When Ashley Yalof finishes a run, either on a treadmill or outdoors, she gets much more than merely a feeling of accomplishment: she knows her average pace, can compare her performance to previous runs and even gets congratulated by a famous athlete. Yalof, 27, is one of a growing number of millennials using health-related mobile apps. While smartphone app use has risen in general, the use of health-related apps is particularly prominent among millennials, or those born between 1980 and the early 2000s, research shows. Among smartphone users of all ages, 19 percent have apps on their phone to track or manage some aspect of their health, according to Pew Research Center’s report “Mobile Health 2012,” the most recent comprehensive report on the topic. In June, Flurry mobile analytics reported that health and fitness apps grew 62 percent in usage from December 2013 to June 2014. The overall growth of app usage was 33 percent.