Comparison of Foot Kinematics and Foot Plantar Area and Pressure Among Five Different Closed Kinematic Tasks.

BACKGROUND: Different closed kinematic tasks may present different magnitudes of knee abduction, foot pronation, and foot plantar pressure and area. Although there are plenty of studies comparing knee abduction between different tasks, the literature lacks information regarding differences in foot pronation and foot plantar pressure and area. We compared foot angular displacement in the frontal plane and foot plantar pressure and area among five closed kinematic tasks. METHODS: Forefoot and rearfoot angular displacement and foot plantar pressure and area were collected in 30 participants while they performed the following tasks: stair descent, single-leg step down, single-leg squat, single-leg landing, and drop vertical jump. Repeated-measures analyses of variance were used to investigate differences between tasks with α = 0.05. RESULTS: Single-leg squat and stair descent had increased foot total plantar area compared with single-leg landing (P = .005 versus .027; effect size [ES] = 0.66), drop vertical jump (P = .001 versus P = .001; ES = 0.38), and single-leg step down (P = .01 versus P = .007; ES = 0.43). Single-leg landing and single-leg step down had greater foot total plantar area compared with drop vertical jump (P = .026 versus P = .014; ES = 0.54). There were differences also in rearfoot and midfoot plantar area and pressure and forefoot plantar pressure. CONCLUSIONS: Differences in foot-striking pattern, magnitude of ground reaction force, and task speed might explain these findings. Clinicians should consider these findings to improve decisions about tasks used during rehabilitation of patients with foot conditions.

Validity and reliability of a 6-a-side small-sided game as an indicator of match-related physical performance in elite youth Brazilian soccer players.

The aims of this study were: (i) to compare the external and internal load during a 6-a-side small-sided game (6v6-SSG) according to age-group; (ii) to relate these parameters between the 6v6-SSG and official matches; and (iii) to test the reliability of the 6v6-SSG. A total of 51 Brazilian youth soccer players participated in this study (U11 [n = 16]; U13 [n = 10]; U15 [n = 9]; U17 [n = 8]; U20 [n = 8]). Three experiments were conducted. Experiment A: fifty-one U11 to U20 players were submitted to 6v6-SSGs (n = 10 games; two for each age-group). Experiment B: thirty-two players were randomized to also play official matches (n = 6 matches). Experiment C: thirty-five youth players played the 6v6-SSG twice for test and retest reliability analysis. External load was obtained using Global Positioning Systems and the internal load parameter was calculated through mean heart rate. Statistical approaches showed progressive increases in all parameters according to categories (U11< U13< U15< U17< U20; p < 0.05; ES = 0.42-23.68). Even controlling for chronological age, all parameters showed likely to almost certain correlations between 6v6-SSG and official matches (r = 0.25-0.92). Collectively, the proposed protocol indicates good reliability (CV% = 2.0-12.6; TE% = 2.3-2.7%; ICC = 0.78-0.90). This research suggests that the 6v6-SSG is an alternative tool to indicate match-related physical performance in youth soccer players.

Relationship between Procedural Tactical Knowledge and Specific Motor Skills in Young Soccer Players.

The purpose of this study was to investigate the association between offensive tactical knowledge and the soccer-specific motor skills performance. Fifteen participants were submitted to two evaluation tests, one to assess their technical and tactical analysis. The motor skills performance was measured through four tests of technical soccer skills: ball control, shooting, passing and dribbling. The tactical performance was based on a tactical assessment system called FUT-SAT (Analyses of Procedural Tactical Knowledge in Soccer). Afterwards, technical and tactical evaluation scores were ranked with and without the use of the cluster method. A positive, weak correlation was perceived in both analyses (rho = 0.39, not significant p = 0.14 (with cluster analysis); and rho = 0.35; not significant p = 0.20 (without cluster analysis)). We can conclude that there was a weak association between the technical and the offensive tactical knowledge. This shows the need to reflect on the use of such tests to assess technical skills in team sports since they do not take into account the variability and unpredictability of game actions and disregard the inherent needs to assess such skill performance in the game.