From what I have read, your muscles store 250-400g of glycogen, and your liver stores another 100g of glycogen. In this discussion (http://www.unm.edu/~lkravitz/Article%20folder/glycogen.html), it is noted that only a modest fraction of glycogen stores are used in an intense anaerobic training session. It has been my experience that aerobic exercise can be fueled quite well with ketones if you are in ketosis. In particular, I don’t need any glucose, I basically burn fat.
I do weight lifting, usually barbell sessions starting with back squats. I’ve not had any problem with energy when on the Dr. B diet, even when clearly in ketosis. All I can tell you is give it a try and see what happens.
As to after workout nutrition, that is another matter. After workout, I make an exception to Dr. B for glycogen replenishment. Although I am usually high (200s)after workout, I am insulin sensitive. I usually have a protein shake with milk. I found the book “Nutrient Timing” by John Ivey helpful understand workout nutrition.
Like Shelia, I’ve never had a doctor believe me that my blood sugar rises during workout. Most doctors are totally clueless about exercise (and nutrition).