If you are more of an endurance athlete that will be perming aerobic activity at a relatively high intensity level for longer periods of time, a targeted ketogenic diet (TKD) may be right for you. This type of diet schedules carbohydrate consumption around exercise on training days to avoid the difficulty of performing long sessions of aerobic activity while in ketosis. Ideally, this system allows you to utilize carbs for the energy required during the activity and rapidly return to ketosis afterword.
Before the Workout
Consuming carbohydrates before the workout should provide a noticeable increase in performance and should maintain glycogen levels allowing a return to ketosis shortly after. Take between 25 and 50 grams of carbs about 30 minutes before the workout depending on the expected intensity. High GI carbs usually work well, but you should experiment with different pre-workout sources and make sure you find one that does not upset your stomach during training.
After the Workout
It is not strictly necessary to consume carbs after the workout as 25-50 grams of protein will often be sufficient to help you recover. However, if the workout duration is long or particularly intense (if you are feeling light-headed afterward), an additional 25-50 grams of carbs should be consumed. For these carbs, you should avoid fructose or sucrose sources, but feel free to experiment with sources and amounts that you feel aid your recovery the most.
Outside of this crucial period of time around training, you should follow a traditional ketogeic diet. However, remember to factor in the amount of carbs consumed around training into your overall macronutrient and calorie ratios. The extra calories from these carbs should be subtracted from the daily fat total to assure that your calories are still on track.