Training Impulse as a Tool for Linking Exercise Dose to Health Outcomes in Adolescents: Evidence from Interval-Based Interventions

Background: The training impulse (TRIMP) method integrates exercise duration and intensity, yet its application in school-based health programs is limited. This study examined dose–response relationships between TRIMP and changes in body fat percentage (%BF), blood pressure, and cardiorespiratory fitness (CRF) in adolescents. Methods: 145 adolescents (69 males, 76 females; aged 15.01 ± 0.54 years) completed eight-week interval-based physical education programs: high-intensity interval training (HIIT) or high-intensity plyometric training (HIPT). Heart rate was continuously monitored, and TRIMP values were calculated across 16 sessions. Outcomes included %BF, systolic (SBP) and diastolic blood pressure (DBP), and maximal oxygen consumption (VO2max), assessed pre- and post-intervention. Results: HIIT elicited higher TRIMP than HIPT in females (η2p = 0.043). Linear dose–response patterns were identified (r = 0.18–0.36) (e.g., SBP in males, r = −0.38, p = 0.001; %BF in males, r = −0.36, p = 0.002). In males, one TRIMP unit reduced SBP by 1.8 mmHg (HIIT) and DBP by 1.6 mmHg (HIPT). In females, HIPT-derived TRIMP predicted reductions of ~0.6% in %BF and~0.9 mmHg in DBP. No significant associations were found for VO2max. Conclusions: TRIMP provides a feasible and sensitive tool for quantifying internal training load in adolescent interventions, linking exercise dose to measurable health benefits and supporting its application in preventive contexts.