Effects of Herbal Supplements on Endurance Exercise Performance

Study Overview
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Brief Summary
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Cordyceps and Rhodiola are two common herbal supplements marketed and consumed as adaptogens to athletes with regard to enhanced performance. The effects of these supplements has been well studied in animals but whether or not the same effects translate to humans is still unclear. Thus, the primary purpose of this study is to determine whether combined supplementation of Rhodiola and Cordyceps, compared to Rhodiola alone and placebo, will demonstrate a greater improvement in oxygen consumption (ie. VO2 max).

Detailed Description
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Herbal supplements are consumed worldwide with surveys approximating five billion dollars spent annually by consumers in the United States alone. Herbal supplements, such as Rhodiola and Cordyceps, both of which are considered to be adaptogens, remain popular among athletes. These adaptogens act as antioxidants, which have been speculated to confer endurance performance benefits by delaying muscle fatigue via the attenuation of muscle damage accumulation and its related by-products during prolonged or exhaustive exercise. Nevertheless, previous research investigating the individual effects of Rhodiola and Cordyceps on aerobic training performance remain equivocal. Moreover, literature elucidating the potential additive effects of Rhodiola and Cordyceps in human subjects are scarce. Therefore, the purpose of the present study is to determine the acute, additive influence of oral Rhodiola and Cordyceps supplementation on VO2 max, with secondary variables of interest being plasma glucose and lactate concentration, and measures of gastrointestinal distress.

Official Title
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Effects of Herbal Supplements on Endurance Exercise Performance

Conditions
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Exercise Performance

Intervention / Treatment
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* Dietary Supplement: Placebo of calcium
* Dietary Supplement: Rhodiola
* Dietary Supplement: Rhodiola and Cordyceps


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Body Mass Index between 18.5 and 35 kg/m^2 Non-smoking (assessed by Health History Questionnaire) English-speaking Regular participation in physical activity (>4 hours per week) Exclusion Criteria: Medical conditions that prohibit physical activity (assessed by Health History Questionnaire) Pregnant women or women expecting/trying to become pregnant BMI greater than or equal to 35 kg/m^2 Current smoker (assessed by Health History Questionnaire)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Blocked-randomized, crossover design
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo of calcium<br>Participants will consume 250 mg of calcium | Dietary Supplement: Placebo of calcium<br>* Ingestion of 250 mg of calcium<br>|
| Experimental: Rhodiola<br>Participants will consume 250 mg of Rhodiola | Dietary Supplement: Rhodiola<br>* Ingestion of 250 mg of Rhodiola<br>|
| Experimental: Rhodiola and Cordyceps<br>Participants will consume a combination of 250 mg of Rhodiola and 225 mg of Cordyceps | Dietary Supplement: Rhodiola and Cordyceps<br>* Ingestion of 250 mg of Rhodiola and 225 mg of Cordyceps<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| VO2 max | Maximum oxygen consumption using the Bruce Protocol | 90 minutes after baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gastrointestinal symptoms questionnaire | Section 1 contains 6 questions assessing upper abdominal problems (reflux, heartburn, bloating, cramps, vomiting, and nausea). Section 2 contains 7 questions assessing lower abdominal problems (intestinal cramps, flatulence, urge to defecate, left abdominal pain, right abdominal pain, loose stool, and diarrhea). Section 3 contains 4 questions assessing systematic problems (dizziness, headache, muscle cramp, and urge to urinate). Each of the 17 questions is answered using a 10-point scale ranging from 0 (no problem at all) to 10 (the worst it has ever been). Each of the 3 sections will be scored separately. Section 1 will be scored on a scale of 0-60. Section 2 will be scored on a scale of 0-70. Section 3 will be scored on a scale of 0-40. | Baseline, 90 minutes, 110 minutes | 
| Blood glucose | Plasma glucose assessed by finger stick | Baseline, 90 minutes, 110 minutes | 
| Blood lactate | Plasma lactate assessed by finger stick | Baseline, 90 minutes, 110 minutes |