Zone 2 Training: Valuable, But Not the Whole Story

If you have spent any time on health and wellness podcasts or social media in the last few years, you’ve almost certainly heard about Zone 2 training. It’s the comfortably uncomfortable, conversational-pace cardio positioned as a cornerstone of metabolic health and longevity. And there’s real value in it. However, a recent narrative review published in Sports Medicine (Storoschuk et al., 2025) raises an important question worth sitting with: Is Zone 2 really the optimal training intensity for the general population, or have we been borrowing a page from the elite athlete playbook that doesn’t quite translate to everyday life?

Zone 2 training refers to low-intensity exercise performed below the lactate threshold, the kind of effort where you can still hold a conversation without gasping for air. Much of the enthusiasm around it comes from the observation that elite endurance athletes spend a large proportion of their training time at this intensity and tend to have exceptional mitochondrial and fat-burning capacity. The logic seems straightforward: if the fittest people on the planet train this way, shouldn’t we all? The problem, as the researchers point out, is that those athletes are also logging 15 to 25-plus hours per week of training. Most of us are working with a fraction of that time. When training volume is limited, intensity becomes a much more important lever. 

The review found that current evidence does not support Zone 2 as the optimal intensity for improving mitochondrial capacity or cardiorespiratory fitness. In fact, the molecular signaling pathways responsible for building new mitochondria, the cellular engines that power everything from a morning walk to a hard bike ride, respond in an intensity-dependent manner. Higher-intensity exercise tends to activate these pathways more robustly than low-intensity steady-state work, particularly given the time-constrained training windows most people actually have available. This does not mean Zone 2 is without value. It means it’s one tool in the toolbox, not the entire workshop. 

The practical takeaway here is not to abandon your easy morning runs or long weekend walks, as those are beneficial for recovery, joint health, mental well-being, and building an aerobic foundation. Instead, it is about ensuring your exercise plan includes deliberate doses of higher-intensity work. Think vigorous intervals on the bike or rower, tempo runs that push you above your comfort zone, or circuit-style resistance training that gets your heart rate up. This kind of work is where the outsized returns on cardiometabolic health tend to live, especially for those of us who cannot dedicate 20 hours a week to training. A well-balanced plan pairs strength training, higher-intensity cardiovascular efforts, and lower-intensity movement in a way that aligns with your goals, schedule, and current fitness level. 

At the end of the day, the best exercise plan is one that keeps you consistent, challenges you appropriately, and supports the way you want to live. Zone 2 training absolutely has a seat at the table, but so do the harder efforts that push your body to adapt in ways that easy movement alone cannot.  

Seeking support? Talk to an exercise physiologist or qualified trainer about how to structure a program that balances all of these elements – or plan a visit to Canyon Ranch with this goal in mind. Your mitochondria and your future self will thank you.