Do You Fuel Yourself Adequately?
Thousands of runners recently attended the Ultra Trail Australia 100 and 50km races in the Blue Mountains. Sometimes it is hard not to be amongst the racing. However, sitting on the other side of the fence whilst the action gallops past gives a wholesome insight into the nutrition & hydration strategies of athletes.
Three Classifications of Athletes
In the race, we observed three types of athletes:
1. The Blank Stare Runner
The scenery of the Blue Mountains is stunning. Jagged tracks clutch to the side of overhanging cliffs. Damp forests hold tumbling waterfalls. However, the Blank Stare Runner will see little of this handsomeness. They also appear not to hear much until they stumble across your wildly clapping hands and goofy grin. They pull a tight smile and march onwards. From close up, they appear to have the ‘lights off’ - the I’m-on-a-mission facade with eyes glazed-over. From afar, there is an element of a plod, a trip, a stumble. One guesses behind it all is a negative mindset.
2. The Weary but Starry Eyed Runner
Fifty or one-hundred kilometers is never going to feel easy. There will always be an association with pain and a little suffering. But no matter how physically fatigued, the Weary but Starry Eyed Runner can maintain a smile. Their eyes sparkle with the challenge and even from a distance they easily acknowledge your excited cheers. They mutter a thanks, give a gentle high-five and then scuffle off around the corner.
3. The Prancer and Dancer Runner
This runner has the ability to make you forget about how much pain everyone else seems to be in. You find yourself pulling out your phone and googling entry dates for the next race. Before you see them, they have seen you. Their iPhone is out and they are happily snapping pictures to capture the memories. They are dancing across the rocks and prancing past the course marshals giving praise and a hearty, ‘thank you’. Their eyes are alight with anticipation. They might be fatigued but they are holding those negative thoughts at bay.
Which type of athlete are you?
You may fall somewhere in the middle and may shift from one to another at different points of a race. However, I am sure that looking back at race photos or your race debrief will help you identify with some of the above analogies?
Athlete Classifications: Symptomatic of Your Nutrition & Hydration
1. Race fuelling is about fuelling your brain not your body
Even for the slimmest athletes, the body has enough adipose tissue (fatty acids) stored to carry you a very, very long way. In endurance activities where the intensity is lower, a reasonably trained athlete should adequately utilize stored fatty acids for locomotive energy. However, there is one organ in the body that cannot use fatty acids for energy, and that is the brain.
The brain’s functional tissues is surrounded by the blood brain barrier. This is a physical block to protect the organ from harmful intruders and substances. When fatty acid is transported in the body, it is attached to a protein called albumin. This creates a molecule too large to pass through the barriers of the brain. Thus, the brain’s fuel source is glucose, the simplest molecular form of carbohydrate.
In races, we require the central nervous system and brain input to keep every other tissue of our body functioning. It drives our breathing, our heart, our working limb muscles. With an inadequate supply of glucose to the brain, this system starts to slow and will eventually grind to a complete halt.
2. Feed your brain glucose
If the brain holds everything together, then we must ensure that it receives an adequate supply of energy in the form of glucose. It is true that we can utilize stored muscle and liver glycogen for conversion into glucose and energy, but these stores are dramatically limited. Therefore, a fueling strategy for endurance race day must included simple forms of glucose, the best of which is a maltodextrin (pure glucose) gel.
3. Glucose absorption requires sodium
The absorption of glucose across cellular membranes requires a transporter protein that sits lodged in the cellular membranes. The functioning of this glucose transporter is often spared as the digestive tract starts to slow (the functioning of the digestive system will be overridden by the blood flow demands of the working muscles). That is, the body will prioritize the functioning of this glucose transporter over the digestion of fats, proteins and more complex carbohydrates, such as fructose.
4. Sweating causes a loss of sodium
Sweating causes large losses of sodium, especially over prolonged periods of time such as during endurance races. The amount of sodium varies from person to person and day-to-day, but can be in the vicinity of 1500-2000mg per 1L of sweat. No other electrolyte loss comes anywhere near the losses of sodium. This is because most other electrolytes, such as magnesium, are found within body cells. That is, sodium is an extracellular molecule floating freely in the bloodstream so it incurs the largest electrolyte losses during exercise.
5. Failing to replace sodium disrupts glucose absorption
If you fail to replace the sodium you are loosing, chances are you will not be absorbing the glucose you are trying to ingest. Without sodium present, the functioning of the transporter proteins slow. Therefore, the cellular membranes of the digestive tract, working muscles and mitochondria (power houses where energy is produced) become impermeable to glucose.
6. Low sodium and glucose intake affect the brain and central nervous system
If you are trying to rehydrate during races on water alone, you will likely be disrupting the body’s ability to absorb nutrition. Further more, if you are using a sports drink or electrolyte with inadequate sodium to meet your losses, you may also be disrupting your nutrition intake. Begin to become aware of your sweat losses both in volume and in the salt crusting that can appear on your clothes if you are a heavier sodium sweater. This can be a great guide to judging your losses.
Your Athlete Classification Explained:
- The Blank Stare Runner
Your central nervous system is seriously affected. In essence, you have become similar to a diabetic with low blood glucose levels. Whatever you are drinking and eating is inadequate to supply sodium and glucose to the transporter pumps in your cellular membranes and thus, energy to your brain. Try to learn to listen to your central nervous system. Negative thought processes, clumsy feet, feeling cold, dizziness, vertigo, numb feet or hands, or even nausea can all be symptomatic of low glucose levels in the brain. If you observe someone like this or their eyes have a glazed-over appearance, feed them instant glucose along with a higher sodium concentration electrolyte. If they are nauseous, you can rinse their mouth with glucose as the oral mucosa has a direct glucose absorption pathway to the brain. If this helps, you can then start to slowly feed them glucose via gels, chemist jelly beans and glucose tablets.
- The Weary but Starry Eyed Runner
Your nutrition and training strategies are strong but likely the quantities need adjusting. Sparkling eyes and alertness suggest that the central nervous system is coping. The physical weariness can be a symptom of further training required, or it may also be that you need to increase the quantity of glucose and electrolyte replacement. You should also be paying close attention to changes in your central nervous system as the race progresses. If negative thoughts, anxiety, clumsiness or any of the other symptoms above settle in, make sure you increase your glucose and sodium intake. This is especially true if you start to experience cramping.
- The Prancer and Dancer Runner
You are nailing it! To run like this, your central nervous system must be functioning fully and you are alert enough to absorb your surroundings. Further to this, it appears that your training has prepared you optimally for the challenge you have embarked upon. However, keep an eye on climatic changes throughout the race as increases in temperature, humidity or wind will alter your evaporative sweat losses. Monitor your thoughts and alertness, with any small changes requiring a top-up of energy.