Schrefl Anna Maria2026-03-032026-03-03https://boris-portal.unibe.ch/handle/20.500.12422/232270In dance, the feet play a central role in performance, enduring high, repetitive loading while simultaneously requiring extreme ranges of motion in ankle and metatarsophalangeal joints (MPJs). The ankle plantar flexors and toe flexor muscles (TFMs) contribute critically to stabilizing the foot, absorbing impact forces, and generating push-off in propulsion. Yet, systematic approaches for assessing and training these muscles remain underdeveloped. This dissertation pursued two complementary aims: (1) evaluation of the single-leg heel rise (SLHR) test as a field measure of ankle plantar-flexor function, and (2) assessment and training of TFMs in dancers. Six empirical studies were conducted. Four studies addressed the SLHR test. A systematic review of 12 studies (n = 427 dancers) revealed heterogeneous protocols, confirming the need for standardization. In the next step, a repeated-measures study (n = 21) established excellent test-retest and interrater reliability for repetitions, heel rise height, and total work (ICC = 0.91-0.96; CV = 3.8-10.2%) when using a standardized protocol that controlled heel rise height with a custom-made laser-pointer device. Minimal detectable change (MDC) values of 9 – 11% were defined, indicating thresholds for meaningful change. Correlation analyses showed no associations with maximal or reactive strength, whereas muscle near-infrared spectroscopy (mNIRS) identified moderate to strong associations between SLHR performance and post-exercise reoxygenation rate, supporting its interpretation as a measure of muscular endurance. Finally, a 36-week prospective cohort study (n = 70 adolescent ballet students) demonstrated that combining a 30-repetition threshold with movement-quality criteria was associated with the injury risk to the lower leg, knee, ankle, and foot, with poor eccentric control emerging as the strongest predictor of both medical-attention and time-loss injuries (OR = 4.49 and 2.96, p < .05). Two studies focused on TFM strength in adolescent ballet dancers. Reliability testing of a custom-made dynamometer demonstrated good to excellent agreement (ICC = 0.89-0.95; CV = 4.6-6.5%), with MDC thresholds of 10 – 14%. A randomized controlled trial (n = 49) demonstrated that a device-based, progressively loaded toe flexor training program elicited significant strength gains (15 - 16%, p < .001, η²p = 0.33 - 0.45), exceeding MDC thresholds, while heel rises on an inclined board provided no additional strength gains, and controls showed small declines. Horizontal jump performance improved in all groups, with the largest effects (r = .82) observed in the device group, whereas vertical jump outcomes showed only minor and inconsistent changes. Together, these findings established reliable, dancer-specific protocols for assessing ankle plantar flexor function and TFM strength and demonstrated that targeted, progressive foot-specific training can enhance TFM strength in adolescent dancers. They mark an important step toward integrating lower-leg and foot assessment and TFM strengthening as integral components of performance enhancement in dance.endance sciencefootbiomechanicsmovement qualityscreening600 - Technology::610 - Medicine & healththesis10.48620/94767