There are two main lines of inquiry in the literature on adherence and/or loyalty to the practice of physical activity and to health services: one focuses on the impact of perceived quality of sports and health services and satisfaction with these services on user loyalty, while the other concludes that users with more self-determined motivation at more advanced stages of physical activity display higher levels of physical activity and greater intentions to continue this activity. The objective of this study is to ascertain the impact of different dimensions of sports service quality on satisfaction and loyalty among users aged 12 to 16 years old and to identify any differences between adolescent users at more and less consolidated stages of physical activity. A total of 1717 minors with a mean age of 13.83 ± 1.32 years who practise organised physical activity at public sports centres in Nuevo León (Mexico), 51.5% of whom were boys, participated in the study. The model of structural equations linking quality, satisfaction, and loyalty displayed adequate indices. The results showed that the staff, specific activity, and user satisfaction are predictors of loyalty. Significant differences were only found between minors at consolidated and non-consolidated stages of physical activity in the relationship between service personnel and loyalty. In conclusion, human resources and their deployment are predictive of loyalty towards sports and health services among adolescents.

La actividad física y su práctica regular contribuyen a mantener un estilo de vida activo y saludable. Los responsables de las organizaciones deportivas deben comprender el comportamiento de los usuarios actuales y potenciales para establecer estrategias de promoción y consolidación de la actividad física. El objetivo de este trabajo es averiguar si en usuarios de servicios deportivos se encuentran asociaciones entre etapas de cambio y tipos de regulación, así como diferentes niveles de satisfacción, lealtad y cantidad de práctica de actividad física realizada en relación a las etapas de cambio. La población objeto de estudio fueron 4236 usuarios inscritos en centros deportivos públicos municipales de Monterrey (México). La edad media es 19.30±12.65, siendo el 55.7% hombres. Se utilizaron varios instrumentos para la investigación: el Behavioural Regulation in Exercise Questionnaire, Cuestionario de etapas de cambio, cuatro ítems del EPOD2, y cuatro ítems de una escala de intenciones futuras de usuarios servicios deportivos. Todos ellos contaban con la validez y fiabilidad necesarias. Se realizaron pruebas de comparación de medias, tablas de contingencia y correlaciones. Los resultados ponen de manifiesto que existe una asociación entre etapas de cambio, regulación, satisfacción, lealtad, tiempo medio de la sesión y frecuencia semanal de práctica, que los responsables de organizaciones, programas y actividades deportivas, deben conocer y utilizar para incrementar las tasas de práctica de actividad física y la consolidación del hábito entre los diferentes grupos poblacionales. Son los usuarios que se encuentran en las etapas de acción y mantenimiento los más satisfechos, los más leales y los que más actividad física realizan.  Abstract. Physical activity and regular practice help to maintain an active and healthy lifestyle. Sport organization leaders are to understand the behaviour of current and potential users to establish strategies for promoting and consolidating physical activity. The objective of this project is to discover whether sports service users find associations between stages of change and types of regulation, as well as different levels of satisfaction, loyalty and amount of physical activity practices completed out in relation to the stages of change. The population under study was 4236 users registered in municipal public sports centers in Monterrey (Mexico). The average age is 19.30±12.65, with 55.7 %males. Several instruments were used for the research: the Behavioural Regulation in Exercise Questionnaire, Stages of Change Questionnaire, four items from EPOD2, and four items from a scale of future intentions of users of sports services. All of them had the necessary validity and reliability. Mean comparison tests, contingency tables and correlations were performed. The results show that there is a partnership between stages of change, regulation, satisfaction, loyalty, average session time and weekly frequency of practice, which those responsible for organizations, programs and sports activities, should be aware of and use to increase rates of physical activity practice and the consolidation of habit among different population groups. It is the users who are in the stages of action and maintenance the most satisfied, the most loyal and the ones that perform the most physical activity.