A dose, not a vague "go and move"
You arrive at this rung already convinced that the body changes only when something demands change of it — that was the lesson of the training principles. Now comes the practical turn: how do you write that demand down so it can actually be delivered, repeated, and adjusted by someone other than yourself? The answer is the central idea of this whole rung, and it is worth stating bluntly. In rehabilitation, exercise is a treatment with a dose, prescribed much as a drug is prescribed — not a vague encouragement to "keep active."
Take the comparison seriously, because it carries real meaning. A drug has an indication — the problem it is meant to fix. It has a dose that is too small to work and a dose that harms; somewhere between lies a therapeutic window. It has a schedule, a route, an expected response, and side effects to watch for. Exercise has every one of these. A weakened quadriceps after knee surgery is an indication; the load and number of repetitions are the dose; doing it three times a week is the schedule; growing strength is the expected response; a flare of swelling is the side effect that tells you the dose was wrong. Once you see exercise this way, the loose phrase "do some physio" sounds as careless as "take some medicine."
FITT: the four dials that write the dose
If exercise is a dose, you need a way to write it that anyone on the team can read and reproduce. That shared notation is FITT — Frequency, Intensity, Time, and Type. You met these four dials in passing among the training principles; here they become the actual language of the prescription. Frequency is how often (days per week). Intensity is how hard (the load lifted, the speed walked, the effort felt). Time is how long (minutes per session, or sets and repetitions). Type is which exercise — a progressive-resistance leg press, an aerobic-conditioning walk, a balance drill, a stretch. Set all four and you have written a dose precise enough for a colleague to deliver tomorrow without guessing.
Two of the four dials are harder than they look. Intensity is the subtle one, because for many patients you cannot simply name a weight. How hard is "hard enough" for a breathless heart-failure patient, or a stroke survivor who cannot yet grade their own effort? Clinicians lean on practical proxies — a rating of perceived exertion, a heart-rate range, a load a person can just manage for a set number of repetitions, or a count of metabolic equivalents borrowed from the formal FITT framework. Type is the quietly decisive one: choosing the wrong type means even a perfect frequency, intensity, and time will train the wrong thing entirely, which brings us to the goal.
ONE FITT PRESCRIPTION (illustrative shorthand, not a real order) GOAL : stand from a chair unaided F Frequency most days of the week I Intensity a load felt as "somewhat hard" / can just finish the set T Time 2-3 sets of a few repetitions, with rest between T Type sit-to-stand practice (the goal task itself) + PROGRESSION : as it gets easy, lower the seat or add reps + REVIEW : re-check at intervals; adjust the dials to the response
Matching the exercise to the goal
FITT tells you *how* to dose; it cannot tell you *what for*. That comes from the goal — and a prescription written before the goal is named is medicine in search of a disease. So the first move is not to pick exercises at all, but to settle what this person is actually trying to get back: to stand from the toilet, to carry a grandchild, to climb the bus step, to last a shift on their feet. A well-formed goal, in the SMART spirit you met earlier, is specific and observable enough that the right type of exercise almost selects itself.
From the goal you reason backward to the type, and the principle of specificity does most of the work: you get back the precise thing you rehearse. If the goal is endurance to last the shift, the dose leans aerobic and long; if it is force to rise from a chair, it leans toward heavy, brief effort and the strength adaptations that follow. And if the goal *is* a real-life action — standing, stepping, reaching — the most faithful choice is often to practise that very action, which is the heart of task-oriented training you will study next. Generic leg-strengthening may help a little, but the brain and muscles must rehearse the actual coordination of the task to own it.
Matching also forces an honest conversation about what kind of result you are aiming at. Recall the distinction between recovery and compensation from the motor rung: are you training a stroke-weakened hand to grip again, or teaching the strong hand to do the job the weak one no longer can? Both are legitimate, and both are real rehabilitation — restoring function, even by a workaround, is the field's honest aim. But they are different goals, and they call for different exercises. Naming which one you are pursuing, with the patient, is part of writing the prescription, not a footnote to it.
Dosing and progression: the prescription that moves
Here is what makes an exercise prescription stranger than a drug prescription: a good one is designed to expire. With most medicines, the right dose today is the right dose next month. With exercise, the whole point is to make the body adapt — and the moment it does, the dose that worked is no longer enough. The load that was "somewhat hard" in week one is comfortable by week three, and comfortable means no further change. So a prescription that never moves quietly stops being treatment and becomes mere maintenance. The cure for this is built in from the start: progression, the planned raising of the dials as the body rises to meet them.
Progression is just FITT in motion. To make the dose harder you turn one dial at a time: add a day (frequency), add load or speed (intensity), add minutes or repetitions (time), or graduate to a more demanding exercise (type). The craft lies in changing one thing at a time and in small steps — partly so you can tell what helped, and partly for safety, since a too-eager jump in load is the classic way to provoke a flare. A common rehab heuristic nudges only one dial by a modest amount and watches how the next session feels before nudging again.
- State the goal first, with the patient — specific and observable, so the right type of exercise is obvious (e.g. "stand from a chair without using the arms").
- Write the starting dose in FITT — frequency, intensity, time, type — set honestly to where this person is today, not to a textbook average.
- Deliver, then watch the response — strength, distance, ease, plus the side effects: pain, swelling, fatigue that does not settle.
- Progress one dial at a time, in small steps, as the dose becomes easy — and ease itself is the signal that it is time to nudge.
Honest limits: where the prescription stops short
It is tempting, having dressed exercise up as a precise drug, to overstate what the prescription can do. So a few honest brakes. First, the dose-response curve for exercise is genuinely well-supported for many goals — strengthening a weak muscle, building walking endurance, improving balance — but it is not infinitely precise. We rarely know the single optimal number of repetitions for *this* patient; good dosing is informed estimation, watched and corrected, not a formula. Second, the prescription asks the body to adapt; it cannot order it to. A severely damaged nerve or a stroke-injured motor pathway may set a ceiling that no correct dose can lift, and recognizing that ceiling is itself good practice, not failure.
Third, and most important to internalize early: even a perfectly dosed, beautifully progressed program restores *function* — it does not cure the underlying lesion. The stroke is still there; the severed ligament is repaired by surgery and time, not by the exercise; the program has rebuilt what could be rebuilt and worked around what could not. That is not a disappointment. Restoring a person's ability to live their life, lesion and all, is precisely what rehabilitation exists to do. The honesty simply keeps the promise sized correctly — to the patient, and to yourself.