Supplementary Table S2. Characteristics of the studies included in the meta-analysis.

Author	Country	Year	Age (mean ± SD)	Sample size (test group / control group)	Intervention Details	Control	Outcome
Gao F.	China	2023	19.3 ± 3.5	15/15	10 weeks Speed Training	Regular Training	30 m sprint
Little T.	UK	2006	24 ± 3	18/18	3 times/week Flexibility Training	Regular Training	20 m sprint COD test
Sayers A.L.	USA	2008	19.35 ± 0.99	20/20	1 week Flexibility Training	Regular Training	30 m sprint
Sánchez-Sánchez J.	Spain	2024	22.9 ± 3.5	10/13	16 weeks Plyometric Jump Training	Regular Training	CMJ test COD test
Hostrup M.	Denmark	2019	22.8 ± 2.2	12/10	10 weeks, 3 times/week Endurance Training	Speed Training	30 m sprint
Nobari H.	Iran	2023	23.1 ± 2.8	10/9	13 weeks Speed Training	Plyometric Jump Training	20 m sprint, 30 m sprint COD test
Wallenta C.	Germany	2016	18.3 ± 2.0	6/6	6 weeks, 2 times/week Speed Training	Traditional Strength Training	CMJ test 5 m sprint
Rønnestad B.R.	Norway	2011	22 ± 2	7/7	10 weeks, 2 times/week Traditional Strength Training	Regular Training	40 m sprint 1RM test
Rønnestad B.R.	Norway	2006	23 ± 2	6/7	7 weeks, 2 times/week Traditional Strength Training	Regular Training	1RM test, SJ test, CMJ test 30 m sprint
Rey E.	Spain	2016	23.6 ± 2.7	10/9	6 weeks, 2 times/week Traditional Strength Training	Speed Training	CMJ test 30 m sprint
López-Segovia M.	Spain	2010	18.43 ± 0.6	19/18	16 weeks, 4 times/week Traditional Strength Training	Regular Training	CMJ test, 20 m sprint 30 m sprint
Moran J.	UK	2024	22.3 ± 2.7	8/8	8 weeks, 2 times/week Speed Training	Regular Training	CMJ test COD test
Gee T.I.	UK	2021	17.1 ± 0.6	9/8	10 weeks, 2 times/week Traditional Strength Training	Speed Training	40 m sprint COD test
Pareja-Blanco F.	Spain	2017	23.8 ± 3.5	8/8	6 weeks, 3 times/week Traditional Strength Training	Regular Training	1RM test, CMJ test 30 m sprint
Loturco I.	Brazil	2015	23.4 ± 3.6	12/11	4 weeks, 2 times/week Speed Training	Plyometric Jump Training	SJ test, 5 m sprint 20 m sprint
Loturco I.	Brazil	2017	21.7 ± 2.4	11/11	5 weeks, 2 times/week Speed Training	Plyometric Jump Training	5 m sprint, 20 m sprint 30 m sprint, COD test SJ test, CMJ test
Iaia F.M.	Italy	2015	18.5 ± 1	6/7	3 weeks, 3 times/week Speed Training	Endurance Training	20 m sprint 40 m sprint
Enright K.	UK	2015	17 ± 2	8/7	5 weeks, 2 times/week Traditional Strength Training	Endurance Training	1RM test, SJ test CMJ test
Kobal R.	Brazil	2017	18.9 ± 0.6	9/9	8 weeks, 2 times/week Traditional Strength Training	Speed Training	CMJ test, 20 m sprint COD test
Soares-Caldeira L.F.	Brazil	2014	22.6 ± 6.7	6/7	4 weeks, 2 times/week Speed Training	Regular Training	SJ test CMJ test
Keiner M.	Germany	2022	17.45 ± 0.52	11/11	40 weeks, 2 times/week Traditional Strength Training	Speed Training	1RM test, 20 m sprint COD test
Milanović Z.	Serbia	2014	18.5 ± 0.4	66/66	12 weeks, 4 times/week Speed Training	Regular Training	20 m sprint
Chelly M.S.	Tunisia	2010	19.1 ± 0.7	12/11	8 weeks, 2 times/week Speed Training	Regular Training	SJ test CMJ test
Bettariga F.	Italy	2022	25.4 ± 4.9	12/12	6 weeks, 2 times/week Plyometric Jump Training	Regular Training	5 m sprint, 20 m sprint 30 m sprint
Silva-Neto M.E.	Brazil	2023	19 ± 0.8	12/12	2 weeks Flexibility Training	Traditional Strength Training	CMJ test 30 m sprint
Dupont G.	France	2004	20.2 ± 0.7	22/22	10 weeks Speed Training	Regular Training	40 m sprint
McMorrow B.J.	Ireland	2019	24.0 ± 3.6	7/6	6 weeks, 1–2 times/week Speed Training	Traditional Strength Training	5 m sprint, 20 m sprint COD test
Hammami M.	Tunisia	2020	16.4 ± 0.2	14/12	10 weeks, 2 times/week Plyometric Jump Training	Regular Training	5 m sprint, 20 m sprint 30 m sprint, 40 m sprint COD test, SJ test, CMJ test
Hammami M.	Tunisia	2018	16.1 ± 0.5	14/12	8 weeks, 2 times/week Traditional Strength Training	Regular Training	SJ test, CMJ test, COD test, 1RM test 5 m sprint, 40 m sprint
Hammami M.	Tunisia	2018	16.8 ± 0.2	16/12	8 weeks, 2 times/week Traditional Strength Training	Regular Training	COD test, SJ test, CMJ test, 1RM test 5 m sprint, 20 m sprint 30 m sprint, 40 m sprint
Hammami M.	Tunisia	2017	16.2 ± 0.6	19/12	8 weeks, 2 times/week Traditional Strength Training	Regular Training	COD test, SJ test, CMJ test, 1RM test 5 m sprint, 20 m sprint 30 m sprint, 40 m sprint

Participants in all studies were soccer players. Data are presented as mean ± standard deviation (SD). Intervention Details specify the duration and weekly frequency of the training programs. Intervention and Control groups are categorized according to the specific nodes used in the network meta-analysis: Traditional Strength Training (high-load resistance), Plyometric Jump Training (ballistic/jump exercises), Speed Training, Endurance Training, Flexibility Training, and Regular Training. Outcomes include linear sprint times (5-40 m), vertical jump height (SJ = Squat Jump; CMJ = Countermovement Jump), maximal strength (1RM = One-Repetition Maximum), and change of direction ability (COD).