Higher cardiorespiratory fitness (CRF) is associated with better executive function and mental health in neurotypical populations. However, these associations warrant investigation for adults with attention deficit hyperactivity disorder (ADHD) who experience executive dysfunction and worse mental health. Adults with ADHD also tend to have lower engagement in physical activity, which contributes to CRF, but the reasons for this are unknown. Using mixed methods, the purpose of this dissertation was to explore associations between CRF and executive functions (Study 1), and mental health (Study 2), and to understand barriers and facilitators to physical activity in an adult ADHD sample (Study 3). Data from Study 1 reveal the association between higher CRF and better inhibitory control; surprisingly, the same associations with CRF were not observed for cognitive flexibility and working memory, suggesting a selective association between CRF and inhibitory control. In Study 2, although adults with ADHD reported significantly higher symptoms of depression, anxiety, and stress than controls, those with higher CRF had better mental health. Together, the findings from Studies 1 and 2 suggest that physical activity interventions aimed at increasing CRF may provide adults with ADHD support for symptom management and mental health. Finally, Study 3 documents the unique barriers and facilitators to getting physically active as described by adults with ADHD. Through semi-structured interviews, the results revealed unique ADHD-related barriers and facilitators to being physically active such that their symptoms could act as both a barrier and facilitator depending on the context. Overall, the results of this dissertation provide valuable information for researchers designing future interventions and professionals recommending physical activity for those with ADHD, with the ultimate goal of creating an inclusive context for movement that is more enjoyable, feasible, and promotes adherence over the long term. / Thesis / Candidate in Philosophy

Cognitive aging has profound effects on the hippocampus, a brain region that is critical for episodic memory formation and spatial navigation. Accurate episodic memory formation requires pattern separation, a neurocomputational process that orthogonalizes similar stimulus input into distinct neural representations and can be examined using behavioral mnemonic discrimination paradigms in humans. Age-related impairment in hippocampally-dependent cognition emphasizes the importance of identifying modulators of hippocampal plasticity. Critically, studies in older adults have demonstrated that greater cardiorespiratory fitness (CRF) is associated with greater volume of the hippocampus, mitigated age-related decline in spatial mnemonic discrimination, and better visuospatial memory. Nonetheless, how CRF modulates the underlying structural and functional neural correlates of mnemonic discrimination and spatial navigation in cognitive aging remains unknown. Therefore, the overall objective of this dissertation was to examine CRF as a modulator of hippocampal memory system structure and function, specifically regarding the hippocampally-dependent processes of mnemonic discrimination and spatial navigation, in cognitively healthy older adults. In a series of three experiments, we tested the central hypothesis that CRF enhances hippocampal plasticity and modulates the underlying neural correlates of mnemonic discrimination and spatial navigation in older adults. Data for these three experiments came from two studies. In the first, young adults (ages 18-35 years) and older adults (ages 55-85 years) underwent high-resolution fMRI to examine hippocampal subfield blood-oxygenation level-dependent (BOLD) signal during mnemonic discrimination. In the second, older adults (ages 60-80 years) underwent whole-brain, high-resolution fMRI to examine whole-brain BOLD signal during spatial navigation. In both studies, participants performed a submaximal treadmill test to estimate CRF and underwent high-resolution structural MRI to measure hippocampal subfield volumes as markers of neuroplasticity in the hippocampus. The primary goal of Experiment 1 was to examine the prediction that CRF is positively associated with mnemonic discrimination task performance and dentate gyrus (DG)/CA3 volume in older adults, given that these hippocampal subfields are thought to support pattern separation. Contrary to our initial prediction, we did not observe a relationship between CRF and mnemonic discrimination task performance or CRF and DG/CA3 volume. Instead, we observed a significant positive relationship between CRF and the volume of another hippocampal subfield, the bilateral subiculum, in older adult women, but not men. The primary goal of Experiment 2 was to examine the prediction that mnemonic discrimination-related BOLD signal in the hippocampal subfields is modulated by aging and CRF in young and older adults. In line with our initial prediction, there was a significant difference between young and older adults in right DG/CA2-3 BOLD signal during mnemonic discrimination task performance. Most importantly, CRF significantly modulated bilateral subiculum BOLD signal in an opposing fashion in young and older adults. The primary goal of Experiment 3 was to extend the current study beyond the function of the hippocampus in isolation and to examine whole-brain activation in association with an ecologically valid task that engages a large network of brain regions including but not limited to the hippocampus. We predicted that CRF modulates BOLD signal activation patterns driven by the employed spatial navigation task, specifically in brain regions in the frontal, parietal, and temporal cortices, and the cerebellum, given that the previously published literature in older adults has suggested that CRF enhances structural integrity in these regions in addition to the hippocampus. Our results demonstrated that CRF is significantly positively associated with BOLD signal in the right cerebellum lobule VIIa Crus I and Crus II, a region that has been implicated in sequence-based navigation. And, consistent with our results from Experiment 2, this relationship was observed in older adult women. Importantly, the findings of these experiments highlight novel targets of fitness-related neuroplasticity in the older adult brain, including the subiculum subfield of the hippocampus and the cerebellum lobule VIIa Crus I and Crus II. Furthermore, these findings underscore the importance of examining sex as a modulating factor of fitness-related neuroplasticity.

Perceived exertion is how hard or heavy an individual feels they are working. Perceived exertion is often quantified using the ratings of perceived exertion (RPE) scale and can be used to measure exercise intensity based on the experience of an individual. While objective methods of assessing exercise intensity, such as measurement of heart rate and percent of peak oxygen uptake, are useful, RPE is commonly implemented for the ease of use and feasibility. For example, RPE is commonly implemented in rehabilitation settings for people with a spinal cord injury and individuals with coronary artery disease because of their non-linear heart rate response to increases in exercise workload. The overarching purpose of this dissertation was to investigate a range of research questions designed to advance the knowledge and use of RPE guided exercise. Through a systematic review and meta-analysis, we examined evidence for the impact on cardiorespiratory fitness and peak power output using RPE-guided interventions in individuals with a spinal cord injury (SCI) and found that RPE-guided interventions improved both after a variety of exercise intervention types and lengths. In a separate retrospective cross-sectional analysis, we then demonstrated that perceived exertion, measured by leg cycling effort during a cardiopulmonary exercise test on a leg cycle ergometer in non-disabled individuals, was predicted by power and maximum power output. After further investigation we found that quadriceps strength predicted maximum power output and therefore is related to leg cycling effort. In the third study of the thesis, we conducted semi-structured interviews in individuals with an SCI and their healthcare practitioners and found that individuals commonly described their sensations associated with the 0-10 RPE scale using muscle sensations when both recalling exercise and after the completion of an acute exercise trial on an arm cycle ergometer. Lastly, we investigated the relationship between psychological and physiological measures and RPE during an arm cycling exercise during a maximal graded exercise test, high intensity interval training, and moderate intensity continuous training using a crossover experimental design in both non-disabled individuals and individuals who were mobility impaired due to SCI. While there were no relationships between any variable and RPE in non-disabled individuals, age and triceps strength predicted central RPE and peak feeling scale predicted peripheral RPE in individuals with an SCI. These mixed methods results collectively suggest that muscle strength, not heart rate, is the strongest predictor of perceived exertion especially in clinical populations completing high intensity exercise. Our novel findings suggest that RPE is regulated through a system of psychological and physiological phenomena, strongly related to muscle sensations arising from the working muscle groups and may have utility and relevance in complementing measures of exercise intensity for a broad range of individuals across the spectrum of health and disease. Future studies should examine the use of muscle sensation descriptions as descriptors of exercise intensity prior to the development of high intensity exercise guidelines in clinical populations, such as individuals with SCI. / Thesis / Candidate in Philosophy / It has been well established that heart rate and ratings of perceived exertion are related in young, healthy individuals, however the nuances of the relationships between other contributors and how clinical populations feel during exercise remain unclear. Using mixed methods, this research sought to determine what sensations help people determine how they feel during exercise, with a focus on high intensity interval training exercise. Our results show that muscle strength may be a key determinant in the perception of effort in individuals with a spinal cord injury and in clinical populations during arm and leg maximal graded exercise tests, but the relationships between physiological variables and perceptions of arm effort in non-impaired individuals remains to be determined. Sensations of effort are regulated through a variety of different mechanisms that vary with population, and the relationships depend on the parameters (e.g., exercise modality and intensity) of the exercise. Future studies should be conducted to determine the individual contributions of different body systems to perceived exertion during exercise in a wide range of populations.

Background Stroke is a major cause of disability worldwide. After treatment in a specialized stroke unit, early supported discharge (ESD) followed by home rehabilitation has shown to be an effective way to improve patient outcome and quality of care for persons with mild to moderate stroke. ESD service is recommended in the national and international guidelines for stroke care, but has only partially been implemented in Sweden. Following stroke, fatigue is a common consequence that often becomes more evident when the patient comes home. Currently, there is insufficient evidence about how to measure, treat and handle post-stroke fatigue. The overall aim of this thesis was to evaluate and implement early supported discharge (ESD) based on stroke patients experience after discharge from the stroke unit and local conditions. The aim was also to evaluate post-stroke fatigue with a potentially valid and reliable scale and finally to prepare for a study to evaluate cardiorespiratory training as a part of ESD service for patients with post-stroke fatigue. Methods In paper I, nine strategically chosen patients were interviewed of their experience of falling ill, the hospital stay, discharge, contact with health care after discharge and their request of support. Papers II-III describe and evaluate the development, content, implementation and effects of a locally adopted method for early supported discharge (Umeå Stroke Center ESD) in modern stroke care. Paper II included 153 consecutive patients and paper III, 30 232 patients with first-ever stroke registered in the Riksstroke registry in Sweden. Paper II evaluated number of patients/year, clinical and functional health status, satisfaction in relation to needs, accidental falls/other injuries and resources with the result summarized in a value compass. The implementation process was evaluated retrospectively by means of Consolidated Framework for Implementation (CFIR). Paper III evaluated patient reported outcome measurements (PROMs) at 3 months. The primary outcome in paper III was satisfaction with the rehabilitation after discharge. Secondary outcomes were information about stroke provided, tiredness/fatigue, pain, dysthymia/depression, general health status and dependence in activities of daily living (mobility, toilet hygiene and dressing). Multivariable logistic regression models for each PROM was used to analyze associations between PROMs and ESD/no ESD. In Paper IV, the Fatigue Assessment scale (FAS) was translated into Swedish and evaluated regarding psychometric properties when self-administered by persons with mild to moderate stroke. 72 consecutively patients selected from the stroke unit admission register received a letter including three questionnaires: the FAS, the Short Form Health Survey (SF-36) subscale for vitality and the Geriatric Depression Scale GDS-15. A second letter with FAS was sent within 2 weeks, for re-test evaluation. Paper V is a study protocol for a planned randomized controlled trial (RCT) of 50 consecutive stroke patients will who receive stroke unit care followed by ESD-service at Umeå Stroke Center, University Hospital, Umeå, Sweden. Paper V will investigate if a structured cardiorespiratory interval training program (CITP) added to the ESD-service may result in relieved post-stroke fatigue and increased oxygen uptake. Results The interviews in Paper I revealed three main categories with subcategories: “Responsible and implicated”, “Depersonalized object for caring measures” and “The striving for repersonalization and autonomy”. The findings indicate that coming home gave the informants’ important insights and understanding of the stroke, its consequences and was also an important factor for the recovery. Paper II-III showed that it is possible to develop and implement an adapted ESD service for stroke patients based on the patients’ experiences and requests, evidence-based recommendations and local conditions. The ESD service reduced dependence of activity, increased mobility with seemingly no increased risk of accidental falls or other injuries. The patient satisfaction in relation to needs regarding the ESD was high. Paper III showed that patients that received ESD were more satisfied with rehabilitation after discharge, had less need for assistance with ADL and less dysthymia/depression compared to patients that did not receive ESD. Study IV showed that the Swedish FAS used at home as a selfadministered questionnaire is a reliable and valid questionnaire for measuring fatigue in persons with mild to moderate stroke. The internal consistency was good, the agreement between the test and retest reliability for individual items (weighted kappa) was for the majority of items good or moderate. The relative reliability for total scores was good and the absolute reliability was 9 points. The Swedish FAS had no floor nor ceiling effects and correlated both with the SF-36, subscale for vitality and the GDS-15 indicating convergent construct validity, but not divergent construct validity. Conclusion It is possible to develop and implement ESD care for stroke patients based on patients’ experience and needs, evidence-based principles and local conditions. Early supported discharge (ESD) in the setting of modern stroke unit care appears to have positive effects on rehabilitation in the subacute phase. The Swedish FAS used at home as a self-administered questionnaire is reliable and valid for measuring fatigue in persons with mild to moderate stroke.

The principle aims of this work were two fold; firstly to identify the current dietary intakes (specifically dietary glycaemic carbohydrate (CHO)) and physical activity (PA) and cardiorespiratory fitness (CRF) levels of a UK, postpubertal, adolescent population (n = 105) and assess the relationship between these factors, adiposity and cardiometabolic health. Diet and health relationships were assessed whilst accounting for energy misreporting and controlling for levels of PA and CRF. The effect of excluding dietary misreporters on the associations between glycaemic CHO and health was assessed whilst comparing an established technique (the Goldberg equation) to a novel approach (the ratio of energy intake (EI) to energy expenditure (EE)), which utilised RT3 accelerometry data (EI:EE(RT3)). Associations of PA and metabolic risk factors were also assessed whilst comparing two child specific PA thresholds for the assessment of PA subcomponents. Secondly, the impact of a flexible, ad libitum, low GI dietary intervention on cardiometabolic health was examined in an „at risk‟, overweight, postpubertal, adolescent population. Glycaemic index (GI) but not glycaemic load (GL) was shown to be associated significantly with anthropometric measures (body mass index (BMI), waist circumference (WC)) and adiposity (body fat percentage (BF%)) in this general group of post-pubertal adolescents from Bedfordshire. When adjusting for dietary intake, CRF was also associated with adiposity but PA was not. The prevalence of misreporting varied depending on the method used to assess the validity of dietary intakes; between 23% and 31% increasing to 62.1% (in overweight) of adolescents under reported energy intakes and up to 11.1% over reported. The novel application of a triaxial accelerometer to measure EE resulted in more under and over reporters being identified than when compared to the widely used Goldberg equation. Increased dietary GI was associated with increased odds of having a high WC; however, associations between GL and other risk factors were less clear; no associations with risk were observed. Excluding dietary misreporters from analysis had important implications for these associations. Only after removal of misreporters by EI:EE(RT3) was a borderline significant positive association between GL and blood glucose (BG) revealed using multiple analysis of covariance (MANCOVA), that was not present in prior analyses. Increased GI (moderate vs low GI intake) was significantly associated with reduced high density lipoprotein cholesterol (HDL) and increased triglyceride (TG) levels (borderline significant) after removal of misreporters. In addition, using different PA thresholds to assess PA intensity resulted in different relationships between PA subcomponents and metabolic risk factors. Regardless of the threshold used, evidence suggested that limiting sedentary (SED) behaviour and engaging in moderate to vigorous PA (MVPA) is beneficial for blood pressure (BP) in this adolescent population. Additionally, irrespective of the threshold utilised, higher levels of vigorous PA (VPA) were associated with reduced odds of having a high clustered risk score and the associations observed between CRF and risk factors were stronger than those observed with PA. Despite a lack of significant improvement in individual metabolic risk factors as a result of the low GI (LGI) dietary intervention, there was a significant reduction in clustered risk score for the LGI group at week 12. A borderline significant improvement in glycated haemoglobin (HbA1c) was also observed as a result of the LGI intervention compared to those in the control group. Conversely, there appeared to be an unfavourable effect of the LGI diet on fasting insulin levels and thus the diet‟s impact on health overall is unclear. The small sample size of this randomised controlled trial (RCT) means that caution is required when interpreting the results. These data suggest that future research in this age group should target improvements in CRF and a lower dietary GI to reduce adiposity. Controlling for dietary misreporting appears to have a significant impact on associations of glycaemic CHO and cardiometabolic health and should be an important consideration of future research. The low GI intervention may be an effective approach for reducing glycaemic CHO, whilst maintaining a healthy macronutrient intake, in comparison to more restricted dietary regimens published in the literature. However, the impact of this regime needs to be confirmed utilising a larger sample of adolescents. This may provide a useful approach for future research aiming to assess the impact of reduced GI and GL.

A criterion method to evaluate cardiorespiratory health is measuring peak oxygen consumption (VO2 peak) from a maximal graded exercise test (GXT). While VO2 peak is a valuable measure, heart rate recovery (HRRec) and endothelial function (EF) also describe cardiorespiratory health and fitness. The purpose of this study was to investigate whether differences exist in VO2 peak, HRRec, and EF between healthy-weight (HW) and obese (OB) women and children and to determine if there were significant correlations among these variables. A total of 60 women and children participated in this study. Anthropometric, body composition, resting heart rate and blood pressure (BP) were measured. EF was evaluated to determine the reactive hyperemia index (RHI). Finally, each subject performed a graded exercise test (GXT) to determine VO2 peak. Following the GXT, the subjects’ recovery responses were monitored for 5 minutes. A factorial MANOVA was used to evaluate differences between obesity status and age in relative VO2 peak and relative HRRec. The MANOVA resulted in a significant (p < 0.001) main effect for obesity status and age, but there was no interaction effect. HW individuals had a greater relative VO2 peak compared to OB individuals. Children had a greater relative VO2 peak and HRRec compared to adults. Absolute VO2 peak and absolute HRRec were examined using univariate ANOVAs. Women had greater absolute VO2 peak values compared to children (p2 peak and absolute HRRec, relative HRRec, and RHI. Relative VO2 peak was significantly correlated to RHI. Absolute HRRec was correlated with relative HRRec and RHI. Relative HRRec was correlated with RHI. Lack of significant differences in HRRec and EF across adiposity levels were likely due to the obese, but otherwise healthy population recruited for this study. Age affected the response to all variables included in this study.

Adolescence is a developmental period during which boys and girls are at high risk of developing major or minor depression. Increases in fitness have been associated with lower levels of depressive symptomatology and improvements in psychological well-being, yet the mechanisms that underlie this relationship have not been thoroughly examined. Three such psychosocial variables (i.e. body satisfaction, social physique anxiety, and physical activity self-efficacy) have been identified as possible mechanisms and although they have theoretical support, additional research is needed to demonstrate empirically the potential effects of these variables. Self-report measures were used to assess the psychosocial variables and the Progressive Aerobic Cardiovascular Endurance Run (PACER) in conjunction with age, Body Mass Index [BMI], and sex was used to determine an estimate of aerobic capacity (VO2max). Path analyses were used to test the proposed model using version 6.2 EQS Multivariate Software. Results of study revealed that the boys’ and girls’ depressive scores were determined based on the extent that their fitness levels improved their satisfaction with their bodies and lowered the anxiety they experience in relation to real or imagined judgments of their physique. Although all pathways in the model were significant, with the exception of physical activity self-efficacy to depression, differences emerged between the boys and girls in terms of the strength of some of the relations amongst the variables. Limitations include restricted generalizability, self-report measures, and cross-sectional design. Results have implications for individuals in a context intended to improve physical and psychosocial well-being of adolescents.

Durante o exercício físico existe uma intensa mobilização encefálica promovendo a tensão muscular, alterações circulatórias e respiratórias. A hipótese é que áreas encefálicas envolvidas no controle cardiorrespiratório participam no exercício físico agudo. Foram utilizados ratos Wistar divididos em grupo exercício e grupo repouso. Houve redução dos níveis de PaCO2 e aumento da PaO2, sem alteração de pH, bicarbonato e lactato após o exercício. Houve aumento da imunorreatividade à Fos em relação ao grupo controle no NTSc, no NTSm, no BVLr, incluindo C1, no NPBL, no CPB, no KF, na PeF/HL, no HDM e no NPV. Ademais, os neurônios quimiossensíveis do NRT ativados representam 18% do total e recebem projeções da região PeF/HL. Neste trabalho, mostramos que após um exercício físico ocorre uma intensa ativação de possíveis áreas encefálicas importantes para o controle cardiorrespiratório, além dos neurônios quimiossensíveis do NRT envolvidos no controle respiratório durante o exercício físico, através da participação do comando central de vias hipotalâmicas. / During exercise there is an intense brain mobilization promoting muscle tension, respiratory and circulatory changes. We tested the hypothesis that brain areas involved in cardiorespiratory control could be activated during the acute physical exercise. Wistar rats were divided into exercise group and non-exercise group. There was decrease in PaCO2, increase in PaO2 and no changes in pH, bicarbonate and lactate after exercise. Increase in Fos immunoreactivity in cNTS, mNTS, VLM, C1 included, LPBN, KF, PeF/LH and PVN. Moreover, the chemosensitivity RTN neurons accounted for 18% of the total and receive projections from the PeF/LH. In the present study, we showed that after running acute exercise there is an intense activation of brain areas important for the cardiorespiratory control. Besides that, the chemosensitivity neurons of the RTN are activated after acute running exercise, showing that these particular subset of neurons have a role of the respiratory control during exercise, through the involvement of the \"central command\" of the hypothalamus.

Introdução: Em particular, não se sabe se o exercício físico termina com falha da homeostase metabólica em intensidades pertencentes ao domínio moderado, pesado e severo. Este estudo examinou as respostas fisiológicas durante exercícios de sobrecargas constantes até a exaustão, executadas em diferentes domínios metabólicos. Métodos: Dez homens saudáveis executaram quarto cargas constantes as quais corresponderam aos domínios de intensidade moderada (LL1), pesada (LL50% e LL2) e severa (LW25%). Parâmetros metabólicos e cardiorrespiratórios e a percepção subjetiva de esforço (PSE) foram medidos em intervalos regulares de tempo. Resultados: O tempo de exaustão em cada carga constante foi: 93,8 (&#177; 18,0), 77,0 (&#177; 22,9), 44,5 (&#177; 16,0) e 22,8 (&#177; 10,6) minutos em LL1, LL50%, LL2 e LW25%, respectivamente. Quando os dados foram analisados em relação ao tempo absoluto de exercício, significantes variações temporais foram encontradas na razão de trocas respiratórias (RER) e nas concentrações plasmáticas de potássio em LL1; no VO2, VCO2, RER, freqüência respiratória (FR), concentrações plasmáticas de norepinefrina e potássio em LL50%; na RER e nas concentrações plasmáticas de norepinefrina, epinefrina e potássio em LL2; em na RER e concentrações plasmáticas de lactato e potássio em LW25%. Quando os dados foram normalizados pelo tempo de exaustão, algumas significantes variações temporais desapareceram. Exceções foram encontradas para RER e potássio em LL1; RER em LL50%; RER, norepinefrina e potássio em LL2; VE, RR, lactato e potássio em LW25%. Entretanto, com exceção da FR, nenhum outro parâmetro metabólico ou cardiorrespiratório aumentou significantemente depois de decorrido 50% do tempo de exercício, em qualquer das intensidades executadas, indicando a presença de um estado de equilíbrio nas variáveis metabólicas e cardiorrespiratórias, em todos os domínios de intensidade analisados. De outro lado, a PSE apresentou aumentou significante depois de decorrido 50% do tempo de exaustão nos domínios pesado (LL50% e LL2) e severo (LW25%.), quando analisada em termos relativos ao tempo de exaustão. A taxa de incremento da PSE em função do tempo de exercício foi significantemente correlacionada ao tempo de exaustão (r = -0,72 à -0,84; P < 0.05) em todas os domínios de intensidade. Conclusão: A exaustão ocorreu sem clara evidência de falha na homeostase, mesmo em exercício de domínio de intensidade severa, uma vez que não houve significante variação temporal nos parâmetros metabólicos ou cardiorrespiratórios depois de decorrido 50% do tempo de exercício. Estes resultados poderiam sugerir um mecanismo de controle centralmente regulado durante o exercício / Introduction: We wished to determine whether exercise at moderate, heavy and severe intensities terminates with evidence of homeostatic failure. This study verified the physiological responses during exercise to exhaustion in different intensity domains. Methods: Ten healthy men performed prolonged exercise at four constant workloads corresponding to moderate (LT1), heavy (TT50% and LT2) and severe (TW25%) intensity domains. Metabolic and cardiorespiratory parameters and the rating of perceived exertion (RPE) were measured at fixed time intervals. Results: The time to exhaustion was 93.8 (&#177;18.0), 77.0 (&#177; 22.9), 44.5 (&#177; 16.0) and 22.8 (&#177; 10.6) minutes at LT1, TT50%, LT2 and TW25%, respectively. When data were analyzed according to absolute exercise duration, significant temporal variations were found in respiratory exchange ratio (RER) and plasma potassium concentrations in LT1; in VO2, VCO2, RER, respiratory rate (RR), plasma noradrenaline and potassium concentrations in TT50%; in RER, noradrenaline, adrenaline and potassium concentrations in LT2; and in RER and blood lactate and potassium concentrations in TW25%. When data were normalized to 100% of exercise duration, some significant temporal variations disappeared. Exceptions were RER and plasma potassium concentrations in LT1; RER in TT50%; RER and plasma noradrenaline and potassium concentrations in LT2; and VE, RR, blood lactate and plasma potassium concentrations in TW25%. Except for RR, no other cardiorespiratory or metabolic parameter increased significantly after the first 50% of any exercise bout had been completed, indicating the presence of a metabolic and cardiorespiratory steady state at all intensity domains. Conversely, RPE rose progressively in all constant workloads when analyzed in both absolute and relative terms. In addition, the slope at which RPE increased was significantly correlated to time to exhaustion (r = -0.72 to -0.84; P < 0.05) at all exercise intensities. Conclusion: Exercise terminated at all intensities without any indication of homeostatic failure. Since there was no significant variation in cardiorespiratory and metabolic parameters after the completion of 50% of any exercise bout these results might suggest a centrally-regulated control mechanism that defends homeostasis

Os objetivos desse estudo foram verificar as associações entre atividade física (AF) organizada fora da escola, aptidão cardiorrespiratória (APCR) e qualidade do sono com os indicadores de saúde mental em crianças e verificar se a AF organizada fora da escola ou a APCR eram moderadores da relação entre a qualidade do sono com os indicadores de saúde mental. É um estudo de corte transversal, desenvolvido em 232 crianças (118 meninos e 114 meninas) de uma escola de ensino fundamental da rede estadual da cidade de Porto Alegre - RS, selecionada por conveniência. A saúde mental foi avaliada através do Strengths and Difficulties Questionnaire, respondido pelos pais. A AF organizada fora da escola e qualidade do sono também foram reportados pelos pais, através de perguntas de uma anamnese. A APCR foi avaliada através do teste de corrida e caminhada de 6 minutos. Como covariáveis, o nível socioeconômico (NSE) foi verificado através de uma adaptação do questionário da ABEP, além do sexo e idade (indicados pelos pais). Para análise de dados utilizou-se estatística descritiva, regressão linear generalizada, correlação e análises de moderação. Os resultados indicaram que, nos meninos, a AF organizada fora da escola apresentou associação com o total de dificuldades (β= 2,691; p= 0,03) e sintomas emocionais (β= 1,528; p< 0,001). A APCR relacionou-se com o total de dificuldades (β= -0,013; p< 0,001), hiperatividade/déficit de atenção (β= -0,006; p< 0,001) e problemas de relacionamento com colegas (β= -0,002; p< 0,001). Nas meninas, houveram associações entre o NSE com o total de dificuldades (β= 2,783; p= 0,03) e hiperatividade/déficit de atenção (β= 1,245; p= 0,01), além da idade com os problemas de conduta (β= -0,136; p< 0,001). A qualidade do sono apresentou associação com total de dificuldades (r= -0,45; p< 0,001), sintomas emocionais (r= - 0,31; p= 0,001), problemas de conduta (r= -0,29; p= 0,001), hiperatividade/déficit de atenção (r= -0,43; p< 0,001), e os problemas de relacionamento com colegas (r= - 0,25; p< 0,001), nos meninos. Já nas meninas a qualidade do sono associou-se com o total de dificuldades (r= -0,27; p< 0,001), sintomas emocionais (r= -0,18; p= 0,05), e problemas de conduta (r= -0,25; p= 0,01). A AF organizada fora da escola e APCR não foram moderadoras da relação entre a qualidade do sono e os indicadores de saúde mental. Diante das associações, conclui-se que crianças que mantém hábitos saudáveis como dormir bem, praticar AF organizada fora da escola e ter bons níveis de APCR, apresentam melhores níveis de saúde mental. / The aims of the present study were to verify the associations between organized physical activity (PA) outside school, cardiorespiratory fitness (CRF) and sleep quality as indicators of mental health in children, and to verify if organized PA outside school or CRF were moderators of the relationship between sleep quality with mental health indicators. It is a cross-sectional study, developed with 232 children (118 boys and 114 girls) of a public from Porto Alegre - RS, selected by convenience. Mental health was assessed through the Strengths and Difficulties questionnaire, answered by the parents. Also, the parents, through an anamnesis, reported organized PA and sleep quality. CRF was evaluated through the running and walking test of 6 minutes. As covariates, socioeconomic status was obtained by an adaptation of the ABEP questionnaire, in addition to gender and age. To data analysis were used descriptive statistics, generalized linear regression, correlation and moderation analyzes. The results indicated that, in boys, organized PA outside school showed association with total difficulties (β= 2.691; p= 0.03) and emotional symptoms (β= 1.528; p< 0.001). CRF was related with total difficulties (β= -0.013; p<0.001), hyperactivity/attention deficit (β= -0.006; p<0.001) and relationship problems with colleagues (β= -0.002; p< 0.001). In girls, there was an association between socioeconomic status with total difficulties ((β= 2.783; p= 0.03) and hyperactivity/attention deficit (β= 1.245; p= 0.01), besides age with conduct problems (β= -0.136; p<0.001). Sleep quality was associated with total difficulty (r= -0.45; p<0.001), emotional symptoms (r= -0.31; p=0.001), behavioral problems (r= -0.29; p=0.001), hyperactivity/attention deficit (r= - 0.43; p<0.001) and relationship problems with colleagues (r= -0.25; p<0.001), in boy. Already in girls, sleep quality was associated with total difficulties (r= -0.27; p<0.001), emotional symptoms (r= -0.18; p= 0.05) and behavioral problems (r= -0.25; p=0.01). Organized PA outside school and CRF were not moderators of the relationship between sleep quality and mental health indicators. Considering the associations, it is concluded that children who maintain healthy habits, such as sleeping well, practicing organized PA outside of school and having good levels of CRF, present better levels of mental health.