Impact of Psychosocial Intervention on Performance Determinants in Competitive Swimmers: Roles of Coach, Family, Environment, and Athlete Characteristics

(1) Background: This study analyzed the effects of intervention programs conducted between 2021 and 2025 as part of the "Aula UCLM-FNCLM" initiative-a partnership between a regional swimming federation and the university-on psychosocial factors in trained swimmers. This program presents interventions for swimmers, their coaches, their families, and their sports environment. (2) Methods: The effects of a 4-year intervention program on the Castilla-La Mancha swimming team, classified as Tier 3 (Tier 3: Highly Trained/National Level), according to the McKay classification framework (2021 team with 55 swimmers, 25 men, and 30 women; 17.3 ± 5.3 years), and the same sample in 2025 (42 swimmers, 19 men, 23 women-17 ± 2.8 years-and 11 dropouts). A self-perception questionnaire on performance in sport (CAED) was used. (3) Results: The results showed higher ratings (<i>p</i> < 0.001, <i>η²</i> = 0.30) from the swimmers of the 2025 CLM team in the coach factor, and moderate changes in the roles played by family (<i>p</i> < 0.05, <i>η</i>² = 0.12) and environment (<i>p</i> < 0.05, <i>η</i>² = 0.11). The only factor that did not improve was personal characteristics. (4) Conclusions: The UCLM-FNCLM program has contributed to improving the role of factors related to performance in sport (coach, family, and sports environment) in a cohort of regional-based swimmers.