Exercise and Fitness
Pilots should try to maintain a good level of personal fitness. Flying is a sedentary activity, which has moments of relatively high stress. There have been many studies that indicate that good overall fitness can help keep people alert during the “down” times of such activities and improve performance during the peak stress periods.
Diet and Nutrition
Staying alert is the prime consideration for pilots and diet can play an important role in this. The two most important considerations are maintaining even blood sugar levels and preventing dehydration. Low blood sugar levels is known as hypoglycemia. Our digestive and regulatory systems are mainly devoted to either, breaking complex foods into these simple sugars, or distributing these to the various parts of our body via the circulatory system.
Hypoglycemia is caused either by too little or too much consumption. The too little is relatively easy to understand, you can’t distribute what you don’t have. Humans have to eat on a regular basis to produce the energy they need for normal functions. However if too much food is eaten in a short period, the body’s regulatory system can overreact and limit the amount of sugar it releases into the blood stream. This overreaction can vary significantly between people and can be quite dependent on diet. Usually it is promoted by eating foods that have a high content of relatively simple sugars, which can be processed quickly and cause the 'overreaction' hypoglycemia.
Dehydration affects both the body’s ability to transport nutrients, and its capacity to regulate temperature. Again humans require the internal temperatures to be very constant for the general functions to operate efficiently. A lower than normal supply of fluid can cause a chain reaction that leads to overall impairment of normal functions. The general rule of thumb is that if your lips are dry then you are in the early stages of dehydration so you should drink.
What you drink can have some implications as well. The body likes to maintain its blood with a certain balance of water, salts, nutrients, and other compounds. When any side of this equation gets out of balance it attempts to recover to the normal state. For instance, if the fluid level is low, then the salts and other compounds become dominant, and the body wants to dilute the concentration of these. The signs that we need fluid start with the drying of the lips which also not surprisingly produces a salty taste when we lick them. This is a sure sign that the balance of fluid to salts has shifted. Hopefully we take the clues and drink fluids. If we are operating in a dehydrating environment such as in the heat or at altitude, we may lose significant amounts of fluid. If we just drink water without eating or taking in some of the salts or other compounds, we can start to dilute our fluids. Our body doesn’t particularly like this and responds by getting us to urinate. When we are in this state, pure water more or less passes through us and is not as useful for hydration. Of course we could drink some fluid with a high sugar content, and risk the effects of the ‘sugar rebound’ type of hypoglycemia. It is wise to avoid many sport, soft, and fruit drinks for this reason.
What to do? There are many sport drinks on the market today that provide a balance of salts and carbohydrates along with the required fluids and these are a good compromise. I say compromise because on long flights (> 3 hours) they also have the problem of supplying too many simple sugars as well. For long flights it is best to take food, some sport drink, and water or some other alternate. Expect in summer conditions or at altitude to carry up to two (2) litres of fluid for flights of 4-6 hours.
Aside from having the fluid, also be prepared with your pilot relief system. If you do not have the urge to expel some fluid, this is another sign of dehydration. If you resist the urge this can be problematic as well. Your system does not like to be backed up as well. Fluid will pool in places that will make your life uncomfortable in the close confines of the cockpit and your physiology will not like it as well.