Thanks for the commiserations,
@DJC3. It was probably a combination of the kitchen cleaning and the lack of wine. Wine tends to dampen the spikes a little. I usually work out at night -- after dinner and wine, so spikes are usually very reasonable, often even stays below 6 mmol.
I see a difference between breaking down my half-hour routine into several smaller bits when it is only slightly raised (today played it safe and did 10 four- to five-minutes intervals and even then it only went up to 5.6) or larger intervals of exercise (15 minutes or more) when it goes higher.
What is your experience when exercising? What type of exercise raises your levels? What type lowers them?