INTRODUCTION Respiratory muscle training is the most commonly used method to revert respiratory muscle weakness; however, the effect of protocols based on non-respiratory maneuvers has not been adequately studied in the pediatric population. The objective of this study was to establish the effect of abdominal muscle training on respiratory muscle strength and forced expiratory flows in healthy adolescents. METHODS This was a quasi-experiment. The sample was made up of healthy adolescents divided into two groups: an experimental group who completed eight weeks of active abdominal muscle training, and an equivalent control group. The following indicators were measured: abdominal muscle strength, maximal inspiratory pressure, maximal expiratory pressure (MEP), peak expiratory flow, and peak cough flow, before and after protocol completion. A value of p < 0.05 was considered significant. RESULTS All studied outcome measures increased significantly in the experimental group but only MEP increased in the control group. In addition, a higher MEP was observed in the experimental group compared to the control group at the end of the protocol, together with a greater increase in MEP and peak expiratory flow. Finally, the increase in MEP was associated with an increase in cough peak flow in the experimental group but not in the control group. CONCLUSION After eight weeks of abdominal muscle training, MEP and peak expiratory flow increased in healthy (sedentary) adolescents. Such effects were associated with intervention-induced increases in cough peak flow.