Fitbit announced a trio of new fitness trackers back in the fall, and today, the company is making moves to improve how those gadgets tackle workouts. The wearable maker acquired FitStar, an app that serves up video-based personal training sessions on your mobile device. If you'll recall, FitStar's roster of experts includes former NFL player Tony Gonzalez and yoga guru Tara Stiles. The purchase allows FitStar users to lump workout details with other gathered stats. Heart rate trends will soon be available for those sessions too -- if you're sporting a compatible device, of course. Fitbit's software already tracks activity, sleep and diet, so the tossing in an on-demand personal trainer is a solid addition. However, a FitStar membership will set you back $8 a month or $40 a year.