Four New Insights on Fuelling Sports Endurance

There is sometimes a gap in sports science between those who do research in labs and those who collaborate directly with elite athletes "at the coalface," as sports nutritionist Louise Burke puts it. Of course, both sides have good ideas, but the best advice comes from people who can see things from both sides.

In this vein, I recently went to a conference in Toronto where Jennifer Sygo gave a talk. Sygo is a dietitian for the Canadian track and field, gymnastics, and Toronto Raptors basketball teams. She is also working towards a PhD at Manchester Metropolitan University, using what she has learned from collaborating with gymnasts. Her talk was about sports nutrition for endurance athletes, giving me some new ideas and points of view.

Here are a few things that stood out to me:

Boost the carbs

I will start with the part of Sygo's talk that did not surprise me the most: endurance athletes need carbs. She discussed the research that suggests low-carb ketogenic diets do not improve performance in Olympic-distance endurance events like marathons. However, she did say that ultramarathoners might choose to make different trade-offs. She said elite marathoners get about 85% of their energy during the race from carbs. Most of which comes from glycogen stored in their muscles and the rest from glucose in their blood.

To keep those carbohydrate stores full, she shared with elite runners some specific carbohydrate intake goals she uses for different distances:

Aim for 7 to 12 grammes of carbs per kilogram of body weight (g/kg) the day before a 10K to give your muscles glycogen. On race day, eat between 1 and 4 g/kg between 1 and 4 hours before the race. If you weigh 155 pounds, that is between 70 and 280 grammes of carbohydrates, an extensive range that shows how different people are in how well they can manage a meal before working out. One hundred grammes of carbs are in a breakfast of 2/3 cup oats, one cup of berries, and one cup of fruit juice.

For a half marathon, please do the same thing, and then, which I had not thought of, take a gel or sports drink after your warm-up to fill up on carbs. It also suggested taking in some carbs or at least rinsing and spitting out sports drinks to benefit the brain. I usually do not think about nutrition during a short race, but Geoffrey Kamworor drank a sports drink at the aid stations when he broke the world record for the half-marathon a few years ago.

For a marathon, the pre-race loading should be increased to 10–12 g/kg for 36–48 hours. That is considerable, and you are only likely to get there by eating carb-heavy meals and drinking juice or a sports drink. So, fill up in the morning and again after your warm-up. And then, try to eat between 30 and 90 grammes of carbs per hour during the race. (I will add that some professional cyclists and scientists are now trying to get closer to 120 g/hour, but I am not sure how well that would work for running.) 


Do not overeat vegetables.

Yes, I was surprised by this message, but keep reading to find out what she meant. In the last ten years, one of the essential ideas in sports nutrition has been that you should not just eat the same things every day. Instead, it would help if you changed what you eat to match what you burn. Sygo showed slides of the Athlete's Plate, an idea from the University of Colorado at Colorado Springs and the U.S. Olympic Committee. It shows how you might eat during light, moderate, or heavy training. The three plates can be seen here.

Half of the easy training plate is filled with fruits and vegetables. On the hard training plate, vegetables only accept a quarter of the space. Since there is no room for fruit, it has been taken off the plate. The point is not that you should not eat vegetables. On the contrary, they are essential. But if you work out hard, your caloric needs become extremely high, and you can only get there by eating vegetables, or even primarily vegetables. They do not have enough calories, and the fibre in them makes them too filling and hard to swallow.

Sygo said that the "big salad," often seen when health-conscious endurance athletes get together, is a common trap. You feel like you are eating a huge meal, but if you are careful, it will have fewer calories than your stomach thinks. Since increased people are learning about the adverse effects of (often unintentional) under fuelling, it is crucial to think about calorie density. Grains and fats are good choices, as are minor changes. For example, there is only fresh fruit on the easy training plate. There are also stewed and dried fruits on moderate and hard plates.


Get rid of useless things.

You have one to two pounds of faeces in your colon and getting rid of it before a competition might give you a tiny edge. Athletes in weight-sensitive sports have used a temporary low-residue diet for a long time. "Residue" is the undigested fibre, bacteria, and water left over after the good stuff has been digested. In real life, you should eat less fibre for a short time.

In a study that came out earlier this year, researchers at Liverpool John Moores University in Britain tried this method. They had nineteen people cut back from their usual thirty grammes of fibre a day to less than 10 grammes for four days straight while keeping the same number of calories and distribution of macronutrients in each meal. In the end, people lost an average of 1.3 pounds, mostly poop. The other effect was that the stools were more complex, and there were half as many of them. However, eighteen of the nineteen volunteers said they would be willing to do the intervention again. 

You may also be interested in a low-residue diet before a race. A few years ago, professional cyclist, Mike Woods told me that before races, he ate like a "five-year-old," which is low in fibre. It is not to lose weight but to keep his stomach from getting upset. Most of us would not go through all the trouble to lose a pound. Sygo pointed out that more is needed for the elites. She recently brought it up with a track athlete, but the athlete stopped her by saying, "I'll do anything to win, but not that."


Turn on your iron.

Sygo does not try to sell supplements. Instead, she mentioned four ergogenic aids for track athletes that have been shown to work: beta-alanine, sodium bicarbonate, creatine, and caffeine. Unfortunately, the only one that has been shown to work reliably for long-distance events is the last. (This is in line with what the International Olympic Committee said in a recent consensus statement, though they also included nitrate on their list.) She also highlighted some essential things to keep an eye on, such as vitamin D, vitamin B12, and iron.

Endurance athletes know about the risk of low iron. I have written before about what levels to aim for and what thresholds to watch out for. Sygo's goals are similar or a little higher. She says that women should aim for ferritin levels of at least thirty micrograms per litre, and men should aim for at least fifty micrograms per litre. In addition, she says that both men and women should aim for a haemoglobin level of at least 130 g/L. Normal minimum haemoglobin levels for healthy women are lower. Still, it needs to be clarified if that is the best or just a reflection of the fact that women tend to have lower (and less-than-best) haemoglobin levels, mainly because they have periods.

One problem for athletes is that when they work out hard, their bodies make more of a hormone called hepcidin, which stops iron from absorbing for up to six hours. So, Sygo says to take supplements outside of training, preferably on an empty stomach, and with vitamin C to help the body absorb them. She added a twist: U.S. Army researchers discovered that hepcidin may be activated by exercise and not eating enough calories to replenish what you burn. Another incentive to save gas.

I only chose the parts of Sygo's talk that I found most exciting or unusual. The big picture is more important in real life than the small details. Still, because everyone is different, getting the proper sports nutrition takes trial and error. You will have to try other things to figure out what works best for you, and you should practise everything you want to try in a competition. And in the end, it is the basics that matter the most: eating a healthy, balanced, and calorie-enough diet will do much more for your health and performance than losing a pound of poop.



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