Investigating the Efficacy of Low or High Dose Tart Cherry on Recovery From Exercise Induced Muscle Damage and Establishing Its Molecular Mechanisms of Action

To determine the dose-response effects of 10-day tart cherry product consumption (0, 30 ml, and 60 ml) on knee extensor isometric strength 24-h and 48-h after muscle damaging exercise and to elucidate the mechanisms of action for TC supplementation.

Montmorency cherry supplementation has been shown to exert antioxidant and anti-inflammatory effects that can be beneficial for improving recovery from exercise. However, the investigator is currently not aware of how tart cherry polyphenol supplementation produces these effects. This study aims to determine the dose-response effects of 10-day tart cherry product consumption (placebo, 30 ml, and 60 ml Montmorency tart cherry concentrate in a 500 ml beverage) on knee extensor isometric strength 24-h and 48-h after muscle damaging exercise on supplementation Day 8; on enhancing recovery of other measures of muscle function (single leg eccentric and concentric force development and single leg jump height) and muscle soreness; on reducing markers of oxidative stress and inflammation in plasma, muscle and urine; on inducing signaling in muscle via the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway to upregulate endogenous antioxidant enzymes in muscle; on inhibiting muscle cyclo-oxygenase (COX-1 and COX-2).

This study also aims to identify and establish the molecular mechanisms of action through which tart cherry polyphenols exert antioxidant and anti-inflammatory effects. Oxidative stress and inflammatory signaling in primary human myogenic cells will be assessed by incubating primary human myogenic cells (commercial cell line) in sera derived from 6 participants consuming 8-day placebo vs. 60 ml/day Montmorency tart cherry concentrate supplement. Subjects are permitted to participate in both the molecular mechanism of action part of the study (Part A, no exercise component) and the damaging exercise muscle recovery part of the study (Part B).

For 60 ml doses in Parts A and B, global proteomics analysis of the muscle tissue will be conducted generate more insight into the mechanisms of action. This would identify the specific pathways that are influenced by cherry supplementation and allow identification of the full range of mechanisms involved, rather than assume antioxidant/anti-inflammatory effects alone.

Eligibility Criteria:
Inclusion Criteria:

1. Male in good health
2. 18-40y
3. BMI ≤ 29.9
4. Recreationally active but not highly trained (Participating in sport or physical activity at least once per week for the last 6 months and lower limb resistance training ≤ 1/week) (Part B only)
5. No lower limb musculoskeletal injury that prevented exercise in the last 3 months (Part B only)
6. Understanding of the procedures to be undertaken as part of the study
7. Willing to participate in the exercise protocols (Part B only) and follow supplementation guidelines and other instructions provided by the experimenter
8. Willing to abstain from caffeine, alcohol and strenuous exercise for two 5 day periods (from 48h prior to muscle damaging exercise and throughout the follow up period; days 6-10 of the trial) for Part B, and abstain from caffeine and alcohol for two 3-day periods for Part A
9. Willing to keep food diaries for the duration of each arm of the trial and avoid multiple servings per day of foods that have a high polyphenol content from a list provided.
10. Willing to construct their diet for the first arm of the trial from a list of recipes provided, and to then replicate this diet during the second arm of the trial.
11. Willing to wear a triaxial accelerometer throughout each arm of the trial, and during the second arm of the trial to replicate their physical activity pattern completed in the first arm of the trial.
12. Willing to abstain from consumption of anti-inflammatory, analgesic medications or those with anti-coagulant effects especially NSAIDs and aspirin for 48h prior to and throughout each arm of the trial. (Part B only)
13. Willing to abstain from icing or applying compression bandages to the exercised/biopsied leg (Part B only)
14. Ability to provide voluntary written informed consent to participate in the study.

Exclusion Criteria:

1. Female
2. \<18y or \>40y
3. BMI ≥ 30
4. Inactive or well-trained (see inclusion criteria) (Part B only)
5. Lower limb musculoskeletal injury in the last 3 months (Part B only)
6. Under the care of a physician
7. Known health condition that could interfere with any element of the data collection protocol. Any known pulmonary, gastrointestinal (e.g., irritable bowel syndrome, Crohn's disease), kidney, cardiovascular, or metabolic diseases, blood-borne infections, or coagulopathies including deep vein thrombosis (DVT)
8. Current regular consumption of nutritional/dietary supplements or previous use of any dietary supplements in the past 6 months known to have a lasting effect.
9. Current use of prescription medication; including the use of an inhaler
10. Non-steroidal anti-inflammatory drugs, aspirin or other analgesic medication or any anti-coagulants are prohibited during the study and for 48h prior to commencing supplementation
11. Allergy/sensitivity/intolerance to cherries, any cherry derived product, or any of the additional ingredients found within the TC test products, including sensitivity to sorbitol.
12. Allergy to lidocaine or other local anaesthetics. (Part B only)
13. Active drug or alcohol dependency
14. Current or active usage of nicotine or tobacco related products
15. Participation in a clinical trial within the past 30 days or concurrently during this trial
16. Participation in any PepsiCo trial within past 6 months, except that Part A participants may take part in Part B after a \>=14 day washout from Part A
17. Inability to provide written informed consent