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Endurance Nutrition: The Ideal Carbohydrate Concentration

As triathletes, we push our bodies to the limit, requiring optimal nutrition to fuel our performance during endurance races. Among the crucial aspects of race preparation, carbohydrate intake stands as a fundamental pillar. The ideal carbohydrate concentration plays a vital role in sustaining energy levels and enhancing performance. In this blog post, we delve into the science behind carbohydrate consumption and explore the optimal concentration for endurance racing.

Understanding Carbohydrates and Endurance Racing: Carbohydrates are the primary source of energy for endurance athletes. During prolonged exercise, the body relies on stored glycogen in the muscles and liver to maintain performance. However, glycogen stores are limited and need to be continually replenished through carbohydrate intake. Consuming carbohydrates before, during, and after a race is essential for sustaining energy levels, delaying fatigue, and improving endurance.

The Importance of Carbohydrate Concentration: Carbohydrate concentration refers to the amount of carbohydrates consumed per unit of fluid or food. It directly affects the rate at which carbohydrates are absorbed and utilized by the body during endurance racing. The optimal carbohydrate concentration ensures efficient absorption and minimizes gastrointestinal distress, both of which are crucial for peak performance. The easiest way to calculate carbohydrate concentration is to divide the amount of carbs in grams by the amount of fluid in mL, then multiply by 100. Example: 50g of carbs / 1000mL of fluid = 0.05 x 100 = 5%

Finding the Sweet Spot: The ideal carbohydrate concentration for endurance racing is generally recommended to be within the range of 6-8% for beverages and 2-8% for gels, bars, or solid foods. This range has been extensively studied and proven to maximize carbohydrate absorption and minimize the risk of gastrointestinal issues.

Factors Influencing Carbohydrate Concentration:

  1. Race Duration: The duration of your race plays a significant role in determining the optimal carbohydrate concentration. Shorter races lasting less than 90 minutes may require a lower concentration, while longer races call for higher concentrations to sustain energy levels throughout.
  2. Individual Tolerance: Every athlete’s body is unique, and individual tolerance to carbohydrates may vary. Some athletes may experience gastrointestinal distress at higher concentrations, while others may be able to handle higher levels without any issues. Experimentation during training is key to finding your optimal carbohydrate concentration.
  3. Environmental Conditions: Environmental factors such as heat and humidity can impact carbohydrate absorption. In hot and humid conditions, it is generally recommended to lower the carbohydrate concentration to facilitate better fluid absorption and prevent dehydration.

Experimentation and Practice: Discovering the ideal carbohydrate concentration for your body requires experimentation and practice during training sessions. It is essential to test different concentrations, fluids, and foods to identify what works best for you. Remember to consider your individual tolerance, race duration, and environmental conditions when fine-tuning your carbohydrate intake strategy.

Personally, I find that mixing my nutrition bottles to be 10% CHO concentration, and supplementing with electrolyte water based on conditions and duration of the event, works for me in most scenarios. I use 750ml bottles and add 75g of CHO to get that mix dialed. I also supplement with gels to bring up my CHO intake per hour, again using on course water to dilute the concentration. I try to take in 100g of CHO per hour on the bike, and closer to 60g of CHO on the run. Again, this is all highly personal and can change depending on what products you use, the conditions, and other factors such as hydration and sweat rate. It’s always best to test these things in training!

Carbohydrate Periodization: In addition to concentration, carbohydrate periodization is a technique that can enhance endurance performance. By strategically manipulating carbohydrate intake during training, you can improve your body’s ability to utilize and store glycogen, thereby maximizing performance on race day. Working with a qualified sports nutritionist or coach can help you develop a personalized carbohydrate periodization plan.

Exogenous Ketones: Another factor to consider, products like Ketone IQ from HVMN can be beneficial to endurance performance. That’s a topic for a future post, but in the meantime you can find more information here: HVMN The Science

Conclusion: Optimizing carbohydrate intake is a key component of successful endurance racing. By understanding and implementing the ideal carbohydrate concentration, triathletes can sustain energy levels, delay fatigue, and ultimately perform at their best. Remember that finding the perfect concentration requires experimentation, practice, and consideration of individual factors. With the right approach to carbohydrate intake, you’ll be one step closer to reaching your triathlon goals and unlocking your full potential as an endurance athlete. If you have any questions, don’t hesitate to reach out!


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Open Water Swimming – A Skill Worth Practicing

“Why don’t I swim as fast in the open water as I do in the pool?” This is a question I hear all the time. You’d think that by adding a wetsuit, which is not only more buoyant but also faster than skin in the water, would make you even faster than your pool pace. And you’d be correct, it should. But open water is different than a calm lane at your local YMCA. It moves. Whether it’s a current, wind, the change in tide,… there are many factors to consider. Here are a few.


If you live in the US, you most likely swim in a 25 yard pool. And although most triathletes aren’t amazing at flip turns and underwaters, we still benefit from the turns. Not only do you receive a little break for your arms, but you also get to push yourself back up to speed off the wall, In fact, the push off the wall is likely the fastest portion of your swim across the pool. We certainly do not benefit from this in the open water. Something I often tell my athletes is that we are only as fast in open water as the slowest point in our swim across the 25 yard pool. Don’t believe me? Try getting into a 50 meter long course pool and see how you feel after 100m.

Glide vs Turnover 

In the pool, having a nice and long gliding swim stroke can be beneficial. You can lower your stroke rate, glide out front, and really focus on being long and efficient in the water because the only thing slowing you down is the water in front of you. You can see the lane line at the bottom to assure you are swimming straight, and there isn’t a current pushing you one way or the other. In open water, aside from a rare extremely calm day, this is not the case. The water moves and you can’t rely on a long glide that produces dead spots in your stroke. I find that for most athletes the key to a faster OWS is to increase their turnover. The best way to do this is the eliminate the time spent out front, reaching and pausing. Instead, I encourage them to get into their catch as early as possible. As far as I’m concerned, the more pulls the better when in open water. The worse the conditions, the more-so this rule applies.

Race Specificity 

Whether it’s a beach start, Aussie exit, mass start, or multiple looped course, spending some time doing practice that is SPECIFIC to your event will benefit you greatly. Also it is more than likely that your competitors did not take the time to do this, giving you a big advantage and level of comfort during one of the more anxiety filled parts of the race.

Ironman 70.3 Oceanside

Body Position 

If the swim is wetsuit legal, a huge benefit will be a natural improvement to your body position. However, this does not mean you can just throw on the wetsuit and magically see huge gains or an easier movement through the water. Your balance is going to be completely different than when you are swimming in a pool without a wetsuit. So you’re going to need to adjust how you hold your body in order to make sure you are using that benefit to swim faster, rather than to simply not kick or rotate. Practice in the open water with a wetsuit is key to dialing in this body position.


That’s right, there is no lane line at the bottom of the lake, river, or ocean you are swimming in. One of the main reasons people tend to swim slower is due to zig zagging their way from buoy to buoy. Sighting is a key factor in not only swimming straight to cover the minimum distance necessary, but it’s also a crucial part of what could be slowing you down if not done properly. Sighting the buoy should be incorporated into your swim stroke in a way that has minimal effect on your body position. However, lifting your head is always going to drop your hips. So how you return to a balanced body position after the sight is key to maintaining speed. I like to have athletes set a rhythm with their sighting, maybe every 6-8 strokes depending on the conditions. This is also something you can practice in the pool, which I highly suggest.


As they say, practice makes perfect. You can’t expect to show up on race day and do something that you haven’t done in training. Even the best of pool swimmers need to spend time in open water to learn the skills necessary to translate their talents to the race. Swimming in open water is not an easy thing to just jump into. It can be scary for beginners and dangerous when solo. I highly suggest getting someone who can provide support via a kayak, SUP, or boat. Even better, join a local group that gets out for open water swim training regularly. Our athletes at Team PBC swim together nearly every week at one of Madison’s local lakes, with a coach on deck for tips, drills, training direction, and safety. If you’re interested in joining or learning more, contact us!

-Coach PB