Objective: This study evaluated the effect of a Transformation through Triathlon after school programme in promoting health status, academic motivation and socioemotional development in at-risk girls aged 11-14 years attending middle school in the USA. Design: A phenomenological approach was employed with elements of grounded theory to analyse data from focus group interviews for insights into programmatic outcomes. Setting: Participants (N = 29) were invited to participate in the 20-week after school triathlon training and health promotion programme, and some volunteered for interviews. They were selected based on school personnel characterising them as at-risk for low self-esteem, a sedentary lifestyle, and/or classification as overweight. The programme combined empowerment lessons, nutrition and health science education twice per week from mid-March until June 2014, and after-school activities such as triathlon-specific training and group fitness classes three times per week through until July, with a culminating youth sprint triathlon (300-yard swim, 7-mile bike ride, and 1.5-mile run). Method: Focus groups of five to six girls were convened immediately after programme completion, and again 12 weeks later. A semi-structured interview protocol was developed with questions regarding individual goals, perceptions of programme structure and setting, and programmatic effects related to academics and motivation. Results: Qualitative analysis revealed that confidence, interest, and self-determination motivational constructs positively influenced goal setting, strategies, health, fitness, motivation, and academic achievement. Conclusion: Intervention participants learned to self-regulate their learning and set goals that promoted fitness, academic achievement, better attitudes, and resilience. After school community and family inclusive programmes with a structured fitness component increase confidence, self-determination and academic achievement though social support structures.