CYCLING PERFORMANCE TIPS
are additives helpful?
First, let's review the basic physiology of providing energy to your muscles. The Calories (energy) in food are released in a process called oxidation. Burning oil (a fat) in a lamp or a flaming sugar cube (a carbohydrate) as a decoration in a dessert are examples of oxidation. The Caloric energy is released as heat and light. In the body food energy is released more slowly in a process that harnesses this energy (via ATP) to support basic cell functions or the shortening of actin-myosin fibers in muscle cells.
All foods are composed of three basic compounds - carbohydrates, fats, and protein. Carbohydrates are the preferred energy source for the average cyclist and is essential for short, maximum performance events. Fats are also available as an energy source (via ATP) assuming more importance in endurance events (< 50% VO2 max). Proteins are only rarely used as an energy source and are instead used in building and repairing body tissues.
The energy content of carbohydrates, fats, and protein is measured in Calories (note the capital C). Carbohydrates and proteins contain 4.1 Calories per gram (120 Calories per ounce) while fat contains significantly more Calories per gram at 9 Calories per gram. Although fat would seem to be the optimal source of energy for physical activity, that is true only for endurance levels of exertion, that is ~ 50% VO2 max. Thus it is not useful for sprint level aerobic activities.
Many studies have confirmed the inability of fats (compared to carbohydrates) to sustain high level (high VO2 max.) aerobic, and anaerobic, performance.
What about a high fat diet for the several weeks? Maybe it would improve fat metabolism and thus change the results in competitive (high VO2max) aerobic performance compared to a diet high in carbohydrates and thus relatively restricted in fat Calories. Various arguments had been put forward, such as:
But there have been two well controlled studies showing high fat diets (70% fat in one, 38% in the other) for 2 weeks before an increasing the time of exercise to exhaustion for endurance level activities at 50% VO2 max (80 vs 42 minutes of cycling in one, 76 vs 70 minutes of running in the other). Glycogen sparing effects were studied to determine if it might have been from a preferential shift to fat metabolism during exercise after a high fat diet, but none were found.
Another study tracked Calorie replacement after exercise in two groups (a low fat diet vs normal/high fat foods) and found that those on a low fat diet did NOT replace all the Calories expended during a training program while the group on a more liberal fat diet did. This suggested another reason for poor performance on a low fat diet - the development of a long term Caloric deficit during training which lead to more limited muscle glycogen stores going into the next ride. But it isn't just about Calories replaced. Good glycogen stores are important and a chronic deficit replacing carbohydrates used in exercise has been linked to chronic fatigue..
In addition to the questionable exercise performance benefits, it has been proven beyond doubt that a long term, high fat diet leads to heart disease. And for those who still aren't convinced, remember that even the leanest athlete has plenty of stored fat available (approximately 100,000 Calories worth in a 70 kg male) on a balanced diet.
FACT NUMBER ONE - BASED ON NUMEROUS STUDIES, GLUCOSE OR CARBOHYDRATES ARE THE PREFERRED TO FAT AS AN ENERGY SOURCE FOR AEROBIC (GREATER THAN 50% VO2 MAX) AND ANAEROBIC EVENTS.
Let's look at the basic energy bar and energy gel.
Commercial power-bars are generally carbohydrates (of varying types) as well as containing special supplements such as those I'll mention below. Their main advantage is being prepackaged, readily available commercially, and offering another taste and texture option for an on the bike snack. But as a carbohydrate, they are no more effective on a gram for gram basis than other other carbohydrates.
A study from Ball State University demonstrated that a pre event meal of old fashioned oatmeal gave the same boost to endurance performance as a commercial energy bars. Or, it has to be assumed, over other commercially available carbohydrate snacks such as fig newtons.
Energy gels (as well as drinks - including powders for your water bottle) are an alternative to the often hard to unwrap, difficult to chew, and frequently tasteless commercial energy bars. These products are a combination of simple and complex carbohydrates packaged in a palm sized packet of plastic or foil with a tear off end which allows the contents to be "sucked" out rather than chewed. They contain between 70 and 100 Calories per packet (17 - 25 grams of carbohydrate) and have the advantage of being completely fat free. They also empty more quickly from the stomach and their only advantage may be that as a liquid or semi-liquid they provide a more rapid absorption and energy boost than solid energy bars.
FACT TWO - THERE IS NO EVIDENCE THAT THE CARBOHYDRATE IN ENERGY BARS OR ENERGY GELS IS MORE EFFECTIVE TO SUPPLY MUSCLE ENERGY THAN, FOR EXAMPLE, THE CARBOHYDRATE IN TRADITIONAL OVER THE COUNTER SNACKS SUCH AS FIG NEWTONS.
Now let's look at some of the additives in bars and gels. They fall into these 4 groups.
Caffeine is a member of a group of compounds called methylxanthines found naturally in coffee beans, tea leaves, chocolate, cocoa beans, and cola nuts. During prolonged exercise, the onset of fatigue correlates closely with the depletion of muscle glycogen stores (and is delayed if glycogen is spared). The metabolism of free fatty acids as an alternative energy source can lead to decreased use of muscle glycogen. Caffeine can increase blood free fatty acids, and in one study produced a 50% increase at 3 to 4 hours. This effect was seen after 300 mg of caffeine (An average 6 ounce cup of brewed coffee contains 100 - 150 mg of caffeine).
There has been speculation that some of caffeine's benefits may be from a central nervous system stimulant effect and some work has demonstrated a direct positive effect on the muscle fiber itself.
In one controlled study, subjects were able to perform for 90 minutes to fatigue as compared to 75 minutes in controls (a 20% increase) after the drinking the equivalent of 3 cups of coffee or 6 caffeinated colas 1 hour before, even though values for heart rate and oxygen uptake were similar in both groups.
But there are potential side effects. Caffeine can cause insomnia and nervous system irritability, and there are the caffeine withdrawal headaches. In addition it is a potent diuretic and may contribute to dehydration. However its biggest negative is that in high concentrations it is considered a drug and is banned by the US Olympic Committee and US Cycling Federation (to exceed the US cycling Federation's legal limit for caffeine - urine concentration of 12 micrograms/ml - one would have to ingest 600 mg of caffeine and have a urine test within 2 to 3 hours).
The bottom line is that most endurance athletes consider caffeine useful if used correctly.
Guarana is a South American herb used as a natural source of caffeine and can be listed as a supplement in energy gels or bars. Cola nut is another natural source of caffeine sometimes found in the ingredient list.
The minerals sodium, potassium, and chlorine are collectively referred to as electrolytes. They are dissolved in the intra (within) and extra (outside) cellular water in your body as charged particles (ions) and are responsible for maintaining a proper electrical gradient across the cellular membrane - required for the proper functioning of each cell.
A normal diet contains these three minerals in excess, and the kidneys control the loss from the body. So there is no requirement (or benefit) in these supplements except in extreme conditions.
Minerals are chemical elements and like vitamins are essential for normal cell functioning. The two most prevalent minerals, calcium and phosphorus, are major components of bone while sodium and potassium are found in all tissue fluids, both within and around cells. Magnesium, chloride, sulfur, and zinc are other minerals that play a key role in cell function. The trace elements iron, manganese, copper, and iodine are found in much smaller quantities, but play essential roles as catalysts in basic cellular chemical processes.
These minerals, found in all foods, are kept in balance through regulation of both absorption and excretion. As a result of this control, they are easily provided by a balanced diet. Only calcium and iron may be required by some athletes in increases amounts. Because of toxic side effects when taken in large amounts, minerals as a group are not recommended as routine dietary supplements.
FACT THREE - ASIDE FROM CAFFEINE, WHICH MAY PROVIDE PERFORMANCE ENHANCEMENT IF USED CORRECTLY AND IN LIMITED AMOUNTS, THERE IS NO EVIDENCE THAT OTHER ELECTROLYTE OR MINERAL ELEMENTS PROVIDE A PERFORMANCE EDGE.
Then there is the issue of the fat content of some energy bars which is alleged to:
If you are a believer in being able "training" your body's metabolism to use fat as an energy source, an alternative to fat supplements in bars would be to focus on a training program of a high mileage at a relatively slow pace (60% VO2 max.) to force metabolism of your own fat stores (of over 100,000 Calories). You could, in addition, avoid carbohydrates while training, minimizing carbohydrate supplements while on that long slow ride, to further force the development of these alternative metabolic pathways for fat (essentially a planned "bonk"). Then, or so goes the theory, when it comes time for that sprint at the end of a competitive event (ridden with appropriate glucose supplementation), having used more fat than glycogen, you would have more glycogen available for that anaerobic sprint at the end. The only problem is that there is very little evidence this happens. And what you get little in return is the chance to train in a chronically glycogen depleted state - feeling as if you are chronically bonked.
Medium chain triglycerides are a form of fat more easily absorbed from the intestinal tract, but metabolized by the muscle cells exactly like any other fats, and are probably of no more benefit than adding an extra pat of butter on your pancakes before the ride. And at a few grams per bar, they provide minimal additional Calories to the carbohydrate content.
FACT FOUR - THERE IS NO EVIDENCE OF PERFORMANCE ENHANCEMENT FROM FORCING DIETARY FAT BEFORE, OR IN A SUPPLEMENT DURING A COMPETITIVE EVENT.
Finally, it has been suggested that a combination of protein (amino acids) and carbohydrates in a ratio of 1:4 is more effective in sports drinks/gels/bars eaten while riding and in supplements for glycogen repletion immediately after a ride. There is no information in the literature supporting a benefit from protein enhanced carbohydrate supplements while riding.
There is data for a benefit of protein increasing glycogen repletion in the post ride recovery period. But simply increasing the amount of carbohydrate Calories to 1 gram/kg/hr x 3 - 4 hours appears to maximize repletion rates.
RED BULL, MONSTER, AND OTHER "ENERGY DRINKS"
Energy bars (the original Clif Bars for example) and gels started off as a convenient source of carbohydrate energy for aerobic muscle metabolism while on the bike. Then the black magic of "additives" was applied and we ended up with energy drinks such as Red Bull and Monster.
Do these energy drinks improve performance? When compared to an carbohydrate equivalent (equi-caloric) caffeine/glucose drink - NO
Are you risking more than your wallet? Are they potentially harmful? - YES.
They not only lead to an immediate increase in blood pressure, but also have been linked to cardiac arrhythmia and sudden death. This interview from Medscape.com provides additional insight into the reasons for their negative cardiovascular effects.
Plus they can increase inflammatory blood markers such as C-reactive protein. This chronic inflammation will injure normal tissues. And when monitored over time, groups with elevated C-reactive protein levels have been shown to have higher rates of diabetes, cardiovascular disease, and cancer.
So what is the bottom line on additives in energy bars and gels?