Six Weeks of Daily Blueberry Consumption Does Not Alter Aged Skeletal Muscle Inflammation Profile or Inflammatory Response to Eccentric-Exercise

Abstract

Muscles of old adults respond to stress with heightened inflammatory signaling that disrupts the regenerative process. This muscle inflammation susceptibility could contribute to the age-related decline in muscle mass, as anti-inflammatory medications taken concurrently with exercise training, have proven beneficial in attenuating age-related loss of muscle mass. With antioxidants and anti-inflammatory potential, blueberries (BB) are a natural alternative that might regulate aged muscle inflammation susceptibility. Objectives: The purpose of this study was to determine the effects of BB consumption on the muscle inflammatory profile of older adults, and to determine the subsequent muscle inflammatory response to exercise. We hypothesized that BB would lower the inflammatory profile of muscle and attenuate the inflammatory response after resistance exercise. Design: Subjects were randomized to receive daily BB or placebo supplements, which were blind to subjects and researchers. All subjects underwent baseline functional testing, post-supplementation testing, and testing post-muscle stress stimulus. Setting: Volunteers were recruited from Western North Carolina region, USA. Participants: Healthy, non-resistance trained adults over 60 years old (n=22) were recruited. Measurements: Profiles of inflammation pathways known to affect muscle mass were established prior to and after 6-weeks of daily consumption of BB. Post-supplementation, subjects performed an exercise protocol to induce inflammation and returned 24 hours post-exercise to determine the muscle inflammatory profiles. Results: Muscle cytokine and soluble cytokine receptor levels were similar between groups and within groups before and after BB consumption. Cytokine and cytokine receptor levels post-muscle stress changed similarly in the BB and placebo group, indicating BB had no effect on the muscle’s inflammatory response. Total plasma antioxidant capacity was 22% higher in the BB group 24-hours post-muscle stress, however, plasma oxidative stress was not different between groups or within groups. Conclusion: While BB consumption did not affect inflammatory signaling pathways within the muscle nor affect inflammation after a regenerative stimulus, a higher plasma antioxidant capacity could contribute to a better long-term regenerative response.