Primarily WHO’s 2020 evidence profiles (plus Willett on measurement). WHO’s own evidence base is other guidance bodies’ reviews — so agreement with PAGAC or the Canadian/Australian guidelines would be structurally guaranteed and worth nothing. A genuinely independent check was hoped for from Muscle-Strengthening Activity and Mortality (Momma 2022) — now ingested, and the honest outcome is that it is NOT that check: Momma is the same observational physical-activity-epidemiology lineage (overlapping cohorts, cites the same prior metas), so it corroborates the strength finding (its all-cause RR 0.85 sits beside the strength-guideline HR 0.80 below) but does not supply independent backing. A genuinely independent family (a different method — e.g. objectively-measured fitness change, or an RCT-grade outcome) is still owed.
The decision this page changes
Most of the mortality benefit arrives at a dose far below what people assume they need — and the curve then flattens. That is a decision-change in the telos’s specific sense: it licenses someone to stop optimizing, which is a result, not a failure to find one.
But the outcome of that activity — cardiorespiratory fitness — predicts mortality even more strongly, and with no plateau -> Cardiorespiratory Fitness and Mortality. The two are not one claim: self-reported activity dose flattens early here, while objectively-measured fitness keeps paying — a discrepancy that is itself informative about measurement, not proof that more activity is always better.
Where the curve bends — named maxima, device-measured
«Maximal risk reductions for light intensity PA was ~375 min/day, low light intensity PA at ~325 min/day, high light intensity PA at ~80 min/day, and MVPA at ~24 min/day.» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
«The maximal risk reduction for total PA was observed at about 300 cpm (adjusted HR = 0.34 [95% CI 0.27 to 0.43]).» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
Certainty: HIGH. The underlying profile is a harmonized meta-analysis of eight prospective cohorts in which all eight used accelerometers rather than self-report, and «A non-linear, dose-response association was found between all exposure variables and mortality (p<0.02 for all exposure variables)». A second profile reports «A curvilinear relationship was found between total PA and all-cause mortality (p non-linearity <0.001).» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
| Exposure | Dose at maximal risk reduction |
|---|---|
| MVPA (moderate-to-vigorous) | ~24 min/day |
| High light intensity | ~80 min/day |
| Low light intensity | ~325 min/day |
| Light intensity (total) | ~375 min/day |
| Total PA | ~300 cpm — HR 0.34 (0.27-0.43) |
Read the table as substitution, not as a target menu. These are different routes to the same maximum, so the operative reading is: roughly 24 minutes of moderate-to-vigorous activity, or a much larger volume of light activity, reaches most of the available benefit. WHO states the intensity-independence directly:
«Any physical activity, regardless of intensity, was associated with lower risk of mortality, with a non-linear dose-response.» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 09]
Two cautions on the HR 0.34. It is a between-quartile contrast in observational cohorts, so reverse causation (illness reduces activity) is not excluded by design — the profile’s HIGH rating reflects consistency and precision, not randomization. And the exposure is total accelerometer counts, which is not a prescription anyone can follow directly.
Strength training — a real independent association, never ranked above aerobic
| Finding | Effect | Certainty |
|---|---|---|
| Strength-guideline adherence vs not (Stamatakis 2018, 11 cohorts, N=80,306) | HR 0.80 (0.70-0.91) | MODERATE |
| Any strength-promoting exercise vs none (same) | HR 0.77 (0.69-0.87) | MODERATE |
| Meeting both aerobic AND strengthening guidelines vs neither | HR 0.71 | MODERATE |
[EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
The operative claim is both, and together — not strength instead of cardio. No profile in the annex ranks resistance training above aerobic activity, and where the two are compared head-to-head (anxiety, 16 RCTs; depression, 33 RCTs; sleep), WHO reports «No significant difference was found between studies examining resistance training vs. aerobic exercise training» — at LOW and VERY LOW certainty. [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
A distinction that is NOT a tension. Siahpush 2019 (N=68,706) reports «There was no association
between all-cause mortality and meeting strength recommendations (and not aerobic PA
recommendations)» — which looks opposed to Stamatakis. It is not: Siahpush’s profile is about
smokers, Stamatakis pools 11 general-population cohorts. Different population, consistent once
matched. Recorded here so the apparent clash is not re-filed later as a [[tension]].
[EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 05]
Sedentary time is a separate exposure with its own thresholds
«For all-cause and CVD mortality, a threshold of 6-8 h/day of total sitting and 3-4 h/day of TV viewing was identified, above which the risk is increased.» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 09]
The relationship is «non-linear for all-cause mortality» and PA-adjusted — i.e. it survives controlling for activity, so sitting less and moving more are not the same lever.
TV viewing carries a lower threshold than total sitting (3-4 h/day vs 6-8 h/day) and stronger
associations. Two behaviours inside one category, behaving differently — though what accompanies TV
viewing is not addressed here, so confounding is not excluded.
-> [[Is the Food Category Doing Any Work]] for the same structure in a different domain.
Older adults — falls, which is a patient-important outcome
«Long-term exercise is associated with a reduction in falls, injurious falls, and probably fractures in older adults, including people with cardiometabolic and neurological diseases.» [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 11]
Falls and fractures are outcomes people care about directly, not surrogates — the strongest outcome class the annex carries for this stratum.
What this page does NOT support
- No compensation analysis exists anywhere in the annex — now held on a sibling page. Whether a given activity dose is offset by reduced activity elsewhere, or by increased intake, is untouched here; Exercise Energy Compensation (Riou 2015) supplies it: compensation is real (~18%, rising to ~84% long-term) but is driven by adiposity/age/duration, not by intensity — so walking is better tolerated than intense exercise remains unsupported (intensity is not a compensation predictor).
- No ranking of modalities. See above.
- Frailty cannot be targeted from this evidence: WHO reports «A lack of consensus regarding the definition of frailty, and an absence of core measures to assess this means any attempt to create an optimal intervention will be impeded.» An ill-defined construct — distinct from a well-defined measure that decays under targeting. [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 11]
- A study-level correlation is not an individual-level one. «At the study level, there was a positive correlation between the size of the exercise-induced effect on physical function and on cognitive function (b = 0.41; p = 0.002).» That does not license “improving function improves cognition” for a person — the ecological-inference trap. [EXTRACTED (WHO - Physical Activity Web Annex Evidence Profiles 2020) chunk 11]
Sedentary behaviour is not the inverse of activity — and devices have type-specific bias [2026-07-28, Willett ch.10]
Two findings from Willett’s physical-activity assessment chapter bear on how this page’s estimates should be read.
1. Sitting and moving are close to independent, not two ends of one scale.
«Interestingly, there is little correlation between sedentary behaviors and physical activity (Hu et al., 2003), suggesting that sedentary behaviors are not simply the opposite of physical activity.» [EXTRACTED (Willett - Nutritional Epidemiology 3e) chunk 14]
So “sedentary time” and “activity” are two exposures, not one variable read in two directions, and a person can be high on both. This is a unit-of-analysis point with a direct consequence: a recommendation phrased as move more does not automatically address sitting, and evidence about one does not transfer to the other. -> Is the Food Category Doing Any Work (same structure, different domain: the label implies a single underlying quantity and there are two).
2. Device measurement is not error-free, and its error is activity-type-specific.
«(2002) found that compared with portable indirect calorimetry, the Tritrac accelerometer overestimated the energy expenditure of walking and jogging, and underestimated that of stair climbing and stationary cycling in middle-aged women.» [EXTRACTED (Willett - Nutritional Epidemiology 3e) chunk 14]
This qualifies rather than undermines the device-measured estimate this page carries. The bias is
differential by activity mode — over on ambulatory movement, under on climbing and cycling — so a
device-measured total activity variable is a weighted mixture whose weights depend on the population’s
activity mix. Two populations with identical true expenditure but different activity profiles will
be measured differently, which is a transportability problem, not an attenuation problem.
[INFERRED (Willett - Nutritional Epidemiology 3e) — the accelerometer findings are Willett's; the transportability reading is this page's]
Note the vintage: this is 2012 hardware (Tritrac). Modern accelerometry and the processing behind the estimate on this page may behave differently, and this wiki holds no source establishing that either way. Recorded as a caution about the class of instrument, not as a defect in the specific estimate.