There is little evidence of any specific apps or design features on mobile devices designed to reduce the risk of RSI. However there may be features that reduce the risk without that specific intent.

There's a nice article in a medical journal from a few years ago interviewing an industrial designer at RIM (remember them?) which goes through some of the benefits of touch screens vs the infamous 'Blackberry Thumb', an RSI-like injury. All the quotes below are from that article.

###Touchscreens Touchscreens implicitly reduce the stress on joints, as there is less tactile pressure needed to input.

That’s one of the aims of touch screen devices, argues Joseph Hofer, senior industrial designer at RIM. They actually reduce fatigue and strain because there is no requirement that a user physically press a button, he says, adding that the smooth glass screen may reduce effort if keys are touched gently and precisely.

###Autocorrect

By reducing the amount of inputs required by tapping on a screen, there is less repetition of movement.

Use of the auto-correct function on mobile devices is another means of reducing the risk of repetitive strain injury, Hofer says. ... “As you’re typing it’s predicting what the next word might be. It places these suggested words above letters that your eyes would naturally be headed towards,” he says.

###Voice-to-text

Avoid repetitive movements by not doing the movement at all!

... voice to text software, which will allow users to communicate on their devices without overuse of their thumbs, should also help to reduce injury.

###Conclusion

So in short, whilst there is not a vast amount of evidence of strategies to reduce RSI in mobile devices, the natural product development has lead to improved ergonomics and functionality to reduce the amount of repetitive motions causing RSI, compared to featurephones and early smartphones.

There is little evidence of any specific apps or design features on mobile devices designed to reduce the risk of RSI. However there may be features that reduce the risk without that specific intent.

There's a nice article in a medical journal from a few years ago interviewing an industrial designer at RIM (remember them?) which goes through some of the benefits of touch screens vs the infamous 'Blackberry Thumb', an RSI-like injury. All the quotes below are from that article.

Touchscreens

Touchscreens implicitly reduce the stress on joints, as there is less tactile pressure needed to input.

That’s one of the aims of touch screen devices, argues Joseph Hofer, senior industrial designer at RIM. They actually reduce fatigue and strain because there is no requirement that a user physically press a button, he says, adding that the smooth glass screen may reduce effort if keys are touched gently and precisely.

Autocorrect

By reducing the amount of inputs required by tapping on a screen, there is less repetition of movement.

Use of the auto-correct function on mobile devices is another means of reducing the risk of repetitive strain injury, Hofer says. ... “As you’re typing it’s predicting what the next word might be. It places these suggested words above letters that your eyes would naturally be headed towards,” he says.

Voice-to-text

Avoid repetitive movements by not doing the movement at all!

... voice to text software, which will allow users to communicate on their devices without overuse of their thumbs, should also help to reduce injury.

Conclusion

So in short, whilst there is not a vast amount of evidence of strategies to reduce RSI in mobile devices, the natural product development has lead to improved ergonomics and functionality to reduce the amount of repetitive motions causing RSI, compared to featurephones and early smartphones.