Dissertation (PhD)--University of Stellenbosch, 2003. / 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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53423 |
| Date | 12 1900 |
| Creators | Strauss, Johannes Albertus de Wet |
| Contributors | Myburgh, K. H., Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | af_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 224 p. : ill. |
| Rights | Stellenbosch University |
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