Seven Days of Highbush Blueberry Supplementation Improves Trail Running Performance in Experienced Runners Without Elevating Physiological or Perceptual Stress Markers.

Trail running, particularly with a downhill segment, can lead to muscle damage, oxidative stress, and inflammation-factors linked to fatigue. Antioxidant-rich foods like blueberries may help reduce these effects and improve performance. We evaluated 7 days of blueberry supplementation on physiological responses, performance, and recovery from a 22.2-km simulated trail race. Nine runners completed the race following 7 days of freeze-dried blueberry (BLU) and placebo (PLA) powder supplementation. Measurements taken prerace, immediately postrace, and 24 hr postrace included symptoms, pulse wave analysis, pulse wave velocity, reactive strength index, drop jump height, muscle soreness, pulmonary function, salivary cortisol, and immunoglobulin A. Fraction of exhaled nitric oxide was measured pre- and postrace. During the race, heart rate and ratings of perceived exertion for legs and lungs were assessed. Race time was significantly faster with BLU (p = .003), with no differences in race heart rate or ratings of perceived exertion. Supine heart rate (p = .031) and feelings of tiredness (p = .005) were lower in BLU, while FEV1/FVC was higher (p = .023). Drop jump height declined at 24 hr after the trail race in PLA (p = .022) but was preserved in BLU. Blueberry supplementation improved running performance without increasing physiological or perceptual stress.