Faktore wat die prestasie en gesondheid van vroue-atlete kan beinvloed

Strauss, Johannes Albertus de Wet (2003-12)

Dissertation (PhD)--University of Stellenbosch, 2003.

Thesis

ENGLISH ABSTRACT: Although it is common knowledge that regular exercise has many beneficial effects on the human body, it is also true that many highly competitive athletes neglect their health for the sake of performance. With this as a general objective for the study, women athletes of the Matie Athletics Club were recruited as subjects and were monitored and tested for several health-related parameters. Current results indicate that, although the average total cholesterol (TC) concentrations of the group were within normal ranges, quite a number of the sprint and field athletes had TC values regarded as a cardiovascular risk (> 5.2 mmol.l"). Serum testosterone levels of the sprint and field athletes were also higher than those of the distance athletes, but a correlation between TC and testosterone was not established. In general, cholesterol intake of women athletes was within the recommended daily allowance (RDA) prescriptions. The high-density lipoprotein fraction was also within the norm, but a better chemical pathological range had been expected. All haematological parameters were within the normal ranges of distribution, but the red blood cell count, haemoglobin concentration and hematocrit were on average lower than the standard average for females. Athletes, quite often, have higher plasma volumes than average and this can disguise normal haematological values and is described as sport anaemia. The current study has also indicated an iron deficiency (83% RDA) in the diet of female athletes in general. Thus the relatively low observed red blood cell count could not necessarily be attributed to sport anaemia. The energy intake was also poor and did not comply with the energy needs of the athletes. Bone mineral density (BMD) and plasma electrolytes were normal. Distance athletes had a higher BMD of the hip compared to the lumbar spine area. This is probably related to the stress to the hip associated with running. A correlation was observed between TC and BMD of the hip of eumenorrheal and amenorrheal athletes, which had not been observed before. The influence of the phase of the menstrual cycle on the immune system is controversial, and the results of the thesis confirm those of other studies that indicated no influence. In addition, it has been shown that the exogenous ingestion of glutamine, before the onset of exercise, can increase the plasma concentration thereof, and that the formerly observed decline (also seen in the current study) after intense exercise can be totally neutralized. This had not been reported before. The physiological significance of this has not been established, but the assumption is that a continuous adequate supply of glutamine will benefit the immune cells with regard to its reaction to pathogens. As reported by others, it has been shown that the ingestion of 5% glucose during long duration exercise eases the stress on the immune system, as both leucocytes and cortisol levels were attenuated compared to intake of a placebo. A new discovery, however, was that the ad libitum ingestion of glucose was not enough to produce desired significant results. The importance of this finding may have practical implications with regard to desirable amounts of glucose supplementation during races. In conclusion: Female athletes of club performance level are on general in a healthy condition, but are not excluded from the risk with regard to cholesterol. The screening of TC alone is insufficient with regard to competitive athletes, unless the sub-fractions are screened as well during routine medical examinations. Adjustments with regard to the energy and iron content of the diet are suggested. Supplementation of glutamine and glucose before and during exercise could be beneficial to the immune system. More studies with regard to the association of cholesterol with BMD are recommended.

AFRIKAANSE OPSOMMING: Alhoewel dit algemeen bekend is dat oefening groot voordele vir die gesondheid van die liggaam inhou, is dit ook so dat atlete wat hoogs kompeterend is hul gesondheid kan verwaarloos ten koste van prestasie. Dit was die oorkoepelende doel van hierdie studie om vroue-atlete van die Maties Atletiekklub as proefpersone te toets en te monitor vir verskeie gesondheidsverwante parameters. Huidige resultate dui daarop dat alhoewel die gemiddelde totale cholesterol (TC) van die groep binne die normale grense was, 'n hele aantal van die naelloop- en veldatlete het TC gehad wat oor die grens was wat as 'n risiko (> 5.2 mmol.l") vir kardiovaskulêre verwante siektes beskou kan word. Serumtestosteroon-konsentrasie van die naelloop- en veldatlete was ook hoër as dié van die langafstandatlete, maar dit het nie gekorrileer met TC nie. In die algemeen was die cholesterolinname van vroue-atlete binne die aanbevole dieettoelaag (ADT) voorskrifte. Die hoë-digtheid-lipoproteïenfraksie was ook binne die normale, maar nie volgens verwagting in 'n meer gunstige chemies-patalogies gebied van verspreiding nie. Alle hematologiese parameters was binne die normale grense, maar die gemiddelde rooibloedseltelling en hemoglobienkonsentrasie, asook die hematokrit was deurgaans laer as die standaard gemiddeld vir dames. Atlete het heel dikwels hoër plasmavolumes as normaal en dit kan normale hematologiese tellings verbloem en word beskryf as sportanemie. Die huidige studie het egter ook getoon dat 'n ystertekort (83% ADT) in die dieet algemeen in vroue-atlete kan voorkom en daarom kan die relatief lae rooiseltellings nie noodwendig aan sport anemie toegeskryf word nie. Die energie-inname was ook laag en het nie aan die energiebehoeftes voorsien nie. Beenmineraaldigtheid (BMD) en plasma-elektroliete was normaal. Langafstandatlete het 'n hoër BMD van die heupbeen teenoor die werwelkolom getoon wat waarskynlik verband hou met die stres wat deur hardloop op die heupbeen geplaas word. 'n Verband is ook gevind tussen die BMD van die heup en TC van eumenorreale en amenorreale atlete wat nie vantevore waargeneem is nie. Die invloed van die fase van die menstruale siklus op die immuunstelsel is kontroversieel en die bevindinge in die tesis dra by tot die stawing van studies wat geen invloed bevind het nie. Voorts is getoon dat die eksogene inname van glutamien voor die aanvang van oefening, plasmaglutamien kan verhoog en dat die verlaging daarvan, wat voorheen (asook in die huidige studie) na intense oefening waargeneem word, geheel en al teengewerk kan word. Dit is nog nie vantevore waargeneem nie, en mag 'n fisiologiese voordeel inhou vir die immuunselle ten opsigte van hul reaksie op patogene. Dit is huidig, ook soos voorheen, aangetoon dat die inname van 5% glukose tydens langdurige oefening die stres wat op die immuunsisteem geplaas word, verminder word. Dit, omrede beide die leukosiete en kortisolkonsentrasies laer was in vergelyking met 'n plaseboproefneming. 'n Nuwe bevinding is egter dat die onvoorgeskrewe inname van glukose nie genoegsaam is om dieselfde insiggewende resulaat te toon nie. Die belang van hierdie bevinding mag praktiese gevolge hê vir die gewenste voorskrifte van glukose-inname tydens wedlope. In opsomming: Vroue-atlete van klubprestasiegehalte is oor die algemeen gesond, maar is nie vrygespreek van risiko in terme van cholesterol nie. Die monitering van TC alleenlik is onvoldoende in kompeterende atlete en die subfraksies moet derhalwe deel wees van roetine ondersoeke. Dieetaanpassings ten opsigte van die energie- en ysterinhoud kan aanbeveel word. Supplementasie van glutamien en glukose voor en tydens oefening respektiewelik, kan voordelig wees vir die immuunsisteem. Verdere studies word aanbeveel in terme van die verbande tussen cholesterol en BMD.

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