There are many misconceptions about foods one should have before an intensive workout. It is necessary that what you eat gives you energy to sustain the whole workout and at the same time it should not be heavy or unhealthy. Exercising with a full stomach is a bad idea and more importantly you must eat the right time. Eat at least 45 minutes before your workout. Being well hydrated will make your exercise easier and more effective. Try to drink half a litre of water during the 1-2 hours before starting your workout.
Oatmeal with fruits is one of the best breakfasts before a workout. Oatmeal is known to settle well and is a great source of energy. For those training for a race, bananas, are perfect in raising potassium levels, which drop when you sweat a lot.
For an added bonus, add a dash of cinnamon. It has been linked to stabilising blood sugar and improving brain function. Many may suggest you against having bananas since they contain sugar, starch and are very rich in carbohydrates. But these very attributes of the fruit will work in your favour if you have it an hour or so before your workout. You can also try having fruits with yogurt, nuts, hummus with raw vegetables, hard boiled eggs (or egg whites), paneer with fruits, milk based chocolate drink, tomato or vegetable juice, yogurt smoothie (with added protein powder, if desired) or even just protein/energy bars. The most important things is to get to know your body and how it responds to your workout, this way you can give it what it needs to perform at its best.