Influence of Almond Supplementation on Energy, Performance, and Inflammation Resolution From Exercise-Induced Muscle Damage

This will be the first study to determine if 4-weeks ingestion of nutrient-dense almonds improves feelings of energy and vitality, and mitigates post-exercise inflammation (plasma cytokine and oxylipin levels), muscle soreness, and muscle damage. An acute 90-minute bout of eccentric exercise will be used to induce muscle damage and inflammation in a group of 60 relatively untrained male and female adults (ages 30-65 years). Using a randomized, parallel group design, almond supplementation (57 g/d) for a 4-week period prior to the eccentric exercise challenge will be investigated as a countermeasure strategy to exercise-induced muscle damage and inflammation. The control group will ingest a calorie-matched common snack (cereal bars). To improve the potential for capturing an intervention effect, advanced mass spectrometry procedures will be utilized to measure changes in 70 different oxylipins and lipid mediators that are involved in regulating inflammation. C-reactive protein (CRP), six inflammatory cytokines, and muscle damage biomarkers will also be measured. Blood samples (7 total) will be collected before and after the 4-week supplementation period, and then daily during 5 days of recovery from the eccentric exercise bout. The Profile of Mood States (POMS) will be used to measure mood state and specific domains including vigor or activity, and fatigue or inertia. Exercise performance will be measured each time a blood sample is collected using a comprehensive battery that includes vertical jump, leg/back muscle strength, bench press muscle endurance, and anaerobic power (30-second Wingate test).

Participants will be randomized to the almond or typical snack (cereal bars) supplement 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 4-week supplementation period, and then Monday (eccentric exercise bout) and Tuesday through Friday (recovery) in an overnight fasted state. The 4-week supplementation period was based on practical issues related to the research design. A 4-week almond supplementation period was commonly used in prior studies and was sufficient to demonstrate favorable blood lipid changes relative to control conditions.

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 complete the POMS (energy, vitality) and provide a muscle soreness rating (DOMS). Physical activity will be monitored during the entire study using the International Physical Activity Questionnaire (IPAQ). The IPAQ was developed to measure health-related physical activity (PA) in populations. The short version of the IPAQ has been tested extensively and is now used in many international studies.

Study participants will come to the performance lab for orientation to the testing 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). This will be followed by another lab session for pre-study measurements and sample collection with subjects in an overnight fasted state (visit #2) (see description below). A 3-day food record will be collected during the end of the 4-week supplementation period to assess the background diet.

Study participants will have to agree to 5 other lab visits during a one-week period (all overnight fasted condition). These lab visits will start at 7:00 am on Monday, with morning visits at 7:00 am on Tuesday through Friday. At each of the 5 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.