Is Zone 2 good for cardiovascular health?

The evidence is still emerging, so it's too early to say for certain. "Zone 2 training" (low-intensity aerobic exercise performed just below the first lactate/ventilatory threshold) has become a popular longevity concept, but the best current evidence is considerably more skeptical of the specific claim than the popular narrative suggests. That's reflected in an evidence score of 38/100 for its role in cardiovascular health, drawn from 7 studies, with an estimated impact on longevity rated limited (22/100).