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Introduction. Exercise and head-out water immersion (HOI) have consistently reported an increase in central blood volume associated with the cephalad shift in blood volume. This causes an increase in left ventricular end diastolic volume and greater stroke volume during exercise compared to exercise in air at similar metabolic costs. In contrast, the metabolic response, specifically, blood lactate accumulation during exercise combined with HOI has yielded varying results depending on the mode of exercise. At present it appears that during exercise at similar metabolic costs, cycle ergometry exercise augments plasma lactate over treadmill running while HOI reduces the plasma lactate response to cycle ergometry exercise. The interaction between treadmill running and HOI appears less certain. Thus, we tested the hypothesis that running on a treadmill on land would result in a lesser accumulation of lactate than during HOI treadmill running. Methods. Eleven subjects' lactate thresholds were determined while running at a 0% grade at increasing speeds on a treadmill on land or during HOI on an underwater treadmill in a randomized cross-over design. Exercise tests were separated by a minimum of 3 days. Lactate concentrations were expressed in mM• kg-1 H2O after correcting for plasma solid concentration. During exercise changes in plasma volume were calculated from changes in hematocrit and hemoglobin. Lactate threshold was estimated from a log-log plot of lactate concentration (mM• kg-1 H2O) as a function of relative oxygen consumption (ml O2•min-1•kg-1 BW). Results. The energy cost and heart rate response to running at speeds between 5.5 and 7.5 mph was similar for land and HOI. During treadmill running on land, plasma volume decreased by 6.4 ± 4.0% at a speed of 7.5 mph. The decrease in plasma volume was significantly greater during HOI and averaged 18.7 ± 1.7% (p <0.05) at 7.5 mph. Plasma lactate was higher at any given treadmill speed ≥ 5.5 mph during HOI compared to land (p <0.05). Lactate threshold during HOI running (21.8 ± 1.6 mM• kg-1 H2O) was lower (p <0.05) than during running on the land treadmill (27.0 ± 1.6 mM• kg-1 H2O). Discussion. HOI running resulted in a consistent shift to the left (rise in plasma lactate occurred at a lower ) in the lactate threshold and elevated plasma lactate concentration at speeds between 5.5-7.5 mph despite similar metabolic and HR responses to the exercise.

Background: The need to find the underlying causes to handball injuries and to develop injury prevention programs is great. In other sports a relationship between maximal oxygen uptake (VO2 max) and injury have been seen. Purpose: To examine the relationship between VO2 max and/or lactate threshold and injuries in elite handball players. Methods: A prospective, non experimental correlational study was conducted. Thirty elite handball players and handball high school players were included. Injuries and test results for VO2-max, lactate threshold and potential confounders ( re-injury of the previous injury, re- injury of previous injury of the lower limb, age, BMI and legs and core strength for the high school players) were registered during the season 2014-2015. A bivariate analysis using Spearman's rank correlation calculation was conducted. Twenty-six respectively 11 of the players had data on VO2-max, respectively lactate threshold. Confounders that showed connection with injuries or injuries in the lower extremity were analyzed for the bivariate correlation with VO2-max and lactate threshold. Results: No significant correlation was found between VO2-max respectively lactate threshold and injury. Significant correlations were seen between previous injury respectively previous injury to the lower extremity and to get a re-injury. A significant correlation were seen between re-injury of a previous injury in the lower limb and VO2-max. Conclusions: Significant associations were seen between re- injury of earlier injury and between re-injury of the lower extremity and VO2-max and should therefore be considered in the clinical practice. Larger studies are needed to clarify the relationship between VO2-max and lactate threshold and injuries. / Bakgrund: Behovet att hitta bakomliggande orsaker till handbollsskador för att kunna utforma skadepreventiva åtgärder är stort. I andra idrotter har ett samband mellan maximal syreupptagningsförmåga (VO2-max) och skador kunnat ses. Syfte: Att undersöka samband mellan VO2-max och/eller laktattröskelvärde och skador hos elithandbollspelare. Metod: En prospektiv icke experimentell sambandsstudie utfördes. Trettio elithandbollsspelare och handbollsgymnasiespelare inkluderades. Skador och testresultat för VO2-max och laktattröskel samt tänkbara konfounders (återskada av tidigare generell skada, återskada av tidigare skada i nedre extremitet, ålder, BMI och ben och bålstyrka för gymnasiespelarna) registrerades under matchsäsongen 2014-2015. En bivariat analys med Spearmans rangkorrelationsberäkning utfördes. Tjugosex respektive 11 av spelarna hade data på VO2-max respektive laktattröskelvärde. Konfounders som visade samband med generella skador eller skador i nedre extremiteten analyserades bivariat för samband med VO2-max och laktattröskelvärde. Resultat: Inga signifikanta samband fanns mellan VO2-max respektive laktattröskelvärde och skador. Signifikanta samband fanns för tidigare generella skador respektive tidigare skada i nedre extremiteten och att återfå densamma samt mellan återskada av tidigare skada i nedre extremiteten och VO2-max. Konklusion: Signifikanta samband fanns för återskada av tidigare skada samt mellan återskada i nedre extremiteten och VO2-max vilket bör beaktas i den kliniska vardagen. Större studier behövs för att klargöra det sambandet mellan VO2-max respektive laktattröskel och skador.

xvii, 245 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / There has been a lot of research investigating the effects of heat stress and exercise on the physiological adaptations to heat acclimation. It is well documented that heat acclimation improves heat tolerance and performance in a hot environment; however, some of the mechanisms of adaptation are not clear. Furthermore, the role of heat acclimation on exercise performance in cool environments is currently unknown. Therefore, in Chapter IV we aimed to determine the effects of heat acclimation on lactate threshold and maximal oxygen uptake (VO 2max ) in cool and hot conditions. We also sought to investigate the effects of heat acclimation on leg blood flow and oxygen delivery during a single-leg knee extensor exercise. We found that heat acclimation improved lactate threshold and VO 2max in cool and hot environments but did not alter the leg blood flow and oxygen delivery during the leg kicking exercise. In Chapter V we investigated the heat acclimation effects on performance during a 1-hour time trial in hot and cool environmental conditions and the potential mechanisms by which this occurs. A secondary objective was to study whether the pacing strategy was modified during the time trial post-heat acclimation. The results demonstrated that heat acclimation improved time trial performance in both thermal environments by approximately 7% but pacing strategy was not altered. The purpose of the studies in Chapter VI were twofold. First, we sought to investigate how heat acclimation affects the skin blood flow and sweating responses to pharmacological treatment with specific dosages of the muscarinic receptor agonist acetylcholine. Second, we examined the maximal skin blood flow responses to a period of heat acclimation by locally heating the forearm with a water spray device for 45 minutes and measured brachial artery blood flow via ultrasound. We found that heat acclimation increased sweat rate and skin blood flow responses to given concentrations of acetylcholine, suggesting a role for peripheral mechanisms. On the other hand, maximal skin blood flow remained unchanged after heat acclimation. / Committee in charge: Christopher Minson, Chairperson, Human Physiology; John Halliwill, Member, Human Physiology; Andrew Lovering, Member, Human Physiology; Michael Sawka, Member, Not from U of 0; Scott Frey, Outside Member, Psychology

Blodlaktatkurvan används inom uthållighetsidrotten för att styra träningen samt för att utvärdera och förutsäga prestation. För att ytterligare beskriva denna kurva används ett flertal laktattröskelkoncept. Det starka sambandet mellan prestation och olika laktattröskelkoncept har gjort att det finns ett stort intresse för så kallad tröskelträning. Begreppet är dock omdiskuterat och uppfattningen att träning på tröskelintensitet skulle vara optimal är ifrågasatt. Samtidigt har tidigare studier gjort det svårt att dra tydliga slutsatser pga. brist i metoder, stor variation i använda tröskelkoncept och att träningen styrts på annat sätt än utifrån uppmätta blodlaktattrösklar. Många studier är dessutom baserade på mindre tränade deltagare vilket gör att resultaten inte nödvändigtvis är överförbara på mer vältränade individer. Syftet var därför att genom en litteraturstudie undersöka tröskelträning för mer vältränade individer där träningen helt eller delvis styrts utifrån ett laktattröskelkoncept. Frågeställningarna var (1) vad är tröskelintensitet och (2) vilka effekter har sådan träning. I resultatet inkluderades totalt åtta studier, tre observationsstudier och fem experimentella studier. Dessa studier använde ett flertal olika tröskelkoncept och således även flera olika sätt att kategorisera och ange intensitet. De inkluderade studierna varierade också stort i utformning, rapportering av genomförd träning och vilka parametrar som mättes. Utryckt i förhållande till procent av maximalt syreupptag (VO2max) var det ingen studie som visade på en förbättring av den anaeroba tröskeln. För övriga här rapporterade parametrar var resultaten motstridiga. Uppsatsen visade att det inte tycks finnas någon enskild intensitet som är optimal, varken med avseende på att förbättra laktattröskeln, testlopp, VO2max, arbetsekonomi, critical power eller hastigheten på VO2max. Vidare framkom ingen tydlig definition av tröskelintensitet. För att bättre förstå effekterna av och samspelet mellan intensitet, volym och frekvens behövs det fler studier som är väl kontrollerade utifrån en individuellt uppmätt laktattröskel. / The blood lactate curve is used in endurance sports for analysis and prediction of performance as well as to prescribe exercise. To further describe this curve, multiple lactate threshold concepts are being used. A strong correlation between these concepts and performance has led to a large interest in how to train to improve the lactate threshold. Training at threshold intensity has been suggested to be optimal but this statement has been questioned. At the same time, previous research makes it hard to draw firm conclusion because of the methods being used. Thus, the aim of this paper was to review the scientific literature to find out (1) what is threshold intensity and (2) what are the effects of this training. A total number of eight studies were included, three observational studies and five experimental studies. Since these studies varied in the threshold concepts being used, the categorization and prescription of intensity varied as well. The studies also varied in prescribed training, reporting of conducted training and measures being used. Expressed as percentage of maximal oxygen consumption (VO2max), no study reported an improvement of the anaerobic lactate threshold.    There seems to be no optimal intensity to improve the lactate threshold, time trial performance, VO2max, work efficiency, critical power nor the speed at VO2max. Also, no clear definition of threshold intensity was found in the literature. To further understand the effects of and interplay between intensity, volume and frequency more studies using the individual lactate threshold need to be conducted.

Orientador: Antonio de Queiroz Neto / Banca: Guilherme de Camargo Ferraz / Banca: Kênia Cardoso Bícego / Banca: José Arnodson Coelho de Sousa Campelo / Banca: Fernando Queiroz de Almeida / Resumo: Testes que avaliam o desempenho e direcionam a intensidade de treinamento de cavalos, como a aferição do limiar de lactato (LL), são muito úteis na medicina esportiva equina. O presente estudo visa determinar se a velocidade correspondente à concentração de lactato mínimo (VLACMIN) é dependente do protocolo utilizado. A VLACMIN determinada por meio de 5 protocolos (P1 - P5) foram comparados com a velocidade obtida no Teste da Máxima Fase Estável de Lactato (VMAFEL). Oito cavalos árabes treinados foram submetidos a várias sessões para determinação da VMAFEL e comparados com 5 protocolos diferentes. Estes protocolos incluíram um período de aquecimento, seguido de um galope de alta intensidade. Após a corrida, a velocidade foi reduzida para 4 m.s-1. Em P1, P2 e P3 o incremento de velocidade foi fixado em 0,5 m.s -1 e as durações das etapas foram de 3, 5 e 7 min, respectivamente. Em P2, P4 e P5, a duração das etapas foi fixada em 5 min, e o incremento de velocidade foi de 0,5; 1,0; e 1,5 m.s-1, respectivamente. A VLACMIN foi determinada pela aplicação de uma função polinomial de segundo grau. A média e desvio-padrão da VLACMIN dos valores de P1, P2 e P3 e do VMAFEL foram respectivamente: 5,61 ± 0,12 m.s-1; 5,26 ± 0,17 m.s-1; 4,96 ± 0,36 m.s-1; 5,48 ± 0,18 m.s-1 e houve diferença significativa quando comparamos VMAFEL e P3 . A média e desvio-padrão da VLACMIN dos valores de P2 , P4 e P5 e do VMAFEL foram respectivamente: 5,26 ± 0,17 m.s-1; 5,84 ± 0,45 m.s-1; 5,99 ± 0,43 m.s-1; 5,48 ± 0,18 m.s-1, e houve diferença significativa quando comparamos VMAFEL e P5. É possível concluir que a capacidade aeróbia mensurada por meio do método VLACMIN é dependente da duração da etapa, e do incremento da velocidade, nas condições analisadas. / Abstract: Tests to evaluate the performance and direct the intensity of the horses' training, such as the determination of the lactate threshold (LT), hold a great importance in the equestrian sports medicine. The present study aims at determining whether the speed corresponding to the minimum lactate concentration (VLACMIN) is dependent on the protocol used. The VLACMIN determined through 5 protocols (P1 - P5) were compared with the speed obtained in the Lactate Maximum Stable Phase Test (VMFEL). Eight trained Arabian horses underwent several sessions for the VMFEL determination and compared with 5 different protocols. These protocols included a warm-up period, followed by a high-intensity galloping. After the run, the speed was reduced to 4 m.s-1. In P1, P2 and P3 the speed increment was established at 0.5 m.s -1 and the phase durations were of 3, 5 and 7 min, respectively. In P2, P4 and P5, the phases duration was established at 5 min, and the speed increment was of 0.5; 1.0; and 1.5 m.s-1, respectively. The VLACMIN was determined through the application of a second-degree polynomial function. The mean and standard deviation of the VLACMIN of the P1, P2 and P3 values, as well as of the VMFEL, were respectively: 5.61 ± 0.12 m.s-1; 5.26 ± 0.17 m.s-1; 4.96 ± 0.36 m.s-1; 5.48 ± 0.18 m.s-1 and there was significant difference when we compared VMFEL and P3 . The mean and standard deviation of the VLACMIN of the P2 , P4 and P5 values, as well as of the VMFEL, were respectively: 5.26 ± 0.17 m.s-1; 5.84 ± 0.45 m.s-1; 5.99 ± 0.43 m.s-1; 5.48 ± 0.18 m.s-1, and there was significant difference when we compared VMFEL and P5. It is possible to conclude that the aerobic capacity measured through the VLACMIN method is dependent on both the phase duration and the speed increment, in the conditions analyzed. / Doutor

Master of Science / Division of Biology / Ashley E. Rhodes / To retain students in science, technology, engineering, and mathematics (STEM) various pedagogical techniques, such as active learning, have been incorporated in STEM courses. Despite the popularity of active learning, it has rarely been empirically tested with a comparison or control group. To compare the benefits of active learning to conventional lecture learning, the aims of this project were twofold: conduct a physiological research project investigating thermoregulation in large ruminants and evaluate the effectiveness of active learning tools for an undergraduate course that focused on core concepts in physiology. Physiological concepts from the thermoregulation study were integrated into the educational portion of the study. Holstein heifers were used as the model organism for the thermoregulation study. Initially, 8 heifers were fitted with indwelling jugular catheters and serial blood samples were collected at 3-minute intervals during exercise of increasing intensity. Blood lactate was then measured and it was determined that the lactate threshold of Holstein heifers occurs on average at a heart rate of 145bpm ± 7.7 and at an exercise speed of 6.44km/h ± 0.3. The results from the lactate threshold test were used to design two 8-week exercise trials with the objective to examine the effects of exercise on heat stress using high-intensity (short bouts of exercise above the lactate threshold), low-intensity (relatively long bouts of exercise below the lactate threshold), and sedentary control treatments. No differences were found in weekly skin temperatures or core body temperatures (p >.05). Expression of lactate dehydrogenase A in skeletal muscle cells decreased in the high-intensity treatment (p =.03). Expression of lactate dehydrogenase B in skeletal muscles decreased in the high-intensity (p =.02) and sedentary control (p =.02) treatments. Skin and core body temperatures from all treatments were correlated with THI (p < 0.001). There were no differences in body weight, body condition score, or conception rate between treatments (p > .05). Although not significant (p > .05), after low-intensity exercise training, skin temperatures increased while core body temperatures decreased. Trends from this study warrant further investigation on the effects of low-intensity exercise on thermoregulation in Holstein cattle. The second component of this project involved the incorporation of core physiological concepts from the thermoregulation project, in conjunction with those identified by the American Physiological Society, into an educational study where the utility of active learning for teaching difficult concepts within an undergraduate physiology course was investigated. Using a design-based research approach, two distinct pedagogical tools were developed: an active learning tool in the form of a case study and a conventional lecture. It was hypothesized that, compared to a conventional lecture, students receiving the active learning tool would perform significantly better on tests measuring their ability to comprehend, apply, and transfer the information to novel scenarios. Results from this project did not support the hypothesis but instead led to the question of is it the method or is it the student? Prior knowledge of students was evaluated using a physiology knowledge assessment. Students with low prior knowledge had greater learning gains from the use of a conventional lecture while students with high prior knowledge had greater learning gains from the use of a case study. Students with fewer college credit hours completed and those with lower ACT scores had larger learning gains after receiving a conventional lecture compared to the use of a case study. Students with more college credit hours completed and those with higher ACT scores had larger learning gains from the use of a case study compared to receiving the information from a conventional lecture. Furthermore, students who relied on memorization for learning new information benefitted more from a conventional lecture, while students who relied on elaboration for learning new information benefitted more from a case study. Thus, the success of active learning likely depends on specific student characteristics. A one-size-fits-all approach to teaching and learning will not suffice; we must first consider the population of students and then select the proper instructional approach.

Tests to evaluate runners' aerobic capacity aiming to design training programs are often performed on a treadmill, while the training mainly takes place on over-ground surfaces. Studies have shown that different degrees of inclination on treadmills can compensate for the differences in heart rate (HR) response between running on treadmills and over-ground surfaces. The purpose of the study was to test whether the blood lactate concentration (BLC) differs between over-ground running and treadmill running at matched HR, and if so; can inclination of the treadmill be adjusted to generate equal BLC at matched HR? Eight male elite runners performed three incremental running tests where HR and BLC were measured; on a flat treadmill at six running velocities, on a running track at six velocities equal to the HR at test one, and on a treadmill at a fixed HR on different inclines (0°, 0.3°, 0.6°, 0.9°, 1.1° and 1.5°). The results revealed a non-significant trend indicating that over-ground running yields higher BLC at matched HR than treadmill running, and that 0.3° incline on treadmill correlated best with over- ground running. This study demonstrates a clear tendency of higher BLC at a given HR when running on an over-ground surface in comparison to running on a treadmill. Furthermore, a 0.3° incline on a treadmill is suggested to compensate for the difference in BLC at matched HR, between running on a treadmill and on an over-ground surface. However, more research with a larger sample size is needed to conclude and generalize the results.

The purpose of the study was to evaluate the generalisability of the heart rate-blood lactate relationship determined in laboratory testing in comparison to running over ground. This plays a crucial role to prescribe exercise intensity from laboratory results. Ten well trained runners performed a maximal oxygen uptake (VO2max) pre-test and an incremental submaximal test performed at a two degrees inclined treadmill and a running track. Statistical analysis included student’s t-test of heart rate at interpolated blood lactate levels and comparison of second order polynomial regression lines. VO2max was 60,4 ± 6 ml/kg/min for men and 56,3 ± 4,3 ml/kg/min for women. There was no significant difference in heart rate at interpolated blood lactate of 3 and 4 mmol/L. There was no significant difference between heart rate values at any running velocity. A significant difference between blood lactate values was observed 14km/h (p=0,04). When considering blood lactate values up to 6mmol/L, heart rate-blood lactate relationships were similar. In conclusion, lactate threshold testing on treadmill through incremental test protocols on a two degrees incline gives similar heart rate- blood lactate relationship as running over ground and may be used to prescribe intensity in training performed over ground.

Introduction Researchers have, for decades, contributed to an increased collective understanding of the physiological demands in cross-country skiing; however, almost all of these studies have used either non-elite subjects and/or performances that emulate cross-country skiing. To establish the physiological demands of cross-country skiing, it is important to relate the investigated physiological variables to the competitive performance of elite skiers. The overall aim of this doctoral thesis was, therefore, to investigate the external validity of physiological test variables to determine the physiological demands in competitive elite cross-country skiing. Methods The subjects in Study I – IV were elite male (I – III) and female (III – IV) cross-country skiers. In all studies, the relationship between test variables (general and ski-specific) and competitive performances (i.e. the results from competitions or the overall ski-ranking points of the International Ski Federation (FIS) for sprint (FISsprint) and distance (FISdist) races) were analysed. Test variables reflecting the subject’s general strength, upper-body and whole-body oxygen uptake, oxygen uptake and work intensity at the lactate threshold, mean upper-body power, lean mass, and maximal double-poling speed were investigated. Results The ability to maintain a high work rate without accumulating lactate is an indicator of distance performance, independent of sex (I, IV). Independent of sex, high oxygen uptake in whole-body and upper-body exercise was important for both sprint (II, IV) and distance (I, IV) performance. The maximal double-poling speed and 60-s double-poling mean power output were indicators of sprint (IV) and distance performance (I), respectively. Lean mass was correlated with distance performance for women (III), whereas correlations were found between lean mass and sprint performance among both male and female skiers (III). Moreover, no correlations between distance performance and test variables were derived from tests of knee-extension peak torque, vertical jumps, or double poling on a ski-ergometer with 20-s and 360-s durations (I), whereas gross efficiency while treadmill roller skiing showed no correlation with either distance or sprint performance in cross-country skiing (IV). Conclusion The results in this thesis show that, depending on discipline and sex, maximal and peak oxygen uptake, work intensity at the lactate threshold, lean mass, double-poling mean power output, and double-poling maximal speed are all externally valid physiological test variables for evaluation of performance capability among elite cross-country skiers; however, to optimally indicate performance capability different test-variable expressions should be used; in general, the absolute expression appears to be a better indicator of competitive sprint performance whereas the influence of body mass should be considered when evaluating competitive distance performance capability of elite cross-country skiers.