Some recommended low to moderate GI carbohydrate sources are brown rice, oatmeal, Ezekiel bread, white rice (long grain) and even whole wheat pasta. Of course, portion control and timing is a must when consuming a meal pre-workout.
If you consume an overabundance of carbs or consume them too close to your workout, your body has insufficient time to metabolize the food.
This results in blood being redirected to your working muscles rather than being reflowed to your stomach to aid in digestion, causing stomach cramps. As a general rule, consume anywhere between 20 to 40 grams of carbohydrates one to two hours before working out.