There is a time counter starting at 0, but what is the actual time?
I suggest the workout timestamp is added or replace the Time-value.
I also suggest it should be able to move fast forward/backward in the data samples. The fast forward/backward controls are not good. You have to click repeatly on those in order to move forward/backward. Better would a slider dragging view of data.
It would also be nice if you set the marker on some point in data charts, and when selecting Edit Data, the actual data values are displayed.