I saw similar rises when I started to exercise. I followed the advice in the book "The FIRST Program: Fighting Insulin Resistance with Strength Training " By Dr William Shang. The suggested regime is pretty intensive and so I suspect that there was some stress related BG rise, as well as that due to the exercise. Conversely, having a brisk walk after lunch would bring my BG down and so it seems different forms of exercise have different effects. I found that after a few weeks my BG suddenly went back to normal. I think that long term, some vigorous effort has benefits in BG control, not least because you develop muscle that metabolises glucose to CO2 and water, never for it to return!