects on quadriceps and hamstrings activation in dancers performing drop landings.

Fatigue may reduce a dancer's ability to maintain the muscle synergies required for stable human movement. Therefore, fatigue presents as a potential risk factor for injury in dancers. Activation patterns of the quadriceps and hamstrings muscle groups in athletic populations have been consistently reported to alter in response to fatigue during landing tasks. It is unknown whether dancers demonstrate similar muscle activation patterns, nor if dancers respond to fatiguing protocols, with regard to muscle activation, in the same manner as their athletic counter-parts. The purpose of this study was to assess quadriceps and hamstrings activation levels in a cohort of dancers performing drop landings before and after completion of a dance-specific fatigue protocol, the High Intensity Dance Performance Fitness Test. Quadriceps and hamstrings co-contraction ratios significantly increased between pre- and post-fatigue conditions in a similar fashion to that reported in the literature. Therefore, the neuromuscular activation of the knee extensors and flexors in dancers changed in response to the dance-specific fatiguing protocol. Furthermore, quadriceps and hamstrings co-contraction ratios were substantially greater than previously reported in other athletic populations, due to low hamstrings activation levels. Future investigation of dancer biomechanical adaptations to fatigue would be beneficial to further examine the potential implications for injury risk.