Short answer: No, for several reasons.
Longer answer: the apparent gravity from centripetal acceleration was low, and the astronauts likely didn't have enough exposure to get any real benefit. I'm going to have to dig up long unused physics knowledge here. The formula for centripetal acceleration is ac = v2 / r, in other words centripetal acceleration is equal to velocity squared divided by the radius of the movement.
I'm going to plug in some educated guesswork figures here, I don't expect them to be exact but they should be good enough. Velocity is a tough one, but from my memories of the videos the it seems to be a slow running pace, kind of a jog, so I'm going to say it's 3m/s. I have no figures on the ring the astronauts ran on, the outer diameter was about 7 meters, so I'm going to say 6 meters, or 3 meters radius. Plugging that into the formula I get 3m/s2. That's less than 1/3 earth gravity. Remember this is not exact, but an estimate, the real figure could be more or less.
While that is a significant acceleration it seems to have been more of a curiosity than a serious form of exercise, so their exposure to it was only a few minutes over the mission. Although we have very limited knowledge on the effects of low gravity on the human body it's very unlikely it would have been measurable.
Lastly, there was nothing to compare to. Skylab was the first US space station, and the first time the US astronauts could spend extended time in space where there was room to move around, before they were in small capsules with limited exercise opportunities. Skylab had a gym which the astronauts used, so differences in bone density would be attributable to exercise.