CPTIPS Nutritional Program

Tips to Enhance

The Benefits of your Nutritional Program

Now that you have reviewed the basics of energy and nutritional physiology, there are a few more tips to maximize the benefits of your cycling nutrition program.

CARBOHYDRATES, FATS, OR PROTEIN??

Focus on carbohydrates! Eating a high carbohydrate diet for several days prior to the event will maximize your internal glucose (glycogen) stores, and will prolong the duration of activity until fatigue occurs. (But it will not increase the muscle's maximum energy output during that time.)

The body's normal liver and muscle glycogen will support the first 2 or 3 hours of exercise at 70% VO2 max. without any need for supplementation. And both a good training program to improve the form and muscle efficiency of the individual as well as riding (or exercising) at a reasonable pace will postpone the onset of glycogen depletion and fatigue.

Taking in carbohydrates during the event provides an additional source of glucose "fuel" that will extend the length of time before the bonk occurs. A well-trained cyclist will need slightly more than 1 gram of carbohydrate per minute to sustain maximum performance, and oral supplementation (started at the beginning of the exercise, not after glycogen depletion has occurred) should replace carbohydrate at that rate.

This is important in rides of greater than 2 hours duration. As a general rule, the body can utilize 60 grams of ingested carbohydrate per hour to supplement muscle glycogen stores, and the stomach can handle between one and two quarts of fluid before nausea occurs. This does put an upper limit on carbohydrate supplementation during a ride but gives you some guidelines for developing your own program. And there is no problem in using solid food supplements as well, as long as enough fluids are taken along with them.

BEFORE THE RIDE

Carbohydrate loading - pack your muscles with glycogen by eating a high carbohydrate diet the three days before the ride.

Insulin surge - avoid the potential hypoglycemia that might occur from sugary drinks ingested in the minutes immediately before a competitive event. Although this can be seen in sedentary individuals eating sweets, rebound hypoglycemia does not appear to be a practical problem for athletes. However, choosing to err on the side of caution, most authorities recommend avoiding all simple carbohydrates for the several hours before an event, starting carbohydrate supplementation in the few minutes immediately preceding the start of the activity.

Pre Ride Meal - There is almost unanimous support for the benefits of a pre ride meal of complex carbohydrates 3 or 4 hours before the event. These carbohydrates will "top off" your muscle and liver glycogen stores, and the slow digestion and absorption of the complex carbohydrates may provide additional glucose supplements to your internal glycogen stores even after the ride has started. Studies have failed to demonstrate that using commercial energy bars or a high fat meal offer a performance advantage over a less expensive complex carbohydrate such as oatmeal.

DURING THE RIDE

Maximizing liquid carbohydrate replacement while riding, especially for events lasting more than 2 hours. 1 to 2 grams of carbohydrate per minute can be absorbed and utilized to supplement internal glycogen stores and help to sustain prolonged exercise. In extreme events such as the Tour de France, as much as 50% of the daily energy expenditures are be replaced while on the bike. Keeping the stomach filled by frequent drinks will enhance the rate of gastric emptying.

As sugar concentration increases, the risk of nausea and bloating rises as well. Almost everyone can tolerate a 7 to 10% concentration of glucose, but many cyclists will tolerate solutions of up to 15% to 20%. And the use of complex carbohydrate polymers will allow more carbohydrates to be ingested and absorbed by minimizing the overall concentration of the solution. A good initial strategy is to drinking 400 ml of an 18% glucose polymer solution at the start of the event and then drinking 100 ml every 10 minutes.

Fluid replacement rates of 500 ml per hour are appropriate for the majority of cyclists during prolonged exercise, but rates of up to 1 to 2 liters per hour have been reported in the Tour de France. Hyponatremia is a risk with larger volumes.

AFTER THE RIDE

Take advantage of the glycogen window that is open in the 4 hours immediately following vigorous exercise. During this interval, ingested carbohydrate will be converted into muscle glycogen at almost 3 times the normal rate (and "the earlier the better" as there is evidence of a 50% fall in the conversion rate by 2 hours and a complete return to normal repletion rate by 4 hours). Muscle glycogen repletion (after a 2 plus hour ride) usually proceeds at a rate of 5% per hour, and although it may require up to 48 hours for complete muscle glycogen replacement, most is accomplished during the first 24 hours post event.

There is some evidence that protein may help the absorption of carbohydrates in the immediate post ride window (several hours) that maximizes glycogen repletion in the muscles. But the most important part is not the protein, but maximizing carbohydrate intake during this time.

The athlete who is training daily, or is in a multiday event, can use this glycogen window to their advantage to get a jump on the normal repletion process and minimize the chance of chronic glycogen depletion (and the fatigue that goes along with it). There is also suggestive evidence that the muscle stiffness that occurs after vigorous exercise is related to muscle glycogen depletion, so rapid repletion may have an added benefit of minimizing this day after effect.

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