Physical Activity
The physical activity domain tests your ability to prescribe movement the way you prescribe medication: a specific dose, a progression, and a safety check, grounded in the 2018 Physical Activity Guidelines for Americans and the 2020 WHO guidance.
The dose
- 150–300 minutes/week of moderate-intensity aerobic activity, or 75–150 minutes/week of vigorous activity, or an equivalent mix.
- Muscle-strengthening on 2 or more days/week for all major muscle groups.
- Replace sedentary time with light activity; the old rule that bouts must last 10 minutes has been dropped - any bout counts.
- More activity yields more benefit; some is always better than none.
Intensity and assessment
Moderate intensity (3–6 METs) lets you talk but not sing. Use the exercise vital sign (minutes/week of moderate activity and days/week of strength training) at every visit, screen readiness with PAR-Q+, and document type, frequency, intensity, time, and progression - the FITT-VP framework.
Evidence anchors
Physical inactivity is a leading modifiable cause of death; activity reduces all-cause mortality, incident type 2 diabetes (as in the DPP), colon and breast cancer risk, and depressive symptoms, and improves cognition and sleep. Exercise is a treatment for knee osteoarthritis, not a contraindication.
Worked example
A 62-year-old sedentary man with knee osteoarthritis and hypertension wants to "get fit". Reasoning: start at a dose he can repeat - 10-minute walks three times daily, five days per week - progressing toward 150 minutes weekly; add resistance bands twice weekly; teach a rating of perceived exertion of 11–13 on the Borg scale; confirm blood pressure control; review at 4 weeks. Prescribing "join a gym" with no dose or follow-up is the error.
Traps
- Prescribing only aerobic exercise and omitting strength training, which carries independent mortality benefit.
- Ignoring sedentary time in a patient who already meets the weekly minutes.
- Treating age or resting pain as an automatic reason to avoid activity rather than a cue to modify the prescription.
- Increasing volume too fast, then losing the patient to soreness or injury.