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Clinical Trial Summary

The purpose of this study is to determine if 2-weeks supplementation with blueberries (1 cup/day) compared to placebo can mitigate muscle soreness and damage, and improve inflammation resolution and metabolic recovery during a 5-day period after engaging in an acute, 90-minute bout of eccentric exercise. The primary outcome will be plasma oxylipin levels, extending previously collected data in our lab that blueberry ingestion decreases post-exercise oxylipins generated from cytochrome P450 enzymes.


Clinical Trial Description

Participants will be randomized to the blueberry or placebo groups. The parallel group design is being utilized in this study because of the "repeat exercise bout" effect (i.e., post-exercise muscle damage and inflammation are reduced when the same bout is repeated within days and weeks of the first bout). Participants will come to the lab at 7:00 am at the beginning of the 2-week supplementation period, and then Monday (eccentric exercise bout) and Tuesday through Friday (recovery) in an overnight fasted state. Seven blood samples will be collected and analyzed for various measures of muscle damage, oxylipins, and inflammation. After each of the blood draws, participants will provide a muscle soreness rating (DOMS). Three 24 h urine samples will be collected and analyzed for key metabolic markers of blueberry ingestion. Visit #1 Pre-Study Study participants will come to the performance lab for orientation to study procedures. This will include a review of the consent form, completion of basic questionnaires, and an introduction to the eccentric muscle exercise bout and the strength/power performance testing protocol (about 1.5 hours) (visit #1). During visit #1, participants will be given two 3-day food records with thorough written and oral instructions on recording procedures (with food models). The 3-day food records will be completed on a Thursday, Friday, and Saturday sequence prior to visits #2 and #3. During visit #1, participants will be given three 24 h urine collection bottles with thorough written and oral instruction on collection procedures. The 24 h urine collection bottles will be collected on the day before visits #2, #3, and #7. This will be followed by another lab session for pre-study measurements and sample collection (visit #2). Participants will be randomized to blueberry or placebo groups, and provided a 2-weeks supply of supplements. Participants in the blueberry and placebo groups will consume 26 g/d powder mixed in water each day in split doses (half in the morning, half in the afternoon). Compliance will be checked weekly through email correspondence from the Research Manager. A 3-day food record will be collected at the beginning and end of the 2-week supplementation period to assess the background diet. The 3-day food record will be turned in and reviewed by the research team, and analyzed for nutrient and flavonoid content using the Food Processor Version 11.1 (ESHA Research, Salem, OR, USA). ESHA's port utility (Version 4.0; ESHA Research, Salem, OR, USA) will be used to upload the Flavonoid Values for USDA Survey Foods and Beverages (FNDDS) 2007-2010 database. Food/beverage intake will be assessed for macro- and micro-nutrients, total flavonoids and subtotals for each of the six flavonoid subclasses, and three individual flavonoid values (quercetin, cyanidin, and epigallocatechin gallate (EGCG)). The study will include 5 other lab visits during a one-week period starting on a Monday (visit #3), with morning visits at 7:00 am on Tuesday through Friday (visits 4-7). At each of the 7 lab visits, study participants will come to the lab at 7:00 am not having consumed food or beverages (other than water) for at least the previous 9 hours, and having abstained from vigorous exercise for at least the previous 24-48 hours. The Monday session will take about 2.5 hours (7:00 to 9:30 am), and the Tuesday through Friday sessions will take about 30-45 minutes each. The total amount of time participants will be asked to volunteer for this study is about 8-9 hours at the performance lab. Baseline Testing (Visit #2) Participants will come to the lab at 7:00 am in an overnight fasted state dressed in exercise clothes. Participants will provide a blood sample using standard phlebotomy procedures. Participants will turn in their 24 h urine collection bottle and 3-day food record. Height, body weight, and body composition will be measured in a private section of the lab. Bioelectrical impedance (BIA) using the seca BIA scale will be used to assess body composition (i.e., the percent of body weight that is fat tissue) and body weight. Participants will remove shoes and socks and stand with bare feet on the seca scale for about 7-10 seconds while grasping side rails with your hands. Percent body fat will also be measured using the BodPod. Participants will sit inside the BodPod with a tight-fitting swim suit for about 10 minutes while body fat is calculated. Delayed onset of muscle soreness (DOMS) will be assessed using a 1-10 scale. Participants will perform some light exercises to warm up, followed by five muscle function tests: vertical jump, bench press, leg-back strength, anaerobic power through the 30-second Wingate test, and 60-yard shuttle run. 1. Vertical jump: Participants will first stand erect with the feet flat on the floor and reach as high as possible with both arms and hands (standing reach height). Participants will then squat down and jump as high as possible with one arm and hand, and tap the measuring device on the Vertec vertical jump apparatus (jump height). This will be repeated three times, with the best score recorded as the difference between the jump and standing reach heights. 2. Bench press to exhaustion at 50%/75%: Participants will lie down supine on a bench, and with spotters standing on either side attempt to bench press a weighted bar equal to 75% (males) or 50% (females) body weight as many times as possible (to a metronome set at 60 beats/min or 30 lifts/min). The bar must touch a foam block on the chest lightly in the down position, and the arms must be straight in the up position. 3. Leg-Back Strength: Leg/lower back strength will be assessed with a dynamometer. With the legs slightly bent at the knee, participants will grasp a bar attached via a chain and a force measuring device with straight arms, and then lift up with maximal effort for several seconds. This will measure the isometric strength of both legs and back, and will be repeated three times. 4. 30-Second Wingate Cycling Test, Anaerobic Power: The Lode cycle ergometer will be adjusted to the participant's body weight (7 watts per kilogram). After a warm up, participants will sprint cycle at maximal speed for 30 seconds. The peak power and average power will be recorded and adjusted to body weight. 5. 60-Yard Shuttle Run Test: The shuttle run is a test of speed and agility. Participants will run back and forth to 5 yards, 10 yards, and 15 yards, for a total of 60 yards. Participants are required to touch the line with their hand at each turn, and run through the finish line. The test involves five touches. The time to complete the test in seconds is recorded. The score is the best time of three trials. Testing Sequence, Day of Eccentric Muscle Exercise (Monday, Visit #3) and 4-Days Recovery (Tuesday through Friday) (Visits #4-7): Participants will come to the lab at 7:00 am in an overnight fasted state (i.e., no food or beverages other than water for at least the previous 9 hours). Participants will turn in their 24 h urine collection bottle and 3-day food record. Participants will be weighed and then provide a blood sample, and give a DOMS rating. The blueberry or placebo supplements (half dose) will be consumed mixed in water. Participants will perform some light exercises to warm up, followed by five muscle function tests: vertical jump, bench press, leg-back strength, anaerobic power through the 30-second Wingate test, and shuttle run. Participants will take these performance tests before and after the 90-minute eccentric muscle exercise bout, and each of the following four mornings at the performance lab. After taking the five performance tests, participants will engage in 90-minutes of eccentric exercise. Immediately following exercise, participants will provide a muscle soreness rating and a blood sample. Participants will then take the five muscle function tests. Participants will ingest the supplements (half dose) during the afternoon (3-6 pm). Participants will return at 7:00 am in an overnight fasted state four days in a row (Tuesday through Friday) after Monday's eccentric exercise bout, and provide DOMS ratings, and blood samples followed by ingestion of the supplements (half dose). Following ingestion of the supplements, participants will take the five muscle function tests. Participants will consume the second half dose of the supplements in the afternoon (Tuesday, Wednesday, Thursday). On Friday morning, participants will provide blood, turn in their 24 h urine sample, and take the supplement (half dose) prior to the muscle function tests. During this week of testing, participants will engage in normal training. ;


Study Design


Related Conditions & MeSH terms


NCT number NCT05184855
Study type Interventional
Source Appalachian State University
Contact David C Nieman
Phone 8287730056
Email [email protected]
Status Recruiting
Phase N/A
Start date December 1, 2021
Completion date October 30, 2022

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