Search

Jiménez-Reyes, P, Garcia-Ramos, A, Párraga-Montilla, JA, Morcillo-Losa, JA, Cuadrado-Peñafiel, V, Castaño-Zambudio, A, Samozino, P, and Morin, J-B. Seasonal changes in the sprint acceleration force-velocity profile of elite male soccer players. J Strength Cond Res 36(1): 70–74, 2022—This study aimed to describe the seasonal changes in the sprint force-velocity (Fv) profile of professional soccer players. The sprint Fv profile of 21 male soccer players competing in the first division of the Spanish soccer league was evaluated 6 times: preseason 1 (September 2015), in-season 1 (November 2015), in-season 2 (January 2016), in-season 3 (March 2016), in-season 4 (May 2016), and preseason 2 (August 2016). No specific sprint capabilities stimuli other than those induced by soccer training were applied. The following variables were calculated from the velocity-time data recorded with a radar device during an unloaded sprint: maximal force (F 0), maximal velocity (v 0), Fv slope, maximal power (Pmax), decrease in the ratio of horizontal-to-resultant force (DRF), and maximal ratio of horizontal-to-resultant force (RFpeak). F 0 (effect size [ES] range = 0.83–0.93), Pmax (ES range = 0.97–1.05), and RFpeak (ES range = 0.56–1.13) were higher at the in-seasons 2 and 3 compared with both preseasons (p ≤ 0.006). No significant differences were observed for v 0, Fv slope, and DRF (p ≥ 0.287). These results suggest that relevant Fv profile variables may be compromised (F 0 more compromised than v 0) toward the end of the competitive season when specific sprint stimuli are not systematically applied. [ABSTRACT FROM AUTHOR]

The article offers information on the study conducted by the authors related to relation between sprint performance and technical ability to produce net positive horizontal force. It states that 12 males without any musculoskeletal injury or pain participated in the study. It mentions that one week before the experiment, they took a session in which they treadmill sprints until they got comfortable with the required running technique. It highlights that 100 meters (m) sprints were performed in which performance was measutred using a radar Stalker ATS System. It reports that ratio of forces (RF) speed relations were linear for all participants. It informs that force application technique is a determinant factor for 100 m sprint performance.

The article discusses research on fatigue during repeated sprints and variability in athletes' performance. The amplitude of reduction in performance, which participants reach by performing the number of sprints necessary to reach a target level of performance decrement, is quantified in 15 healthy men. Peak power output (PPO) and a fatigue index are used in the analysis.

The article discusses a study on the changes of one's running mechanics and spring-mass behavior during a 24-hour treadmill run (TR). It says that the subjects of the study were 10 ultraendurance male runners who have completed a minimum of 100-kilometer race. It tells that the runners used an instrumented treadmill dynamometer and that the contact and aerial times, which were identified through the ground reaction force (GRF) signals, were utilized to calculate for step frequency. It states that statistical methods implemented include Shapiro-Wilk normality test, analysis of variance (ANOVA), and Student-Newman-Keuls post hoc tests. Results reveal the kinematic, kinetic, and spring-behavior changes including increased leg stiffness, improved step frequency, and reduced loading rate.

The article presents the results of a study which compared the electromyographical data produced in subjects exercising with an elastic fitness device to data produced by performance of the bench press. A description of the flexible, multigrip elastic fitness device is provided, along with details of the experimental protocol. Evidence that the device could be useful for physical therapy is presented.

Purpose: The objective of this study is to quantify the contribution of the force-velocity (F-v) properties to bilateral force deficit (BLD) in ballistic lower limb push-off and to relate it to individual F-v mechanical properties of the lower limbs., Methods: The F-v relation was individually assessed from mechanical measurements for 14 subjects during maximal ballistic lower limb push-offs; its contribution to BLD was then investigated using a theoretical macroscopic approach, considering both the mechanical constraints of movement dynamics and the maximal external capabilities of the lower limb neuromuscular system., Results: During ballistic lower limb push-off, the maximum force each lower limb can produce was lower during bilateral than unilateral actions, thus leading to a BLD of 36.7% ± 5.7%. The decrease in force due to the F-v mechanical properties amounted to 19.9% ± 3.6% of the force developed during BL push-offs, which represents a nonneural contribution to BLD of 43.5% ± 9.1%. This contribution to BLD that cannot be attributed to changes in neural features was negatively correlated to the maximum unloaded extension velocity of the lower limb (r = -0.977, P < 0.001)., Conclusion: During ballistic lower limb push-off, BLD is due to both neural alterations and F-v mechanical properties, the latter being associated with the change in movement velocity between bilateral and unilateral actions. The level of the contribution of the F-v properties depends on the individual F-v mechanical profile of the entire lower limb neuromuscular system: the more the F-v profile is oriented toward velocity capabilities, the lower the loss of force from unilateral to bilateral push-offs due to changes in movement velocity.