Variety Is the Clue, Not the Cause

A study published in BMJ Medicine [1] followed more than 111,000 adults for over three decades, and it landed somewhere worth your attention. The people who practiced the widest range of physical activities had a 19% lower risk of death from any cause than those who practiced the narrowest range. Variety — independent of how much total exercise anyone did. Doing a great deal of one thing was not the same as doing several different things.

Did we really need thirty years and a hundred thousand people to find this out? The body has been saying it for three million. But a study can only measure what it can count, and what this one counted was activities — walking, cycling, tennis, rowing, weights, stair climbing — boxes ticked on a questionnaire. It found that more boxes meant more years. What it could not examine is why. And this is exactly where most readers will draw the wrong conclusion: that the answer is to collect more activities. Wrong. A person can move through eleven different exercises on eleven different machines and still starve the body of what it is actually asking for. Variety is not the cause of anything. It is a clue. Follow it, and underneath it you find two things — and both of them matter far more than the word itself.

The body was built for a particular kind of movement. And that movement was never meant to happen in a box.

The Body Was Built for a Particular Kind of Movement

What is the best exercise for a human body? It is the same question as asking what the best exercise is for a tiger, and it has the same answer: move the way the animal was shaped by evolution to move. The human body was assembled over close to three million years of one specific repertoire — walking long distances, carrying loads, climbing, crawling, balancing, throwing, lowering to the ground and rising back up, many times a day. That is not a “style” of exercise. It is the set of demands the body evolved expecting. Daniel Lieberman has argued [2] that physical activity is not optional maintenance but an evolved requirement: the body builds the capacity a demand calls for, and only when that demand actually arrives. Remove the ancestral demand and the body does the logical thing. It downgrades.

This is not nostalgia. It is observable. Contemporary hunter-gatherers such as the Hadza accumulate [3] close to fourteen times the moderate-to-vigorous movement of the average adult in a wealthy country — sustained well into old age, alongside cardiovascular health most modern populations will never see. And when they rest, which they do for about as many hours as we do, they squat and kneel [4] instead of collapsing into a chair, so the lower body stays lightly loaded rather than switched off. James O’Keefe and his colleagues made the case [5] years ago that the human genome was selected under exactly this pattern of movement. The body has not changed. Our behavior has. That gap has a name — evolutionary mismatch — and it is not some exotic condition. It is the ordinary condition of nearly everyone reading this.

Here is the sharpest piece of it. The plain ability to lower yourself to the floor and rise back up — no equipment, no aerobic component, pure natural movement — independently predicts how long you will live [6]. And the single activity most strongly tied to a longer life in the variety study was not some clever modern protocol. It was walking. The oldest and most universal human movement there is. Even the shoe interferes: six months of ordinary daily activity in minimal footwear [7] raised foot strength by more than half, because the modern shoe quietly removes a demand the foot was built to meet. None of this is a coincidence. The movements that protect you most are the movements closest to the ones the body was designed around. Which tells you what variety actually is. It is not the goal. It is a wider net — and a wider net simply catches more of the ancestral demands that any single modern exercise leaves on the floor.

That Movement Was Never Meant To Happen In A Box

Now the second thing, and it is the one modern fitness erases most completely. When you practice more types of activity, you are far more likely to be moving against an environment that changes — and that, not the count of activities, is the hidden variable. Life asks two different things of a body. The predictable, it asks you to be adapted to. The unpredictable, it asks you to be adaptable to. Those are not the same word, and they are not the same quality. A treadmill, a stationary bike, a weight machine — every one of them was engineered for one purpose: to hold the environment still so the body can repeat a motion cleanly. Real movement never holds still. The ground is uneven. The load shifts. The next obstacle sits at a different height than the last one. The body has to read what is in front of it and adjust, without pause. Strip that away and you have not made training simpler. You have removed the thing training was for.

And the adjustment is the training. Walking over ground that is merely uneven raises [8] the metabolic cost, and the work demanded of the knees and hips, well past what flat and predictable ground asks for. Runners on broken terrain do not pre-plan each footfall; they adapt the leg in real time [9] to whatever arrives under it. The systems that perform that adapting can only be built by an environment that demands it — which is why the largest review of fall prevention [10] in older adults found that the programs that actually work are the ones that deliberately challenge balance, not the ones that keep it comfortable. 

Life asks two different things of a body. The predictable, it asks you to be adapted to. The unpredictable, it asks you to be adaptable to.

Motor science says the same thing from another direction. Practice under varying, unpredictable conditions [11] produces skill that lasts and carries over; practice that repeats the same conditions produces a narrow skill that performs well only in the room where it was trained. Even the brain follows the environment — movement in reactive, changing settings sharpens executive function [12] more than the same dose of repetitive, closed exercise. Closed exercise trains the body to perform a known task. Adaptable movement trains it to meet an unknown one. And the unknown one is the only kind the real world has ever delivered.

This is the quiet price of training built for repeatability. Fixed-form exercise can make you fit. It cannot make you adaptable, because it has removed the single ingredient adaptability requires: variability itself. Strength, endurance, mobility — those are physical qualities, and a machine can build them. Adaptability is a quality too. It is the one no machine will ever hand you, because the machine exists precisely to take it away. So ask yourself the honest question. Do you want to be adapted to clean, flat, predictable ground — or adaptable to whatever the day puts under your feet?

One detail in the study is hard to walk past. Swimming was the only common activity it did not tie to a lower risk of death. The researchers point, reasonably, to measurement limits — a self-reported swim says little about real intensity. Fair enough. But swimming is also the one activity on that list that removes ground contact, unloads the body from gravity, and erases terrain, all at once. The study cannot tell you that is the reason. Neither can I. But it is a sharp coincidence, and I would not look away from it too quickly.

So the study found something real and gave it the only name epidemiology had on hand. Variety. Read it more closely and it is pointing at something far more precise. The body wants the movement repertoire it was built around, and it wants that repertoire delivered by an environment varied enough to force it to adapt. Variety, biomechanical fidelity, adaptability — these are not three separate findings. They are three views of one thing. Natural Movement® was built on all three. It is evolutionary, it is adaptable, it is environmental, by design and not by accident. That was never a slogan. It was an attempt to describe what the body had been asking for all along.

So do not read this study as a longer menu. If your training is one mode, repeated indoors, on equipment engineered to hold the world still, then yes — it is telling you, plainly, to broaden. But you do not broaden by collecting more machines. You broaden by moving the way the body was built to move: on the ground and off it, carrying, climbing, balancing, crossing terrain that refuses to stay flat.

Do that, and variety stops being something you chase. It is simply what Natural Movement looks like. It was always the symptom. It was never the cause.

Scientific Sources & References

[1] Han H, Hu J, Lee DH, et al. Physical activity types, variety, and mortality: results from two prospective cohort studies. BMJ Medicine, 2026. https://bmjmedicine.bmj.com/content/5/1/e001513

[2] Lieberman DE. Is exercise really medicine? An evolutionary perspective. Current Sports Medicine Reports, 2015. https://pubmed.ncbi.nlm.nih.gov/26166056/

[3] Raichlen DA, Pontzer H, et al. Physical activity patterns and biomarkers of cardiovascular disease risk in hunter-gatherers. American Journal of Human Biology, 2017. https://onlinelibrary.wiley.com/doi/abs/10.1002/ajhb.22919

[4] Raichlen DA, Pontzer H, et al. Sitting, squatting, and the evolutionary biology of human inactivity. PNAS, 2020. https://www.pnas.org/doi/10.1073/pnas.1911868117

[5] O’Keefe JH, Vogel R, Lavie CJ, Cordain L. Achieving hunter-gatherer fitness in the 21st century. The American Journal of Medicine, 2010. https://www.amjmed.com/article/S0002-9343(10)00463-8/fulltext

[6] de Brito LBB, et al. Ability to sit and rise from the floor as a predictor of all-cause mortality. European Journal of Preventive Cardiology, 2014. https://journals.sagepub.com/doi/abs/10.1177/2047487312471759

[7] Francis P, et al. Daily activity in minimal footwear increases foot strength. Scientific Reports, 2021. https://www.nature.com/articles/s41598-021-98070-0

[8] Voloshina AS, Ferris DP. Biomechanics and energetics of walking on uneven terrain. Journal of Experimental Biology, 2013. https://pubmed.ncbi.nlm.nih.gov/23913951/

[9] Dhawale N, Venkadesan M. Real-time leg adjustment when running on uneven terrain. eLife, 2023. https://pubmed.ncbi.nlm.nih.gov/36810138/

[10] Sherrington C, et al. Exercise for preventing falls in older people living in the community. Cochrane Database of Systematic Reviews, 2019. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD012424.pub2/full

[11] High contextual interference improves retention in motor learning: a systematic review and meta-analysis. Scientific Reports, 2024. https://www.nature.com/articles/s41598-024-65753-3

[12] Open-skill versus closed-skill exercise and executive function. Applied Sciences, 2020. https://www.mdpi.com/2076-3417/10/8/2737