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The Healf Source
This Ancient Movement Metric Tells You A Lot About Your 'Fitness'
Movement coach and New York Times bestselling author Dr. Kelly Starrett explains why mobility is the “acid test” for functional fitness into old age.
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Written by: Tom Ward
Written on: July 17, 2026
This piece originally appeared in The Source: The Anti-Optimisation Issue, Healf's print magazine.
In another life, Kelly Starrett was all about going further, faster, and harder than anyone else. As a competitive kayaker on the US team, an alpine ski racer, and later, an early CrossFit adherent, he was obsessed with the same sort of performance metrics as the rest of us. Then, something changed. As Starrett, a world-renowned physical therapist, speaker, CrossFit trainer, and author of Becoming a Supple Leopard, moved away from competitive sport and started studying physical therapy, he began to reassess his approach.
Speak to Starrett now, and you’ll discover a man who is focused not on PBs and VO2 max, but on an altogether simpler metric: mobility.
Forget traditional metrics like calorie burn and mileage, Starrett believes that this more primal criterion, mobility, can tell us everything we need to know about our physical fitness. “We should use movement practices as an acid test of ‘Is what I’m doing working or not?’” he says.
In his view, it’s a vital foundation of our wellbeing, and one that we should pay far more attention to. “We’re starting to appreciate moving our bodies in ways that we love,” Starrett says of the gradual transition away from trend-based workouts towards more essential, movement-forward programmes like Reformer Pilates.
Starrett has been spreading the word since the publication of his first book in 2013, with the goal of helping people access “their native physiology at a moment’s notice”. Thirteen years on, his mission remains the same.
The philosophy is simple: basic mobility is a core part of being human. It helps us dance, chase our kids, climb, kick a ball. But somewhere along the way, we’ve forgotten to prioritise it. These days, most humans are unable to access many of the most basic, primal movements that our ancestors relied on every day for survival. Our sedentary lives are leading to chronic pain and a lack of mobility that can significantly shorten our lifespans — ideas he explores further in his 2016 book about the health effects of our office-based existences, Deskbound.
Part of the problem is that our concept of ‘fitness’ has become far more complex than it needs to be. “In an hour training block, we are now supposed to train every energy system, learn every single skill, develop every single rotational capacity,” Starrett says. It isn’t about doing everything, but doing what really matters. “People rattle off a list of 15 supplements they take, but they can’t tell me what normal hip rotation looks like, or what they should do when their knee hurts,” Starrett says.
Instead of training for aesthetics, or to rank high on a scoreboard, Starrett thinks a workout should serve two main functions: it should allow you to do what you want to do with your body, and build a body that is functional throughout life’s adventures. That, in his view, is far more essential for longevity than a bench press PB. Workouts should be fun, and at the end, you should ask yourself: Do I have less pain? Did this restore my range of motion? Am I a more durable person? And if the answer is no, then according to the most mobile man we’ve met, you should start to think long and hard about how you approach your workouts.
Of course, he’s not advocating we ditch gym routines altogether. Strength training will always be vital for building essential bone mass and density along with muscle function, while cardio supports our heart, lungs, and entire circulatory system. Instead, try to approach workouts with greater functional intentionality. This, Starrett believes, will keep us active — and mobile — for decades to come. “What we start to ask,” Starrett says, “is not ’How do I become a bodybuilder?’ but ‘What is essential?’”
Working on your mobility isn’t rocket science. Starrett also wants his mobility maxims to be accessible for all, so his YouTube channel, The Ready State, provides one simple idea each day to focus on.
Aim to get 8,000 to 10,000 steps per day. Practice a deep squat at home, holding onto the wall to begin with if needed. Sit on the floor every day for 20 minutes while watching Netflix. Practice sitting down on the ground and then standing back up without using your hands. “The number one reason people end up in nursing homes or the ER is they fall and can’t get up, so let’s practice that,” he says. Eat well and hydrate often so that you’re fuelled for your workout, and, of course, get enough sleep to drive recovery.
Finally, make sure to sign up for that lower-intensity Pilates or yoga class. “If you’re a strength athlete and you get your ass kicked in yoga or Pilates, you have a problem,” Starrett says. These workouts ask us to “explore and expose normal range of motion.”
Because at the end of the day, being able to access your native physiology at a moment’s notice isn’t just aspirational, it’s truly essential.
This article is for informational purposes only, even if and regardless of whether it features the advice of physicians and medical practitioners. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The views expressed in this article are the views of the expert and do not necessarily represent the views of Healf
Tom Ward is a former Men's Health features editor, and writes regularly on sports, fitness and adventure for the Red Bulletin, Outside, and the Sunday Times. He is the author of the novels The Lion and The Unicorn, and TIN CAT.
