The FitStar Personal Trainer app has been updated with new features based on users’ feedback to “keep users motivated.”

First, there’s the new Challenges feature that enables users to engage with friends. According to FitStar, workouts are more motivating with friends so you can now earn bragging rights by seeing who can burn calories the fastest, workout the longest, or complete the most Sessions.

Freestyle Sessions can now be resumed with a simple tap.Another new thing comes in the form of improved Session summary that recaps workouts, highlighting minutes completed, calories burned and a snapshot of Moves completed. This “enhanced visual recap” lets users motivate themselves and share the fund with others.

There’s also better Session control which makes sure you can resume Freestyle Sessions with a simple tap.

Finally, FitStar has incorporated the referral mechanism within its mobile app, so that users can earn a free week of FitStar Premium for every new referral. Each user is given a unique referral code that can be sent and shared with as many people as they like via Twitter, Facebook or email.

Recently, FitStar announced expansion to the “yoga market” with the FitStar Yoga app, which is coming this fall to iPhone, iPad and iPod touch.