The impact of parkrun on life satisfaction and its cost-effectiveness: A six-month study of parkrunners in the United Kingdom.

An intervention suggested by the World Health Organisation that might increase life satisfaction is parkrun, a free, weekly, timed five kilometre run or walk. The issues with such interventions are (1) whether they impact on the life satisfaction of their participants, and (2) whether they are cost-effective. A study of 548 newly registered parkrunners were asked about their life satisfaction at baseline and six months later. A change of one life satisfaction point per year per participant was defined as one WELLBY (wellbeing adjusted life year), with a value of £13,000. Three approaches were used to estimate the additionality (added value) of parkrun: (1) by comparing a participant's number of parkruns to total activity; (2) by accounting for the participant's perceived impact of parkrun across 16 measures; and (3) combining these two methods equally. After six months, weighted, seasonally adjusted life satisfaction increased from a mean of 7.489 to 7.746, a change of 0.257. Both life satisfaction improvement and additionality were greatest for the least active. Assuming only half a year of benefit, the total value of the life satisfaction change for the 2019 parkrun population of 400,167 participants was estimated as £667.4m, with the least active accounting for almost half. Comparing to the cost of running parkrun in 2019 and using the activity, impact and combined methods for additionality, benefit-cost analysis ratios were found to be 16.7, 98.5 and 59.3 to 1, respectively. These were between 2.8 to 16.7 times that of other population-level physical activity interventions. Physical health was a mediator between activity and life satisfaction; mental health was only found as a mediator when combined with physical activity. Successful features of parkrun that might guide other interventions include its framing (role, time, place and cost) and ability to forge both strong and weak social ties.