Exercise at a relatively low effort for a long time is now called Zone 2. In it someone can carry a slightly strained conversation while exercising. This is becoming popular as the right way to exercise and is the best way to build a sustained and stable way to health. It stimulates our cell's powerhouses say experts and converts into better health and athletic fitness. It is the secret of great elites that helps them faster for longer, says an expert at UT Medical Center in Dallas. As we age we lose mitochondrial function so it is even more important to so this kind of exercise. Mitochrondrial refers to the mitochondria, the battery packs in our cells that convert fat and cars into energy. Zone 2 exercise stimulates mitochondria effectively. About 80% of training can be Zone 2, and 20% at higher intensity to achieve the right balance.