Adolescents' Responses to High-Intensity Versus Standard Physical Education on Body Fat, Blood Pressure, and VO₂max:...

Background/Objectives: A persistent challenge in adolescent health promotion is insufficient exercise intensity during physical education (PE) lessons, limiting their potential to reduce cardiometabolic risk. National curricula further restrict teacher flexibility in implementing effective preventive strategies. Brief, high-intensity exercise protocols may provide a scalable solution within school systems. Although their general effectiveness is established, less is known about the variability of individual health responses, particularly across multiple outcomes and in relation to sex and intervention type. This study aimed to (1) assess the prevalence of responders (Rs) and non-responders (NRs) by sex and intervention type, (2) examine sex-by-intervention interactions, and (3) evaluate the likelihood of combined positive health responses across body fat percentage (BFP), systolic and diastolic blood pressure (SBP and DBP), and cardiorespiratory fitness (maximal oxygen consumption [VO₂max]). Methods: A total of 145 adolescents (aged 16 years; 48% males) from experimental school-based PE programs were analyzed. Two intervention modalities were implemented: high-intensity interval training (HIIT) and high-intensity plyometric training (HIPT). Rs were identified using typical error (TE) methodology. Statistical analyses included chi-squared tests (χ²), log-linear modeling, and odds ratios (ORs). Results: Chi-squared analyses indicated sex-by-intervention associations in the distribution of responder classifications for body fat percentage (BFP), systolic blood pressure (SBP), diastolic blood pressure (DBP), and VO₂max (χ² range = 8.26-10.10, p < 0.01). A simple association between intervention type and DBP was also observed (χ² = 6.49, p = 0.011). However, logistic regression analyses yielded odds ratios with wide 95% confidence intervals crossing the null value for all outcomes, indicating limited precision and the absence of statistically robust interaction effects. Multinomial logistic regression examining combined responses (two or three concurrent improvements) revealed no statistically significant main or interaction effects (all p > 0.05). Conclusions: Brief high-intensity exercise protocols delivered within school-based physical education were associated with favorable changes in adiposity, blood pressure, and cardiorespiratory fitness in a substantial proportion of adolescents. However, sex- and intervention-specific differences in responder classification were not statistically significant and should be interpreted as exploratory. Further adequately powered studies are required to determine whether individual characteristics meaningfully moderate responsiveness to specific high-intensity exercise modalities.