Kinetic factors differentiating mid-to-late sprint acceleration performance in sprinters and soccer players

High-speed running in soccer is an important skill, however, the underlying kinetic factors are not fully understood. Ground reaction forces from steps 8 to 24 of maximal-effort sprints were captured for 24 soccer players and 28 track and field athletes using 54 force plates. Correlations between discrete force variables and horizontal acceleration were assessed, and statistical parametric mapping revealed performance associations across entire waveforms. Track and field athletes produced higher forces (mean anteroposterior: 1.56 N•kg-1) across shorter contacts (0.101 s) than soccer players (1.27 N•kg-1, 0.110 s). Interestingly, the technical ability to apply force and the performance-differentiating parts of stance were similar across groups. Thus, practitioners should perhaps target physical (force production) rather than technical factors to improve soccer players’ sprint abilities

Differences in ground reaction waveforms between elite senior and junior academy sprinters during the block phase and first two steps

The block start and initial steps following block exit are fundamental aspects of sprinting and their development is key to junior athletes’ progression. This study assessed the difference in force production between elite senior (including two sub-10 s 100-m sprinters) and junior academy sprinters during the block phase and the first two steps of a sprint. Thirty-seven male sprinters (17 senior, 20 junior) performed a series of maximal effort 20–40 m acceleration from blocks on an indoor track, with the ground reaction forces produced during the block phase and first two steps measured using force platforms. Senior athletes produced better block-phase performances (average horizontal external power; 15.52 ± 1.48 W/kg, M ± SD) compared with the juniors (12.37 ± 2.21 W/kg; effect size ± 90% confidence interval = 1.28 ± 0.38). However, force production during the initial two steps was comparable across groups. Specifically, senior athletes exhibited higher relative force production and ratio of forces during the early (∼15–35%) block phase and higher anteroposterior forces during the transition from bilateral to unilateral pushing (58–62% of the block phase). Front foot force production was also found to differentiate senior and junior groups at rear block exit (∼55% of the block phase). This may be a required response to the greater centre of mass displacement in order to prevent over-rotation in the senior athletes during the front block pushing phase. Collectively, these results indicate that the progression of junior athletes is non-uniform across the block phase and subsequent two contacts, which should be considered when attempting to progress junior athletes towards senior ranks.</p

Using Computer Vision and Deep Learning Methods to Capture Skeleton Push Start Performance

This study aimed to employ computer vision and deep learning methods in order to captureskeleton push start kinematics. Push start data were captured concurrently by a markerbased motion capture system and a custom markerless system. Very good levels ofagreement were found between systems, particularly for spatial based variables (steplength error 0.001 ± 0.012 m) while errors for temporal variables (ground contact time andflight time) were within 1.5 frames of the criterion measures. The computer vision basedmethods tested in this research provide a viable alternative to marker-based motioncapture systems. Furthermore they can be deployed into challenging, real worldenvironments to non-invasively capture data where traditional approaches would fail

LOWER LIMB ASYMMETRY DURING THE SKELETON PUSH START

The aim of this study was to identify the presence and performance implication of asymmetry within the skeleton push start. Motion data were captured on 13 international skeleton athletes, using a custom 9-camera computer vision system. 6 maximal effort pushes were captured allowing the reconstruction of a 0–15 m push. Intra-limb differences for spatiotemporal variables and the change in velocity (ΔV) across a step were analysed. A negative relationship existed between 5 – 15 m split time and ΔV across a stride. Athletes who maximise their velocity across a stride were more likely to perform well in the skeleton push start. Though athletes employed different strategies based on inside and outside leg ΔV to achieve their performance outcome

Part 2 of the 11+ as an effective home-based exercise programme in elite academy football (soccer) players:A one-club matched-paired randomised controlled trial

Background:Although the 11+ is known to reduce injuries and improve performance in adolescent footballers, its duration presents a notable barrier to implementation. Hence, this study investigated injury and performance outcomes when 65 elite male academy footballers either performed Part 2 3x/week at training (TG) or at home (HG). Methods:Time to stabilisation (TTS), eccentric hamstring strength (EH-S) and countermovement jump height (CMJ-H) were collected 4 times during the 2019 football season. Linear mixed models were used to evaluate main and interaction effects of group and time. Bonferroni post-hoc tests were used to account for multiple comparisons. Differences in time loss and medical attention injuries were determined using a two-tailed Z test for a comparison of rates. Results:Relative to baseline, EH-S (HG 4.3 kg, 95% CI 3 to 5.7, p \u3c 0.001; TG 5.5 kg, 95% CI 4.3 to 6.6, p \u3c 0.001) and CMJ-H (HG 3.5 cm, 95% CI 2.2 to 4.7, p \u3c 0.001; TG 3.2 cm, 95% CI 2.2 to 4.3, p \u3c 0.001) increased, with no difference between groups observed at the end of the season. All injury outcomes were similar. Conclusion: Rescheduling Part 2 did not affect performance or increased injury risks in academy footballers

Part 2 of the 11+ as an effective home-based exercise programme in elite academy football (soccer) players:a one-club matched-paired randomised controlled trial

Background: Although the 11+ is known to reduce injuries and improve performance in adolescent footballers, its duration presents a notable barrier to implementation. Hence, this study investigated injury and performance outcomes when 65 elite male academy footballers either performed Part 2 3x/week at training (TG) or at home (HG). Methods: Time to stabilisation (TTS), eccentric hamstring strength (EH-S) and countermovement jump height (CMJ-H) were collected 4 times during the 2019 football season. Linear mixed models were used to evaluate main and interaction effects of group and time. Bonferroni post-hoc tests were used to account for multiple comparisons. Differences in time loss and medical attention injuries were determined using a two-tailed Z test for a comparison of rates. Results: Relative to baseline, EH-S (HG 4.3 kg, 95% CI 3 to 5.7, p &lt; 0.001; TG 5.5 kg, 95% CI 4.3 to 6.6, p &lt; 0.001) and CMJ-H (HG 3.5 cm, 95% CI 2.2 to 4.7, p &lt; 0.001; TG 3.2 cm, 95% CI 2.2 to 4.3, p &lt; 0.001) increased, with no difference between groups observed at the end of the season. All injury outcomes were similar. Conclusion: Rescheduling Part 2 did not affect performance or increased injury risks in academy footballers.</p

KINETIC FACTORS DIFFERENTIATING MID-TO-LATE SPRINT ACCELERATION PERFORMANCE IN SPRINTERS AND SOCCER PLAYERS

High-speed running in soccer is an important skill, however, the underlying kinetic factors are not fully understood. Ground reaction forces from steps 8 to 24 of maximal-effort sprints were captured for 24 soccer players and 28 track and field athletes using 54 force plates. Correlations between discrete force variables and horizontal acceleration were assessed, and statistical parametric mapping revealed performance associations across entire waveforms. Track and field athletes produced higher forces (mean anteroposterior: 1.56 N·kg-1) across shorter contacts (0.101 s) than soccer players (1.27 N·kg-1, 0.110 s). Interestingly, the technical ability to apply force and the performance-differentiating parts of stance were similar across groups. Thus, practitioners should perhaps target physical (force production) rather than technical factors to improve soccer players’ sprint abilities