The objective was to analyze the changes in the horizontal force-velocity profile (HFVP) during the execution of repeated sprinting. Methods: Seventeen first-division Chilean soccer players completed a repeated sprint protocol consisting of eight sprints of 30 m with 25-s pauses between repetitions. The behavior of HFVP variables in each attempt was recorded from video recordings and analysis in the MySprint^® application. Results: Differences (p < 0.05) were found between sprints in the following: time (T), starting from sprint 5 (F = 35.6; η²p = 0.69); theoretical maximum speed (V0), starting from sprint 4 (F = 29.3; η²p = 0.51); maximum power (PM), starting from sprint 5 (F = 17; η²p = 0.52); rate of decrease in force index produced at each step (DRF), starting from sprint 1 (F = 3.20; η²p = 0.17); and RF10, starting from sprint 1 (F = 15.5; η²p = 0.49). In comparison, F0 and RFpeak did not present any differences (p > 0.05). Conclusion: The HFVP variables more sensitive to the effects of fatigue induced by an RSA protocol are those associated with the production of force at high speeds, being V0, DRF, and Pmax, while those that contribute to the generation of force at the beginning of the sprint, F0 and RFpeak, do not present essential variations.

Profile determination in field hockey is critical to determining athletes’ physical strengths and weaknesses, and is key in planning, programming, and monitoring training. This study pursued two primary objectives: (i) to provide descriptive data on sprinting, deceleration, and change of direction (COD) abilities and (ii) to elucidate the mechanical variables that influence sprint and COD performance in elite female field hockey players. Using radar and time-gate technology, we assessed performance and mechanical data from 30 m sprinting, deceleration, and COD tests for 26 elite female hockey players. A machine learning approach identified mechanical variables related to sprint and COD performance. Our findings offer a framework for athlete categorization and the design of performance-enhancing training strategies at the international level. Two pivotal mechanical variables—relative maximum horizontal force (F0) and maximum velocity (Vmax)—predominantly influence the times across all tested distances. However, the force–velocity profile (FVP) and horizontal deceleration do not influence the variance in the COD test outcomes. These insights can guide the design, adjustment, and monitoring of training programs, assisting coaches in decision making to optimize performance and mitigate injury risks for female hockey players.

Objective: To analyze and compare the viscoelastic properties of the Achilles and patellar tendons in elite athletes from different sports and determine whether there are significant differences attributable to sport-specific mechanical loading. Methods: This is a cross-sectional study in which a total of 105 elite athletes (33 females; 72 males) from 11 distinct sport disciplines (road cycling, roller hockey, karate, athletics, volleyball, taekwondo, speed skating, judo, archery, handball, and boxing) were evaluated at a national high-performance sports center. The viscoelastic properties (stiffness, relaxation, decrement, among others) of both tendons were measured bilaterally using a portable myotonometry device (Myoton Pro®, Myoton, Tallinn, Estonia). The primary outcome was tendon stiffness. Results: Significant differences were found in all measured variables for both tendons (p < 0.001) across sports, except for the decrement parameter in the patellar tendon (p = 0.45). The Achilles tendon demonstrated greater sport-specific adaptation, with stiffness showing the highest number of inter-sport differences (29 significant pairwise comparisons). Relaxation was the most variable parameter in the patellar tendon (9 significant comparisons). Conclusions: The findings demonstrate that the viscoelastic properties of the Achilles and patellar tendons differ significantly based on the sport practiced by elite athletes. This suggests that long-term, sport-specific mechanical loading plays a crucial role in tendon adaptation, leading to functional specialization. While the cross-sectional design precludes causal inference, these results provide valuable reference data for training prescription and injury prevention strategies tailored to specific athletic disciplines.