The aim of this research programme was to investigate the effects of different music applications: The differentiated exposure of music and the synchronous application of music. In Study 1, participants completed a series of 10-km cycling time trials under four single-blinded conditions: No-music control, music 0-10 km (M1), music 0-5 km (M2), and music 5-10 km (M3). The largest performance gains were noticed under M1, followed by M3, when compared to control, while the most positive psychological response was observed only in M3. Study 2 further examined the notion of differentiated music exposure by incorporating both quantitative and qualitative modes of inquiry. In addition, participants were given foreknowledge of the experimental conditions. Although no performance gains were found across conditions, M3 significantly reduced perceived exertion and prevented affective decline. Qualitative findings suggest that prolonged exposure to music may have negative psychological and psychophysical consequences. The last study contrasted the effects of synchronous and asynchronous application of music in a 6-min submaximal cycling task. Synchronous music was more effective than asynchronous music in terms of reducing perceptions of exertion and increasing subjective arousal. Although no changes in oxygen uptake were found across conditions, auditory-motor synchronisation appeared to reduce heart rate. The contribution of this thesis is twofold. Firstly, the provision of music in the latter stages of a task appears to have significant psychological and psychophysical benefits when compared against constant music exposure. Secondly, more positive effects, in terms of perceived exertion and subjective arousal, are observed when music is applied synchronously compared to asynchronously; this suggests a need for a separate conceptual framework for the application of synchronous music.

Abstract Aim The aim of this study was to determine whether 30-minute time trial (30MTT) is an accurate estimator of the lactate threshold (LT) relative to direct measures of LT and whether 30MTT is applicable for untrained individuals. Question formulations: (1) Is 30MTT an accurate method for estimation of the LT in a group with varied VO2-peak? (2) Is there a difference in the accuracy of the 30MTT between a group with low and high VO2-peak? (3) Is the method applicable for untrained individuals? Method A quantitative study was conducted consisting of 10 subjects (age=26±2.15 years, BMI=21.7 ±2.76, VO2-peak=47.45 ±6.34ml·kg-1·min-1) who participated during two testing occasions. The sample consisted of women (n=4) and men (=3) with varied physical ability. During the first occasion the subjects took part in a direct measure of their LT followed by a test to measure their maximal oxygen uptake. Four methods were used to determine the subjects LT from the direct measures; LTD-max-c, LTVisual, LTΔ1 and LT4.0. During the second occasion the subjects performed a 30MTT from where their pace (LTV) and heart rate (LTHR) at LT were calculated. After the tests were concluded the direct measure was compared to the 30MTT. Three participants were excluded from the study due to insufficient data. Results The results showed that 30MTT was an accurate and reliable method for estimation of the LTV for a group with varied VO2-peak. No significant differences were seen between the direct methods for LTV and 30MTT. Strong correlations were seen between the direct methods and 30MTT (r≥0.91). LTHR showed significant differences (p=0.05) between the direct measures and 30MTT. No correlations were seen for LTHR. Because of the limited selection question formulations two and three were left unanswered. Conclusion 30MTT appears to be an accurate method for estimation of the LT. A significant correlation was seen for LTV between the direct methods of LT and 30MTT. No correlation was seen for LTHR since there appears to be a systematic elevation of heart rate. These results show that 30MTT appears to be an accurate method for estimation of LTV but not LTHR for group of individuals with varied VO2-peak. Because of a limited selection some caution should be applied when rendering these results. The limited selection also means that potential differences between 30MTT and the direct measures among individuals with low and high VO2-peak weren’t possible to evaluate. / Sammanfattning Syfte och frågeställningar Syftet med studien var att undersöka noggrannheten av uppskattning av laktattrösklar i 30-minuters “time trial”-test i förhållande till fastställda laktattrösklar med hjälp av uppmätta blodlaktatnivåer samt om metoden är applicerbar på individer med varierande VO2-peak. Frågeställningar: (1) Är 30MTT en giltig indirekt metod för fastställande av LT för en grupp med varierande VO2-peak? (2) Skiljer sig noggrannheten mellan individer med låg och hög VO2-peak i 30MTT? (3) Är 30MTT-metoden giltig för otränade individer? Metod En kvantitativ studie bestående av 10 försökspersoner (FP)(ålder=26±2.15 år, BMI=21.7 ±2.76, VO2-peak=47.45 ±6.34 ml·kg-1·min-1) deltog vid två testtillfällen. Urvalet bestod av kvinnor (n=4) och män (n=3) med varierad fysisk förmåga. Vid testtillfälle 1 genomfördes mätning av blodlaktatkoncentrationer för en direkt erhållen LT samt mätning av maximalsyreupptagningsförmåga. Fyra metoder tillämpades för identifiering av LT; LTD-max-c, LTVisual, LTΔ1 samt LT4.0. Vid det andra tillfället genomfördes en indirekt mätning av LT genom 30MTT varefter hastighet (LTV) samt puls (LTHF) vid LT kunde beräknas. Efter genomförda test jämfördes direkt mätning med indirekt mätning av LT. Tre FP exkluderades från studien på grund av ej tillräcklig erhållen data. Resultat Resultaten visade att 30MTT var en reliabel metod för en grupp med varierande VO2-peak för beräkning av LTV. Inga signifikanta skillnader sågs mellan samtliga direkta metoder och 30MTT för LTV. Däremot kunde starka korrelationer ses mellan samtliga direkta metoder samt 30MTT (r≥0.91) för hela urvalet. För LTHF sågs signifikanta skillnader (p=0.05) mellan samtliga direkta metoder samt 30MTT. Inga signifikanta samband kunde ses för LTHF för hela urvalet. På grund av det begränsade urvalet lämnas frågeställning två och tre obesvarad. Slutsats 30MTT tycks vara en reliabel metod för uppskattning av LT. Signifikanta samband kunde ses mellan samtliga direkta metoder för LT och 30MTT gällande LTV. För LTHF sågs inga samband, däremot sågs en systematisk förskjutning av hjärtfrekvensen. LTV enligt 30MTT verkar vara en giltig metod för en grupp individer med varierad VO2-peak. På grund av ett begränsat urval bör en viss försiktighet tillämpas i tolkning av dessa resultat. Vidare kunde det på grund av det begränsade urvalet inte göras någon bedömning på eventuella skillnader mellan individer med låg och hög VO2-peak.

Monitoring progress of athletes is an essential component of the training process. Collegiate distance running coaches often use field tests to assess progress because of a lack of time and resources to do laboratory testing. The purpose of this dissertation was to examine the relationships between physiological and strength variables measured in a laboratory and field testing measures in collegiate distance runners. Collegiate distance runners completed a series of tests in the Sport Science laboratory at East Tennessee State University to obtain physiological and strength parameters, such as V̇ O2max and vertical jump height. The athletes then completed one of two field tests (either a 3 km time trial or a 3 minute all out run test). There were strong correlations between the laboratory measures and the field test performances. These results indicate that strength is an important factor in run performance. Also, a 3 km time trial and a 3 minute all out run test are suitable for athlete monitoring.

The purpose of this study was to compare high-resistance cycle training (HRCT) with resistance training (RT), and their effects on Wingate anaerobic test watt max (Wmax) and watt average (Wave), strength (improvement in 1 repetition max [RM]), and time-trial performance. Twenty-five healthy college-age untrained male subjects were randomly assigned to the HRCT (n=10), RT (n=10), or control (n=5) group. All subjects completed pre and posttesting for the leg press (LP), 30 s Wingate anaerobic test, and 15-min time-trial. Subjects also completed familiarization tests prior to pretesting in the Wingate anaerobic test and 15-min time-trial. HRCT and RT subjects trained 2x/wk for 8 weeks with at least 48 hrs between training sessions. During each training session HRCT completed 4 x 30 sec efforts increasing resistance when >65 rotations per minute (rpm) could be maintained for the full training session. RT completed 3 x 10 repetitions of leg press with weight increasing 5 -10 lbs when all repetitions were completed during a training session. ANOVA with Tukey post-hoc was used to determine if differences existed between the groups. Within group change was analyzed using paired T-test. Effect size was computed to determine meaningfulness of differences. HRCT and RT groups both showed statistical significance (p < 0.05) pre to posttesting in LP, Wingate anaerobic test Wmax and Wave, and 15-min time-trial. Control group also showed statistical significance (p < 0.05) pre to posttesting in LP and 15-min time-trial. Significant between group differences were noted between HRCT and control in Wingate anaerobic test Wmax (p=0.03) and Wave (p = 0.007) and 15-min time-trial (p = 0.003). There was a significant difference between RT and control on the 15-min time-trial (p = 0.008). When comparing HRCT and RT no statistical difference was seen in LP, Wingate anaerobic test Wmax and Wave, and 15-min time-trial. High-resistance cycle training and RT resulted in similar strength gains. However, HRCT showed greater improvements in cycling specific activities: 30 s Wingate anaerobic test Wmax and Wave, and 15-min time-trial. Results suggested that HRCT may increase performance on bike related assessments when compared to RT.

O objetivo do estudo foi examinar a influência de variáveis fisiológicas, perceptuais e mecânicas nas diferentes estratégias de corrida e no desempenho de atletas. Doze corredores especialistas em 5.000m realizaram: 1) um teste escalonado máximo para identificação do consumo máximo de oxigênio (VO2máx), velocidade de corrida associada ao VO2máx (vVO2máx), pico de velocidade em esteira (PVE) e velocidade de corrida associada ao limiar anaeróbio (vLAn); 2) uma prova de corrida de 5.000m avaliada a cada trecho (n = 5) de 1.000m em pista de atletismo para registro da frequência cardíaca (FC), percepção subjetiva de esforço (PSE) e velocidade de corrida. Os sujeitos foram divididos em dois grupos: saída lenta (SL) e saída rápida (SR) de acordo com a estratégia adotada, que por sua vez foi baseada na relação da velocidade de corrida no trecho inicial (Vel20%) com a velocidade média do teste de 5.000m. Os dados foram comparados entre os grupos de estratégia e posteriormente entre os trechos da prova esportiva para cada variável analisada. A velocidade de corrida no trecho inicial (SL = 16,9km.h-1 e SR = 19,1km.h-1) e no trecho final (SL = 19,1km.h-1 e SR = 16,7km.h-1) foi significantemente diferente (p < 0,05), o mesmo não ocorreu com a PSE. Já a FC nos três últimos trechos (SL = 185; 188 e 195 bpm e SR = 191; 193 e 200 bpm) apresentou diferença significante (p < 0,05) entre os grupos avaliados. Adicionalmente, foram encontradas associações entre PVE e Vel20% (rs = 0,57; p < 0,05), vVO2máx e Vel20% (rs = 0,55; p < 0,05), e entre vLAn e Vel20% (rs = 0,54; p < 0,05). Quando os parâmetros de desempenho (FC, PSE e velocidade de corrida) foram comparados dentro de cada grupo, apresentaram diferença significante (p < 0,05) entre todos os trechos analisados do teste. Dessa forma, concluímos haver influência da estratégia adotada no início da prova sobre a regulação da velocidade e sobre o desempenho na corrida de 5.000m, sobretudo, quando relacionada a parâmetros fisiológicos, perceptuais e mecânicos / The objective of this study was to examine the influence of physiological, perceptual and mechanical parameters in different pacing strategies and performance of athletes. Twelve runners performed: 1) a test scaled maximal to identify the maximum oxygen uptake (VO2max), running velocity associated with VO2max (vVO2max), peak treadmill velocity (PTV) and running velocity associated with the anaerobic threshold (vAnT); 2) a time trial evaluated in each 1,000m in the track to record heart rate (HR), rating of perceived exertion (RPE) and running speed. The subjects were divided into two groups: slow start (SS) and fast start (FS) in accordance with the strategy used, which in turn was based on the ratio of the velocity of the initial split (Vel20%) with the speed average of the time trial. Data were compared between groups of the pacing strategy for each variable analyzed. The velocity at the initial split (SS = 16.9 km.h-1 and FS = 19.1 km.h-1) and in the final split (SS = 19.1 km.h-1 and FS = 16.7 km.h-1) was different significantly (p < 0.05), but the same did not occur with the RPE. The HR in the last three splits (SS = 185, 188 and 195 beats.min-1 and FS = 191, 193 and 200 beats.min-1) showed significant difference (p < 0.05) between groups. In addition, associations were found between PTV and Vel20% (rs = 0.57, p < 0.05), vVO2max and Vel20% (rs = 0.55, p < 0.05) and between vAnT and Vel20% (rs = 0.54, p < 0.05). When the performance parameters (HR, RPE and running speed) were compared within each group, there were significant differences (p < 0.05) among all splits analyzed. Thus, we conclude there is influence of the strategy adopted at the start of the time trial and the speed regulation on the performance in the 5,000m running, especially when related to physiological, perceptual and mechanical parameters

O objetivo do estudo foi examinar a influência de variáveis fisiológicas, perceptuais e mecânicas nas diferentes estratégias de corrida e no desempenho de atletas. Doze corredores especialistas em 5.000m realizaram: 1) um teste escalonado máximo para identificação do consumo máximo de oxigênio (VO2máx), velocidade de corrida associada ao VO2máx (vVO2máx), pico de velocidade em esteira (PVE) e velocidade de corrida associada ao limiar anaeróbio (vLAn); 2) uma prova de corrida de 5.000m avaliada a cada trecho (n = 5) de 1.000m em pista de atletismo para registro da frequência cardíaca (FC), percepção subjetiva de esforço (PSE) e velocidade de corrida. Os sujeitos foram divididos em dois grupos: saída lenta (SL) e saída rápida (SR) de acordo com a estratégia adotada, que por sua vez foi baseada na relação da velocidade de corrida no trecho inicial (Vel20%) com a velocidade média do teste de 5.000m. Os dados foram comparados entre os grupos de estratégia e posteriormente entre os trechos da prova esportiva para cada variável analisada. A velocidade de corrida no trecho inicial (SL = 16,9km.h-1 e SR = 19,1km.h-1) e no trecho final (SL = 19,1km.h-1 e SR = 16,7km.h-1) foi significantemente diferente (p < 0,05), o mesmo não ocorreu com a PSE. Já a FC nos três últimos trechos (SL = 185; 188 e 195 bpm e SR = 191; 193 e 200 bpm) apresentou diferença significante (p < 0,05) entre os grupos avaliados. Adicionalmente, foram encontradas associações entre PVE e Vel20% (rs = 0,57; p < 0,05), vVO2máx e Vel20% (rs = 0,55; p < 0,05), e entre vLAn e Vel20% (rs = 0,54; p < 0,05). Quando os parâmetros de desempenho (FC, PSE e velocidade de corrida) foram comparados dentro de cada grupo, apresentaram diferença significante (p < 0,05) entre todos os trechos analisados do teste. Dessa forma, concluímos haver influência da estratégia adotada no início da prova sobre a regulação da velocidade e sobre o desempenho na corrida de 5.000m, sobretudo, quando relacionada a parâmetros fisiológicos, perceptuais e mecânicos / The objective of this study was to examine the influence of physiological, perceptual and mechanical parameters in different pacing strategies and performance of athletes. Twelve runners performed: 1) a test scaled maximal to identify the maximum oxygen uptake (VO2max), running velocity associated with VO2max (vVO2max), peak treadmill velocity (PTV) and running velocity associated with the anaerobic threshold (vAnT); 2) a time trial evaluated in each 1,000m in the track to record heart rate (HR), rating of perceived exertion (RPE) and running speed. The subjects were divided into two groups: slow start (SS) and fast start (FS) in accordance with the strategy used, which in turn was based on the ratio of the velocity of the initial split (Vel20%) with the speed average of the time trial. Data were compared between groups of the pacing strategy for each variable analyzed. The velocity at the initial split (SS = 16.9 km.h-1 and FS = 19.1 km.h-1) and in the final split (SS = 19.1 km.h-1 and FS = 16.7 km.h-1) was different significantly (p < 0.05), but the same did not occur with the RPE. The HR in the last three splits (SS = 185, 188 and 195 beats.min-1 and FS = 191, 193 and 200 beats.min-1) showed significant difference (p < 0.05) between groups. In addition, associations were found between PTV and Vel20% (rs = 0.57, p < 0.05), vVO2max and Vel20% (rs = 0.55, p < 0.05) and between vAnT and Vel20% (rs = 0.54, p < 0.05). When the performance parameters (HR, RPE and running speed) were compared within each group, there were significant differences (p < 0.05) among all splits analyzed. Thus, we conclude there is influence of the strategy adopted at the start of the time trial and the speed regulation on the performance in the 5,000m running, especially when related to physiological, perceptual and mechanical parameters

abstract: This study investigated the effect of environmental heat stress on physiological and performance measures during a ~4 mi time trial (TT) mountain hike in the Phoenix metropolitan area. Participants (n = 12; 7M/5F; age 21.6 ± 2.47 [SD]) climbed ‘A’ mountain (~1 mi) four times on a hot day (HOT; wet bulb globe temperature [WBGT] = 31.6°C) and again on a moderate day (MOD; WBGT = 19.0°C). Physiological and performance measures were made before and throughout the course of each hike. Mean pre-hike hydration status (urine specific gravity [USG]) indicated that participants began both HOT and MOD trials in a euhydrated state (1.016 ± 0.010 and 1.010 ± 0.008, respectively) and means did not differ significantly between trials (p = .085). Time trial performance was impaired by -11% (11.1 minutes) in the HOT trial (105 ± 21.7 min), compared to MOD (93.9 ± 13.1 min) (p = .013). Peak core temperatures were significantly higher in HOT (38.5 ± 0.36°C) versus MOD (38.0 ± 0.30°C) with progressively increasing differences between trials over time (p < .001). Peak ratings of perceived exertion were significantly higher in HOT (14.2 ± 2.38) compared to MOD (11.9 ± 2.02) (p = .007). Relative intensity (percent of age-predicted maximal heart rate [HR]), estimated absolute intensity (metabolic equivalents [METs]), and estimated energy expenditure (MET-h) were all increased in HOT, but not significantly so. The HOT condition reduced predicted maximal aerobic capacity (CRFp) by 6% (p = .026). Sweat rates differed significantly between HOT (1.38 ± 0.53 L/h) and MOD (0.84 ± 0.27 L/h) (p = .01). Percent body mass loss (PBML) did not differ significantly between HOT (1.06 ± 0.95%) and MOD (0.98 ± 0.84%) (p = .869). All repeated measures variables showed significant between-subjects effects (p < .05), indicating individual differences in response to test conditions. Heat stress was shown to negatively affect physiological and performance measures in recreational mountain hikers. However, considerable variation exists between individuals, and the degree of physiological and performance impairment is probably due, in part, to differences in aerobic fitness and acclimatization status rather than pre- or during-performance hydration status. / Dissertation/Thesis / Masters Thesis Exercise and Wellness 2019

Introduction Performance in cross-country skiing is influenced by the skier’s ability to continuously produce propelling forces and force magnitude in relation to the net external forces. A surrogate indicator of the “power supply” in cross-country skiing would be a physiological variable that reflects an important performance-related capability, whereas the body mass itself is an indicator of the “power demand” experienced by the skier. To adequately evaluate an elite skier’s performance capability, it is essential to establish the optimal ratio between the physiological variable and body mass. The overall aim of this doctoral thesis was to investigate the importance of body-mass exponent optimization for the evaluation of performance capability in cross-country skiing. Methods In total, 83 elite cross-country skiers (56 men and 27 women) volunteered to participate in the four studies. The physiological variables of maximal oxygen uptake (V̇O2max) and oxygen uptake corresponding to a blood-lactate concentration of 4 mmol∙l-1 (V̇O2obla) were determined while treadmill roller skiing using the diagonal-stride technique; mean oxygen uptake (V̇O2dp) and upper-body power output (Ẇ) were determined during double-poling tests using a ski-ergometer. Competitive performance data for elite male skiers were collected from two 15-km classical-technique skiing competitions and a 1.25-km sprint prologue; additionally, a 2-km double-poling roller-skiing time trial using the double-poling technique was used as an indicator of upper-body performance capability among elite male and female junior skiers. Power-function modelling was used to explain the race and time-trial speeds based on the physiological variables and body mass. Results The optimal V̇O2max-to-mass ratios to explain 15-km race speed were V̇O2max divided by body mass raised to the 0.48 and 0.53 power, and these models explained 68% and 69% of the variance in mean skiing speed, respectively; moreover, the 95% confidence intervals (CI) for the body-mass exponents did not include either 0 or 1. For the modelling of race speed in the sprint prologue, body mass failed to contribute to the models based on V̇O2max, V̇O2obla, and V̇O2dp. The upper-body power output-to-body mass ratio that optimally explained time-trial speed was Ẇ ∙ m-0.57 and the model explained 63% of the variance in speed. Conclusions The results in this thesis suggest that V̇O2max divided by the square root of body mass should be used as an indicator of performance in 15-km classical-technique races among elite male skiers rather than the absolute or simple ratio-standard scaled expression. To optimally explain an elite male skier’s performance capability in sprint prologues, power-function models based on oxygen-uptake variables expressed absolutely are recommended. Moreover, to evaluate elite junior skiers’ performance capabilities in 2-km double-poling roller-skiing time trials, it is recommended that Ẇ divided by the square root of body mass should be used rather than absolute or simple ratio-standard scaled expression of power output. / <p>Incorrect ISBN in printed thesis: 973-91-7601-270-3</p>

Several research has shown that caffeine ingestion (1, 2, 7 trimethylxanthine) increases performance. Due to these findings and their removal from the list of banned substances in 2004 by the international anti doping agency, athletes of various sports have widely used caffeine in order to increase performance during competitions. Studies have shown an increase in performance in high-intensity exercise after caffeine ingestion. The increase in performance with the use of caffeine in this type of performance, seems to be related to increasing the anaerobic contribution . On the other hand, depletion of glycogen stores appear to reduce performance during high intensity exercise. This reduction according studies appears to be due to a reduction of the anaerobic contribution. More recently, research has been conducted in order to investigate whether supplementation of carbohydrate with the addition of caffeine provides the additional effect on performance. Thus, the goal of this dissertation was: 1) review the main findings about the effects on performance in time trial and what the mechanisms involved in the combined supplementation of caffeine and carbohydrate (review article). 2) verify if intake of caffeine can reverse the impairment in performance and anaerobic contribution caused by depletion of muscle glycogen during 4000m cycling time trial (results article). In the studies reviewed in the review article found that most studies with combined ingestion of caffeine and carbohydrate showed a further increase in performance. However, more studies need to be performed to elucidate what are the mechanisms of action during time trial arising from the combined ingestion of caffeine and carbohydrate. In the article results the caffeine reversed the performance impaired prior by depletion of muscle glycogen and anaerobic contribution increased to levels above the conditions with muscle glycogen depletion with ingestion of placebo and control / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Diversas pesquisas têm demonstrado que a ingestão de cafeína (1, 2, 7 trimetilxantina) aumenta o desempenho. Devido a esses achados e de sua retirada da lista de substâncias proibidas no ano de 2004 pela agência internacional anti doping, atletas de várias modalidades esportivas tem amplamente utilizado a cafeína com intuito de aumentar o desempenho durante as competições. Estudos tem evidenciado um aumento no desempenho em exercícios de alta intensidade após a ingestão de cafeína. O aumento no desempenho com o uso da cafeína nesse tipo de exercício, parece estar relacionado ao aumento da contribuição anaeróbia. Por outro lado, a depleção das reservas de glicogênio muscular parece reduzir o desempenho durante exercícios de alta intensidade. Essa redução segundo estudos parece ser devido a uma redução da contribuição anaeróbia. Mais recentemente, pesquisas têm sido realizadas com objetivo de investigar a relação entre suplementação de carboidrato com a adição de cafeína sobre o desempenho. Desta forma o objetivo dessa dissertação foi: 1º) Revisar os principais achados acerca dos efeitos da ingestão combinada da cafeína e carboidrato sobre o desempenho em exercícios contra-relógio e quais os mecanismos de ação estariam envolvidos (artigo de revisão). 2º) Verificar se a ingestão de cafeína reverte o desempenho e a contribuição anaeróbia prejudicados com a depleção de glicogênio muscular durante 4000m de ciclismo contra-relógio (artigo de resultados). Nos estudos revisados no artigo de revisão foi constado que a maioria dos trabalhos com ingestão combinada de cafeína e carboidrato demonstraram aumento adicional no desempenho. Entretanto mais estudos necessitam ser realizados para elucidar quais são os mecanismos de ação durante exercícios do tipo contra-relógio decorrentes da ingestão combinada de cafeína e carboidrato. No artigo de resultados, a cafeína reverteu o desempenho antes prejudicado com a depleção de glicogênio muscular e aumentou a contribuição anaeróbia para níveis acima do encontrado na condição controle

Many athletes incorporate high training volumes and limited recovery periods into their training regimes. This may disrupt the fragile balance and the accumulation of exercise stress may exceed an athlete's finite capacity of resistance. A state of elevated fatigue, increased mood disturbance and decreased exercise performance can result. This is commonly known as overreaching and if increased training and limited recovery is continued, it is believed that the more serious state of overtraining may develop. This is relatively commonly experienced in athletes, however little scientific investigation has been conducted to determine the characteristics and underlying mechanisms. The overall aim of this thesis was to gain a greater understanding of the state of overreaching and to specifically provide new information on potential markers of this state as well as possible mechanisms. To study the cumulative effects of exercise stress and subsequent recovery on performance changes, fatigue indicators and possible mechanisms, the training of endurance cyclists was systematically controlled and monitored in two separate investigations. A number of variables were assessed including performance, physiological, biochemical, psychological, immunological and hormonal variables. In addition heart rate variability and serotonergic responsiveness were also assessed. Some of the more pertinent effects of overreaching included an increase in heart rate variability, a reduction in carbohydrate oxidation, an increase in serotonergic responsiveness and a reduction in stress hormone concentrations. These results suggest that autonomic imbalance in combination with decreased hormonal release appears to be related to the decline in performance and elevated fatigue apparent in overreached athletes. Additionally it also appears that alterations in the hypothalamic-pituitary adrenal axis may occur in overreached athletes.