Fitness built on one capacity can hide gaps in the others. Running, lifting or eating well can each be excellent while range of motion, balance or the ability to get up from the floor quietly decline. After 40, check several capacities separately and start with the weakest, without dropping what already works.
You have been training for years. Not perfectly, but consistently, which counts for more.
Then one afternoon you are down on the floor, reaching for a dog or a dropped earring or a grandchild, and getting back up takes a hand on the coffee table. Nothing hurts. Nothing is injured. You just noticed something.
The training was real, and it was working on everything it covered. The floor was not on the list.
The Runner
A client came to me at fifty-four, a runner since her twenties. Four days a week for three decades, through two pregnancies, a cross-country move and a long stretch of night shifts. She could still cover ten miles on a Saturday. By any reasonable measure, she had done the work.
She could not get off the floor without putting a hand down.
Nothing had failed. Her heart and lungs were in better shape than those of most people fifteen years younger, and they still are. What she had trained was excellent. What she had never trained had been drifting for twenty years, quietly, while she was busy not missing a run.
That is the most common version of this I see in people over forty who train seriously. Neglect is rare. What I usually find is a coverage gap: some capacities trained thoroughly for years, others never touched.
The training was real, and it was working on everything it covered. The floor was not on the list.
Why This Matters After 40
In your twenties, a capacity you ignore mostly holds on its own. In my experience, after forty the ones you do not train start to drift, and they drift independently of the ones you do. Strong lungs do not keep your hips mobile. Strong legs do not keep your balance sharp. A single good number, however impressive, tells you about that one capacity and very little about the rest.
The tempting move is to look for the one thing: one number, one habit, one lever that moves everything downstream. Most of what gets written for people over forty assumes that lever exists and the only question is which one it is.
What the Research Shows
One recent study tested that assumption in an unusual way. Researchers built a working computer model of anabolic resistance, the blunted response older muscle shows to the inputs that normally maintain it, then broke one piece at a time and watched what the whole system did (McColl et al., 2026).
No single broken piece reproduced what actually happens to muscle as people age. It took several drifting at once. And repairing any one of them, on its own, did not bring the system back.
That is a model rather than a study of people, so it frames the question rather than settling it, and it sits below human evidence. The paper describes several interacting problems without naming which ones matter most, and I have not named them either. The specific thresholds in the Eight Signals rest on their own human evidence, not on this paper.
It does match what walks through my door with unnerving consistency. The person who has protein handled and never trains hard. The person who lifts well and sleeps badly. The runner who cannot get off the floor.
Several capacities drift at once. Fixing the one you are already good at does not bring the others back.
Why There Are Eight Signals
This is the whole reason the Eight Signals list has eight entries: protein, easy aerobic work, near-maximum effort, strength loading, sleep consistency, morning light, loaded carry and single-leg balance. Eight is not there to sound thorough, and a longer list does not make the work more serious. Capability is held up by several things that fail independently, and a number on only one of them tells you about that one.
Where FACE Fits
If you have been around this work for a while, you have seen two frameworks, and it is worth saying plainly how they sit together.
FACE is the assessment: Flexibility, Aerobic capacity, Carry a load, Equilibrium. It runs at baseline and tells us where someone actually stands before anything gets programmed. The Eight Signals are the operating layer, what gets measured week to week once the assessment is done.
They are different lists on purpose. Flexibility has no weekly signal. Mobility drifts over months rather than weeks, and putting a weekly number on it would impose a rhythm the capacity itself does not have, so it gets re-checked monthly instead.
It still gets loaded, number or not. A heavy carry held for a full minute is not available to someone with meaningfully restricted ankles or a locked-up upper back. Restriction shows up as a failed carry. The assessment catches it, and the loaded carry signal trains it.
The Ninth Signal I Left Out
I built one. Mobility, as a weekly number, with a threshold and a self-test, sitting alongside the other eight. Then I took it out.
The reason is the standard everything else here runs on. The research behind a weekly mobility number does not carry the weight the other eight do. One paper does not isolate the thing it usually gets cited for. Another looks at a single moment in time rather than at what happens to people over years. A third claim had already been dropped once a newer paper found no independent link.
All of that is fine as a reason to work on mobility, which I do with every client I have. None of it is enough to put a number on a page and tell you that you either hit it or you did not.
A ninth signal would have looked more complete. It would also have been borrowing confidence the evidence does not have.
Eight is where the evidence actually reaches, so eight is where the list stops.
Start With the One You Skimmed
Not all eight at once. Pick the one you are worst at. That is harder than it sounds, because the instinct runs the other way. The runner wanted to talk about her mileage. It was the best thing about her and the least useful place to spend the next six months.
Keep everything you are already doing. None of this replaces it. The point of separate signals is that adding one does not cost you another.
The runner can get off the floor now. It took about four months, and it was the least interesting part of her training. It was also the part that was missing.
Capability is several things, each of which can quietly go while the others hold. That is how you can be in good shape and still get caught out on an ordinary afternoon, reaching for a dropped earring.
What to Do This Week
- Read through the Eight Signals and find the one you skimmed, the one you already had an explanation ready for. That is your starting point this week, not all eight.
- Test the floor: from standing, sit down on the floor and stand back up using as little support as you can. Note every hand or knee you needed. Do it on a soft surface with something stable within reach.
- Keep everything you already do and add one session this week aimed only at your weakest capacity. If you have heart, joint or balance concerns, talk to your physician before adding strenuous work.
Sources
- McColl TJ, Moore DR, Emberly E, Church DD, Clarke DC (2026). Multifactorial nature of anabolic resistance in ageing skeletal muscle: a systems modelling study. The Journal of Physiology. doi:10.1113/JP290799 PMID 42464764.
Client stories may combine details from more than one person, with identifying details changed for privacy. This article is educational and is not medical advice.
Also published in Built to Endure, our free weekly publication.