Quercetin is a flavonoid found in commonly consumed fruits and vegetables that has exhibited powerful antioxidant and anti-inflammatory properties in rodents and in vitro. In humans, the ergogenic effects of antioxidant supplementation on exercise performance and adaptations are still equivocal and need to be further investigated. A powerful antioxidant such as quercetin may inhibit the high levels of oxidative stress associated with the high volume and intensity of exercise training seen with trained individuals. There have been equivocal findings thus far regarding the ergogenic effect of either acute or chronic supplementation of quercetin on exercise performance. PURPOSE: To determine the effect of 28 days of daily quercetin supplementation on cycling time trial performance and the associated exercise performance variables. METHODS: Thirteen trained cyclists (VO2peak 58.8 ± 3.9 ml/kg/min) were recruited for this study from the University of Texas at Austin and the local Austin, Texas community and participated in this placebo controlled, randomized, crossover designed study. After initial assessment of baseline data (VO2peak, lactate threshold, and two familiarization time trials), participants began daily supplementation of either an antioxidant supplement containing vitamins and quercetin (Q-VIT: 1000mg quercetin, 820mg Vitamin C, 40mg Vitamin B3) or the same vitamin supplement without quercetin (VIT: 820mg Vitamin C, 40mg Vitamin B3). A simulated time trial using an electromagnetically braked cycle ergometer in which subjects had to complete a set amount of work (kJ) as fast as possible was performed on the last day of supplementation. Measured performance variables included: time to completion, average power output, average oxygen consumption (VO2), Respiratory Exchange Ratio (RER), gross mechanical efficiency (GE), heart rate (HR), and rating of perceived exertion (RPE). RESULTS: Quercetin had no effect on HR, RER, power output, or RPE. There was also no difference in time to complete the time trial between treatments. However, an approximately ~2% higher, but not significantly different, VO2 during Q-VIT supplementation significantly lowered the GE compared to VIT (Q-VIT: 20.49 ± 0.26 % and 19.94 ± 0.33 %; VIT: 20.9 ± 0.24 % and 20.37 ± 0.33 %; p < .01) at 15 and 30 min respectively. CONCLUSION: Chronic supplementation for 28 days with a quercetin based antioxidant supplement lowered cycling gross efficiency in well trained cyclists, but it did not affect performance time. The results of the current study suggest that chronic supplementation with quercetin does not influence aerobic exercise performance in well trained athletes. / text

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Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis aims to determine whether supplementation with a grape-seed derived antioxidant, oligomeric proanthocyanidin (PCO) or the glutathione precursor, N-acetylcysteine (NAC) may prove beneficial as treatment for exercise induced muscle damage (EIMD) in athletes. In this double-blind cohort study, 21 healthy, uninjured male rugby-players in mid-season training phase, aged between 18 and 25 years were randomly divided into three treatment groups. Participants received 210 mg PCO, NAC or placebo treatment for 9 consecutive days. The study comprised a 6-day wash-out period (protocol days: -12 to -7), followed by a 6-day supplement loading period (protocol days: -6 to -1) a plyometric exercise intervention (protocol day 0) and continued supplementation for 2 days (protocol days: 1 to 2). The exercise intervention comprised 15 sets of 10 near maximal, vertical plyometric squat jumps. Blood samples and delayed onset of muscle soreness (DOMS) scores were collected on protocol days: -6, 0, 1 and 2. Assessments included serum creatine kinase (CK) activity, oxygen radical absorbance capacity (ORAC), malondialdehyde (MDA) and soluble vascular cell adhesion molecule-1 (sVCAM-1) concentrations over time as well as a differential circulating leukocyte count (neutrophils, lymphocytes, monocytes, eosinophils and basophils). Data analysis of CK activity revealed no significant differences between groups. However, PCO treatment prevented a significant peak in the CK response at 24 h (as seen in the placebo and NAC groups) when compared to baseline, pre and post readings (p<0.05). NAC supplementation significantly improved serum ORAC after the exercise intervention. By 48 h, serum ORAC had improved significantly from readings taken immediately post exercise (p<0.05) only in the NAC group. For all groups, absolute neutrophil counts peaked at 6 h post exercise from baseline or pre readings (p<0.05). In both NAC and placebo treated groups, neutrophil counts had decreased significantly in circulation by 24 h post exercise from the 6 h time-point (p<0.05). However, neutrophil counts only reached significantly lower levels by 48 h post exercise (p<0.05) in the group supplemented with PCO. The monocyte count also peaked significantly at 6 h post exercise when compared with other time-points before and after the exercise intervention (p<0.05) in all treatment groups. Neither antioxidant treatment significantly altered the responses of other leukocyte sub-populations, MDA or sVCAM-1 concentrations where main effects of plyometric exercise was evident. Although not statistically significant, a trend toward diminished sVCAM-1 expression with either antioxidant supplementation was apparent. These findings suggest that PCO supplementation (210mg/d) which includes a 7 day loading period may diminish plyometric EIMD by limiting (but not completely inhibiting) the neutrophil response. Secondary muscle damage may be prevented by partially blunting neutrophil infiltration, rather than only quenching free radicals released during the neutrophil oxidative burst. Furthermore, the finding that NAC supplementation improves serum ORAC only after exercise may provide added benefit when administered in combination with PCO. / AFRIKAANSE OPSOMMING: Hierde tesis is daarop gerig om vas te stel of aanvulling met ‘n druifsaadekstrak (DSE) gederiveerde antioksidant: pro-antosianiedoliese oligomeer (PSO), of die glutathione voorloopermolekule, N-asetielsistien (NAS) voordelig beskou kan word as behandeling vir atlete onderhewig aan spierskade veroorsaak deur oefening. Gedurende hierdie dubbelblinde kohort studie is 21 gesonde, manlike rugbyspelers sonder beserings tussen die ouderdom van 18 en 25 jaar in middel-seison fase ewekansig in drie behandelingsgroepe verdeel. Deelneemers het elk 210 mg PSO, NAS of placebo-aanvulling geneem vir nege agtereenvolgende dae. Die studie het bestaan uit ‘n 6-dag uitwasperiode (protokoldae: -12 tot -7), as ook ‘n 6-dag aanvullings periode (protokoldae: -6 tot -1), gevolg deur ‘n pliometriese oefeningsintervensie (protokol dag 0) en verdere aanvulling tot en met 2 dae na die oefening (protokol dae: 1 tot 2). Die oefeningsintervensie het 15 stelle van 10 naastenby maksimale, vertikale pliometriese hurkspronge behels. Bloedmonsters en vertraagde aanvang spierseerheid (VAS) tellings is op protokoldae: -6, 0, 1 en 2 geneem. Analiese het serum kreatien kinase (KK) aktiwiteit, suurstof radikaal absorpsie kapasiteit (SRAK), Malondialdahied (MDA) en oplospare vaskulêresel adhesie molekule-1 (oVAM-1) konsentrasie bepalings asook ‘n differentiële sirkulerende leukosiet seltelling ingesluit. KK aktiewiteit het geen merkwaardige verskil tussen groepe getoon nie. PSO aanvulling het wel gelei tot die voorkoming van ‘n merkwaardige piek in die KK response soos in die placebo en NAC behandelde groepe bevind is by die 24 h tydspunt in vergelyking met basislyn-, voor- en na-oefeningslesings (p<0.05). NAS het ‘n merkwaardige verbetering in serum SRAK getoon, maar eers teen 48 h na oefening. Slegs die NAS behandelde groep het op hierdie tydspunt ‘n betekenisvolle verbetering in SRAK getoon in vergelyking met lesings direk na oefening (p<0.05). Vir alle groepe is ‘n betekenisvolle toename in absolute neutrophiltellings waargeneem 6 h na oefening in vergelyking met basislyn- en vooroefeningslesings (p<0.05). Beide NAS en placebo-behandelde groepe het ‘n betekenisvolle afname in neutrophiltellings teen 24 h na oefening getoon in vergelyking met die 6 h tydspunt (p<0.05) maar met die PSO-behandelde groep word hierde afname eers teen 48 h waargeneem (p<0.05). Monosiettellings het in alle groepe 6 h na oefening ‘n betekinsvolle piek getoon (p<0.05). Waar slegs die hoofeffek van die pliometriese oefening betekenisvol was, het nie een van die twee antioksidant aanvullings ‘n merkwaardige verandering aan die respons van ander leukosiet sub-populasies, MDA of oVAM-1 konsentrasies getoon nie. Al kon statistiese beduidenheid nie bewys word nie, wil dit blyk dat ‘n verminderde oVAM-1 uitdrukking onstaan het in die geval van beide antioksidant-behandelde groepe. Tesame stel hierdie bevindinge voor dat PSO toediening (210mg/d) insluitende ‘n 7-dag aanvullingsperiode die vermoë verleen om die neutrophielrespons gedeeltelik te onderdruk (sonder om dit heeltemal te inhibeer) en sodoende spierskade verminder. Dus word verdere spierskade moontlik verlaag deur die voorkoming van neutrophil weefsel infiltrasie eerder as verwydering van reaktiewe spesies wat vrygestel word tydens oefening. Die bevinding dat NAS aanvulling serum SRAK eers na oefening merkwaardig verbeter, kan as voordelig beskou word, veral wanneer toegedien in samewerking met PSO om verdere spierskade te voorkom en herstelling vinniger te bewerkstellig.

Made available in DSpace on 2016-12-06T17:07:17Z (GMT). No. of bitstreams: 1 Michele de Souza.pdf: 715322 bytes, checksum: 7f1d26921367b31e72a3ad9eedc3fcee (MD5) Previous issue date: 2008-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The purpose of the study was to analyze the relation between the antioxidant supplementation and the variation in the concentrations of the biomarkers of muscular injury in professional volleyball athletes. 11 professional volleyball players had been part of the study, between the ages of 18 and 35 years, which have been subdivided in two experimental groups: group 1 - supplementation of 750mg/day of ascorbic acid and group 2 - supplementation of 750mg/day of &#945;-tocopherol. Dosages had been carried through biochemists of the biomarkers of muscular injury before, immediately after, and 12 hours after a rectangular load test at 80% of the speed peak that was previously determined in a maximum test. These procedures were carried out before, and after 60 days of supplementation. On the basis of these results, it was verified that the exercise can increase the CK release and it is expected that even after 12 hours of recovery these values continue increasing, therefore ore this enzyme can have a peak up to 24 or 48 hours after the accomplishment of the activity. Enzyme LDH seems to be Iess influenced by the action of the exercise, even so the concentrations tends to be higher at the end of the exercise. The exercise also influences the AST release, which increases to the end of the activity, and tends to return to the previous value 12 hours after recovery. Still, from the results, it was observed that in the group supplemented with ascorbic acid, the vitamin seems not to have exerted an influence on the reduction in the concentrations of CK, LDH, AST and ALT, since they had increased in relation to the period pre-supplementation. Meanwhile, the group supplemented with &#945;-tocopherol, besides presenting an increase of CK, LDH and AST as influenced by the action of the exercise, had also been present in significantly lesser amounts in the period pre-supplementation. Moreover, the group supplemented with vitamin E presented lower concentrations of biomarkers of muscular injury than during the period pre-supplementation and, as these biochemical parameters can be used as indications of stress during periods of predominantly anaerobic effort, the supplementation with vitamin E can be said to have exerted a protective effect in relation to this stress. / Este trabalho teve por objetivo avaliar a relação entre a suplementação com vitaminas antioxidantes C e E e variação nas concentrações de biomarcadores de alteração muscular em atletas masculinos profissionais de voleibol. Fizeram parte do estudo 11 jogadores profissionais de voleibol, com idades entre 18 e 35 anos, os quais foram subdivididos em dois grupos experimentais: grupo 1 suplementação de 750mg/dia de ácido ascórbico e grupo 2 suplementação de 750mg/dia de &#945;-tocoferol por 60 dias. Foram realizadas dosagens bioquímicas dos biomarcadores de lesão muscular creatino cinase (CK), lactato desidrogenase (LDH), aspartato amino transferase (AST) e alanina amino transferase (ALT) antes, imediatamente após e 12 horas depois de um teste de carga retangular a 80% do pico de velocidade que foi determinado em um teste máximo. Estes procedimentos foram realizados antes e após 60 dias de suplementação. Com base nos resultados, foi verificado que o exercício pode aumentar a liberação de CK e o esperado é que mesmo após 12 horas de recuperação estes valores continuem aumentando, pois esta enzima pode ter um pico em 24 a 48 horas após a realização da atividade. A enzima LDH parece ser menos influenciada pela ação do exercício, embora as concentrações tendam a estar mais elevadas no final do exercício. O exercício também influencia a liberação de AST, que aumenta ao final da atividade, e tende a retornar a valores prévios após 12 horas de recuperação. Foi observado que no grupo suplementado com ácido ascórbico, a vitamina parece não exercer influência sobre a redução nas concentrações de CK, LDH, AST e ALT, pois as mesmas aumentaram em relação ao período pré-suplementação. No entanto, o grupo suplementado com &#945;-tocoferol, apesar de apresentar aumento de CK, LDH e AST influenciados pela ação do exercício, estes valores apresentaram-se significativamente menores do que no período pré-suplementação. Além disso, o grupo suplementado com vitamina E, apresentou as concentrações de biomarcadores de lesão muscular menores do que no período pré-suplementação e, como estes parâmetros bioquímicos podem ser utilizados como indicadores de estresse durante protocolos de esforços predominantemente anaeróbios, pode-se dizer que a suplementação com vitamina E parece ter exercido um efeito protetor em relação a este estresse.

Master of Science / Department of Kinesiology / Timothy I. Musch / Aged rats exhibit a decreased muscle microvascular O[subscript]2 partial pressure (PO[subcript]2mv) at rest as well as during contractions compared to young rats and this may contribute to their reduced exercise tolerance. Age-related reductions in nitric oxide (NO) bioavailability due, in part, to elevated reactive O[subscript]2 species (ROS) constrain muscle blood flow (Qm). Therefore, antioxidants may restore NO bioavailability, Qm and ameliorate the reduction in PO[subscript]2mv and hence the decrease in exercise tolerance seen in aged rats. PURPOSE: To test the hypothesis that antioxidants would elevate Qm at rest and during contractions and therefore PO[subscript]2mv in aged muscle. METHODS: PO[subscript]2mv and Qm were measured in the spinotrapezius while muscle oxygen consumption (VO[subscript]2m) was estimated in 20 anesthetized male Fisher 344 x Brown Norway hybrid (F344xBN) rats at rest and during 1 Hz contractions before and after antioxidant intravenous infusion (76mg/kg vitamin C and 52mg/kg tempol). Moreover, muscle force production was measured in a subset of animals. RESULTS: Before infusion, contractions invoked a biphasic PO[subscript]2mv that fell from 30.6 [plus or minus] 0.9 mmHg to a nadir of 16.8 [plus or minus] 1.2 mmHg with an 'undershoot' of 2.8 [plus or minus] 0.7 mmHg below the subsequent steady-state (19.7 [plus or minus] 1.2 mmHg). Antioxidants elevated baseline PO[subscript]2mv to 35.7 [plus or minus] 0.8 mmHg (P<0.05) and reduced or abolished the 'undershoot' (P<0.05) without changing the steady-state contracting PO[plus or minus]2mv. Antioxidants did not change Qm at rest but during contractions Qm was reduced from 157 [plus or minus] 28 to 91 [plus or minus] 15 ml min[superscript]-1 100g[superscript]-1 (P<0.05). Antioxidants produced no significant effect on VO[subscript]2m. However, antioxidant supplementation produced a 16.5% decrease (P<0.05) in muscle force production that occurred within the first contraction and remained throughout the duration of stimulation. In addition, the ratio of muscle force production to VO[subscript]2m (F/VO[subscript]2m) actually increased from 0.92 [plus or minus] 0.03 to 1.06 [plus or minus] 0.6 (P<0.05) following infusion of antioxidants. CONCLUSION: Antioxidant supplementation significantly alters the balance between muscle O[subscript]2 delivery and VO[subscript]2 at rest and during contractions, which modifies the microvascular PO[subscript]2mv profile. Specifically, antioxidants elevate PO[subscript]2mv, which improves the potential for diffusive blood-myocyte flux. This effect arises, in part, from the unanticipated fall in muscle force production consequent to antioxidant supplementation.

La réhabilitation respiratoire tient une place importante dans la prise en charge des patients atteints de Broncho-pneumopathie chronique obstructive (BPCO) stables en induisant des bénéfices au niveau de la tolérance à l’effort, la fonction et la masse musculaire périphérique. La présence d’un stress oxydant élevé à l’état basal, considéré comme un des principaux facteurs impliqués dans l’atteinte musculaire périphérique, est bien admise malgré les discordances rapportées dans la littérature notamment au niveau du système antioxydant. L’absence d’amélioration des marqueurs du stress oxydant au cours d’un programme de réhabilitation respiratoire constitue une limite probable aux adaptations musculaires escomptées. Cependant, même si une supplémentation en antioxydants semble être une intervention adaptée permettant de réduire le stress oxydant et d’améliorer l’atteinte musculaire périphérique, son efficacité reste toujours à prouver chez les patients BPCO.Ainsi, nos objectifs étaient de déterminer et caractériser l’hétérogénéité des marqueurs du stress oxydant en vue d’étudier les effets d’une supplémentation en antioxydants adaptée sur des marqueurs spécifiques de l’atteinte musculaire périphérique des patients BPCO stables. A travers une analyse globale intégrant toute la complexité du stress oxydant, ce travail de thèse a montré que les principaux déficits en antioxydants chez les patients BPCO stables se situent au niveau de l’équilibre vitamine C/E, du zinc et du sélénium. De plus, nos résultats ont permis de déterminer des profils de patients caractérisés notamment par des sous-groupes de femmes ayant une majoration des taux de peroxydes lipidiques. Basé sur les principaux déficits identifiés et malgré l’importante hétérogénité des réponses, nous avons montré qu’une supplémentation en antioxydants permettait d’optimiser les bénéfices d’un programme de réhabilitation respiratoire en améliorant la FMIV, la Vo2sl et la surface de section transversale (SSt) des fibres musculaires de patients BPCO stables. Ainsi, dans l’optique d’une approche par phénotypes, l’utilisation de valeurs de références de la SSt, comme établies dans notre seconde étude, semble constituer un biomarqueur adapté mais celles-ci doivent être optimisées afin d’être applicable chez les patients BPCO. Pour conclure, outre l’intérêt pour l’utilisation d’une supplémentation en antioxydants au cours d’un programme de réhabilitation respiratoire, nos résultats contribuent à améliorer les connaissances sur le rôle du stress oxydant dans la physiopathologie de l’atteinte musculaire périphérique des patients BPCO. De plus, une meilleure compréhension et caractérisation de l’hétérogénéité, à la fois du stress oxydant et de l’atteinte musculaire périphérique, ouvrent des perspectives de recherche prometteuses dans l’optique d’une adaptation de la prise en charge des patients BPCO. / Pulmonary rehabilitation is considered as a major component in the management of chronic obstructive pulmonary disease (COPD) patients by inducing benefits on exercise capacity, peripheral function and muscle mass. Elevated oxidative stress at baseline, considered as one of the main factors involved in peripheral muscle impairment, is well accepted despite the discrepancies reported in the literature especially on antioxidant system. The absence of oxidative stress marker improvement following a pulmonary rehabilitation program is a likely limit to the expected muscle adaptations. However, although antioxidant supplementation seems to be an appropriate intervention for reducing oxidative stress and improving peripheral muscle impairment, its effectiveness remains to be proven in COPD patients.Thus, our objectives were to determine and characterize the oxidative stress marker heterogeneity in order to study the effets of a suitable antioxidant supplementation on specific peripheral muscle markers in stable COPD patients.Through a comprehensive analysis integrating the oxidative stress complexity, this work showed that the main antioxidant deficits in stable COPD patients are on the vitamin C/E balance, zinc and selenium. Moreover, our results allowed to determine patient profiles characterized in particular by a women subgroup with an increased rate of lipid peroxides. Based on the main identified deficits and despite the large response heterogeneity, we have shown that antioxidant supplementation may optimize the benefits of a pulmonary rehabilitation program by improving especially muscle fiber strength, cross-sectional area (CSA) and maximal oxygen consumption of stable COPD patients. Thus, from the perspective of a phenotype approach, the use of CSA reference values, as established in our second study, appears to be a suitable biomarker but these should be optimized in order to be relevant in COPD patients.Finally, besides the benefits of using an antioxidant supplementation during pulmonary rehabilitation program, our results contribute to improve our knowledge about the role of oxidative stress in the pathophysiology of peripheral muscle impairment in COPD patients. Furthermore, a better understanding and characterization of heterogeneity of both oxidative stress and peripheral muscle impairment opens up promising research prospects with a view of adjusting the management of COPD patients.