Have you ever been out on a long distance training session and started to feel fatigued, unmotivated, lightheaded, and dreaming about your next meal? Chances are, you weren’t giving your body enough fuel. Long training sessions (> 2 hours) test your training endurance, but they also deplete your body’s reserves, and can be a stark reminder of why your body needs fuel to move. In the early season, many nordic skiers focus on getting more “time on snow” to dial in proper technique and help transfer dryland training gains to ski-specific physiological adaptations. This is a perfect time to also practice nutrition strategies.

uOttawa Nordiq skiers had extra motivation this December in the form of distance challenges: the Nakkertok Nordic Nakkerboard (log your daily kilometers in December and compete with your team), and the UBC Ski Team longest ski challenge day among University Nordic Ski teams (get out for a really long ski!).

Despite some challenges limiting group training, our athletes skied almost 5000 km in December, and several of our athletes skied more than 100 km for the UBC Ski Team Longest Ski Challenge (we won the challenge!).

Athletes can get away with ignoring nutrition during shorter training sessions (although this isn’t always desirable - see our fueling for intensity sessions article); but neglecting fuel during long endurance efforts can turn a dynamic glide into a sorry shuffle, lead to extreme fatigue, lightheadedness, and eventually will grind a skier to a halt (like a car running out of gas). Even before the ski-stopping consequences set in, lack of fuel can affect speed, technique, and motivation.

Fatigue due to underfueling that impairs performance is likely a result of depleting muscle glycogen stores, liver glycogen stores, dehydration, or a combination of these. Muscle glycogen is the primary fuel for endurance athletes. Although you also burn small amounts of fatty acids and amino acids, glycogen is the major player.

What is glycogen? Glycogen is a storage form of glucose and carbohydrates. When you consume carbohydrates, your body breaks them down into glucose, and it is stored in your muscle cells where it provides energy to help you move.

• You have a limited supply of stored glycogen in your muscles, and once you have used it all up, exhaustion sets in quickly. Low glycogen impairs performance, and with very low glycogen, your muscle cells have difficulty contracting, so at first you may compensate by using other muscle groups. You may have observed some of these glycogen-depleted individuals out on a race course or crossing the finish line with less than perfect form!

• Long exercise sessions deplete your muscles of glycogen, and your hungry muscles begin to draw more glucose from your blood, which leads to low blood glucoses. Your liver releases its stored glycogen as glucose into the bloodstream to fuel your brain and nervous system. At this point, your liver may not be able to maintain adequate blood glucose levels, making you feel tired, lightheaded, uncoordinated, and unable to concentrate. This low blood sugar induced mental fatigue can lead to a perception of muscular fatigue, even when muscle glycogen is not fully depleted. Your brain processes all kinds of information during a strenuous training exercise session – your blood pressure, hydration status, stress hormones, etc. If enough of these are out of whack, it may just decide to slow or even shut your body down as a protective mechanism.

• Drink up! In addition to muscle and liver glycogen depletion, dehydration can impair your performance. During exercise, you are constantly losing water through sweating and evaporation. What some athletes interpret at low blood sugar levels or low energy stores may be fatigue from dehydration. Even if you are eating properly, dehydration can impair how your body absorbs and uses the fuel you’re consuming.

Here are some tips to fuel properly for long skis, runs, or bike rides. You’ll enjoy long training session more and be able to stave off exhaustion if you fuel properly! Of course, training plays a role as well, so beginners need to be even more conscious of proper fueling: your muscles can increase their capacity to store glycogen through exercise (a trained individual may store about 20 to 50 percent more glycogen than an untrained individual).

Consuming carbohydrates has been consistently shown to improve time to exhaustion and performance, so carbs should be your primary fuel source. Assuming that the pace is more relaxed than a race and you are stopping briefly for breaks, you can choose more complex carb options (bars/cookies/fruit/dried fruit) over simple carbs, or a mix of both (see Best Carbs for Exercise figure), and even foods with a little protein and fat like a fruit & nut bar or a peanut butter & jelly sandwich. Fueling strategies for an endurance race (i.e. 50k ski event/marathon) are similar, but require tailoring for ease of digestion, fueling, and a higher intensity. We’ll cover that in another article so check back!

When Should I Fuel? Drinking and eating carbohydrate-containing foods and fluids delays fatigue by keeping blood glucose levels elevated, maintaining central nervous system function, preventing dehydration, and supplying fuel for the working muscles. Don’t wait until you are hungry or thirsty! Start consuming liquids and carbs early – 15 mins into your activity, and it’s best to consume small amounts frequently (about every 15 minutes) for best absorption. Though underfueling can have severe consequences, overeating, or eating the wrong foods can be problematic – so it’s worth experimenting to see what works for you!

How Much? The amount you need to consume depends on the length and intensity of your session, the climate, and what your digestive system can tolerate. Current guidelines are to consume 30-60 g carbohydrates/hour for exercise lasting 2 hours, and more (up to 90g if tolerable) for exercise sessions lasting longer than 2 hours. These high intakes are associated with better performances, but that might take gut training and more attention to the specific types of carbs – we’ll cover that in another article but here’s some info).

Don't Forget Hydration. Sip on water, or sports drink if you don't think you can get enough carbs from food sources in good time (sometimes it's more difficult to access food compared to drink while you're skiing (mittens, gloves, weather, pack dynamics) so having carbs/sugar when you hydrate might be important if you can’t get to your food when you need it!).

Check out the carb content of some foods and fuel for reference. For a long ski training day, I encourage a variety of carb sources – the intensity isn’t as high so digestion isn’t as much of a concern and real whole foods can work well (and you can sneak more nutrition in instead of relying solely on simple sugars), as can some specialized sports products, or a combination of both. Here are a few examples, but it's worth checking out the nutrition label or looking up the carb content of what you're eating.

• Peanut butter and jelly sandwich (~42g carbs).

• Raisins, ¼ cup (~29g carbs)

• 1 orange (~15 g)

• Fruit 2 (xact) (25 g)

• 500 ml sports drink (30g)

Consider making your own tasty treats to help energize your workout. Beyond great taste, you will have control over the ingredients.

• Sheila’s Quick & Easy Oatmeal Bars (26g carbs)

• Double Chocolate Peanut Butter Energy Bites (17g carbs)

• Sesame Date Energy Bites (19g carbs)

• Almond Butter Chocolate Chip Bars (25g carbs)

• Ginger Bars with Chocolate (25g carbs)

It’s a good idea to practice eating and drinking during training to find out what works for you – and you likely have many opportunities, so use them! Keep in mind that in addition to training your muscles, you can train your GI system to adapt to more carbohydrates (something that many distance cyclists and marathoners do), and you may need to be more picky about the type of carbohydrates for higher intensities.

If you practice these strategies, you’ll help keep your distance training energized, higher quality, improve your ability to go further and longer, and you’ll recover faster. It just takes a little planning and preparation, but the benefits are worth it!