Static and dynamic stretching are routinely used in pre-competition warm-ups, yet their application remains inconsistent due to ongoing debate over their relative efficacy. This systematic review examined the acute and chronic effects of static, dynamic, and combined stretching on athletes' sprint speed, jump performance, muscular power, agility, and flexibility. Following PRISMA 2020 guidelines, a search was conducted using the Scopus database, resulting in 259 initial records. After screening and quality appraisal using the four-domain FICO framework, 50 studies were retained for qualitative and thematic synthesis; meta-analysis was omitted due to high outcome measure heterogeneity. Findings indicate that a single session of static stretching generally impaired maximal strength and jump performance, whereas dynamic stretching acutely enhanced sprint, agility, and vertical jump outcomes. Multi-week stretching programs improved flexibility and selected strength metrics without acute performance deficits, while combining stretching with other modalities (e.g., foam rolling) yielded mainly additive but inconsistent benefits. Consequently, practitioners should prioritize dynamic warm-ups immediately prior to competition and reserve static stretching for dedicated flexibility sessions. Future research should focus on dosage standardization, sport-specific metrics, and chronic intervention designs.