Study design
DOMS, inflammation, post-exercise muscle damage
INFLAMMATION, BLOOD
This study employed a randomized parallel group, placebo-controlled, double-blinded design with a 2-week supplementation period, 90-min eccentric exercise bout challenge, and seven lab visits at the Appalachian State University Human Performance Laboratory (HPL) at the North Carolina Research Campus, Kannapolis, NC. The parallel group design was utilized as in previous studies 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)Study participants were recruited by the research manager (C.S.) and randomized to the blueberry and placebo groups using random.org (1:1 allocation). The 2-week supplementation period was based on previous studies with blueberries showing bioactive effects within this length of timeComparison between the blueberry and placebo supplements.Blood samples were collected in overnight-fasted study participants before and after 2-weeks supplementation. Additional blood samples were collected immediately post-exercise, and then each morning (overnight fasted state) during four days of recovery. Three 24-h urine samples were collected (total urine output) before and after the 2-week supplementation period, and then the day before the final blood draw (day 18). Ascorbic acid (300 mg) and boric acid (10 g) were added to the 24-h urine containers to help stabilize the phenolic molecules. After each of the blood draws (each overnight fasted except immediately post-exercise), participants completed the abbreviated Profile of Mood States (POMS) questionnaire using procedures described in an earlier study in our labStudy participants signed the consent form and were given a complete orientation to the study protocol during the first lab visit. The orientation included an introduction of the exercises included in the eccentric exercise bout and the muscle function tests. Study participants practiced the exercises and function tests during the orientation period. During the second lab visit (overnight fasted, pre-supplementation), study participants provided a blood sample, turned in the 24-h urine collection bottle, and provided responses to POMS and DOMS questionnaires. Height and body weight were assessed, with body composition measured using the BodPod system (Cosmed, Rome, Italy). Participants then performed five muscle function tests as described previouslyParticipants returned for their third lab visit after the 2-week supplementation period in an overnight fasted, turned in 3-day food records and 24-h urine bottles, gave responses to DOMS and POMS questionnaires, and provided a blood sample. Blueberry and placebo supplements (half doses) were ingested followed by muscle function testing. As described previously, participants then engaged in a 90-min eccentric exercise bout that consisted of 17 different exercises, most with 2 to 3 sets and 30–60 s of rest between sets