Rozprawy doktorskie na temat „Endurance sports”

Background: Chronic diseases of lifestyle (CDL) are associated with high rates of morbidity and mortality in South Africa. Although prevalence of CDL has been established in the general population, there is limited research regarding the prevalence and risk factors for CDL in individuals taking part in regular physical activity. Endurance running is a popular sport, with growing levels of participation. Anecdotally, many individuals who participate in endurance running do not undergo formal pre-participation cardiovascular screening. It is also unclear if endurance runners are meeting the World Health Organisation’s recommended weekly moderate to vigorous intensity physical activity hours, or if they have other risk factors for CDL. It is therefore important to establish the prevalence and risk factors of CDL in this active population. Aim and Objectives: The aim of this study was to determine the prevalence of CDL and the associated risk factors in endurance runners in South Africa. The specific objectives of the study were: (a) to determine the presence of risk factors for the development of chronic diseases of lifestyle, including body mass index (BMI), waist circumference, body fat percentage, blood pressure, blood glucose, blood cholesterol, smoking history, dietary intake and weekly physical activity time in South African endurance runners; (b) to determine the presence of non-modifiable risk factors to the development of CDL, namely age and income, in South African endurance runners; (c) to determine whether South African endurance runners are fulfilling the World Health Organization’s recommended weekly moderate to vigorous intensity physical activity hours; and (d) to assess whether there are any relationships between the running characteristics, namely weekly training hours, running speed and level of competition; and the risk factors for chronic diseases of lifestyle. Methods: This study had an analytical, cross-sectional design. Two hundred participants between the ages of 18 to 69 years old, who reported endurance running as their main sport, and ran at least three kilometres twice a week for the past year were included in the study. Participants were excluded if they were pregnant or within six months post-partum, had an injury that required a minimum of two weeks rest or did not complete the questionnaire or physical testing component of the testing process. Participants were recruited through local running clubs and running races in the areas of Nelspruit, Mpumalanga and Cape Town, Western Cape. All participants gave written informed consent, and completed a questionnaire including socio-demographic characteristics, running training characteristics, the International Physical Activity Questionnaire short questionnaire, the modified Borg scale of perceived exertion, and the five-a-day community evaluation tool. Body mass, stature, skin folds and waist circumference were assessed. Blood pressure was measured using an automatic blood pressure monitor. A finger prick test was used to determine random blood glucose and cholesterol concentrations. Participants were requested to fast for three hours prior to testing to standardise the test in a non-fasted state (20). Results: One hundred and twenty four (62%) participants were found to have at least one risk factor for CDL. A high BMI was the most common risk factor for CDL (n=90; 45%). Nineteen participants (9.5%) did not meet the recommended duration of 150 minutes of physical activity per week. Seven percent of female participants (n=7) smoked, which is equivalent to the female population average of South Africa. Multiple risk factors were identified in fifty seven (28.5%) participants, ranging from two risk factors (n=37; 18.5%) to six risk factors (n=1; 0.5%). The majority of participants had no prior medical diagnosis of CDL or risk factors for CDL. The overall self-reported prevalence of a medically diagnosed CDL was 5.5% (n=11). Type 2 diabetes was the most commonly diagnosed CDL (n=6; 3%). Waist circumference, systolic blood pressure and cholesterol were significantly elevated in the older age group. There were no significant differences in risk factors for CDL according to income status. Female runners had significantly higher average sitting times compared to male runners. In addition, participants with a BMI ≥ 25 kg.m-2 had significantly slower 10 km running speeds and lower average weekly training distance, compared to participants with BMI within normal ranges. Conclusion: A high prevalence of risk factors for CDL was identified in South African endurance runners. The majority of endurance runners included in this sample are fulfilling the World Health Organisation’s recommended weekly moderate to vigorous intensity hours. However, the endurance runners in this study remain at risk for developing a CDL due to the presence of other risk factors for CDL. The knowledge and awareness of risk factors for CDL among South African endurance runners needs to be further investigated. Health care professionals are required to improve the prevention and management of risk factors of CDL through education and promotion of healthy lifestyles. A stronger emphasis on the prevention of risk factors for CDL in South African endurance runners is needed.

Combining strength and endurance training within the same regimen is aptly referred to as “concurrent training”. Research conducted over the previous 3 decades has indicated concurrent training can result in attenuated development of strength, power and hypertrophy when compared to strength training in isolation. Despite extensive research the mechanisms contributing to this so called “interference effect” are yet to be fully elucidated, as is the influence of manipulating acute training programme variables within a concurrent regimen. As such, the purposes of this thesis were to investigate and draw conclusions regarding underlying physiological mechanisms relating to the interference effect. Additionally, this thesis sought to examine the effects of manipulating programme variables, including frequency and sequencing of exercise within concurrent training regimens on strength related adaptation. The findings of this thesis indicate overall training volume and frequency of endurance training within a concurrent intervention influences the presence and magnitude of the inhibition of strength development. Concurrent training volumes of 3 d·wk-1 elicited muted strength development, whereas lower frequencies did not. Whilst interference was not attributable to neuromuscular factors, it was reported that cortisol was only elevated following higher training frequencies, indicating training stress and catabolism may contribute to interference. Additionally, the sequencing of strength and endurance training can influence endocrine and signalling responses associated with strength adaptation, and it appears strength prior to endurance elicits greater increases in growth associated signalling. The findings of this thesis indicate that overall training stress influences the presence and magnitude of interference experienced, and is reflected in catabolic endocrine responses. Additionally, strength prior to endurance training promotes more favourable anabolic signalling than vice versa, which over time may contribute to greater strength type adaptations.

This study aimed to distinguish the coping efforts of athletes who endured shorter, and longer, durations of competitive suffering. Eleven male and 15 female endurance athletes (Mage= 35.8, sd= 12.1) completed a 5km competitive suffering running time-trial task. Following the task, threat perceptions and coping function use (problem focused, PFC; emotion focused, EFC; and avoidance, AvC) were measured in 200 meter intervals using video mediated recall. Control beliefs were also assessed. Those who suffered for shorter durations used more EFC during initiation and at the peak of competitive suffering, as well as less AvC during initiation, in comparison to longer duration sufferers. PFC use did not distinguish competitive suffering duration. Non-significant correlations were revealed between control beliefs and both suffering duration and coping function use. Overall, the results imply that emotion-focused coping is the most appropriate coping function to decrease competitive suffering duration, regardless of control beliefs.
xi, 106 leaves : ill. ; 29 cm

Thesis (M.S. in human nutrition)--Washington State University, August 2009.
Title from PDF title page (viewed on Aug. 12, 2009). "School of Food Science." Includes bibliographical references (p. 73-93).

Thesis (M Sport Sc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Compression socks (CS) are used as an ergogenic aid during and after exercise by many athletes of elite and recreational status. The exact mechanism whereby CS affect performance and postexercise recovery is not yet elucidated. Some research ascribes the beneficial effects to improved lactate removal rates with CS. One hypothesis is that CS improve venous return and thereby remove the lactate from the tissue to other tissues such as the liver, and the second hypothesis is that the CS cause retention of the lactate within the muscle and therefore improve the oxidation of the lactate within the muscle (Berry & McMurray, 1987). The current study endeavoured to test the hypothesis set by Berry and McMurray (1987) by measuring the effect of CS as well as flight socks (FS) on muscle oxygenation during exercise and recovery in endurance trained runners and triathletes. Eleven male endurance trained runners and triathletes (age = 34.8 ± 3.8 years, VO2max = 52.4 ± 7.1 mL.kg-1.min-1) participated in the study. They completed an incremental exercise test to exhaustion to determine their maximal aerobic capacity (VO2max) and peak treadmill velocity (PTV). Then they completed two 10 km treadmill running tests at 80 % of their PTV. During these two trials participants wore either CS or FS; the order of treatment was randomly selected. A subset of the study sample (n = 5) also completed a control test wearing only their ankle length sport socks (NS). After these trials, participants completed a 60 minute passive recovery period in the seated position while muscle oxygenation was measured. Compression under the socks was measured at several anatomically determined measurement points prior to the commencement of the exercise test, along with the determination of blood haemoglobin concentration ([Hb]). During the exercise trials, blood lactate concentration ([BLa]), skin temperature (ST),oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate (HR), and muscle oxygenation variables (oxy-haemoglobin (O2Hb), deoxy-haemoglobin (HHb), tissue oxygenation index (TOI) and total haemoglobin index (nTHI)) was measured . During the 60minute passive recovery period, [BLa], ST, O2Hb, HHb, TOI, and nTHI measurements were continued. The results showed that there were differences in the pressure exerted between the two pressure condition (CS and FS) at the posterior ankle, and under the elastic of the sock as well as on the anterior calf at the level of greatest calf circumference. Differences in ST between the CS and NS and the FS and NS conditions were found between the first four 2 km intervals of the exercise protocol, but not during recovery. No differences were found in [BLa] between the three different compression conditions during either the exercise (p = 0.19) or recovery period (p = 0.63), as well as no differences in the cardiorespiratory variables during exercise between the three different compression conditions (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36). With regard to the muscle oxygenation variables, no differences were found between the three compression conditions during exercise, however there was a trend for lower oxygen utilization (HHb) during exercise in the NS condition (p = 0.57, medium to large practical significance). There were also no differences in these variables (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) during recovery, although oxygen utilization (HHb) showed a faster recovery rate with increasing external pressure. From the results obtained, it seems that external compression caused a decrease in the blood flow velocity within the muscle, thereby increasing oxygen diffusion rate. During exercise this did not facilitate differences in [BLa], however, after the first 10 minutes of the recovery period, large practical differences were found between the NS and both sock conditions, suggesting that the increase in oxygen diffusion improved lactate clearance. This could support the hypothesis set by Berry and McMurray (1987).
AFRIKAANSE OPSOMMING: Kompressie sokkies (CS) word gereeld deur beide rekreasie- en elite atlete gebruik as ‘n ergogeniese hulpmiddlel tydens oefening en herstel. Die presiese meganisme waardeur CS prestasie en post-oefening herstel beïnvloed is nog nie volledig verklaar nie. Sommige navorsing skryf die voordelige effekte toe aan die vinniger herstel van laktaat in die sirkulasie. Daar is tans twee hipoteses vir die meganisme waardeur CS laktaat verwydering verbeter. Die eerste hipotese is dat CS die veneuse terugvoer verbeter en daardeur die laktaat van die weefsel verwyder en na ander weefsels soos die lewer vervoer vir verwydering. Die tweede hipotese is dat CS veroorsaak dat die laktaat in die spierweefsel teruggehou word wat dan tot gevolg het dat die laktaat in die spier self deur middel van oksidasie verwyder word (Berry & McMurray, 1987). Hierdie studie poog om Berry en McMurray (1987) se hipotese te toets deur die effek wat CS sowel as vlugsokkies (FS) op spieroksigenasie het gedurende oefening en herstel in geoefende uithouvermoë hardlopers en driekamp atlete vas te stel. Elf ingeoefende langafstand hardlopers en driekampatlete (mans) (ouderdom = 34.8 ± 3.8 jaar; VO2maks = 52.4 ± 7.1 mL.kg-1.min-1) het aan hierdie studie deel geneem. Die deelnemers het ‘n inkrementele toets tot die punt van uitputting voltooi om hul maksimale aërobiese kapasiteit (VO2maks) en piek trapmeul snelheid (PTV) vas te stel. Die elf deelnemers het ook twee 10 km hardlooptoetse teen 80 % van hul PTV voltooi. Gedurende hierdie twee toetse het die deelnemers óf CS óf FS gedra; die volgorde van die intervensie was lukraak aan hulle toegeken. ‘n Subgroep van die steekproef (n = 5) het ook ‘n kontrole toets voltooi waartydens hulle hul eie enkelhoogte sport sokkies (NS) gedra het. Aan die einde van die hardloop protokol het die deelnemers ‘n 60 minuut passiewe herstel periode in die sittende posisie voltooi terwyl spieroksigenasie gemeet is. Kompressie onder die sokkies is voor die aanvang van die hardloop protokol by verskeie anatomies gedefinieerde punte gemeet. Verder was die bloed hemoglobien konsentrasie ([Hb]) ook gemeet voor die hardloop protokol. Tydens die oefeningtoets is bloedlaktaat konsentrasie ([Hb]), veltemperatuur (ST), suurstof verbruik (VO2), koolstofdioksied produksie (VCO2), harttempo (HR), sowel as spieroksigenasie veranderlikes (oksi-hemoglobien (O2Hb), deoksi-hemoglobien (HHb), weefsel oksigenasie indeks (TOI), en totale hemoglobien indeks (nTHI)) gemeet. Gedurende die 60 minuut passiewe hersteltydperk is [BLa], ST, O2Hb, HHb, TOI en nTHI metings geneem. Die resultate toon dat daar ‘n verskil is in die druk wat uitgeoefen word in die onderskeie druktoestande (CS en FS) op die been by die posterior enkel en onder die rek van die sokkie, sowel as op die anterior kuit waar die kuit die grootste omtrek het. Verdere verskille tussen die CS en NS en die FS en NS toestande is in ST gevind in the eerste vier 2 km intervalle van die oefeningtoets, alhoewel geen verskille tydens die herstelperiode gevind is nie. Tydens beide die oefening (p = 0.19) en herstel (p = 0.63) protokol is geen verskille tussen die drie kompressie toestande met betrekking tot [BLa] gevind nie. En so ook is daar geen verskille tussen die onderskeie kompressie toestande in kardiorespiratoriese veranderlikes (VO2, p = 0.06; VCO2, p = 0.12; HR, p = 0.36) tydens oefening gevind nie. Met betrekking tot spieroksigenasie veranderlikes was daar geen verskil gevind tussen die drie kompressietoestande gedurende oefening nie, alhoewel daar ‘n tendens was vir die NS toestand om tydens oefening minder suurstofverbruik (HHb) (p = 0.57, medium tot groot praktiese effek) te lewer. So ook gedurende herstel is daar geen verskil in hierdie veranderlikes (O2Hb, p = 0.65; HHb, p = 0.57; TOI, p = 0.39; nTHI, p = 0.22) gevind nie, alhoewel die suurstofverbruik (HHb) vinniger na die basislyn herstel het met ‘n toename in druk. Die resultate toon dat eksterne kompressie ‘n afname in die bloedvloei tempo in die spier veroorsaak wat dan ‘n verlengde suurstof diffusie tyd veroorsaak. Hierdie verlengde suurstof diffusie tyd het geen effek op [BLa] tydens oefening gehad nie, alhoewel daar na die eerste 10 minute van die herstelperiode ‘n groot praktiese verskil tussen die NS en sokkie toestande gevind was in [BLa]. Hierdie verskil kan daarop dui dat die toename in suurstof diffusie verbeterde laktaat verwydering tot gevolg het, wat dan die hipotese van Berry en McMurray (1987) ondersteun.

This study examined the effects of two distinct phases of endurance training (summer and in-season training) in previously well-trained male and female high school cross-country runners. Eleven males and 11 females from the same high school training program were recruited for the three testing sessions: post-track season (June), postsummer training (mid-August), and post-cross-country season (early-November). However, due to injury and other circumstances, only 10 males and 4 females completed all testing sessions. Thus, baseline characteristics were analyzed for both genders; however, longitudinal analysis was only conducted using the males. Submaximal measurements included running economy (RE), blood lactate concentration ([BLa]), and heart rate (HR) at three running speeds in females (6, 7, and 8 mph), and males (7, 8, and 9 mph). Maximal measurements of oxygen uptake (VO2max) and HR, neuromuscular characteristics of isokinetic knee extension strength and vertical jump height, and body composition were also measured. Baseline results showed that the males possessed a higher VO2max, greater neuromuscular characteristics, and lower submaximal [BLa] and HR values than the females. Longitudinal analysis of the males showed that there was an increased VO2max, decreased maximal HR, and decreased neuromuscular strength following summer training. In-season training precipitated further increases in VO2max, an increase in maximal and submaximal HR, and increased neuromuscular characteristics. RE and [BLa] did not significantly change (p<_ 0.05) throughout the course of the study. Likely, it is the subtle changes in these variables in previously welltrained runners which account for the slower performance times at the beginning of the cross-country season and the improvements thereafter.
School of Physical Education

Includes abstract.
Includes bibliographical references.
Distance running has become increasingly popular in recreational runners. The gastrocnemius is the main muscle used for propulsion in running, and may be at risk for injury due to its morphology. In previous studies, changes in the morphology and architecture of the gastrocnemius muscle have been evident following training, but it is unclear whether these changes are related to training or youth. Previous studies of runners have shown a decrease in gastrocnemius and soleus flexibility, as well as changes in the fascicle length and pennation angle. Gastrocnemius volume has not been compared in low physical activity and active participants. Physiological cross sectional area, based on volume and fascicle length measurements may also provide valuable information about the muscle’s ability to produce force. Ultrasound may be a useful tool in assessing potential training adaptations in the morphology and architecture of the gastrocnemius muscle. The aim of this cross-sectional descriptive study was to assess the differences in architecture and function of the gastrocnemius in endurance runners compared to low physical activity participants. (a) To assess differences in calf function and flexibility between endurance runners and low physical activity individuals, and between male and female participants; (b) To determine differences in gastrocnemius muscle architecture and composition between endurance runners versus low physical activity individuals, and between males and females; and (c) To determine whether there are any relationships between training factors and the structure and function of the gastrocnemius muscle. Thirty participants between 20 and 45 years old were recruited for this study and allocated to groups based on their level of physical activity. The low physical activity group (n = 14) were not participating in any regular physical activity, while the endurance running group (n = 16) were running a minimum of 40 km.wk-1, and had participated in at least one full marathon (42.2 km) in the previous six months. All participants completed informed consent, a physical activity and training questionnaire, and a Physical Activity Readiness Questionnaire (PAR-Q) at the first session. The first session also included body composition measurements; ultrasound imaging to measure gastrocnemius length, thickness, fascicle length, pennation angle and volume; and familiarisation with all physical tests. Physical tests were conducted in the second session, including gastrocnemius and soleus flexibility, calf raise endurance and vertical jump height to assess the function of the components of the triceps surae. There were no significant differences between low physical activity and running groups for gastrocnemius thickness, fascicle length, pennation angle and gastrocnemius length. Gastrocnemius volume (p = 0.02) and physiological cross sectional area (p = 0.01) were significantly greater in the running group compared to the low physical activity group. There were no significant differences between low physical activity and running groups in flexibility or vertical jump height, although male participants had significantly decreased gastrocnemius muscle flexibility (p = 0.046) and significantly greater vertical jump heights (p = 0.01) than females. Calf raise endurance was significantly greater in the running group than in the low physical activity group (p = 0.03). Endurance running leads to specific adaptations in participants in both structure and function. While ultrasound appears to be a reliable measure for assessing architectural components of the gastrocnemius muscle in both active and inactive populations, further cadaver studies may provide valuable information on muscle architecture.

Thesis (MHSc--Health Science) -- AUT University, 2007.
Includes bibliographical references. Also held in print (x, 133 leaves : ill. ; 30 cm.) in North Shore Campus Theses Collection (T 612.22 VIC)

Due to the broad spectrum of physical characteristics necessary for success in field sports, numerous training modalities have been used develop physical preparedness. Sports like rugby, basketball, lacrosse, and others require athletes to be not only strong and powerful but also aerobically fit and able to recover from high-intensity intermittent exercise. This provides coaches and sport scientists with a complex range of variables to consider when developing training programs. This can often lead to confusion and the misuse of training modalities, particularly in the development of aerobic and anaerobic conditioning. This review outlines the benefits and general adaptations to 3 commonly used and effective conditioning methods: high-intensity interval training, repeated-sprint training, and small-sided games. The goals and outcomes of these training methods are discussed, and practical implementations strategies for coaches and sport scientists are provided.

Endurance exercise improves health partly though improvements in skeletal muscle function. Mitochondrial biogenesis is one of the mechanisms that underpin the positive health benefits of endurance exercise. Endurance-exercise and energy sensitive pathways signal to promote transcriptional processes that initiate the adaptive response. Thus the aim of this thesis was to further understand the regulation of post-exercise signalling within skeletal muscle, with specific focus on the activation of energy-sensitive mitochondrial biogenic signalling pathways. It was demonstrated that muscle-specific knockout of p53 does not impair mitochondrial protein content or enzyme activity within mouse skeletal muscle. In human skeletal muscle, fasting and fasted-exercise augment CREB\(^S\)\(^e\)\(^r\)\(^1\)\(^3\)\(^3\) and AMPK\(^T\)\(^h\)\(^r\)\(^1\)\(^7\)\(^2\) phosphorylation, while the mRNA expression of \(PDK4\) but not \(PPARGC1A\) is also increased in the fasted state. Finally, one week of nicotinamide riboside supplementation did not alter skeletal muscle mitochondrial respiration and whole-body substrate utilisation at rest or during endurance exercise, while SIRT1 and 3 activity and \(PPARGC1A\) mRNA expression at rest and following endurance-exercise are also unaffected by nicotinamide riboside supplementation. Overall, this thesis contributes novel data to the understanding of metabolism and skeletal muscle signalling following endurance exercise and how nutrition and endurance exercise could be integrated to optimise specific adaptations.

Doctor of Philosophy
Department of Human Nutrition
Mark D. Haub
Maximizing performance and results in competitive events is something that all athletes strive to achieve. Nutritional strategies have been developed to best optimize the likelihood of success in competitive events. While dietary protein was classically believed to be the key macronutrient in exercise performance, overwhelming evidence now supports the role of maximizing carbohydrate intake and availability in endurance performance. The role of carbohydrate intake prior to, during and after endurance exercise has been heavily studied and relevant literature will be discussed herein. This paper consists of three chapters and a summary related to carbohydrate intake and performance outcomes in endurance sports. While nutritional status surrounding the endurance events is discussed, this paper focuses on the ergogenic and metabolic effects of carbohydrates during the endurance bout. Chapter one serves as a literature review of carbohydrate administration during endurance exercise. Types of carbohydrates, their role as substrates in liver and skeletal muscle during exercise, and their effects on endurance performance are discussed. The role of carbohydrate on central factors of fatigue and motor output also are covered. Chapter two addresses the role of multiple carbohydrate supplements on cycling performance. The role of these supplements on blood glucose, insulin, lactate, and IGFBP-1 also are discussed. Chapter three addresses the effect of nutritional status prior to exercise on the ability of a carbohydrate mouth rinse to impart a performance enhancing effect. There were no treatment effects (p>0.05) of the type carbohydrate ingested, compared with placebo, on selected metabolic and performance outcomes. Likewise, there was no ergogenic effect of mouth rinsing, in the fasted or fed state, in moderately trained endurance cyclists.

The purpose of this study was to investigate whether a strength training program, as an additive to endurance training, would cause significant improvements in 3km run time in a group of recreational female endurance runners when compared to endurance training only. Subjects were 16 active women, randomly assigned to either a running only group (control group, n=9) or a combined strength and endurance training group (experimental group, n=7). The ten-week training program for both groups consisted of an endurance running program three times per week, which included steady-state endurance running, tempo runs and interval training. The experimental group however, participated in additional strength training with heavy loads (up to five repitition maximum). Subjects were tested pre• and post-training in a 3km time trial, VO2 peak, running economy, muscular strength (lRM), as well as body composition and girth. A one-way ANCOVA, with the pre-training values as the covariate, was used to analyse the data. Both training groups showed a non-significant improvement in 3km performance times after the respective training programs. However, it was found that the experimental group times were not significantly different (p>0.05) to the control group post training. There was a trend (p=0.08) evident in the experimental group's time which improved 106.7 ± 91.4 seconds, while the control group improved 77.3 ± 93.0 seconds. The combined strength and endurance training group showed a significant increase (p<0.05) in lower body strength for the parallel squat (6% increase) and hamstring curl (45.1% increase) and a strong trend (p=0.06) for an increase in upper body strength for the bench press (11.9% increase). No significant strength changes were found for the control group. There were no significant differences evident in either group for VO2 peak running economy, body composition or girth measurements. This study found a non-significant trend for improvement in 3 km times when low repetition strength training was added to a running program. The main reason for the trend in improvement in the experimental group seemed to be the increased lower limb strength levels, which may improve variables such as increased stride length. It is concluded that combined strength and endurance training may improve running performance and its inclusion is recommended in the training programs of recreational athletes.

Includes abstract.
Includes bibliographical references (leaves 55-79).
The effects of long-term participation in ultra-endurance exercise on the cardiovascular system have recently been the subject of much interest. It is well known that HRV, a marker of autonomic activity, is enhanced with long-term aerobic exercise training. However, after acute exercise, HRV is reduced, but recovers over time depending on the intensity of the prior bout of exercise. A limitation of previous research is that exercise bouts of only up to 120 minutes have been studied. A modified Stroop Task is a laboratory stressor to assess executive cognitive function by means of reaction time and accuracy. The resting HRV is directly related to these prefrontal neural functions, but the effect of an altered HRV on cognitive function has never been investigated. We determined the effects of an ultra duration (10 – 15 hours) exercise event on parameters of HRV and cognitive function during a Modified Stroop Task, 60 – 200 minutes after the 2007 South African Ironman Triathlon event (3,6km swim; 180 Km cycle; 42,2 Km run). 1 Female and 13 male competing triathletes (IRON; ages 33.7±7.9) and 7 control subjects (CON; 2 female and 5 males aged 42 ±4.5) completed a Modified Stroop Task before and after the event. The individual HRV parameters, heart rate (HR), respiratory frequency (RF), reaction time (RT) and % of mistakes made were recorded via the Biopac MP150WSW System (Goletta, California, USA). Data was transformed by auto regressive analyses (Biomedical signal analysis group, University of Kuopio, Finland) into LF (0.04 - 0.15 Hz) and HF (0.15 - 0.5 Hz) components. Additional calculations included %LF and %HF as well as the central or peak frequencies in both the LF and HF bands.

Elite athletes of today use specialized, scientific training methods and the increasing role of science in sports is undeniable. Scientific methods and equipment has even found its way into the practice of everyday exercisers, a testament to the impact of sport science. From the experiential, personal training regimes of the first half of the 20th century to the scientific training theories of the 1970s, the ideas about training and the athletic body shifted. The rationalization process started in endurance sports in the 1940s. It was part of a struggle between two models of training; natural training and rational training. Physiologists wanted to rid training of individual and local variations and create a universal model of rational, scientific training. The rationalization of training and training landscapes is here understood as an aspect of sportification, a theory commonly used to describe similar developments in sports where increasing regimentation, specialization and rationalization are among the main criteria. This dissertation adds the concept of technologies of sportification to explain the role that micro-technologies and practices (such as training logs, training camps and scientific tests) have in the scientization of training. This thesis thus sets out to analyze the role that science has played in training during the 20th century. It is a history about the rationalization of training, but also about larger issues regarding the role of personal, experiential knowledge and scientific knowledge. The main conclusions are that the process of scientization never managed to rid training of components from natural, experiential training, and that the effort by Swedish physiologists to introduce rational training was part of the larger rationalization movement at the time. In the end, training knowledge was a co-production between practitioners and theoreticians, skiers and scientists.

QC 20161114

Rationell träning: vetenskapliggörandet äv träning för längdskidåkning

Iron deficiency anaemia (IDA) negatively impacts oxygen transport and maximal aerobic capacity (VO2 max). Iron deficiency non-anaemia (IDNA) is often observed amongst endurance athletes, yet the influence of IDNA on iron metabolism and endurance performance is not clear. The aim of this thesis was to investigate physiological and haematological responses to changes in iron status in elite endurance athletes.