A collaborative approach between health scientists, designers and social media experts has produced a health app that actually works to get normal people to be more active.

The multidisciplinary research group from the University of South Australia designed the trial Facebook app to harnesses the power of friendship to increase physical activity.

Named 'Active Team', the pilot app allows users to invite Facebook friends to join them in a physical activity challenge, using a pedometer to track and increase their exercise.

An eight-week pilot study in South Australia found that compared to groups of friends not using Active Team, average weekly physical activity increased by over two hours per person in the groups with app access.

Project leader Dr Carol Maher admits even the research group was surprised about the results.

"Seeing a two hour increase in average physical activity levels associated with Active Team usage was quite exciting for us," she said.

"Often more conventional new health interventions will only lead to physical activity improvements of the order of 20 minutes or so."

The results from the Active Team pilot trial are being prepared for publication this year.

While more research is currently underway to determine exactly why the app was so effective, Dr Maher believes the key lies in its careful formulation. A team of health scientists working with experts in marketing, social media and graphic design created Active Team.

"At the planning stages, we paid careful attention to the way that people already use Facebook," she said.

"Active Team users interact within their existing social networks, and take part in friendly rivalry using light hearted and humorous language."

The app allows participants to log their daily steps, see a tally board with their and their friends' steps, send virtual gifts - such as gold sneakers to congratulate a friend on a good performance, or flowers for encouragement - and communicate via a discussion board.

"We want people to use the app because they are motivated to do so, and because it's fun and easy to use," said Dr Maher.

"It's quite different from other social media-based health interventions that rely on conversations between users who don't know each other, or through private groups," she said. "Those examples typically experience low engagement."

University of Melbourne researcher in online behaviour Associate Professor Shanton Chang - who was not involved in the Active Team study - believes the poor performance of many health platforms stems from a lack of expert contribution.

"At last count, there were about 98,000 health apps in the world," said Chang. "But very few of these have any clinical input or have been verified for usability or clinical effectiveness."

However he sees strong potential for social media in addressing some areas of public health.

"Social media will be important for many health issues," he said. "In fact, information technology is likely to be one of the major ways we monitor many areas of wellbeing in the future."

For this to occur, Chang emphasises the importance of proper evidence and accountability in assessing new health apps.

"People are starting to say - yes, you have a new app, but we need a proper trial to establish its effectiveness," he said. "To date, very few studies have evaluated efficacy of social media apps for improving health."

Dr Maher has secured funding from Australia's National Health and Medical Research Council to conduct rigorous trials with the Active Team app before it can launch.

To confirm and extend the pilot results showing the effectiveness of the app for increasing physical activity, she will conduct a randomised controlled trial - the gold standard for testing medical interventions - with 400-500 participants.

"The higher number of study participants will also enable us to ask some more subtle questions relating to the app," she said. "Is the efficacy due to the social influence, is it that the users are feeling accountable, or do they like being able to keep a record?" she said.

In addition, the funding will be used to improve the app software, to ensure it works well on mobile platforms, and to examine its capacity to spread across social networks.

"The development of this app is motivated purely by public health goals," said Dr Maher.

"We want to see whether Active Team is an intervention that can really work in the real world."

Dr Maher will be looking for volunteers to help with the randomised controlled trial later in 2015.