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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
34
Color, taste, aroma, and calorie matched water base
Montmorency cherry concentrate
Montmorency cherry concentrate
University of Exeter Sport and Health Sciences Department
Exeter, UK, United Kingdom
Isometric knee extensor strength
Maximum voluntary contraction (MVC) as a measure of functional recovery from muscle damage. Unit of measurement is Newtons. Stronger is better.
Time frame: Changes from immediately before and immediately after muscle damaging exercise on day 8 of tart cherry supplementation to 24 hours and 48 hours after muscle damaging exercise (days 9 and 10 of supplementation).
Single leg eccentric and concentric isokinetic force production
Dynamic muscle strength measured by isokinetic contraction (IKC, 60 deg.s-1). More forceful is better.
Time frame: Changes from immediately before and immediately after muscle damaging exercise on day 8 of tart cherry supplementation to 24 hours and 48 hours after muscle damaging exercise (days 9 and 10 of supplementation).
Single leg vertical jump height (SLVJ)
Dynamic muscle strength measured by jump height (cm). Higher is better.
Time frame: Changes from immediately before and immediately after muscle damaging exercise on day 8 of tart cherry supplementation to 24 hours and 48 hours after muscle damaging exercise (days 9 and 10 of supplementation).
Leg muscle soreness by Pressure Pain tolerance (PPT)
Pressure pain tolerance (PPT) measured by algometer. Higher tolerance is better.
Time frame: Changes from immediately before and immediately after muscle damaging exercise on day 8 of tart cherry supplementation to 24 hours and 48 hours after muscle damaging exercise (days 9 and 10 of supplementation).
Leg muscle soreness by Visual Analogue Scale (VAS)
Measured using a visual analogue pain scale from 0 mm (no pain) to 100 mm (extremely painful). Lower score is better.
Time frame: Changes from immediately before and immediately after muscle damaging exercise on day 8 of tart cherry supplementation to 24 hours and 48 hours after muscle damaging exercise (days 9 and 10 of supplementation).
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Leg muscle biopsy for nuclear factor k-B (NFκB)
Inflammation marker expression activity of the NFκB pathway will be measured by immunoblotting. Lower is better.
Time frame: Changes from pre and post exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for cyclo-oxygenase COX1 protein
Inflammation marker of cyclo-oxygenase measured by total protein carbonylation (immunoblotting). A reduction (inhibiting) is better.
Time frame: Changes from pre and post exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for cyclo-oxygenase COX1 activity
Inflammation marker of cyclo-oxygenase activity measured by commercially available colorimetric assay. A reduction (inhibiting) is better.
Time frame: Changes from pre and post exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for nuclear factor erythroid 2-related factor 2 (Nrf2), absolute expression, nuclear translocation
Oxidative damage marker Nrf2 pathway intended to upregulate endogenous antioxidant enzymes in muscle. Induction of signaling is better.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for global proteomics analysis of muscle tissue samples for the 60 ml dose only
Tissue analysis to identify pathways influenced by cherry supplementation and identify mechanisms of action.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for endogenous antioxidant enzyme expression
Enzymes (superoxide dismutase 1, superoxide dismutase 2, glutathione peroxidase 1 and catalase) protein expression quantified by immunoblotting. Higher values (upregulation by Nrf2) is better.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Leg muscle biopsy for immune cell infiltration
Inflammation marker response measured by immunohistochemistry. Less infiltration is better.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Biopsies are done after blood samples and before muscle soreness measures.
Plasma interleukin-6 (IL-6)
Plasma inflammatory stress response measured by ELISA. A reduction is better.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Pre exercise blood sampling is done after urine collection. Post exercise blood sampling done before biopsy.
Plasma protein carbonyls
Oxidative stress response and antioxidant status measured by ELISA. A reduction is better.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Pre exercise blood sampling is done after urine collection. Post exercise blood sampling done before biopsy.
Plasma phenolic concentration
LC-MS-MS metabolite analysis to evaluate plasma levels associated with tart cherry supplementation at 0, 30 and 60 ml/day.
Time frame: Changes from pre and post muscle damaging exercise on day 8 of tart cherry supplementation to pre-exercise on days 9 and 10 of supplementation. Pre exercise blood sampling is done after urine collection. Post exercise blood sampling done before biopsy.
Urine oxidation-reduction potential (ORP)
Urinary oxidation-reduction potential to measure oxidative damage and antioxidant status measured by probe. Less oxidative stress/free radical production is better.
Time frame: Change from pre-exercise value day 8 to days 9 and 10 of tart cherry supplementation. Collected upon arrival to the study site.