This study examined differences and relationships between high intensity, intermittent work and menstrual phase. Six performed (10) 6-second sprints on a cycle ergometer in the luteal (LP) and follicular phase (FP) of the menstrual cycle. The average 6-second work was greater in the LP (39.3 (3.4)Jkg) than during the FP (38.3 (3.1)Jkg). There was no difference in peak 6-second power (6.8(0.6)W/kg in FP, 6.9(0.6)W/kg in LP) and the drop-off in work (1.2(3.5)J/kg in FP and 1.0(2.7)J/kg in LP) between menstrual phases. There was no significant difference in sprint V02 or recovery V02 between FP (2.3 (O.S)rnL/kg/min and 24.1 (2.5)mL/kg/min) and LP (2 1.8(1.6)mL/kg/rnin and 23.7(2.8)mL/kg/min). In sprints 2 to 10, recovery V02 was greater in LP (26.3(2.4)mL/kg/min) than FP (25.0(2.6)rnL/kg/min). Recovery V02 and average 6- second work positively correlated (0.78 in FP, 0.77 in LP). In summary, oxygen consumption between sprints 2-10 and average work was greater in LP than FP.

Specific dietary intakes were compared by menstrual status among endurance-trained athletes categorized as either eumenorrheic (EU) (N = 11), oligomenorrheic (OL) (N = 4) or amenorrheic (AM) (N = 5). It was hypothesized that nutrient intakes among endurance-trained women would be significantly different based on menstrual status. No significant differences in nutrient intakes were found among groups. The OL and the AM groups were significantly (p ≤ .05) younger than the EU group and the AM group had a significantly higher percent body fat when estimated by hydrostatic weighing (PFHW) than the EU group. Further comparisons of nutrient intakes were made between EU (N = 10) and AM (N = 4) runners. Zinc intake was significantly lower in the AM runners as compared to the EU runners. The AM runners were also significantly younger and had significantly higher PFHW than the EU runners. In conclusion, energy nutrient intakes appeared to not be significant factors in menstrual status. However, zinc intake was significantly lower (p ≤ .05) in AM runners as compared to EU runners.

Graduation date: 1994

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.

The purpose of this study was to examine power output and fatigue from power-time curves of cycle ergometer and isokinetic dynamometer tests. Fifteen physically active female university athletes performed a 45 s cycle ergometer test at resistances of 0.075, 0.085, and 0.095 kp/kg bw, as well as a 45 s and a 3 repetition isokinetic flexion and extension test at velocities of 60, 180, and 300$ sp circ$/s. Results revealed that peak power, mean power (W and W/kg), and fatigue (W/kg) were highest at the 0.095 kp/kg bw resistance and lowest at the 0.075 kp/kg bw resistance. Significant differences among the three cycle ergometer conditions existed for peak power, mean power, and fatigue. Peak power and mean power (W and W/kg) were highest at 300$ sp circ$/s and lowest at 60$ sp circ$/s. Results revealed significant differences among the isokinetic dynamometer conditions for peak and mean power. Mean power output (W) was significantly correlated (range of r = 0.56 to r = 0.74) for the cycle ergometer and the isokinetic dynamometer test conditions.

The purpose of this study was to examine the vertical component of the American College of Sports Medicine (A.C.S.M.) Guidelines equation to predict the oxygen cost of grade running. The A.C.S.M. Guidelines equation is: VO$ sb2$(ml/kg.min) = 3.5 + 0.2 speed(m/min) + 0.9 (speed(m/min) * grade(frac)). Twenty-three female runners (20 to 33 years) participated in (1) a VO$ sb2$max test, (2) five 6 min running economy (RE) tests at 133 m/min, (3) five 6 min RE tests at 160 m/min, and (4) three 6 min RE tests at 186 m/min. The RE tests at 133 and 160 m/min were performed at the following grades: 0, 2.5, 5.0, 7.5, and 10.0%. The RE tests at 186 m/min were performed at 0, 2.5, and 5.0% grade. The RE tests were administered in random order. There was a linear relationship between VO$ sb2$ and horizontal running velocity with a slope of 0.20 ml/kg.m (r = 0.996; p $<$.01). There was a linear relationship between VO$ sb2$ and percent grade when running on a treadmill. The correlations for the regression equations at speeds of 133, 160, and 186 m/min were 0.90 (p $<$.01), 0.86 (p $<$.01), and 0.73 (p $<$.01), respectively. Inclusion of a grade component in the regression analysis equation increased the accuracy for predicting the VO$ sb2$ of grade running. VO$ sb2$ consumption for grade running can be predicted using the following equation: VO$ sb2$ (ml/kg.min) = 3.5 + 0.198(speed in m/min + 0.932 grade(%)) + 0.006(speed(m/min) * grade(%)). The new equation explained 99.5% of the variance (R$ sp2$) compared to the 78.0% of the variance (R$ sp2$) that was explained by the A.C.S.M. Guidelines equation.

No description available.

No description available.

This study investigated whether or not a relationship exists between ventilation and oxygen uptake at 40% and 85% of V02 peak intensity in 30 upper body fit and 30 unfit 18- 35-year-old women. The correlations between ventilation and oxygen uptake at 40% of peak intensity for the fit group (r = -.51) and the unfit group (r = -.48) were modestly negative. At 85% intensity the relationship between ventilation and oxygen uptake in the two groups was -.44 and -.66, respectively. The lower correlations between ventilation and oxygen uptake observed at the 85% level of peak intensity among the unfit group could be due to a lower ventilatory threshold (66% = fit; 49% = unfit), lesser local muscle changes, along with reduced lactate and C02 management; all of which would be improved with training.

This thesis examined the impact of oxygen (O2) availability on prefrontal cortex and muscle tissue oxygenation during repeated-sprint exercise (RSE) in men and women. Men and women matched for initial-sprint mechanical work performed during ten, 10-s sprints (30s of rest) in normoxia (21% FIO2) and acute hypoxia (13% FIO2). Mechanical work and arterial O2-saturation (SPO2) were obtained for every sprint. Oxy- and deoxygenated haemoglobin concentrations (O2Hb, HHb) were obtained via near-infrared spectroscopy. Hypoxia elicited lower SPO2 and work (14.8% & 7.4%, P < 0.05), larger (45.1%, P < 0.05) and earlier reductions in cortical oxygenation, and no differences between sexes. Cortical de-oxygenation and work decrement were strongly correlated (R2=0.85, P < 0.05). Muscle de-oxygenation was greater in men than women (67.3%, P < 0.05). These results show that O2 availability influences cortical oxygenation and performance equally in men and women, and suggest a more efficient muscle O2 uptake in women. / ix, 108 leaves : ill. ; 29 cm