Flexibility and jump are crucial capabilities for dancers but reaching good performance in
both is a challenge. Given that muscle-tendon stiffness (SMTU) might affect both these
capabilities and that muscle structure and concentration of female hormones across the
menstrual cycle may affect SMTU, this thesis aimed to determine the factors that might affect
SMTU and, therefore, physical performance in female dancers, especially through the
menstrual cycle. A piece of equipment to measure and train flexibility in highly flexible
participants was developed and validated. Then, fifteen young adult dance students under
oral contraception, eleven dance students without contraception and twenty non-dancers
without contraception completed several laboratory-based tests. Participants underwent
semitendinosus and rectus femoris ultrasound imaging, flexibility and vertical jump tests
including electromyography, kinematics, and pain mixed-method assessment. Participants
also provided serum/saliva samples on test days, including ovulatory, follicular and luteal
phases. An intervention involving stretching the most flexible limb allowed evaluation of
limb asymmetries and impact on function. Results showed no statistical structural and
functional differences between dancers and non-dancers. Asymmetries in flexibility, but
SMTU, between limbs, were found for all groups. Those asymmetries appear to not influence
jump performance. Four-series of passive constant torque stretch was not sufficient to
cause or increase any asymmetry or to affect SMTU. Stretching did not change jump height,
muscle activation and kinematics of vertical jumps. Dancers presented irregular menstrual
cycle with the change in hormone across the phases being associated with changes in key
outcome variables. Thus, oestrogen and relaxin appear to be positively correlated to muscle
laxity while progesterone is positively correlated to SMTU. This thesis’ results will provide data
for the development of training strategies to improve performance and potentially decrease
injuries in dancers. Additionally, contributing to research on hormonal factors in female
performance and, therefore, women’s health
