In California, where he works at a Fleet Feet running-gear shop, the 24-year-old uses MapMyRide to track his course in an archive.

Bethany Scribner, a runner who also works at the fitness-gear retailer, likes the apps MapMyRun and Livestrong, which tracks nutrition in a daily pie chart showing fat, protein and carbs. Saucony Run4Good is a favourite, too, says Scribner, 21, because the company donates to anti-obesity programs for kids if enough runners cover enough miles.

MapMyRide, MapMyRun, Livestrong, Run4Good, MyFitnessPal – they’re all part of an exploding arena of health and fitness applications for smartphones. The trend, which falls under the umbrella of Health 2.0, an international tech movement grounded in San Francisco, is proving an obsession for programmers at code-a-thons, as well as users who get hooked on tracking their workouts, calorie intake and weight loss.

Among users, a pinch of competition – a social network of friends who sign up to share fitness scores – is all you need to make this an activity as additive as Twitter is for some and Facebook is for others.

The Pew Research Centre, in a new report titled Mobile Health 2012, found smartphone owners in the vanguard, with 52 per cent gathering health information on their palm-sized, micro-computers. That compares with 6 per cent of owners of regular mobile phones.

Also, Pew found, 19 per cent of smartphone owners have at least one health app – with exercise, diet, and calorie-counting programs the most popular.

Overall, the proportion of mobile phone owners who use their phones to access health data nearly doubled, from 17 per cent two years ago, to 31 per cent today.

Apps are proliferating. Click on Apple’s health and fitness apps page and you’ll find iRunner, Fitocracy, Fitter Fitness, Fitness Buddy, Fitbit, Fitness Pro, miCoach, Abs Workout, RunKeeper, Virtual Trainer – and about 250 more.

And it’s not just fitness. There’s a parallel world of apps geared to other aspects of health and wellness: iTriage, iFirstAidLite, InstantHeartRate, CuresA-Z, not to mention a host of downloadable apps such as OvulationCalendar that help women track their menstrual and fertility cycles.

The medical community is embracing the trend, holding contests to encourage programmers to design disease-specific apps that doctors can ‘‘prescribe’’ to patients.

In the meantime, the private sector is leading the charge at Health 2.0-inspired code-a-thons, live events where developers gather to build apps and tools for improved health care. AAP