O presente estudo teve por objetivo obter evidências da validade de identificação dos limiares de lactato e de percepção subjetiva de esforço (PSE) em teste de campo, comparando com o desempenho, em ciclistas de estrada. Esta é uma modalidade em que a aptidão aeróbia é uma importante determinante de desempenho; porém, haja vista que o VO2máx parece sofrer poucas alterações com o treinamento, são interessantes outras variáveis que permitam um efetivo e acessível planejamento e controle do treinamento. Testes de campo respeitam a especificidade do treinamento, avaliando atletas em situações próximas da realidade do esporte. Neste sentido, as concentrações de lactato sangüíneo ([La]) e a PSE parecem ferramentas eficazes através de seus limiares e correspondentes valores de FC e velocidade. Foram realizados dois testes: avaliação do desempenho (Teste de 40 km) e um teste de campo com intensidades crescentes controladas por valores fixos de FC (135±5, 145±5, 155±5, 165±5 bpm e esforço máximo), em circuito de 5 km, com registro das velocidades, [La], FC e PSE e posterior identificação dos limiares através do método Dmáx. Os LL também foram identificados a partir de concentrações fixas de 2, 3 e 4 mmol.L-1. A normalidade da amostra foi determinada por Kolmogorov-Smirnov; a comparação entre os métodos de identificação dos limiares em campo através de ANOVA de Um Fator e a comparação das relações entre os limiares obtidos nos testes CR-40 km e 5x5 km pela Correlação de Pearson, além do Teste de Friedman para comparação entre as médias dos limiares. Os resultados demonstraram a possibilidade de utilização do LL4 como preditor de desempenho, além de indicarem associações significativas entre a FC e a PSE e entre La e FC / The present study had the objective to obtain validity evidences of identificating lactate and rate of perceived exertion (RPE) metabolic thresholds in field tests, comparing them to performance, in road cyclists. Road cycling is a sport in which aerobic condition is an important performance determinant; however, considering that VO2max seems not to change with the training season, it is necessary that other condition markers can be used, leading, this way, to an effective and acessible training plan and control. Field tests respect the training principle of specificity, evaluating athletes in situations as closest as possible from the sports reality. Concerning to this, blood lactate concentrations ([La]) and RPE have shown to be efficient tools for that, throughout the identification of their thresholds and corresponding heart rate and velocity values. Cyclists developed a performance test (40 km TT) and a field test in which intensity was controled by HR fixed values (135±5, 145±5, 155±5, 165±5 bpm and maximal effort), in a 5 km extension circuit, with velocities, [La], HR, and RPE records, and posterior thresholds identification by the Dmax method. LT were also identified from fixed [La] of 2, 3, and 4 mmol.L-1. The sample degree of normality was determined by the Kolmogorov-Smirnov test; the comparision between the field thresholds identification methods were calculated by One-Factor ANOVA, and the comparision of the relationship between the thresholds obtained in the CR40 and in the field tests by Pearsons correlation, besides the use of Friedman test for comparing the thresholds mean values. Results presented the possibility of utilizing LL4 in order to predict performance in field tests, and also showed a significative association between HR and RPE and La and HR

Os efeitos da glicemia materna na regulação da freqüência cardíaca fetal (FCF) constituem aspecto controverso na literatura, principalmente em gestações complicadas pelo diabetes mellitus. O objetivo deste trabalho foi estudar a influência da glicemia materna na FCF analisada pela cardiotocografia computadorizada. Método: Trinta e nove gestantes com diabetes mellitus pré-gestacional foram avaliadas prospectivamente na Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, no período compreendido entre julho de 2003 e fevereiro de 2005. As pacientes incluídas possuíam o diagnóstico de diabetes pré-gestacional, gestação única, idade gestacional entre 36 e 40 semanas e ausência de malformações fetais. Para a realização do estudo, cada paciente foi avaliada pela cardiotocografia computadorizada, durante uma hora, sendo analisados os seguintes parâmetros da FCF: freqüência basal, tempo para atingir os critérios de normalidade, freqüência de movimentos fetais, número de contrações uterinas, número de acelerações e desacelerações, episódios de alta e baixa variação, variação de curto prazo. Realizou-se a glicemia capilar imediatamente antes do início da cardiotocografia, 30 e 60 minutos após o começo do exame. Utilizou-se a média glicêmica para análise das relações com os achados cardiotocográficos, com os valores de corte de 100 mg/dL e 120mg/dL. Resultados: Do total de 39 pacientes analisadas, 25 (64,1%) apresentavam média glicêmica &#8805; a 100 mg/dL e 19 (48,7%) &#8805; a 120 mg/dL. A média da FCF mostrou aumento significativo nos grupos com a média glicêmica &#8805; a 100 mg/dL (p<0,05) e a 120mg/dL (p<0,05). Houve correlação positiva significativa (p<0,05 e r=0,57) da FCF com a média glicêmica no exame. Verificou-se correlação negativa significativa (p<0,05) da quantidade de acelerações transitórias acima de 10 bpm (r=-0,32) e de 15 bpm (r=-0,44) com a média glicêmica no exame. A variação de curto prazo da FCF apresentou associação significativa (p<0,05) com a média glicêmica acima de 120mg/dL. Ocorreu correlação negativa significativa (p<0,05) da variação de curto prazo da FCF (r=-0,47) com a média glicêmica no exame. Os demais parâmetros avaliados pela cardiotocografia computadorizada não mostraram diferença significativa com a média glicêmica. Conclusão: os níveis glicêmicos maternos, durante o exame, exercem influência sobre parâmetros da FCF analisada pela cardiotocografia computadorizada. / The effects of maternal glycemia over the of fetal heart rate (FHR) regulation appoint a controversial subject in the literature, mainly in pregnancies affected by diabetes mellitus. The objective of this research was to investigate the influence of maternal glycemia in the FHR indices analysed by computerized cardiotocography. Methods: Thirty nine patients with pre-gestational diabetes mellitus were examined prospectively in the Obstetrics Department of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo- Brazil in a period of time between July of 2003 and February of 2005. The patients included had pre-gestational diabetes diagnosis, single pregnancy, gestational age between 36 and 40 weeks and absent of fetal malformations. Each patient were evaluated by computerized cardiotocography during 60 minutes, with analysis of these follow FHR parameters: basal FHR, time necessary to reach normality criteria, fetal movements rate, contraction peaks, accelerations and decelerations, episodes of high and low FHR variation, short-term FHR variation. The capillary glycemia were colleted immediately before the cardiotocography be performed, 30 and 60 minutes after the beginning of the exam. The glicemic mean level was used for analysis with the cardiotocografics results, with the cut values of 100 mg/dL and 120mg/dL. Results: From 39 patients studied, 25 (64,1%) presented glicemic mean &#8805; to 100 mg/dL and 19 (48,7%) &#8805; to 120 mg/dL. 1) The mean of FHR showed significant elevation in the groups with the glicemic mean &#8805; to 100 mg/dL and to 120mg/dl (p<0,05); 2) There was significant positive correlation (p<0,05 and r=0,57) between the FHR and the mean glicemic; 3) There was significant negative correlation (p<0,05) between the number of transitory accelerations &#8805; than 10bpm (r=-0,32) and &#8805; than 15 bpm (r=-0,44) and the mean glicemic; 4) The short-term FHR variation presented significant association (p<0,05) with the mean glicemic &#8805; 120mg/dL; 5) There was significant negative correlation (p<0,05) between short-term FHR variation (r=-0,47) and the mean glicemic. The others indices evaluated by computerized cardiotocography didn’t exhibit significant difference with the mean glicemic. Conclusions: The maternal glicemic levels during computerized cardiotocography seem to have influence over these analised FHR parameters.

This research compares methods for measuring pilot mental workload (MWL) from the electrocardiogram (ECG) signal. ECG-based metrics have been used extensively in MWL research. Heart rate (HR) and heart-rate variability (HRV) exhibit changes in response to varying levels of task demand. Classical methods for HRV analysis examine the ECG signal in the linear time and frequency domains. More contemporary research has advanced the notion that nonlinear elements contribute to cardiac control and ECG signal generation, spawning development of analytical techniques borrowed from the domain of nonlinear dynamics (NLD). Applications of nonlinear HRV analysis are substantial in clinical diagnosis settings; however, such applications are less frequent in MWL research, especially in the aviation domain. Specifically, the relative utility of linear and non-linear HRV analysis methods has not been fully assessed in pilot MWL research. This thesis contributes to aforementioned research gap by comparing a non-linear HRV method, utilizing transition probability variances (TPV), to classical time and frequency domain methods, focusing the analysis on sensitivity and diagnosticity. ECG data is harvested from a recent study characterizing spatial disorientation (SDO) risk amongst three candidate off-boresight (OBS) helmet-mounted display (HMD) symbologies in a tactically relevant live-flight task. A comparative analysis of methods on this dataset and supplemental workload analysis for the HMD study are presented. Results indicate the TPV method may exhibit higher sensitivity and diagnosticity than classical methods. However, limitations of this analysis warrant further investigation into this question.

Recently, the body mass of college football lineman has increased markedly and places them at higher risk for a number of postcompetitive pathogenic chronic health consequences. Recognition of problems associated with oversized athletes is easily accepted intellectually–however, the practicalities of solving the problem have not been fully realized.

Firefighting is a strenuous occupation that increases the risk of cardiovascular events. Greater levels of physical fitness and training improve firefighters’ occupational performance, but little is known whether they are related to lower physiological stress and recovery from fire ground tasks. Heart rate, heart rate recovery and heart rate variability have been used to evaluate physical stress in association with exercise and fire ground tasks. However, there is a paucity of research evaluating the effects of physical fitness and training on heart rate dynamics during a simulated fire ground test (SFGT). Therefore, the primary purposes of this study were to evaluate the relationships between heart rate dynamics during a SFGT and to determine the effects of physical characteristics, fitness and physical training on these measures. The secondary purpose was to assess the relationship between maximal pace SFGT time and heart rate responses from a standardized pace SFGT. This information will help to understand the relationship between occupational performance and level of physical stress associated with work on the fire ground. Twenty-one firefighter academy recruits (Age = 28.4 ± 4.0 yr; Height = 177.1 ± 6.9 cm; Body mass = 88.3 ± 15.4 kg) participated in this cross-sectional and longitudinal study. The subjects completed a battery of physical fitness tests, including a 1.5-mile run, maximal pull-ups, push-ups, sit-ups, and isometric plank hold. In addition, the subjects completed a standardized pace SFGT that consisted of typical fire ground tasks performed in succession, without recovery (i.e., high-rise pack carry, hose drag, equipment carry, ladder raise, forcible entry, search, and victim rescue tasks). Heart rate variability was measured pre- and post-SFGT, and heart rate and 60 s heart rate recovery were measured during and post-SFGT, respectively. After a 10 wk physical training intervention, composed of approximately four physical training sessions per week, the measurements were repeated. A subsample of the original cohort (n = 11) also completed a maximal pace SFGT where their completion time was used as a measure of work capacity. Independent variables for this study included the physical and fitness test measures, physical training and maximal pace SFGT completion time. Dependent variables for this study were mean heart rate reserve during the SFGT (HRRes), difference between resting and mean heart rate during SFGT (HRSFGT-Rest), 60-second heart rate recovery (HRR60), and the difference between resting and post-SFGT root mean square of standard deviation between consecutive heart beats in logarithmic scale (LnRMSSDPost-Rest) measured with standardized pace SFGT. Independent and dependent variables were obtained at baseline and after physical training. Pearson r correlation coefficient was used to evaluate associations between outcome measures. Dependent samples t-test was used to compare differences in outcome measures at baseline and following physical training. Linear regression was used to evaluate the association between independent and dependent variables with standardized pace SFGT at baseline. Linear regression was used to assess the relationship between maximal pace SFGT time and outcome measures during the standardized pace SFGT. The level of significance was set as p ≤ 0.05 for all statistical analyses. In the standardized pace SFGT there was a positive correlation between HRSFGT-Rest and HRRes (R = .79, p < .01). LnRMSSDPre-Post was positively correlated with HRRes (R = .47; p < .05) HRSFGT-Rest (R = .70; p = .01) and HRPost-Rest (R = .84; p < .01). There was also a significant inverse correlation between HRPost-Rest and HRR60 (R = -.46; p < .05). Greater height and fat-free mass were favorably associated with HRSFGT-Res (R2 = .57; p = .02), HRRes (R2 = .55; p = .003) and HRPost-Rest (R2 = .59; p = .02). Height was also associated with attenuated depression of LnRMSSDRest-Post. After accounting for the effect of other independent variables in the multiple linear regression models, height was the only significant predictor for HRSFGT-Rest (β = -.90), HRRes (β = -.64), HRPost-Rest (β = -.76) and LnRMSSDRest-Post (β = -.06). A significant decrease in HRRes (80.1 ± 6.7% vs. 76.0 ± 6.7%; p < 0.001) and increase in HRR60 (29.4 ± 8.3 b∙min-1 vs. 37.8 ± 9.0 b∙min-1; p < .001) were observed after the physical training intervention. There was a significant correlation between maximal pace SFGT time and the standardized pace SFGT HRR60 (R = -0.70; p = 0.02), but not with other dependent variables. In summary, these findings indicate that greater cardiovascular demand during fire ground tasks is related to greater physical stress and lower parasympathetic activity during recovery. Greater height and fat-free mass as well as physical training are associated with lower physiological stress and accelerated recovery from fire ground tasks. Support for relationships between work capacity and heart rate dynamics during a standardized submaximal pace SFGT is limited, indicating that independent SFGT conditions may be necessary to provide work capacity and health information, respectively.

Left coronary blood flow (LCBF), left ventricular oxygen, extraction [(a-v)O₂ ], and myocardial oxygen consumption (MVO₂) were monitored in 10 dogs. HR was paced at 120 bpm and then increased to 180 bpm to elicit a hyperemic response (ΔLCBF). During the hyperemia, the vaso-dilatory response to exogenous adenosine (F_AD) was tested. Twenty min. after injection of aminophylline (100 mg/i.v.), HR was again increased. F_AD was again tested. The pacing-induced increase in MVO₂ (ΔMVO₂) was not affected by aminophylline (P>0.05). However, the slope ΔLCBF/ΔMVO₂ was decreased, and the slope (a-v)O₂ /ΔMVO₂ was increased. F_AD was also decreased and the magnitude of the reduction was correlated with the decrease in ΔLCBF/ΔMVO₂ (r=0.82). These results suggest that adenosine may play an role in coronary functional hyperemia induced by increases in heart rate.

Background The canine cardiac system has been the model against which many Class III cardiac devices are validated. Thus, it is expected that the canine heart has very similar electrical model to that found in humans. In 1999, the absence of Heart Rate Turbulence (HRT) after a single Pre-Ventricular Contraction (PVC) was linked to high-risk patient after acute myocardial infarction. Studies of HRT were performed on high-risk patients with Holter-Monitors as were most subsequent HRT studies. If HRT could potentially be used as a risk factor of heart disease, it is interesting to study whether HRT is present following a PVC in otherwise healthy canines. Methods For multiple months, five non-medicated, healthy canines were chronically monitored from between 1 and 8 sessions each. At each session, the canines were ventricularly paced to induce PVCs. Electrical signals, as seen through both a right-ventricular lead and Electrocardiogram (ECG) signals, were captured and analyzed to determine whether the canines displayed HRT following each induced PVC. As a contrasting data set, for the majority of the canines, data was also collected once the canines were sedated. Results HRT was noted in all non-medicated and healthy canines. Of the two factors of HRT (slope and onset), TS was the most prominent indicator of HRT. In each canine, the slope was far greater than the 2.5 ms per RR interval threshold varying from 9.8 to 68.8 ms per RR interval. The onset was marked as HRT (onset less than 0%) in 22 of the 26 session. Additional data was analyzed for healthy yet medicated canines showed that sedation affected HRT, but that HRT was generally noted. Conclusion The canine model displayed a similar HRT characteristic as humans during normal and parasympathetic inhibited states. The presence of HRT in canines is most reliable when using TS. Further study in this area with naturally occurring PVCs would be of interest.

Anxiety Sensitivity (AS), the belief that anxiety-related sensations may have harmful implications, can alter autonomic nervous system (ANS) function. Exercise has previously been shown to reduce AS; however, the effects of an exercise intervention on heart rate variability (HRV), a measure of ANS function, has not been evaluated in individuals with high AS. This study sought to 1) compare resting HRV in individuals with either low (LAS) or high AS (HAS) and 2) evaluate the effects of a 2-week exercise intervention on HRV and AS. Using the Anxiety Sensitivity Index (ASI-3), participants were identified as LAS (n=9; ASI-3=5.89±1.39) or HAS (n=15; ASI-3=32.87±2.49) and subsequently completed six 20-minute moderate intensity exercise sessions. HRV and psychosocial measures were obtained at baseline and following the 2-week intervention. No significant differences (p>0.05) in time or frequency domain HRV values between groups were revealed at baseline; however, when considering the HAS group alone, strong associations were observed between the ASI-3 score and HRV values in the time domain: RMSSD (r=-0.56), SDNN (r=-0.61), and pNN50 (r=-0.53). Following the intervention, changes observed in HRV and the higher and lower order (subscale) ASI-3 scores were not different between the groups; however, a medium to large effect was observed for the higher order ASI-3 and the cognitive subscale score, suggesting that our findings were likely limited by the small sample size. Further research is warranted to evaluate the relationship between HRV and AS and should seek to determine the most effective exercise interoceptive exposure for improving AS symptomology.

Freshwater mussels are a viable option to detect real-time changes in water quality within aquatic ecosystems. Known as ecosystem engineers, freshwater mussels are constantly filtering particles and recycling nutrients in the benthic community. Therefore, identifying their physiological responses to alterations in water quality will enable mussels to not only serve as biomonitors but help model their impact on nitrogen cycle. This research focuses on identifying how mussel gape and heart rate respond to the addition of phytoplankton following a period of limited food availability. Immediately following phytoplankton addition, mussels show a decreased gape position linked with changes heart rate. As the gape returns to an open position, overlying ammonia concentrations increase showing an end of the metabolism process. As a result, pairing physiological changes with increased concentrations of phytoplankton, freshwater mussels' impact on ammonium concentrations can be accurately predicted. By inputting experimental excretion rates combined with variations in gape position, dynamic models will be simulate ammonium concentrations in the overlying water.

Numerous agencies have accumulated evidence since 1964 which implicates habitual cigarette smoking as a causal or facilitating factor in the development of many circulatory and respiratory diseases. This study sought to identify those psychological variables which possibly contribute to the maintenance of cigarette smoking and therefore, had two main purposes. First, this study investigated the individual and simultaneous physiological changes, i.e., Electroencephalography, Electromyography, Heart Rate, Blood Pressure and Skin Temperature that occurred during and immediately after the smoking of one cigarette. Second, the study investigated the hypothesis that smoking frequency would decrease when individuals were trained via biofeedback procedures to increase 8-12 Hz occipital EEG activity as a substitute for smoking. Three male, very heavy smokers (35 or more cigarettes per day ) and three male moderate smokers (15-24 cigarettes per day) physiologies were monitored while smoking, non-smoking and while they were provided with 8-12 Hz occipital EEG biofeedback training using a multiple baseline design. Results of the study indicate that of the six smokers physiologically monitored, four or more of the smokers demonstrated the following physiological changes while actually smoking one cigarette: the percent of time producing 4-8 cycles per second bra .in waves increased (S2 ,S3 ,S5); heart rate (beats per minute) increased (Sl,S2,S3,S4,S5,S6); and the percent of time producing 8-12 cycles per second (Hz) brain waves decreased (Sl,S2,S3,S4,S5,S6). Immediately after the smoking of one cigarette, four or more of the smokers demonstrated an increase in their rates (Sl,S2,S3,S4,S5, S6) and subjects 1,4,5 and 6 demonstrated an over-the-entire-session decrease in their skin temperatures. There did not appear to be any specific consistent brain wave changes across the subjects. However, the following subject-specific brain wave changes were evident: Subject 1 data indicates an increase in Alpha brain waves (8-12 Hz), a decrease in Theta brain waves (4-8 Hz), and a decrease in Beta brain waves (12-20 Hz). Subject 2 data indicates a decrease in Alpha brain waves, an increase in Theta brain waves, and a decrease in Beta waves. Subject 3 data indicates an Alpha wave decrease, Theta wave increase, and Beta wave increase. Subject 4 data indicates an Alpha wave decrease, Theta wave increase, and no observable change in Beta activity. Subject 5 data indicates an Alpha increase, a Theta decrease, and no observable change in Beta activity. Subject 6 data indicates an Alpha decrease, a non-observable change in Theta production and an increase in Beta activity. During the training period, when the smokers were given music feedback whenever they produced 8-12 Hz, four of the six smokers learned to increase the percent of time producing 8-12 Hz, (Sl,S2,S5, S6). Two of these four smokers were able to continue producing high levels of 8-12 Hz activity without the use of biofeedback equipment (Sl,S2). These smokers had quit smoking completely at the end of a six-month follow-up period. These two smokers were contacted by phone at the eight-month follow-up period and reported they were still absent from any cigarette smoking. The four smokers who could not increase their 8-12 Hz activity without the use of 8-12 Hz auditory feedback (Phase D) decreased their frequency of cigarette smoking at the six-month follow-up period as follows: Subject 3, from 38 to 15 cigarettes smoked per day; Subject 4, from 50 to 44 cigarettes smoker per day; Subject 5, from 18 to 8 cigarettes smoked per day; and Subject 6, from 17 to 10 cigarettes smoked per day. Possible reasons why Subjects 1 and 2 quit smoking are discussed and directions for future research are presented.