We’ve talked about carbohydrate recommendations during training and racing, but sometimes it’s hard to EAT 60+ grams of carbs per hour, especially if you are out for a long/hard ride.
Did you know you can also meet (at least a portion) of your hourly carbohydrate goals with a carb-electrolyte drink (CHO-E)? But, before you go that route, you want to know the contents of what you are drinking, the mixing instructions, and scale the serving size information from the nutrition label to the amount of fluid in the bottle you are using.
If you are also using gels or chews, make sure you are factoring in the total grams of carbohydrate and milligrams of sodium the products are providing you together, with your CHO-E drink. Here are some of the more common drinks and their CHO and sodium content per 24 oz (710 ml).
Skratch Hydration: 31 g CHO, 570 mg sodium
Skratch Superfuel: 120 g CHO, 480 mg sodium
Tailwind Endurance Fuel: 50 g CHO, 600 mg sodium
Gu Roctane: 69 g CHO, 366 mg sodium
SWORD Performance: 45 g CHO, 600 mg sodium
As always, try it first during training, try it at race pace, and over time in multiple environmental conditions before you settle on a race day plan!
Do we need sex-specific carb intake recommendations during endurance exercise?
Ingestion of ~90 g CHO/h in the form of glucose or maltodextrin-fructose can increase exogenous CHO utilization and improve endurance performance. However, the majority of research in this area has been completed in males, but do women require different CHO intake recommendations during endurance exercise?
In general, women are able to oxidize a greater percentage of fat versus stored CHO (glycogen), compared to men completing endurance exercise at the same relative intensity. However, current research does not suggest a sex-difference in exogenous CHO oxidation during exercise after ingesting a glucose solution. What about the ingestion of multiple-transportable CHO (e.g. glucose-fructose solution) > 60 g/h?
A recent study provided elite male and female cross-country ski athletes an 18% maltodextrin and fructose hydrogel beverage at a rate of 2.2 g/min (132 g/h) during a 2 h roller skiing protocol in cold ambient conditions at 70% max. Neither group experienced GI symptoms and there were no significant differences in glycogen utilization change, peak rate of exogenous CHO oxidation (though females tended to have lower peak oxidation rates than males, 1.2 vs 1.5 g/min), RPE, or performance between males and females in response to CHO ingestion.
Results from other studies measuring exogenous CHO oxidation in females vs. males are mixed. Some indicate that exogenous CHO oxidation is ~2-4% higher in females compared to males while others found the opposite or no difference. More research is needed to answer this question specifically, but at this point there is insufficient evidence to indicate CHO intake recommendations should be different for females and males engaging in endurance exercise. Further, it has been demonstrated that both male and female athletes can tolerate high rates (>90 g/h) of CHO (glucose-fructose) intake without experiencing GI symptoms in cool conditions.
Finally, because hormonal changes throughout the menstrual cycle may iinduce changes in fuel utilization, eating a pre-exercise CHO meal in addition to ingesting ~90 g of multiple transportable CHO per hour during endurance exercise > 2.5 h may help minimize hormonal effects and help support performance.
PMID: 10953068, 12070184, 14750011, 14967866, 16278245, 20019632, 31655603, 34015236
Practical tips for training the gut
Higher carbohydrate intake is associated with improved endurance performance but it’s not always comfortable to take in 60-90 grams (or more!) per hour when you haven’t practiced it. If you have a hard time taking in the recommended amount of hourly carbohydrate intake, you aren’t alone! The most common reasons for not reaching the recommendations seem to be:
- GI issues
- Too full
- Carrying that much fluid/food for several hours
- Low appetite and feeling like you’re “forcing” nutrition intake
- More carbs doesn’t seem necessary if you feel like you are performing well with less
In this post I want to address one of the most common complaints: GI issues. But, GI symptoms don’t have to be a regular occurrence if you work on TRAINING THE GUT...Yes! The gut is trainable just like the rest of your body. If you are barely able to reach the 60 g CHO/h intake recommendation then it’s not likely that you will be able to easily go out and throw back 90 g CHO/h without issues. That’s why we need to be deliberate in how we train our body’s ability to digest, absorb, and utilize that amount of hourly carb intake.
One of the best ways to adapt our GI system to a higher carbohydrate intake during exercise is to eat more carbohydrates in your regular diet. Repeated exposure to carbohydrates, including glucose and fructose, can speed up gastric emptying rates of these monosaccharides and increase the transporter activity to facilitate better absorption and oxidation of the carbohydrate. Benefits may include decreased feelings of “fullness”, less GI distress, and better overall performance. There are several other things you can implement when “training the gut”:
1) Start euhydrated (consume ~2-4 ml/lb fluid with sodium 2-4 h prior to establish euhydration)
2) Hydrate with ~ 400-800 ml/h using fluid with sodium (adjust as needed based on environmental conditions)
3) Gradually increase the hourly rate of carbohydrate intake
4) Practice ingesting carbs during different types of workouts (intermittent high intensity intervals and steady state, short and long duration)
5) Train shortly after a meal
6) Decrease fat/fiber/protein leading in the meal(s) prior to the training session
7) Practice your race nutrition strategy in different conditions well in advance of your goal event
PMID: 28332114, 26891166
