Key Takeaway
Resisted sprint training effectively improves acceleration in young soccer players (SMD -0.41) but is not superior to unresisted sprint training
Summary
This systematic review and meta-analysis examined the effects of resisted sprint training (RST) using both weighted vests and sleds on sprint performance in young soccer players under 20 years of age. The authors stratified results by equipment type (vest vs sled) and resistance magnitude (above and below 20% body mass).
The analysis found meaningful improvements in the acceleration phase (SMD = -0.41) and full sprint time (SMD = -0.36), but negligible, non-significant improvements in the maximum-velocity phase (SMD = -0.25). Interestingly, vest training outperformed sled training for acceleration (vest SMD = -0.70 vs sled SMD = -0.27), while sled training produced slightly better full sprint improvements (sled SMD = -0.44 vs vest SMD = -0.26).
Both lighter (<20% BM) and heavier (>=20% BM) loads produced similar acceleration benefits, with lighter loads showing a slight edge (SMD = -0.55 vs -0.31). Critically, when compared to unresisted training control groups, no significant differences were found, suggesting that while RST is effective, it does not offer clear superiority over conventional sprint training in this population.
Methods
- Systematic review and meta-analysis of controlled studies
- Population: young soccer players under 20 years old
- Compared vest-based and sled-based resisted sprint training
- Results stratified by equipment type and resistance magnitude (<20% vs >=20% BM)
- Standardized mean differences (SMD) calculated for sprint phases
- Included both acceleration, full sprint, and maximum-velocity outcomes
Key Results
- Acceleration phase: SMD = -0.41 (meaningful improvement)
- Full sprint time: SMD = -0.36 (modest improvement)
- Maximum-velocity phase: SMD = -0.25 (non-significant)
- Vest training better for acceleration (SMD = -0.70 vs sled SMD = -0.27)
- Sled training better for full sprint (SMD = -0.44 vs vest SMD = -0.26)
- Light loads (<20% BM) SMD = -0.55; heavier loads (>=20% BM) SMD = -0.31
- No significant differences vs unresisted training control groups
Limitations
- Limited to young soccer players, may not generalize to other sports or adults
- Heterogeneity in training protocols across included studies
- Not superior to unresisted sprint training in direct comparisons
- Cannot determine optimal loading dose for this specific population
- Few studies examined long-term effects or in-season programming