James Brouner

Influence of tart cherry juice on indices of recovery following marathon running

This investigation determined the efficacy of a tart cherry juice in aiding recovery and reducing muscle damage, inflammation and oxidative stress. Twenty recreational Marathon runners assigned to either consumed cherry juice or placebo for 5 days before, the day of and for 48 h following a Marathon run. Markers of muscle damage (creatine kinase, lactate dehydrogenase, muscle soreness and isometric strength), inflammation [interleukin‐6 (IL‐6), C‐reactive protein (CRP) and uric acid], total antioxidant status (TAS) and oxidative stress [thiobarbituric acid reactive species (TBARS) and protein carbonyls] were examined before and following the race. Isometric strength recovered significantly faster (P=0.024) in the cherry juice group. No other damage indices were significantly different. Inflammation was reduced in the cherry juice group (IL‐6, P<0.001; CRP, P<0.01; uric acid, P<0.05). TAS was ∼10% greater in the cherry juice than the placebo group for all post‐supplementation measures (P<0.05). Protein carbonyls was not different; however, TBARS was lower in the cherry juice than the placebo at 48 h (P<0.05). The cherry juice appears to provide a viable means to aid recovery following strenuous exercise by increasing total antioxidative capacity, reducing inflammation, lipid peroxidation and so aiding in the recovery of muscle function.

The reliability of electromechanical delay and torque during isometric and concentric isokinetic contractions

The purpose of this investigation was to examine the intra-subject reliability of electromechanical delay (EMD) and torque of the dominant and non-dominant elbow flexors during isometric and isokinetic muscle contractions repeated over five consecutive days. Eleven volunteers that were unfamiliar with isokinetic dynamometry participated in this study and were asked to attend the laboratory on five consecutive days. An isokinetic dynamometer was used to exercise the elbow flexors under isometric, slow (60 degrees s(-1)) and fast (210 degrees s(-1)) isokinetic conditions; surface electromyography was recorded from the belly of biceps brachii and the signal was synchronised with the dynamometer to determine EMD. Intra-subject reliability for all measures was good (CV range, 3.1-6.5%) with no discernable difference between the dominant and non-dominant arms during isometric and isokinetic conditions. In addition, there was little difference in EMD and torque variability between the dominant and non-dominant arms which may have applications for clinicians and future research design when monitoring and investigating human muscle function. These data provide researchers and clinicians with an indication of the magnitude of change that is required to elucidate the presence of a meaningful change to muscle function in the elbow flexors.

Antioxidant supplementation does not attenuate exercise-induced cardiac troponin release

Clinically, cardiac troponins (cTn) are used as sensitive markers ofcardiomyocyte damage [1,2] with any elevation in cTn being related topoor prognosis [3]. Recently, however, exercise has also been shown tostimulate the release of cTn [4–6]. The mechanism responsible forexercise-induced cTn release is not known, and is currently a matter ofdebate [7]. Notwithstanding this, it has been proposed, due to therelatively low post-exercise cTn concentrations and its rapid clearance,that cTn is likely released from the cytosolic pool and not from thebreakdownofcontractileapparatus.Previousauthors[8]havesuggestedthatoxidativestressassociatedwithprolongedexercisemaydamagethecardiomyocyte membrane, resulting in cTn release from the cytosol.Antioxidant supplementation has been shown to attenuate oxidativestress, inflammation and muscle damage indices following strenuousexercise [9]; therefore, if post-exercise cTn release is related tocardiomyocyte membrane damage we hypothesised that antioxidantsupplementation would reduce cTn release following marathonrunning.The institutional ethics committee approved all procedures [11].Followinghealth-screeningandgainingconsent,16marathonrunners(11 male and 5 female), a subset from a previous study [9], free fromnutritional supplements and medication, volunteered to participate.Runners were assigned to either a placebo or antioxidant group in adouble-blind, randomised fashion. Antioxidant or placebo supple-mentation was administered each day from 5 days prior to 48 hfollowing the marathon. Indices of cardiac damage (cTnI), inflamma-tion (IL-6 and C-RP), muscle damage (CK), and total antioxidativecapacity (TAC) were taken before supplement (TAC only), before therace, immediately post, 24 and 48 h following completion of themarathon.The antioxidant supplement (tart cherry juice, Cherrypharm, Inc,Geneva, NY) has previously been shown to reduce skeletal muscledamage [10], reduce lipid peroxidation and aid recovery followingrunning [9]. Two servings (morning and afternoon) of approximately225 mL (equating to ~50–60 cherries) were consumed per day; thejuice contained ~600 mg of phenolic compounds such as anthocya-nins and other flavonoids (quercetin, kaempferol and isoramnetin)and ~55 mmol L

Intra-session and Inter-day Reliability of the Myon 320 Electromyography System During Sub-maximal Contractions

Electromyography systems are widely used within the field of scientific and clinical practices. The reliability of these systems are paramount when conducting research. The reliability of Myon 320 Surface Electromyography System is yet to be determined. This study aims to determine the intra-session and inter-day reliability of the Myon 320 Surface Electromyography System. Muscle activity from fifteen participants was measured at the anterior deltoid muscle during a bilateral front raise exercise, the vastus lateralis muscle during a squat exercise and the extensor carpi radialis brevis (ECRB) muscle during an isometric handgrip task. Intra-session and inter-day reliability was calculated by intraclass correlation coefficient, standard error of measurement and coefficient of variation (CV). The normalized root mean squared (RMS) surface electromyographic signals produced good intra-session and inter-day testing intraclass correlation coefficient values (range: 0.63–0.97) together with low standard error of measurement (range: 1.49–2.32) and CV (range: 95% Confidence Interval = 0.36–12.71) measures for the dynamic-and-isometric contractions. The findings indicate that the Myon 320 Surface Electromyography System produces good to fair reliability when examining intra-session and inter-day reliability. Findings of the study provide evidence of the reliability of electromyography between trials which is essential during clinical testing.

An isokinetic method for inducing a localised fatigue effect in the plantarflexors and dorsiflexors of the ankle

To examine the effects of dysfunction of specific musculature of the shank a reliable and valid protocol can be used to induce a localised fatigue effect. A localised dynamometry based protocol was developed to illicit a fatigue effect in either plantar flexors or dorsiflexors. An isokinetic protocol allowing for movement through the full range of motion, set at an angular velocity of 45°s(-1), was used to allow fatigue to be developed. Fatigue was established when three consecutive torque measures dropped below 50% of the average three peak contractions. Bouts of activity were based on a ratio of 40 contractions interspaced with a 30s rest. Results suggest that the protocol elicited a fatigue effect in the prime movers of either plantar flexion or dorsiflexion, supported through the analysis of power spectral density and amplitude shift of surface electromyography measures. The protocol demonstrated sound reliability with Interclass Correlation scores for all measures ranging from 0.441-0.962. The protocol is a valid and repeatable process for establishing muscular weakness in the working muscles of either plantar or dorsi flexion, as observed in the fatigued state. This can allow further examination of the effects of a localised muscular weakness on daily living tasks.