High-intensity training, including resistance training (RT) and high-intensity interval training (HIIT), has demonstrated acute change cardiovascular on blood pressure (BP) and heart rate variability (HRV).This study aimed to analyse the acute effects of RT and HIIT on BP and HRV among young adults. This study used a crossover trial design conducted with 15 participants (19-25 years old). Participants underwent RT and HIIT sessions. BP systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) and HRV (SDNN, RMSSD, pNN50) were measured at baseline (pre), immediately post-intervention (post), and after 8 minutes of recovery (post 8 min). The results showed that both types of training significantly increased SBP and DBP immediately post-exercise (p < .001). DBP demonstrated a significant reduction at post 8 min for RT (p = .003). HRV indices showed significant reductions post-intervention in both training modalities (SDNN: RT, -11.6 ms; HIIT, -26.1 ms; p = .01). HIIT resulted in greater decreases in HRV parameters compared to RT (p = .01). In conclusions, RT and HIIT elicit significant acute changes in BP and HRV, with HIIT demonstrating a more pronounced impact on autonomic modulation. These findings highlight the differential cardiovascular responses to high-intensity training modalities and suggest potential implications for exercise prescription.