If you exercise and lowcarb your muscles can experience a special kind of pain not normally associated with the standard fitness programs. This problem is 'solved' by the ingestion of dextrose (not fructose or sucrose) within 15 minutes of the end of your workout. Cheap sources of dextrose include sweet tarts, pixie stix and smarties. Take in 15-30 grams of carbs using these and your muscles will suck up the carbs to restore depleted muscle glycogen, by-passing liver re-glycogenation, and not interferring with ketosis. Most of the time you don't need to worry about counting these carbs in your carb total for the day, unless you are especially sensitive to carbs. Remember, no table sugar or fruit is to be used here, just dextrose (or you could substitute expensive glucose tablets found in the diabetic supplies section of your local pharmacy.)
While ketosis is not usually interrupted, the citric acid present in some dextrose containing candies might kick citric acid sensitive folks out of ketosis. Don't worry, this is temporary and should only last, at the longest, a few hours. It is also not necessary to do this after every work out. You can save this for those times when your muscles seem especially painfilled and tired.
The above information was "gleaned" from the lowcarb + exercise list. One especially helpful poster from that list has written what looks to be the definitive book on lowcarb and keto dieting for the athlete. His name is Lyle McDonald. Look for this book soon.