Research comparing the effects of different small-sided soccer game (SSG) training formats on physical adaptations remains scarce. This study aimed to compare small-format SSGs (SSG_SF: 1v1 to 3v3) with large-format SSGs (SSG_LF: 6v6 to 8v8) on vertical jump, change-of-direction (COD), linear speed and aerobic capacity adaptations in youth female soccer players over a six-week training period. Using a simple randomized, parallel, controlled design, players were assigned to one of two experimental groups (SSG_SF or SSG_LF) or a control group. Forty-five female youth players (15.7 ± 0.5 years old) competing at a developmental level participated in the study. All participants had a minimum of two years of playing experience and adhered to at least 90% of the intervention protocol. The experimental groups received two additional SSG sessions per week, while the control group maintained their regular training routines. Baseline and post-intervention assessments included countermovement jump height (CMJ), change of direction deficit in the 5-0-5 test (COD deficit), 30-meter linear speed, and final velocity in the 30-15 intermittent fitness test (VIFT). The SSG_SF group exhibited a significantly smaller CODdeficit compared to the control group (p = 0.026; d = 1.032, moderate) after the intervention. The SSG_LF group exhibited a significantly smaller 30-m sprint time compared to the control group (p = 0.044; d = 0.303, small). Both the SSG_SF (p = 0.039; d = 0.880, moderate) and SSG_LF (p = 0.026; d = 1.043, moderate) groups exhibited a significantly greater V_IFT compared to the control group. In conclusion, the findings suggest that SSG_SF may be more beneficial for improving COD ability, while SSG_LF could potentially be more effective for enhancing linear sprint performance. Both formats appear to have a positive impact on aerobic performance, though the extent of their effects might be similar. Coaches might consider these differences when selecting SSG formats, as each format could contribute differently to physical performance adaptations.

• SSGSF (1v1–3v3) significantly improved change of direction (COD) ability.

• SSGLF (6v6–8v8) led to greater improvements in linear sprint performance.

• Both formats effectively enhanced aerobic fitness (VIFT) compared to the control.