Assessing the Effect of High Intensity Interval Training and Fast Continuous Training on Resting Heart Rate and VO2 Max of Adult Athletes

Background: Cardiovascular fitness, measured through Resting Heart Rate (RHR) and Maximal Oxygen Uptake (VO2 Max), is critical for optimizing athletic performance. High-Intensity Interval Training (HIIT) and Fast Continuous Training (FCT) are two aerobic conditioning modalities widely used to improve cardiovascular efficiency, but their comparative effects remain insufficiently studied in adult competitive athletes. Aim: This study aimed to compare the effects of an 8-week HIIT and FCT program on RHR and VO2 Max in adult athletes, thereby evaluating the efficacy of each training modality in enhancing aerobic performance. Methods: A randomized controlled trial design was employed involving 90 adult athletes (45 males and 45 females, aged 21-26), randomly located into three groups: HIIT (n=30), FCT (n=30), and Control (n=30). RHR and VO2 Max were assessed during pre- and post-intervention using Polar H10 monitors and Vmax Encore Metabolic Cart, respectively. Data were analysed using ANCOVA (Analysis of Covariance) to control for pre-test differences, followed by Tukey’s post-hoc comparison. Results: Post-intervention results revealed statistically significant improvements in both RHR and VO2 Max across the training groups (p < 0.05). The HIIT group exhibited the most significant reduction in RHR (62.72 bpm) and the highest increase in VO2 Max (52.12 ml/kg/min), outperforming both FCT (RHR = 65.06 bpm; VO2 Max = 49.40 ml/kg/min) and the Control group (RHR = 70.32 bpm; VO2 Max = 41.28 ml/kg/min). Effect sizes were large for both RHR (η² = 0.950) and VO2 Max (η² = 0.982), indicating robust model fit. Conclusion: The findings confirm that both HIIT and FCT are effective in improving cardiovascular parameters among adult athletes, with HIIT demonstrating superior efficacy in a shorter duration. These results support the strategic incorporation of HIIT in training regimens aimed at maximizing aerobic performance and cardiovascular health.