Table 4.

Solutions to reduce barriers.

Barrier			Solution
Barriers to physical activity
	Joint pain and fatigue	Explain that being physically active can help reduce joint pain and fatigue
	Reduced motivation	Offering rewards inside the challenge for regularity and improvements
	Lack of time (eg, working again, family commitment)	Show different ways to gain steps each day without needing a lot of time (eg, leaving the bus/metro one stop early, parking the car farther away from the workplace/stores, taking the stairs, using the bathroom on another floor at work). Help participants to find ways of freeing some time
	Counterintuitiveness of being active when fatigued or feeling pain	Explain that being physically active can help reduce joint pain and fatigue; tell them they will likely feel it after a few days
Barriers to the use of mHealth and challenge improvements
	Complexity of the device’s use	A simpler way to record steps
	Device only adapted to walking	An only device recording all kind of physical activity (cycling, swimming, etc)
	Visibility of new messages in the chat	Build a pop-up alert when a new message is posted in the chat
	Visibility of the itinerary (world tour) of the challenge on a mobile device	Seeing the map of the challenge more clearly on the phone (world tour) or finding another way to present it
	Information about step counts	A day-by-day recap of the step count
	Reduced motivation	Add more mini-games, more interactions between participants
	Playing with strangers	Use the challenge in groups that already know each other