Mostly-Easy Polarized Training Beat Threshold Workouts on Endurance Markers, Not VO2max

The evidence is a randomized controlled trial published in Frontiers in Physiology in 2026 by Wang, He and Xie. It enrolled 32 male table tennis players, aged about 22 on average, who trained at a competitive club or university level. The authors call them Tier 2 athletes. That is a small, young, singlesport group, so the findings are early evidence, not a guide for the general public.

Players were randomly assigned to one of two plans. The polarized plan put 80% of training in Zone 1 (easy, below the first ventilatory threshold), 5% in Zone 2 and 15% in Zone 3 (hard, above the second threshold). The threshold plan put 50% in Zone 1, 45% in Zone 2 (around the second threshold) and 5% in Zone 3. Both groups did five supervised, on-court sessions a week, each 90 to 120 minutes. The researchers aimed to keep the internal workload similar between groups.

Ventilatory thresholds are points during rising effort where breathing changes in a way that marks a shift in how the body produces energy. The authors use them as markers of submaximal cardiorespiratory fitness, meaning fitness at efforts below your maximum.

According to the paper, the first threshold rose 9.8% in the polarized group and 6.4% in the threshold group (p = 0.03). The second threshold improved only in the polarized group, by 5.0%, while the threshold group changed by −1.0%. Heart rate recovery one minute after exhaustive exercise improved 11.7% in the polarized group (p = 0.040). Target accuracy at the end of a fatiguing test improved 7.8% (p = 0.041). The authors report that time to exhaustion on a table tennis–specific test also improved in the polarized group. They report no statistically significant improvements in these outcomes for the threshold group.

Maximal oxygen uptake, or VO2max, was the exception. There was no significant difference between groups in how it changed (p = 0.821). The authors had predicted comparable VO2max gains, so this matches their hypothesis. Put plainly, the polarized plan did not raise the ceiling more. It shifted the markers of submaximal fitness, and how quickly the heart settled afterward.

The study has limits. Participants and coaches could not be blinded to which plan they followed, though the assessors and the data analyst were blinded. All participants were men. The sample was small, and it was calculated for one main outcome, time to exhaustion. The trial lasted only eight weeks. The authors also frame their conclusion cautiously, saying polarized training "may be more effective" for these players.

For everyday adults, the practical question is how to divide easy and hard effort. This trial suggests that a mostly easy week with a small share of hard intervals can build endurance markers at least as well as a week spent largely at moderate-hard effort, at least in trained young athletes. It does not show the same would happen in older adults, women or people new to exercise. It also does not test long-term health outcomes.

The next step is replication in other sports, in women, and in non-athletes and older adults, ideally over longer periods and with health measures such as blood pressure and glucose control.

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