New data shows that Zone 2 training is the common thread linking health and performance in runners of all levels
Runners at all levels seem to have an edge when it comes to longevity. Studies suggest that elite runners—those capable of running a sub-four-minute mile—live nearly five years longer than the general population. But you don’t have to be an Olympian to reap the benefits. Large-scale reviews indicate that regular runners have up to a 40% lower risk of premature death and, on average, live about three years longer than their non-running peers. So what can we learn from their training habits for our own lives?
A study published recently in Sports Medicine analyzed 92 sub-elite marathon training plans and found that more than 65% of total running time was spent in Zone 2. It’s not just a tool for longevity; it’s the foundation of elite endurance training. The best runners in the world don’t grind away at high intensities day after day. Instead, they spend the majority of their training time at a controlled, easy effort, prioritizing aerobic development over short-term gains. This principle doesn’t just apply to elite athletes—it’s just as relevant to recreational runners looking to improve their performance and healthspan.
Expanding on these insights, a new study published in Sports Medicine analyzed training data from over 120,000 runners who logged their workouts on Strava, providing an unprecedented look at how training habits translate to race outcomes. The biggest predictor of marathon performance wasn’t speed workouts or high-intensity intervals—it was how much easy running runners did. Sub-2:30 marathoners averaged 67 miles per week, nearly three times the mileage of those finishing slower than 4:30. Interestingly, runners of all abilities completed similar amounts of hard training; the key difference was that the fastest runners accumulated vastly more low-intensity miles. This reinforces the importance of steady aerobic development, pointing once again to Zone 2 training as a fundamental principle for both longevity and performance.
The Rise of Zone 2 Training
Zone 2 training is having a moment. It’s not just runners and cyclists embracing it—longevity researchers, health podcasters, and exercise physiologists are all touting the benefits of steady, moderate-intensity workouts. Some of the most vocal proponents, call it the cornerstone of a long and healthy life, highlighting its ability to improve fat oxidation, mitochondrial function, and heart efficiency. The concept is simple: training at a pace where you can still hold a conversation—pushing just enough to stimulate adaptations but not so hard that you accumulate excessive fatigue—builds the endurance engine that sustains long-term health and fitness.
As someone who has completed several marathons, I’ve followed a similar philosophy. While many training programs include a mix of paces, I leaned heavily into Zone 2—up to 90% of my training. The goal wasn’t just to build endurance but to prevent injury, accumulate a reliable aerobic base, and make training more enjoyable. This approach allowed me to sustain high mileage without breaking down and, ultimately, improved my race-day performance.
The Science of Zone 2: Building a Better Heart and Metabolism
At its core, Zone 2 training is about efficiency. Running, cycling, or hiking at a steady, controlled effort allows your body to generate energy primarily through fat oxidation rather than carbohydrate metabolism. This keeps blood lactate levels stable, allowing for sustained effort without early fatigue. But the real magic happens at the cellular level. Zone 2 training stimulates mitochondrial biogenesis, increasing both the number and efficiency of mitochondria—the tiny power plants responsible for producing energy. More mitochondria mean greater ATP production, delaying fatigue and making faster paces feel easier. This is why top endurance athletes dedicate so much time to aerobic base-building: without it, high-intensity workouts wouldn’t be nearly as effective. From a cardiovascular perspective, Zone 2 strengthens stroke volume—the amount of blood the heart pumps per beat—leading to a lower resting heart rate, improved vascular elasticity, and enhanced cardiovascular resilience. These adaptations explain why Zone 2 training is now widely viewed as an investment in heart health, reducing the risk of heart disease, hypertension, and metabolic disorders like insulin resistance.
Finding Your Zone 2 (Without a Lab Test)
Many people assume they need expensive gadgets—heart rate monitors, lactate threshold testing, or metabolic assessments—to determine their Zone 2 range. While heart rate tracking (typically 60-70% of max HR) can provide a guideline, your body has built-in indicators to help you find the right effort level. The talk test is one of the simplest and most reliable methods: if you can hold a conversation in full sentences without gasping for air, you’re in Zone 2. If speaking becomes difficult, you’ve likely shifted into a higher zone. Another method is perceived exertion (RPE)—on a scale from 0 to 10, Zone 2 should feel like a 3 or 4: a moderate effort that’s sustainable for hours but still engaging enough to feel like work.
The biggest challenge isn’t physiological—it’s psychological. Because Zone 2 feels easy, there’s a temptation to push harder. Many amateur athletes fall into the trap of running too fast on easy days and too slow on hard days, getting stuck in a “gray zone” that’s not hard enough to improve speed but too intense to build proper endurance. Trusting the process and staying in true Zone 2 is key to unlocking long-term gains.
How Much Zone 2 Do You Need?
The Sports Medicine study found that most successful marathon training plans dedicate 65-70% of total training time to Zone 2, with the remainder split between moderate and high-intensity efforts. But if your primary goal is to build endurance or improve cardiovascular health, up to 90% of your weekly training could be Zone 2 without any downside.
(Photo: Sports Med)
When I trained for my first marathons, I leaned even more heavily into Zone 2 than the study suggests. Instead of following a rigid plan, I structured my weeks around long, steady efforts, ensuring I could sustain high mileage without excessive fatigue. This aligns with recent endurance coaching philosophies:
- 5K training: Zone 2 should make up most base mileage, with occasional short intervals or tempo runs.
- Half marathon training: 40-60 minutes for most easy runs, extending to 90+ minutes for long runs.
- Marathon training: Long runs (up to 20 miles) should be mostly in Zone 2, with some race-pace efforts sprinkled in.
If there’s one thing we can learn from runners—elite or not—it’s that longevity and performance share a common thread: consistent low-intensity movement. Whether you’re looking to improve endurance, reduce injury risk, or simply support long-term health, Zone 2 training is one of the most effective tools available. What’s particularly interesting is how much of it elite runners do. While many assume their success comes from pushing harder, data from Strava and endurance training research suggest otherwise. The biggest differentiator between elite and non-elite runners isn’t just talent or intensity—it’s time spent in easier zones. Some follow an 80/20 rule, dedicating around 80% of their training to low-intensity movement. Others, myself included, have even pushed closer to 90%, reinforcing just how critical a strong aerobic base is. And this isn’t just a lesson for runners. Whether through cycling, hiking, or simply integrating more low-intensity movement into daily life, prioritizing Zone 2 is one of the simplest, most sustainable ways to improve both health and performance. The question isn’t whether it works—it’s how much of it you’re willing to do.