Everyone Is Talking About Training Age in Running. But What Is It?
- Jun 8
- 6 min read
Why running experience may matter more than your physical ability when it comes to building towards longer distances.
It feels like everyone is running a marathon now. Or an ultra. Or both… on the same day… every day. Scroll Instagram long enough and you can convince yourself that running 26.2 miles is simply a question of booking a place and getting through it, even a training plan is negotiable. And to be fair, many people do exactly that. But beneath the surge in marathon participation sits an increasingly important conversation around something called “training age” in running.
Because while you may be 28 years old, your body might only have two years of running experience. In running, this is often referred to as your training age. Someone else may be 28, but started running at 8 and have spent their entire childhood on athletics tracks, football pitches or cross-country courses. Chronological age and training age are not the same thing. Obviously interlinked but the distinction matters.
What is training age in running?
In simple terms, training age refers to how many years your body has consistently adapted to a specific training stimulus. Not your VO2 max. Not your PB. Not how much training you did in a six-week block. It is chronic, accumulated exposure. The number of years your body has spent learning how to tolerate running. That includes hundreds, to thousands of stress and recovery cycles in response to all the different forces absorbed during running and consistent loading over time. And crucially, training age is not just about cardiovascular fitness. Because your lungs often adapt faster than the rest of you.
Your engine might be ready before your chassis is
This is where things become interesting. Many newer runners are capable of building aerobic fitness surprisingly quickly, many of the essential adaptations that allow you to run for longer happen in a matter of weeks to months. Increases in how much blood you have, therefore increasing oxygen carrying capacity, increases in the enzymes that help to breakdown the fuel in the muscle all happen rapidly. Especially now that there is more access to structured plans/groups, fuelling advice, super shoes (helping to decrease impact load, therefore do more training) and training content. But fitness is only part of the picture.
Tendons adapt slowly. Ligaments adapt slowly. Bones adapt slowly. Movement efficiency (running economy) and pacing judgement often take years to develop properly. Which means someone may become “marathon fit” before they become particularly durable. You’ve built the engine before your chassis is ready.
So should you only build up to certain distances over time?
This is where training age becomes difficult to quantify because there is no universally agreed formula. You cannot simply say training for one year equals a half marathon or five years equals an ultra. Human beings are far too complicated for that. Someone who has spent ten years in a variety of different ways may have a far greater training age than someone who only started exercising recently, even if both are “new” to running. Equally, someone running 20 miles per week consistently for six years may tolerate training very differently to someone who has run 70-mile weeks for the same amount of time. Training age is not linear but it's linked to the variability of all the component parts of training referred to as Integrative Neuromuscular Training. This concept acknowledges the health and skill related components of physical fitness interact.
Even though this research was around how to train young athletes and reduce their risk of injury. The same system can be applied to all ages to build a picture of how to maximise training age.
The training adaptations compound over time but it is never too late to start as improvements in health and skill related physical fitness has been seen in ages up to 983.
Can you measure training age?
Not exactly. But there are useful questions runners can ask themselves before jumping towards bigger goals. How consistent have you been? Not for six weeks. Over years. How well do you tolerate load? Can you handle increased mileage without constantly picking up niggles? What does your injury history look like? Recurring issues are often signs that your body has not fully adapted to the training demand. Understanding how your body responds to training load is one reason many runners choose to undertake a biomechanics assessment. What is your broader athletic background? Years spent moving still count. And how well do you recover? Recovery literacy is part of training age too.
Marathon readiness vs training readiness
Completing the marathon, completing the training to do the marathon and being ready to tolerate the training to do the marathon are 3 different things. A higher training age allows you to tolerate training loads more easily, therefore you can train more (volume, intensity, frequently) and then race longer distances. We see a lot of the professional athletes going up to the marathon later in life having done a whole career at the shorter distances. The goal is not simply to survive the distance once. It is to build a body that still wants to run ten years later.
Why elite athletes are different
This is partly why comparisons can become misleading. Professional endurance athletes often have enormous training ages before they even reach adulthood. Many have run competitively since childhood (many starting at 8-10 years old), built years of aerobic development and accumulated thousands of miles of running before their professional careers begin. What seems like a debut marathon is often sitting on top of fifteen or twenty years of adaptation. That context matters. Especially in an era where social media compresses timelines and makes rapid progression feel normal. Genetics also play a huge part in this journey to being a professional athlete. Your genetic make up will predispose you to being better at tolerating and responding to training, it doesn’t replace the training, but it can make it easier to bounce back from sessions etc.
The pressure to progress quickly
Modern running culture and data rewards escalation. First 10k. First half marathon. First marathon. First ultra. The milestones arrive quickly and there is often an unspoken sense that further equals better. But slower progression is not failure. In many cases, it is probably the thing that allows runners to stay healthy enough to keep enjoying the sport long term. Because some adaptations simply cannot be rushed and in fact might need some structured time off (deloading).
So what does this actually mean?
Not that newer runners should avoid marathons. Not that people need years of permission before attempting something ambitious. But perhaps it is a reminder to respect the process a little more. Fitness can arrive surprisingly fast. Durability usually takes longer. And while training age may not be perfectly measurable, most people don’t intuitively know when they are building on solid foundations and when they are skipping steps. This is the aim of this article, to highlight the steps that need to be taken and pose the question, are you ready?
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