Feasibility and Preliminary Effectiveness of a School-Based Speed- Related Fitness Program in Primary School Children: A Large Quasi-Experimental Study

Technical Summary: Feasibility and Preliminary Effectiveness of a School-Based Speed-Related Fitness Program

Problem Statement
Speed-related fitness is a critical component of children's health and skill-related physical fitness, routinely monitored in Chinese schools via the 50-meter sprint. While Speed, Agility, and Quickness (SAQ) training offers a structured framework for developing these capacities, existing evidence is predominantly derived from youth athletes and specialized sports contexts rather than ordinary primary school populations. There is a scarcity of pragmatic, school-based evidence demonstrating whether equipment-light, progressively organized SAQ activities can be effectively embedded into regular physical education (PE) lessons to improve sprint performance among unselected children, given constraints such as large class sizes, limited space, and minimal equipment.

Methodology
The study employed a large, two-group pretest-posttest quasi-experimental design with intact-class allocation conducted in a single primary school in Sichuan Province, China.

• Participants: 1,254 children (627 in the SAQ intervention group; 627 in the routine PE control group) from grades 1–6.
• Intervention: The SAQ group participated in an 8-week program integrated into regular PE lessons (twice weekly, ~35 minutes per session, totaling 16 sessions). The program utilized a station-based rotation model with small groups (6–8 children) and light, portable equipment (cones, agility ladders, soft low hurdles, batons). The curriculum progressed from reaction and starting initiation (Weeks 1–2) to acceleration mechanics and coordination (Weeks 3–5), and finally to integration and sprint maintenance (Weeks 6–8).
• Control: The control group continued with standard routine PE lessons, which included general warm-ups, basic running/jumping, and games but lacked the structured, technique-focused SAQ progression.
• Outcome Measures: The primary outcome was the 50-meter sprint time, measured via handheld stopwatch at pretest and posttest.
• Statistical Analysis: Analyses included paired and independent-samples comparisons, Analysis of Covariance (ANCOVA) with robust standard errors (adjusting for baseline time, age, and sex), linear mixed-effects models, and cluster-robust models using grade cohort as a proxy for higher-level grouping. Responder analyses defined "positive responders" (improvement > 0 s) and "meaningful responders" (improvement ≥ 0.30 s).

Key Contributions
This study extends SAQ research from elite youth sports to the context of ordinary primary school education. Its primary contribution is demonstrating that a structured, equipment-light SAQ framework can be feasibly delivered by regular PE teachers within standard lesson constraints to produce measurable improvements in speed-related fitness. The study provides preliminary evidence that such interventions do not require intensive sport-training resources to be effective.

Results

• Primary Outcome: The SAQ group demonstrated a significant improvement in 50-m sprint time, reducing their mean time by 0.41 seconds (95% CI: 0.34 to 0.49; p < 0.001). In contrast, the control group showed negligible change (0.06 s improvement; p = 0.15).
• Between-Group Difference: The difference in improvement between the SAQ and control groups was 0.36 seconds (95% CI: 0.25 to 0.47; p < 0.001), corresponding to a Hedges' g of 0.37.
• Adjusted Models: After adjusting for baseline time, age, and sex, the SAQ group remained significantly faster at posttest (β = -0.36 s; 95% CI: -0.44 to -0.28; p < 0.001).
• Responder Analysis: A significantly higher proportion of SAQ participants were "meaningful responders" (58.7% vs. 35.6%; OR = 2.57) and "positive responders" (70.3% vs. 51.4%; OR = 2.25) compared to controls.
• Subgroup Consistency: The intervention-associated benefit was observed across all baseline speed strata (faster, intermediate, slower), sexes, and grade levels. The largest standardized difference was observed in children with intermediate baseline speeds, though formal interaction tests were not statistically significant.
• Robustness: Sensitivity analyses excluding outliers and harmonizing recording precision confirmed the stability of the primary findings.

Significance and Claims
The authors conclude that an 8-week, physical-education-embedded SAQ program is associated with greater improvement in 50-m sprint performance compared to routine physical education. They characterize these findings as preliminary and pragmatic evidence supporting the feasibility of using equipment-light, progressively organized SAQ activities to support speed-related fitness in real-world school settings.

The paper explicitly states that due to the non-randomized, intact-class design and the lack of class identifiers in the dataset, the results should be interpreted as intervention-associated changes rather than definitive causal effects. The authors acknowledge limitations including potential selection bias, the inability to fully model class-level clustering, the use of handheld timing, and the lack of long-term follow-up. Consequently, they call for future cluster-randomized controlled trials with broader outcomes and longer follow-up to confirm effectiveness, elucidate mechanisms, and establish sustainability.