Effectiveness of Interval Training in Increasing Cardiorespiratory Endurance: A Systematic Review

Background. The rise in cardiovascular diseases has necessitated implementing effective interventions to improve cardiorespiratory endurance. Objectives. This systematic review aimed to evaluate the effectiveness of interval training (IT), particulary high-intensity interval training (HIIT), in enhancing cardiorespiratory endurance across various demographics. IT, characterized by high-intensity exercise followed by recovery periods, has gained attention for its potential to improve key cardiovascular markers such as VO₂max and cardiovascular efficiency. Materials and methods. A comprehensive literature search was conducted using multiple databases, adhering to the PRISMA guidelines. From 893 initially screened articles, eight studies met the inclusion criteria. These studies examined the effects of IT, especially HIIT, on cardiorespiratory endurance across various population groups, including sedentary individuals, athletes, and older adults. Metrics such as VO₂max and cardiovascular efficiency were the primary outcomes measured. Results. The findings indicate that IT, especially HIIT, consistently improves VO₂max and overall cardiovascular fitness in diverse populations. HIIT has been observed to outperform moderate-intensity continuous training (MICT) in generating faster cardiovascular adaptations. Despite its benefits, the high intensity of IT requires careful individualization to mitigate the risk of injury, particularly in populations with lower baseline fitness levels. Conclusions. This review concludes that IT is an effective and time-efficient method for improving cardiorespiratory endurance. It should be considered a viable option in both clinical and athletic populations. However, further research is recommended to investigate the long-term safety of HIIT in high-risk populations and to enhance adherence to these exercise protocols.