Carbohydrate Supplements for Gastrointestinal Function During Running

Overseen By Patrick Wilson

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Old Dominion University

Disqualifiers: Cardiovascular disease, Metabolic disorder, others

Compensation: Varies

Number of Visits: 2

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to determine if drinking a carb-rich beverage while resting can help runners feel better during exercise. Researchers seek to discover whether this method can improve energy use and reduce stomach issues when consuming carbs during workouts. Participants will drink either a carbohydrate beverage or a placebo for five days. This trial suits runners who log at least 15 miles a week, have run over 60 minutes recently, and have completed a marathon in the past year. As an unphased trial, it offers runners a unique opportunity to contribute to innovative research that could enhance athletic performance and comfort.

Do I have to stop taking my current medications for this trial?

The trial information does not specify whether you need to stop taking your current medications.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Studies have shown that carbohydrate supplements can sometimes cause stomach issues like bloating and diarrhea, especially in large amounts. However, mixing two types of sugar, glucose and fructose, reduces these problems, making it easier on the stomach.

One study found that a carbohydrate-rich drink used before medical procedures was safe and improved patient comfort. While these findings are encouraging, it's important to remember that everyone’s body is different, and some people might still experience mild discomfort. Overall, research suggests that the carbohydrate drink is generally safe for most people, though minor stomach issues can still occur. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the carbohydrate beverage for improving gastrointestinal function during running because it utilizes a glucose-fructose mixture to deliver a concentrated 100 grams of carbohydrates daily. This contrasts with traditional hydration or energy supplements that may not specifically target gastrointestinal function with such a precise blend. The combination of glucose and fructose is designed to optimize carbohydrate absorption and energy delivery, potentially improving endurance and comfort for runners. This targeted approach could offer a more efficient and effective solution for athletes looking to maintain gut health while maximizing performance.

What evidence suggests that this trial's treatments could be effective for gastrointestinal function during running?

Research shows that carbohydrate supplements taken during exercise can boost endurance and reduce stomach discomfort. In this trial, participants will receive either a Carbohydrate Beverage or a Placebo Beverage. Studies indicate that consuming carbohydrates, such as those in drinks or gels, helps the body use energy more efficiently and can make exercise feel easier. Regular carbohydrate intake before and during exercise can train the gut to better handle and absorb nutrients, reducing the gut issues athletes sometimes face. Some evidence suggests that the right amount of carbohydrates might decrease the chances of stomach problems during workouts. ^{6 7 8 9 10}

Who Is on the Research Team?

Patrick Wilson, PhD

Principal Investigator

Old Dominion University

Are You a Good Fit for This Trial?

This trial is for distance runners who've done a run over 60 minutes in the past month, are running at least 15 miles weekly, and have finished a marathon in the last year. It's not for those with allergies to beverage ingredients, cardiovascular or metabolic disorders, or who experience symptoms like shortness of breath or chest pain with exercise.

Inclusion Criteria

Have completed one or more marathons within the past year

Be currently running ≥15 miles per week

Have completed at least one run >60 minutes over the past month

Exclusion Criteria

I experience symptoms like shortness of breath, dizziness, or chest pain with exercise.

I have a heart condition or a metabolic disorder.

Allergies/intolerances to any of the ingredients in the beverages

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Baseline Assessment

Participants undergo baseline assessments including a 60-minute run and collection of expired air samples for hydrogen levels, respiratory gases, and gastrointestinal symptom ratings

1 day

1 visit (in-person)

Intervention

Participants ingest a carbohydrate-rich beverage or placebo beverage for 5 days

5 days

Post-Intervention Assessment

Participants undergo post-intervention assessments including a 60-minute run and collection of expired air samples for hydrogen levels, respiratory gases, and gastrointestinal symptom ratings

1 day

1 visit (in-person)

Follow-up

Participants are monitored for any delayed effects or adverse events after the intervention

1-2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Carbohydrate Beverage
• Placebo Beverage

Trial Overview The study tests if drinking a carbohydrate-rich beverage while resting (not during training) over five days can change metabolism and reduce gut issues when carbs are consumed during exercise. Participants will compare effects of this drink against a placebo.

How Is the Trial Designed?

Group I: Carbohydrate Beverage Experimental Treatment 1 Intervention

A glucose-fructose beverage mixture supplying 100 grams of carbohydrate per day for 5 days

Group II: Placebo Beverage Placebo Group 1 Intervention

An artificially-sweetened beverage containing aspartame

Who Is Running the Clinical Trial?

Old Dominion University

Lead Sponsor

Trials

25

Recruited

15,500+

Published Research Related to This Trial

In a study of 18 highly-trained runners, consuming a flavored placebo drink led to a 0.9% improvement in half marathon performance compared to the first race, indicating that hydration may play a key role in endurance performance.

The use of a carbohydrate gel did not significantly enhance performance and was associated with gastrointestinal discomfort in some runners, suggesting that while carbohydrate intake during exercise is important, the type and method of consumption may need further investigation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of carbohydrate intake on half-marathon performance of well-trained runners. Burke, LM., Wood, C., Pyne, DB., et al.[2019]

Carbohydrate supplementation significantly improved exercise performance in trained male cyclists, particularly during submaximal exercise followed by a time trial, reducing exercise time by an average of 0.9 minutes compared to controls.

The most effective carbohydrate concentration for enhancing performance was found to be between 6% and 8%, leading to increased mean power output during prolonged exercise lasting over 90 minutes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A systematic review and meta-analysis of carbohydrate benefits associated with randomized controlled competition-based performance trials. Pöchmüller, M., Schwingshackl, L., Colombani, PC., et al.[2018]

Consuming a larger volume of carbohydrate sports drink (200 mL every 20 minutes) during prolonged running significantly increased carbohydrate oxidation rates by 23% compared to a smaller volume (50 mL every 5 minutes).

Both drinking patterns did not lead to significant gastrointestinal discomfort, indicating that athletes can choose either method without worrying about severe GI issues.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Sports Drink Intake Pattern Affects Exogenous Carbohydrate Oxidation during Running. Mears, SA., Boxer, B., Sheldon, D., et al.[2021]

In a study involving 98 well-trained runners, the use of carbohydrate-containing sports drinks resulted in a higher incidence of gastrointestinal (GI) complaints compared to water, with significant increases in flatulence and reflux symptoms.

Despite the higher GI complaints, there were no significant differences in running performance among the three drinks tested (water, sports drink, and sports drink with caffeine), indicating that sports drinks do not enhance performance over water during an 18-km run.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of two sports drinks and water on GI complaints and performance during an 18-km run. van Nieuwenhoven, MA., Brouns, F., Kovacs, EM.[2022]

High-intensity shuttle running (LIST) significantly slows gastric emptying of both carbohydrate-free and carbohydrate-electrolyte drinks compared to walking exercise, indicating that exercise intensity affects how quickly the stomach processes fluids.

During variable-intensity running, carbohydrate-electrolyte drinks empty from the stomach at a similar rate as carbohydrate-free drinks, suggesting that hydration strategies can be flexible without compromising gastric emptying.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of intermittent high-intensity running on gastric emptying of fluids in man. Leiper, JB., Nicholas, CW., Ali, A., et al.[2019]

In a study with five participants, lowering the carbohydrate concentration in a sports drink from 6% to 3% did not improve gastric emptying, intestinal absorption, or performance during a cycling time trial.

While total solute absorption and plasma glucose levels were higher with the 6% carbohydrate drink, reducing the carbohydrate concentration led to decreased absorption without enhancing performance, indicating that a higher carbohydrate concentration may be more beneficial for endurance activities.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Gastric emptying and intestinal absorption of a low-carbohydrate sport drink during exercise. Rogers, J., Summers, RW., Lambert, GP.[2019]

In a study involving 12 well-trained male cyclists, carbohydrate bars were found to significantly reduce peak power output and increase gastrointestinal discomfort compared to gels, indicating they may be less effective for endurance performance.

While drinks and gels showed similar performance outcomes, carbohydrate bars led to higher levels of nausea and perceived exertion, suggesting they are not the best choice for athletes seeking optimal energy sources during intense exercise.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Solid, Gel, and Liquid Carbohydrate Format Effects on Gut Comfort and Performance. Guillochon, M., Rowlands, DS.[2017]

Almost half of the 600 Polish professional athletes surveyed reported using dietary supplements, with isotonic drinks being the most popular choice among them, consumed by 75.4% of athletes.

Despite the widespread use of supplements, there appears to be a lack of awareness among athletes regarding the effectiveness and safety of these performance-enhancing aids, as indicated by the varying rates of usage and the low frequency of creatine consumption.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prevalence of the use of effective ergogenic aids among professional athletes. Frączek, B., Warzecha, M., Tyrała, F., et al.[2022]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10054587/

Carbohydrates and Endurance Exercise: A Narrative Review ... Carbohydrate (CHO) supplements such as bars, gels, drinks and powders have become ubiquitous as effective evidence-based CHO sources that improve endurance ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12258207/

Nutritional strategies for minimizing gastrointestinal symptoms ... Optimizing carbohydrate intake during exercise according to current recommendations has been associated with lower incidence and severity of GI ...

3. mdpi.com mdpi.com/2072-6643/17/5/918

A Review of Carbohydrate Supplementation Approaches ... The repeated intake of high carbohydrates before and during training has been demonstrated to condition the gastrointestinal system, improving its function, ...

4. tandfonline.com tandfonline.com/doi/full/10.1080/15502783.2025.2529910

Full article: Nutritional strategies for minimizing ... Intentionally training the gut by consuming large amounts of food or drink during exercise may enhance the absorption of macronutrients and reduce the severity ...

5. sciencedirect.com sciencedirect.com/science/article/pii/S0022316622025913

Carbohydrate Ingestion during Endurance Exercise ... The data support that ingestion of CHO between 30 and 80 g/h enhances endurance exercise performance in adults.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11901785/

A Review of Carbohydrate Supplementation Approaches and ... High doses of either glucose or fructose alone can cause gastrointestinal issues, such as diarrhea, abdominal pain, and bloating. However, the combination of ...

7. nature.com nature.com/articles/s41598-022-22363-1

Efficacy and safety of pre-gastroscopy commercial ... Commercial carbohydrate-rich whey protein beverage is associated with higher gastric residual volume, better well-being and safe.

8. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/8289607/

Gastrointestinal problems as a function of carbohydrate ... The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) problems as a function of carbohydrate-rich (CHO) supplements ...

9. sciencedirect.com sciencedirect.com/science/article/pii/S2161831323000753

Gastrointestinal Effects and Tolerance of Nondigestible ... However, as overconsumption of certain NDCs can lead to undesirable side effects, such as bloating and flatulence, that reduce consumer acceptance, additional ...

10. mdpi.com mdpi.com/2674-0311/2/3/21

Exercise-Induced Gastrointestinal Symptoms in Endurance ... Moreover, the intragastric pressure may rise due to ingestion of hyperosmolar carbohydrate sport drinks delaying the gastric emptying time in athletes [75,76].