THE EFFECTS OF A SINGLE DOSE OF ARONIA MELANOCARPA EXTRACT ON BIOMARKERS ASSOCIATED WITH DELAYED ONSET MUSCLE SORENESS (DOMS).

Background.

Delayed-onset muscle soreness (DOMS) is the pain felt in skeletal muscle in the days following a bout of exercise. Associated with eccentrically biased resistance exercise, DOMS pain can restrict activities of daily living, is a barrier to engagement in further exercise and can hinder sports performance. From a public health point of view exercise is an important mediator of disease. To effectively facilitate exercise engagement, it is important to understand the mechanisms that underpin DOMS and identify interventions that alleviate the symptoms. Current theories of DOMS are based around the inflammatory response caused by exercise induced muscle damage (EIMD) leading to the sensitisation of pain receptors. It has been shown that DOMS and other indices of EIMD can be blunted by ingestion of polyphenol compounds. Aronia Melanocarpais an antioxidant rich berry, the concentrated dried powder of this berry has been shown to have powerful antioxidant properties. Establishing an evidence based exercise protocol that consistently elevates biomarkers is required for DOMS intervention testing, this research was created to establish such a protocol. Ingesting polyphenols may attenuate indices of exercise-induced muscle damage. Thus, this research investigated whether consuming a single dose of polyphenol rich Aronia Melanocarpa would attenuate biomarkers of DOMS. The endocannabinoid Anandamide (AEA) has been shown to have pain modulating capability and is of interest in this research.

Purpose.

The purpose of this study was to design a protocol to determine the optimum level of exercise to induce measurable changes in the biomarkers associated with DOMS. Once the protocol was established, it was then used to investigate the effect of a single dose of polyphenols rich Aronia melanocarpaon those biomarkers.

Design.

Phase one utilised a randomised independent group design. Twenty-five healthy men (31.6 ± 13.2 years; 83.2 ± 13.0 kg; 179.0 ±6.9 cm) were randomly assigned to perform either 48, 60 or 72 repetitions of maximal eccentric elbow flexion exercises. Phase two was conducted using a randomised, single blind, placebo controlled independent group design. Seventeen healthy male participants (27.1 ± 10.2 years; 77.8 ±10.3 kg; 177.7 ± 7.0 cm) were randomly assigned to ingest either a placebo drink or polyphenol rich Aronia melanocarpa drink after a bout of elbow flexion exercises. In both phase one and phase two, levels of the following biomarkers were assessed before, immediately after and 48 hours after exercise; DOMS, CK, IL-6, AUC, ROM and Anandamide (AEA).

Results.

Phase one: After 48 hours, the highest mean DOMS scores (VAS) were recorded in the 60 repetition group; 5.1cm (± 2.2) compared to 48 repetitions 4.3cm (± 2.1) and 72 repetitions 4.6cm (± 2.6). However, the group differences did not reach statistical significance (p=0.766). The UAC was significantly increased over the 48-hour period for 48 and 60 repetitions only (p=0.005 and p=0.008 respectively). A significant 48-hour time effect on the ROM was apparent in the 60 repetition group (p=0.013) and 72 repetition group (p=0.018), but not 48 repetition group (p=0.262). There was no statistical difference between AEA concentrations at any time-point. Phase two: After 48 hours, participants in the Aronia melanocarpa group reported 14% less pain than in the control group with mean pain scores of 4.4cm (±2.2) and 5.1cm (±2.2) respectively. However, the difference in pain scores did not reach statistical significance (p=0.556). After 48 hours, plasma CK had significantly increased by 462% (p=0.036) in the placebo group. There was no significant increase in CK activity in the Aronia melanocarpagroup (p=0.173). Despite this, no significant difference between the two groups was found (p=0.248). There was a significant reduction in the ROM of the elbow joint over 48 hours of 16.5° (p=0.012) in the control group, but no change in ROM in the Aronia melanocarpa group over the same time period (p= 0.122). Despite this, no significant group x time interaction (p=0.111) was found for ROM.

Conclusions.

The developed exercise protocol consistently elevated biomarkers of DOMS and was therefore used to test the polyphenol intervention. The findings indicate that a single dose of polyphenol rich Aronia melancarpadoes not attenuate exercise-induced DOMS in healthy men. However, Aronia melanocarpamay confer a small blunting effect on other indices of EIMD, specifically ROM and CK.