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The Effect of Olive Leaf Extract on Upper Respiratory Illness in High School Athletes: A Randomised Control Trial.
Somerville, V, Moore, R, Braakhuis, A
Nutrients. 2019;11(2)
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When an individual exercises, there is a 3 to 72 hour subsequent period known as the ‘open window’ where they are susceptible to illness due to altered immune function and activity. The aim of this study was to determine the effect of olive leaf extract (OLE) supplementation on upper respiratory illness (URI) incidence and duration in high school athletes. The study was a two-month parallel double-blind randomised controlled trial. The study recruited 32 students (females n = 22) aged between 16 and 19 years. The participants were randomly allocated to one of the two groups: OLE or placebo tablets group. Results indicate that there were 17 participants who experienced a total of 26 URI episodes. There was no significant difference in incidence; however, there was a significant 28% reduction in sick days. Authors conclude that OLE supplementation could be used to alleviate the effect of URI on high school athletes.
Abstract
Upper respiratory illness (URI) has a major impact on both training and competition in an athletic setting. High school athletes are a sub-category who have reported higher illness rates than professional and sub-elite high school athletes of the same sport. Olive leaf extract (OLE) is an over-the-counter supplement that contains polyphenols, notably oleuropein and hydroxytyrosol, that have antiviral, antibacterial, anti-inflammatory and antioxidant properties that may reduce URI rates. Thirty-two high school students who play sport for the elite team at their school were recruited to a randomised controlled trial and allocated to a daily placebo or OLE (extent equivalent to 20 g of olive leaf, containing 100 mg oleuropein) supplementation for nine weeks during their competitive season. Twice weekly measures of wellbeing, training load and respiratory illness (sporting upper respiratory illness (SUPPRESS) questionnaire) were recorded at trainings, meetings or games. There was no significant difference in illness incidence (odds ratio (OR): 1.02 (95% confidence interval (CI) 0.21⁻4.44)), but there was a significant 28% reduction in sick days (OR: 0.72 (95% CI 0.56⁻0.93) p-value = 0.02) when supplemented with OLE. The dietary intakes of the athletes were sub-optimal with regard to immune support. OLE supplementation over a season did not significantly reduce URI incidence, but did decrease duration in high school athletes, potentially aiding return to play.
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Effect of bilberry juice on indices of muscle damage and inflammation in runners completing a half-marathon: a randomised, placebo-controlled trial.
Lynn, A, Garner, S, Nelson, N, Simper, TN, Hall, AC, Ranchordas, MK
Journal of the International Society of Sports Nutrition. 2018;15:22
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There is a growing interest in identifying alternative approaches for reducing inflammation and lessening recovery time among long distance runners. This type of exercise causes inflammation and muscle soreness which impacts performance and ability to train. Recent studies have shown that various plant-derived polyphenols can counter exercise-induced inflammation and muscle soreness. The aim of this single blind, randomised, parallel study was to investigate whether supplementation of bilberry juice (BJ), a polyphenol-rich fruit, would reduce inflammation and muscle soreness in 19 runners completing a half marathon. Participants were randomised to consume BJ or a placebo fruit drink for 5 days prior to the half marathon, on the day of the race and for two days after the race. Blood samples were collected at baseline, pre-race, post-race, 1 day post-race and 2 days post-race and markers of muscle soreness and damage were measured. Contrary to hypothesis, this study found evidence that BJ produced possibly harmful effects on muscle soreness and inflammatory markers compared to placebo. Based on these results, the authors recommend a larger study to confirm the findings and further explore the underlying cause of the observed detrimental changes.
Abstract
BACKGROUND Emerging evidence indicates that fruits rich in polyphenols may attenuate exercise-induced muscle damage and associated markers of inflammation and soreness. This study was conducted to determine whether bilberry juice (BJ), which is particularly rich in polyphenols, reduces markers of muscle damage in runners completing a half marathon. METHODS A total of 21 recreationally trained runners (age 30.9 ± 10.4 y; mass 71.6 ± 11.0 kg; M = 16; F = 5) were recruited to a single blind, randomised, placebo-controlled, parallel study. Participants were block randomised to consume 2 × 200 ml of BJ or energy-matched control drink (PLA) for 5 d before the Sheffield Half Marathon, on race day, and for 2 days post-race. Measurements of delayed onset muscle soreness (DOMS), muscle damage (creatine kinase; CK) and inflammation (c-reactive protein; CRP) were taken at baseline, pre-race, post-race, 24 h post-race and 48 h post-race. The effect of treatment on outcome measures was analysed using magnitude-based inferences based on data from 19 participants; 2 participants were excluded from the analyses because they did not provide samples for all time points. RESULTS The half marathon caused elevations in DOMS, CRP and CK. BJ had a possibly harmful effect on DOMS from pre-race to immediately post-race (11.6%, 90% CI ± 14.7%), a likely harmful effect on CRP from pre-race to 24 h post-race (mean difference ES 0.56, 90% CI ± 0.72) and a possibly harmful effect on CRP from pre-race to 48 h post-race (ES 0.12, 90% CI ± 0.69). At other time points, the differences between the BJ and PLA groups in DOMS and CRP were unclear, possibly trivial or likely trivial. Differences in the changes in CK between BJ and PLA were unclear at every time point other than from baseline to pre-race, where BJ had a possibly harmful effect on reducing muscle damage (ES 0.23, 90% CI ± 0.57). CONCLUSION Despite being a rich source of antioxidant and anti-inflammatory phytochemicals, BJ evoked small to moderate increases in exercise-induced DOMS and CRP. Further larger studies are required to confirm these unexpected preliminary results.
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The effect of green tea extract supplementation on exercise-induced oxidative stress parameters in male sprinters.
Jówko, E, Długołęcka, B, Makaruk, B, Cieśliński, I
European journal of nutrition. 2015;54(5):783-91
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High intensity exercise generates reactive oxygen species (ROS), which help with muscle recovery. However, when produced in excess, ROSs cause oxidative stress and cellular damage. Antioxidants produced in the body or taken in through the diet are able to make ROSs inactive. This double blind, randomised controlled trial aimed to evaluate the effects of Green tea extract supplementation on oxidative stress in 16 male sprinters. The study found no significant difference between the group given the supplement and the placebo group in terms of muscle damage recovery and exercise performance. However, an increased levels of polyphenols were observed in the supplement group post-exercise in comparison to the placebo group.
Abstract
BACKGROUND Although research suggests that antioxidant supplementation can protect against exercise-induced muscle damage and oxidative stress, also delayed post-exercise muscle recovery and hindered adaptation to training were reported in the supplemented athletes. PURPOSE The purpose of the study was to evaluate the effects of green tea extract (GTE) supplementation on selected blood markers of oxidative stress and muscle damage in sprinters during preparatory phase of their training cycle. METHODS Sixteen sprinters participated in a double-blind, randomized, placebo (PL)-controlled crossover study, including two 4-week treatment periods with PL and GTE (980 mg polyphenols daily). The sprinters performed two repeated cycle sprint tests (RST; 4 × 15 s, with 1-min rest intervals), after PL and GTE supplementation. Blood was sampled before (at rest), 5 min after RST, and after the 24-h recovery. The activities of superoxide dismutase (SOD) and glutathione peroxidase were measured in erythrocytes, and total polyphenols, total antioxidant capacity (TAC), uric acid (UA), albumin (AL), malondialdehyde (MDA), and creatine kinase (CK) were determined in blood plasma. RESULTS Repeated cycle sprint test performed after PL induced an increase in MDA, TAC, and SOD. Moreover, an increase in UA, AL, and CK was observed after RST irrespective of experimental conditions (PL, GTE). Supplementation with GTE caused an increase in total polyphenols and TAC at rest, and a decrease in MDA and SOD after RST. No significant changes in sprint performance were noted after GTE, as compared to PL. CONCLUSIONS Supplementation with GTE prevents oxidative stress induced by RST in sprinters. Furthermore, GTE supplementation does not seem to hinder training adaptation in antioxidant enzyme system. On the other hand, neither prevention of exercise-induced muscle damage, nor an improvement in sprint performance is noted after GTE administration.