Force-Velocity Profile in Middle- and Long-Distance Athletes: Sex Effect and Impact on Endurance Performance Determinants

Background: Muscle strength plays a critical role in the performance of middle- and long-distance athletes. However, the vertical force–velocity (F–V) profile has not been studied in this population. The objectives of this study were twofold: (i) to characterize the F–V profile in middle- and long-distance athletes and (ii) to explore its relationship with physiological and biomechanical performance variables. Methods: Thirty-nine highly trained athletes (13 middle-distance and 26 long-distance athletes), comprising men (18) and women (21), participated in this study. Each athlete performed a squat-jump to determine their F–V profile, followed by two 5 min bouts of low-intensity running and a graded exercise test to assess physiological and kinematic parameters. Results: Significant differences (p ≤ 0.05) were observed in maximal estimated power (Pmax) and jump height between middle- and long-distance female athletes (21.20 ± 4.78 W·kg−1 vs. 15.80 ± 2.83 W·kg−1; 26.00 ± 0.05 cm vs. 19.50 ± 0.03 cm), and between male and female long-distance athletes (19.70 ± 2.87 W·kg−1; 24.10 ± 0.02 cm). Stride length during low intensity running showed significant correlations with Pmax (r = 0.340) and jump height (r = 0.374). Pmax was positively associated with running economy (RE) (r = 0.396) and VO2max (r = 0.346), and negatively correlated with F–V imbalance (FVimb) (r = −0.531). Conclusions: Middle- and long-distance athletes demonstrate similar F–V profiles; however, middle-distance athletes exhibit a rightward shift, resulting in higher Pmax and jump height, particularly among women. Nevertheless, F–V profile characteristics display only weak associations with physiological and kinematic variables which directly influence performance.