A study of New Zealand's six biggest cities has drawn a compelling link between high rates of cycling and walking and their residents' overall health.
The Otago University-led pilot study focused on rates of walking and cycling and key health indicators in the cities, showing that the more often a city's population cycled and walked, the higher its overall level of physical activity was.
More importantly, there was a further correlation with lower levels of harm to health from inactivity-related conditions, such as high blood pressure, obesity and diabetes.
In cities with higher levels of people cycling and walking for transport, more people had "adequate" levels of physical activity for health, and fewer had diagnosed diabetes or hypertension or were obese or overweight.
The study also included some slightly unusual mental health data, showing higher levels of people with doctor-diagnosed depression, bipolar disorder and anxiety in cities with higher levels of physical activity.
Diagnosis, access to primary and secondary care, cultural factors and, possibly, disclosure of diagnosis to survey interviewers may explain the finding, the study authors said.
"Because of the nature of the ecological-level data we used, we can not assume that there is a relationship between levels of active transport and health on the individual level.
"However, other research tells us that this is likely to be the case."
The study's lead researcher, Dr Caroline Shaw of Otago University, said the overall findings were what could be expected, "but we also found some surprising results such as that the weather does not necessarily influence whether more people cycle and walk".
"For example, Wellington, Christchurch and Dunedin with their colder, wetter and windier climates had the highest levels of people walking and cycling for transport."
How the cities compared
Walking was the most common form of "active transport" (walking and cycling combined) but the proportion of trips taken by walking ranged from 12 per cent in Hamilton to 27 per cent in Wellington.
In Auckland, 79 per cent of people preferred to make their trips by car, compared with walking (17 per cent) taking the train or bus (4 per cent) and cycling (0.4 per cent).
This differed greatly from Wellington, where 64 per cent of people drove, 27 per cent walked, 7 per cent took public transport and 1.5 per cent cycled.
In Christchurch, 75 per cent of people preferred vehicles, with 18 per cent walking, 3.6 per cent cycling and 3 per cent using trains or buses.
Tauranga and Hamilton had the lowest combined rates of cycling and walking - 14.9 per cent and 13.1 per cent respectively - and well below Dunedin's combined rate of 24.3 per cent.
Further, two thirds of cycling trips were made by men, whereas walking was more common among women, while cycling and walking were more common in younger age groups in most, but not all, of the cities.
All the cities had basic cycling and walking infrastructure, but this varied widely from city to city.
"We found that on-road cycle lanes without physical protection from cars do not particularly appear to be associated with high levels of cycling," Shaw said.
"For example, Tauranga and Hamilton report the highest percentage of roads with these types of cycle lanes (15 and 18 per cent of roads), but levels of cycling for transport in these cities are still quite low."
There appeared to be "poor connectivity" between cycling needs and public transport, even in cities with larger numbers of cyclists, with, for example, a lack of bicycle storage at bus stops.
However, all of the cities had bicycle skills education for children and young people and all supported special programmes such as bike/walk to work days and "open streets" events, mostly run by city councils.
Public bike-sharing schemes were in place in Christchurch and planned in Dunedin, but not in the other cities.
Only Wellington had an online journey planner including active transport, provided by the regional council.
Most cities had also factored walking and cycling into their climate change policies.
The study was inspired by a US benchmarking programme by the Alliance for Biking and Walking, which reports every two years on the state of active transport in 50 states and 50 cities.
No one has previously looked systematically at how New Zealand cities support cycling and walking.
"We wanted to see if we could establish a baseline for a similar series of studies in New Zealand," study co-author Dr Marie Russell said.
The report was funded by the University of Otago and the Resilient Urban Futures programme in the New Zealand Centre for Sustainable Cities.