Adolescence marks a critical phase in the developmental journey of life, with mental health being a state of persistent psychological well-being and positivity. Engaging in sports actively contributes to enhancing the mental health status of teenagers, regulating their emotional states, dismantling psychological barriers, and bolstering their social adaptability. Within the scope of this study, a clustering algorithm is employed to conduct an empirical analysis on the impact of physical exercise on the mental health levels of adolescents, as well as to investigate the intermediary mechanisms at play. At the beginning of the outbreak of the epidemic, the overall level of teenagers' mental health decreased, and negative emotions such as depression and anxiety increased. In addition to emotional problems of different degrees, teenagers also showed physical and behavioral responses such as insomnia and fatigue, chest tightness and headache, and loss of appetite. Some studies also found that home-based teenagers did not have obvious anxiety, but had a high level of perceived stress, and perceived stress was positively correlated with anxiety. The normalization of epidemic prevention and control has had a great impact on teenagers' thoughts and behaviors, and even greater impact on teenagers with psychological problems. The research shows that in the face of the multi-point epidemic, the closed or semi closed management of the campus, and the continuous epidemic prevention and control work of the school, teenagers cannot travel freely and can only move in the campus every day. Some teenagers have bad emotions such as boredom, panic and anxiety, which bring many new problems and new situations to the physical and mental progress of teenagers and school management.