likely as not the benefits of getting sunshine and producing vitamin D has more to do with joggers longevity than the exercise itself... time of day of sun exposure is a big factor When the sun is elevated about 50 degrees you get more UVB producing vitamin D relative to UVA that damages skin. Along the Central Coast of California currently that's at 9:20am and 2:30pm or so, fifteen minutes at those times of day will be good for a person.. Joggers are going to go out when it's a little cooler and get a worse quality of sunlight, perhaps if they just sunned twice a day in the optimum fashion they would live nearly as long?