Athletes’ diet

The triathletes who ate nearly twice as much, yet gained no weight, and improved their performance times by 8 per cent

Most athletes say they are aware of the importance of good nutrition, but when they sit down to eat, their patterns of food intake are often considerably less than optimal. One key problem is that athletes often take in less energy than they really need to support strenuous training. Another is that they simply don’t ingest enough carbohydrate.

Despite Dave Costill’s excellent research (and fine follow-up investigations by Clyde Williams at the University of Loughborough in England), which showed that endurance athletes who train fairly strenuously need about 4 to 4.5 grams of carbohydrate (CHO) per pound of body weight per day to maintain normal leg-muscle glycogen stores, most endurance athletes don’t eat that much CHO.

In fact, studies reveal that athletes often end up eating less than 3 grams of CHO per pound per day, even when they think they are ‘stocking up’ on carbos (‘Dietary Carbohydrate as an Ergogenic Aid for Prolonged and Brief Competitions in Sport,’ International Journal of Sport Nutrition, vol. 5, pp. S13-S28, 1995). Costill’s work is now nearly 10 years old, but athletes still haven’t gotten the message.
Of course, if you give such athletes more CHO and energy, their performances will often improve because they suddenly have enough fuel to sustain high intensities of effort for longer periods of time. Such improvements will occur without corresponding rises in VO2max, lactate threshold, or economy because they are primarily the result of cleverer lifting of the fork at the dinner table – not better training.

This ‘eating makes you better’ principle was reinforced recently in research carried out at Xavier and Dayton Universities in Ohio. There, a group of male and female triathletes preparing for the Hawaiian Ironman Triathlon pepped up their short-course triathlon performances by boosting their intakes of carbos, total calories, zinc, and chromium (‘Increased Energy and Nutrient Intake during Training and Competition Improves Elite Triathletes’ Endurance Performance,’ International Journal of Sport Nutrition, vol. 7(1), pp. 61-71, 1997).

At the beginning of the study, when the athletes were following their own natural dietary inclinations, they competed in a short-course triathlon (1.3-K swim, 40-K bike, and 10-K run). At this time, the athletes weighed about 154 pounds, possessed 8-per cent body fat, and trained about 11 hours per week.

Average daily caloric intake was 2318 calories, with 59 per cent of the calories coming from CHO and 18 per cent from fat. Despite the not-too-bad 59-per cent figure, daily carbo intake was actually a miserly 344 grams per athlete, or only 2.2 grams per pound of body weight. This situation points to a basic problem associated with the current, red-hot debate concerning what percentage of an athlete’s diet should be devoted to carbos. Lots of ‘experts’ suggest that if endurance athletes take in 70 per cent or more of total calories as CHO, they will be all right, forgetting that 70 per cent of a too-low total caloric intake will produce too few carbos in the diet. (As an aside, the controversial-yet-popular 40-30-30 plan advocated by the entrepreneurial Barry Sears – and followed rather closely and spontaneously by the sedentary, overweight British and American populations – will seldom ever supply adequate CHO to keep leg-muscle glycogen brimful, even when one’s dinnertime portions are truly prodigious. For example, a 154-pound athlete enthralled with Searsian eating would need to ingest about 6000 calories of food each day to keep the leg muscles well supplied with glycogen.)
The vitamin and mineral consumption patterns of the Ohio triathletes were pretty good, except for zinc and chromium, with intakes of both averaging less than 66 per cent of the RDAs (Recommended Dietary Allowances). Zinc intake was a mere 7 mg per day (the RDA is 15 mg for males and 12 mg for females), while chromium totalled only 18 micrograms, a very low quantity when you consider that about 200 daily ‘mikes’ of this trace mineral are often recommended for endurance athletes. The only other problem was that the triathletes were eating only two servings of vegetables each day, preferring instead to fill up on fruits and grain products (sound familiar?).

The change-over
After completing the short-course triathlon, the athletes met with the researchers to discuss ways of improving their eating patterns. After these meetings, the athletes then raised their daily caloric consumption to 3992 calories, boosted carbo intake to 65 per cent of total energy, and heightened daily grams of CHO ingested to 650, or 4.2 grams per pound of body weight, nicely within the Costill-Williams zone of optimal carbo feeding.

Overall patterns of eating changed considerably, with the number of daily milk servings advancing from one to four, vegetable portions climbing from 2 to 10, fruits increasing from seven to 12, breads and cereals exploding from 11 to 23, and meat servings declining from seven to six. To supplement dietary energy, the athletes also consumed an eight-ounce serving of Innergize, a sports drink, and one 40-gram Ultra Bar both before and after their training sessions. Since one serving of each of these products contains 50 micrograms of chromium, the extra bar and sports drink helped the athletes shoot their daily chromium consumption up to well over 200 micrograms. Zinc intake also soared above the RDA (because of the greater quantity of food ingested and also because Innergize and Ultra Bar contain some zinc).

The athletes followed their new eating plans for four weeks, after which they completed a second short-course triathlon. The general training scheme during this four-week period was the same as it had been prior to the first triathlon (the frequency of interval and long-duration workouts didn’t change), and the pre-competition meals were also identical. During each triathlon, the triathletes consumed 32 ounces of sports drink.

Better eating = better performing
The results? Well, you might be thinking that the triathletes gained a lot of weight. After all, they were eating about 1700 more calories per day, compared to their own previous eating stratagems, a pattern which continued for four whole weeks. That adds up to approximately 47,000 additional calories per person, enough to prop up about 13 pounds of body fat, but there were no significant gains in weight or percent body fat! That’s because the additional energy was probably used to make needed body repairs and fuel higher-intensity training sessions.

And that better-quality training really paid off: in the second triathlon, the athletes improved their performance times by an average of almost 8 per cent (from 5 hours, 25 minutes to 5 hours flat)! And that was in spite of the fact that environmental conditions were brutal for the second event, with temperatures averaging 92 degrees, compared to a considerably less steamy 82 degrees during the first short-course triathlon.

Of course, another key factor was that the athletes were better ‘loaded’ for the second event. Since they were routinely eating enough calories and carbos, their leg muscles were fully stocked with glycogen on the second race day – and thus better able to sustain a high intensity of exercise for a prolonged period of time.

The message
What does this study really tell us? Well, the Ohio research showed, as many other studies have also verified, that most endurance athletes really aren’t consuming enough total calories to support their training. One athlete in the Ohio investigation was ingesting only 1875 calories per day, even though close to 4000 were actually needed. Once that kind of undereating is corrected, performances improve – often fairly dramatically. As Kenyan runners like to say, ‘You must eat to train and race hard – not to get skinny’.

The study also reinforces the idea that many endurance athletes also don’t take in enough carbohydrate. One research study after another has documented low intakes of just two to three grams per pound of body weight per day, a pattern which leaves muscle cells sad and depleted of glycogen. Often, athletes who are stingy with the CHO end up feeling ‘overtrained’, but their overtraining syndrome disappears rather rapidly when they begin to stock up on carbos properly.

And, of course, the Ohio research shows that dramatically increased eating does not automatically lead to unnecessary and counter-productive weight gain. Instead, the heightened fuelling augments metabolic rate, fills glycogen stores, and permits higher-intensity exertion levels to be sustained for longer periods of time during training and racing. The extra calories are burned off – and as they are burned they make you considerably fitter! Eating more – not less – is often a key way to improve performances.

Although such eating will produce alarming results at first as the improved glycogen storage chaperones more water into muscle cells (see the article on rapid weight gain and loss in the March issue of PP), such weight gain is very transient in nature because it stimulates higher-quality training, makes it easier to train for longer periods of time, and thus ‘melts down’ unneeded body blubber.

So, what should you do? If you train fairly strenuously five or more times per week, weigh yourself and multiply your weight by four to obtain the number of daily grams of CHO that you need (multiply by four yet again to obtain the number of daily carbo calories). Get out a handbook which lists grams or calories of CHO per serving of various food items, and reckon how many CHO calories you are taking in now. Then, create a new eating scheme for yourself by adding in additional CHO-containing foods until you have passed the wondrous four-grams per pound threshold. Follow this new plan for a couple of weeks, and watch out! You will perform much faster than you expect during workouts and races, and you will be considerably more fatigue-proof.

What about zinc and chromium? Several other studies have reported rather low total intakes of these minerals in athletes, so you might want to consider some supplementation. As mentioned, you could start with about 200 micrograms of chromium daily. The zinc RDA is 15 mg for men and 12 mg for women, so a daily zinc lozenge or two or else increased consumption of oysters or dark meat should do the trick (bear in mind that iron supplements tend to interfere with zinc absorption, so if you are taking iron supplements your dietary zinc requirements may increase). Don’t overdo it, though: Although zinc is needed for good immune-system functioning and the healing of injuries and wounds, excessive zinc intakes can hurt your copper status and might also lower your high-density lipoprotein cholesterol levels.

The bottom line? It’s nice to know that an activity which most athletes enjoy – good eating – can be a very effective way to upgrade performances.

Owen Anderson