[1]
;
Samuel José Octavio Gaviria Alzate
[2]
Colombia
Colombia
This exploratory single-group study examined changes in 60-m sprint time and late-segment stride measures during six weeks of horizontal plyometric training. Nine male track-and-field athletes aged 12-13 years were assessed before and after a programme of 12 planned sessions. Sprint time was recorded with a smartphone application, and stride length, stride time and ground contact time were assessed from 120-Hz video over 40-48 m. Pre-test-post-test changes were analysed at the athlete level. Mean 60-m sprint time decreased from 10.46 ± 0.39 to 10.18 ± 0.28 s (mean change −0.282 s, 95% CI −0.479 to −0.085 s; p = .011; \(d_z\) = −1.10). Changes in stride length, stride time and ground contact time within the 40-48-m segment were inconclusive, with all confidence intervals including zero. Lower whole-sprint time was therefore accompanied by uncertain late-segment estimates, leaving the phase and mechanical basis of the change unresolved. The uncontrolled design and measurement uncertainty preclude attribution to the training programme. For youth sprint monitoring, total timing, phase-specific assessment and mechanical analysis provide complementary information; a change in overall performance does not, by itself, establish where or how that change occurred.
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