The Effect of Polarized Training Intensity Distribution on Maximal Oxygen Uptake and Work Economy Among Endurance Athletes: A Systematic Review.

High-intensity training (HIT) has commonly been the most effective training method for improvement in maximal oxygen uptake (VO) and work economy, alongside a substantial volume of low-intensity training (LIT). The polarized training model combines both low- and high-intensity training into a specific training intensity distribution and has gained attention as a comprehensive approach. The objective of this review was to systematically search the literature in order to identify the effects of polarized training intensity distribution on VO, peak oxygen uptake (VO), and work economy among endurance athletes. A literature search was performed using PubMed and SPORTDiscus. A total of 1836 articles were identified, and, after the selection process, 14 relevant studies were included in this review. The findings indicate that a polarized training approach seems to be effective for enhancing VO, VO, and work economy over a short-term period for endurance athletes. Specifically, a training intensity distribution involving a moderate to high volume of HIT (15-20%) combined with a substantial volume of LIT (75-80%) appears to be the most beneficial for these improvements. It was concluded that polarized training is a beneficial approach for enhancing VO, VO, and work economy in endurance athletes. However, the limited number of studies restricts the generalizability of these findings.