Physical activity has the strongest evidence base of any health behaviour, and access to it varies enormously in ways that individual advice does not address.
The activity gradient
Activity levels differ substantially by income, and the gap has been documented consistently.
Which reflects access, cost, time, safety and provision rather than differences in motivation.
Occupational activity complicates the picture, since some manual work involves substantial physical activity that does not confer the same benefits as leisure activity, a finding described as the physical activity paradox.
Cost
Gym membership, classes, equipment and clothing all cost money.
Which excludes a substantial group, and free provision varies enormously by area.
Walking, running and bodyweight exercise are free and depend on having somewhere safe to do them.
Safe space
Perceived and actual safety determine whether people exercise outdoors.
Which affects women, older people and people in areas with higher crime disproportionately, and it is documented in surveys.
Street lighting, path maintenance, traffic and the presence of other people all affect this.
Facility provision
Public leisure facilities, parks and playing fields are unevenly distributed.
Which correlates with deprivation, generally unfavourably.
Facility closures under funding pressure have concentrated in areas with fewer alternatives.
Time and caring
Scheduled activity requires time and, for people with caring responsibilities, someone to cover.
Which is why provision including childcare has better participation among the groups least likely to be active.
Activity integrated into daily routine — active travel, activity with children — avoids the scheduling problem entirely.
Disability
Physical activity participation among disabled people is substantially lower.
Which reflects facility accessibility, transport, staff training, and the design of activities.
Inclusive provision generally improves the experience for everyone rather than only for the intended group.
What has worked
Free or low-cost community programmes with social components.
Active travel infrastructure, with documented increases in cycling where protected infrastructure was built.
Referral schemes from primary care with subsidised access.
And programmes designed with the target group rather than for them, which consistently outperform those that are not.
The individual level
Choosing something tolerable and convenient beats choosing something optimal, since the optimal thing not done has no effect.
Enjoyment predicts adherence better than any belief about benefit.
And the steepest health benefit comes from moving out of the least active category, which means the target is doing something rather than doing enough.
Anyone with a cardiac condition or significant deconditioning should speak to a doctor before starting anything vigorous.
The dose question
Guidelines specify weekly amounts of moderate or vigorous activity plus strength work.
Which most people do not meet, and the guidelines have been revised to emphasise that any amount confers benefit.
The dose-response curve is steepest at the low end, meaning the first increment matters most.
Strength training
Consistently under-emphasised relative to its evidence, particularly for older adults.
Which matters for maintaining muscle mass, bone density and functional independence.
It requires little equipment, and bodyweight approaches are effective for most purposes.
Active travel
Walking and cycling for transport rather than for exercise.
Which accumulates activity without requiring scheduled time, and it is determined largely by infrastructure.
Cities that built protected cycling infrastructure show substantially higher cycling rates, and the effect appears in the data reliably.
Sedentary time
Separate from activity — someone can meet activity guidelines and still sit for most of the day.
Which is associated with outcomes independently in several analyses, and breaking up prolonged sitting appears to matter.
Workplace interventions on this have modest evidence and are cheap.
Older adults
Falls prevention programmes combining strength and balance work have good evidence.
Which is one of the clearer intervention effects in the field, and provision varies enormously by area.
Referral is generally through primary care or through community services.
Getting started safely
Building gradually reduces injury, and most early injuries follow doing too much too soon.
Which is more common in people returning after a long gap who remember their previous capacity.
Anyone with a health condition should get advice about what is appropriate first.
Women and girls
Participation drops sharply in adolescence and does not fully recover.
Which has been studied extensively, with body image, changing facilities, kit, safety and confidence all appearing.
Programmes designed around these findings have shown better retention than general provision.
Workplace and school provision
School physical education is where most people form their relationship with activity.
Which means an experience of humiliation or exclusion there has effects that persist for decades.
Curricula emphasising participation and enjoyment over competitive performance are associated with better adult activity levels.
Measuring the wrong thing
Programmes evaluated on attendance rather than on sustained activity overstate their effect.
Which is common, since attendance is easy to count and behaviour change is not.
What happens after a programme ends is the outcome that matters and is measured least often.
Consistency over intensity
Regular moderate activity outperforms occasional intense activity for most health outcomes.
Which favours whatever can be sustained over whatever looks most effective.