Estudio del umbral anaerobio en nadadores que entrenan en Bogotá a 2600 metros de altitud / Study of the anaerobic threshold of swimmers training in Bogotá at an altitude of 2 600 meters

Introducción: Las altitudes intermedias entre 1500-3000 m sobre el nivel del mar generan cambios en el metabolismo basal, incrementados con el entrenamiento físico en deportes donde predominan esfuerzos aerobios superiores a tres minutos. Objetivo: Determinar el umbral anaerobio para nadadores que entrenan en Bogotá a 2600 m de altitud. Métodos: Fueron evaluados treinta nadadores: 12 mujeres y 18 hombres de las categorías juvenil y mayores, entre 16-24 años, modalidades bialetas, natación de carreras y deportistas que se preparan para campeonatos nacionales, se les aplicaron las siguientes mediciones: prueba de 30 min de natación continua, medición de la frecuencia cardíaca al inicio y final de la prueba, medición de ácido láctico al finalizar, análisis corporal y máximo consumo de oxígeno. Los registros de las mediciones fueron analizados estadísticamente. Resultados: Se encontraron al final de la prueba de los 30 min de natación continua, concentraciones de ácido láctico para los hombres de hasta 14 mmol/L, 9 para las mujeres y frecuencias cardíacas máximas y submáximas. En cuanto a los porcentajes de grasa, el promedio de los mejores para las mujeres fue de 20 y para los hombres 10 y porcentajes de masa muscular 33 para las mujeres y 41 para los hombres. Conclusiones: Los registros de ácido láctico en altitudes intermedias son muy superiores a las propuestas en la bibliografía existente para determinar el umbral anaeróbico, al igual que la frecuencia cardíaca, los porcentajes de grasa corporal promedio para hombres es 10 y para mujeres 20. La prueba de 30 min puede ser adecuada para determinar la velocidad de umbral anaerobio en altitudes intermedias, el volumen de entrenamiento de dicha capacidad puede ser equivalente al obtenido en ella y puede ser fraccionado utilizando distancias de 200 m, con pausas breves entre 10 y 30 s(AU)

Introduction: Intermediate altitudes between 1 500 and 3 000 above sea level bring about changes in basal metabolism, which are increased by physical training in sports with a predominance of aerobic efforts extending for more than three minutes. Objective: Determine the anaerobic threshold of swimmers training in Bogotá at an altitude of 2 600 meters. Methods: Thirty swimmers were evaluated: 12 women and 18 men from the youth and senior categories, age 16-24 years, bifin modes, racing swimming, and sportspeople training for national championships. The following measurements were taken: 30-min continuous swimming test, heart rate at the start and end of the test, lactic acid at the end, body analysis and maximal oxygen consumption. Measurement records were analyzed statistically. Results: At the end of the 30-min continuous swimming test lactic acid concentrations were up to 14 mmol/l for men and 9 mmol/l for women, and heart rates maximal and submaximal. The best mean body fat percentages were 20 for women and 10 for men, whereas muscle mass percentages were 33 for women and 41 for men. Conclusions: Lactic acid and heart rate values at intermediate altitudes were found to be much higher than those proposed by the existing bibliography to determine the anaerobic threshold. Mean body fat percentages were 10 for men and 20 for women. The 30-min test may be appropriate to determine the anaerobic threshold speed at intermediate altitudes. The training volume for that capacity may be equivalent to the one obtained from it, and may be split up using 200-meter distances with brief pauses of 10 to 30 seconds(AU)

Physiological profile of adult male long-distance trail runners: variations according to competitive level (national or regional) / Perfil fisiológico de corredores de trilhas de longa distância adultos do sexo masculino: variações segundo o nível competitivo (nacional ou regional)

ABSTRACT Objective To describe and identify the importance of different indicators of the aerobic and anaerobic fitness of male ultra-trail runners according to their level of participation (regional or national). Methods Forty-four male ultra-trail runners were assessed (36.5±7.2 years). They were classified as regional (n=25) and national (n=19). Wingate test was used to assess the anaerobic pathway. A progressive incremental running test was performed and ventilatory thresholds registered, in parallel to heart rate and lactate concentration at the end of the protocol. Comparison between groups was performed using independent samples t-test. Results No significant differences were found between outputs derived from Wingate test. For aerobic fitness, while examining absolute values, differences were uniquely significant for the second ventilatory threshold (ultra-trail regional runners: 3.78±0.32L.min-1; ultra-trail national runners: 4.03±0.40L.min-1 p<0.05). Meantime, when aerobic fitness was expressed per unit of body mass, differences were significant for the second ventilatory threshold (ultra-trail regional runners: 50.75±6.23mL.kg-1.min-1; ultra-trail national runners: 57.88±4.64mL.kg-1.min-1 p<0.05) and also maximum volume of oxygen (ultra-trail regional runners: 57.33±7.66mL.kg-1.min-1; ultra-trail national runners: 63.39±4.26mL.kg-1.min-1 p<0.05). Conclusion This study emphasized the importance of expressing physiological variables derived from running protocols per unit of body mass. Also, the second ventilatory threshold appears to be the best and the only aerobic fitness variable to distinguish between trail runners according to competitive level. Maximal oxygen uptake seems of relative interest to distinguish between long distance runners according to competitive level.

RESUMO Objetivo Descrever e comparar indicadores de aptidão metabólica em corredores de trilhas de longa distância (ultra trail running) adultos do sexo masculino, de acordo com o nível de competição (regional ou nacional). Métodos Foram avaliados 44 corredores masculinos com média de idade de 36,5±7,2 anos classificados como de nível regional (n=25) ou nacional (n=19). Foi utilizado o teste de Wingate para avaliação da via anaeróbica, enquanto o teste incremental de corrida em esteira também foi realizado para determinar os limiares ventilatórios, o consumo máximo de oxigênio, a frequência cardíaca e a concentração de lactato ao final do protocolo. A comparação entre os grupos foi realizada por estatística teste t para amostras independentes. Resultados As variáveis obtidas do teste Wingate não diferiram de forma significativa entre os grupos. No que diz respeito à aptidão aeróbica, foram encontradas diferenças significativas entre variáveis expressas em valores absolutos no segundo limiar ventilatório (corredores de nível regional: 3,78±0,32L.min-1; corredores de nível nacional: 4,03±0,40L.min-1; p<0,05). Quando considerados os valores expressos por unidade de massa corporal, o segundo limiar ventilatório (corredores de nível regional: 50,75±6,23mL.kg-1.min-1; corredores de nível nacional: 57,88±4,64mL.kg-1.min-1; p<0,05) e o volume máximo de oxigênio (corredores de nível regional: 57,33±7,66mL.kg-1.min-1; corredores de nível nacional: 63,39±4,26mL.kg-1.min-1; p<0,05) também diferiram de forma significativa. Conclusão Este estudo destacou a importância de se expressarem variáveis fisiológicas derivadas de protocolos de corrida por unidade de massa corporal. Além disso, o segundo limiar ventilatório pareceu ser o melhor e único indicador de aptidão aeróbica para a diferenciação de corredores de trilha de longa distância, segundo o nível competitivo. O consumo máximo de oxigênio não é especialmente relevante para distinguir os corredores de trilha de longa distância, segundo o nível competitivo.

Test-Retest Reliability of Non-Invasive Cardiac Output Measurement during Exercise in Healthy Volunteers in Daily Clinical Routine / Confiabilidade Teste-Reteste de Medição Não-Invasiva de Débito Cardíaco durante Exercício em Voluntários Saudáveis sob Condições Clínicas de Rotina

Abstract Background: Thoracic bioreactance (TB), a noninvasive method for the measurement of cardiac output (CO), shows good test-retest reliability in healthy adults examined under research and resting conditions. Objective: In this study, we evaluate the test-retest reliability of CO and cardiac power (CPO) output assessment during exercise assessed by TB in healthy adults under routine clinical conditions. Methods: 25 test persons performed a symptom-limited graded cycling test in an outpatient office on two different days separated by one week. Cardiorespiratory (power output, VO2peak) and hemodynamic parameters (heart rate, stroke volume, CO, mean arterial pressure, CPO) were measured at rest and continuously under exercise using a spiroergometric system and bioreactance cardiograph (NICOM, Cheetah Medical). Results: After 8 participants were excluded due to measurement errors (outliers), there was no systematic bias in all parameters under all conditions (effect size: 0.2-0.6). We found that all noninvasively measured CO showed acceptable test-retest-reliability (intraclass correlation coefficient: 0.59-0.98; typical error: 0.3-1.8). Moreover, peak CPO showed better reliability (intraclass correlation coefficient: 0.80-0.85; effect size: 0.9-1.1) then the TB CO, thanks only to the superior reliability of MAP (intraclass correlation coefficient: 0.59-0.98; effect size: 0.3-1.8). Conclusion: Our findings preclude the clinical use of TB in healthy subject population when outliers are not identified.

Resumo Fundamento: A biorreatância torácica (BT), um método não invasivo destinado à medição do débito cardíaco (DC), mostra boa confiabilidade teste-reteste em adultos saudáveis examinados em condições de pesquisa e repouso. Objetivo: No presente estudo, avaliamos a confiabilidade teste-reteste da avaliação do DC e trabalho cardíaco (TC) durante exercício, avaliado por BT em adultos saudáveis sob condições clínicas de rotina. Métodos: 25 indivíduos realizaram teste ergométrico gradual sintoma-limitante em ambiente ambulatorial em dois dias diferentes, com intervalo de uma semana. Parâmetros cardiorrespiratórios (trabalho cardíaco, VO2máx) e hemodinâmicos (frequência cardíaca, volume sistólico, DC, pressão arterial média, TC) foram medidos em repouso e continuamente sob exercício utilizando sistema espiroergométrico e cardiógrafo de biorreatância (NICOM, Cheetah Medical). Resultados: Após 8 participantes terem sido excluídos devido a erros de medição (outliers), não houve viés sistemático em nenhum dos parâmetros em todas as condições (tamanho do efeito: 0,2-0,6). Observamos que todos os débitos cardíacos medidos de forma não invasiva apresentaram níveis aceitáveis de confiabilidade teste-reteste (coeficiente de correlação intraclasse: 0,59-0,98; erro típico: 0,3-1,8). Além disso, TC máximo apresentou melhor confiabilidade (coeficiente de correlação intraclasse: 0,80-0,85; tamanho do efeito: 0,9-1,1), seguido do DC pela BT, graças apenas à confiabilidade superior da PAM (coeficiente de correlação intraclasse: 0,59-0,98; tamanho do efeito: 0,3-1,8). Conclusão: Nossos achados impedem o uso clínico da BT em indivíduos saudáveis quando outliers não forem identificados.

Heart rate deflection point as an alternative to determining the anaerobic threshold in dyslipidaemic patients

Aim: The aim of the present study was to verify the agreement between the ventilatory method (VT) and the alternative method of heart rate deflection point (HRDP) in determining the anaerobic threshold (AT) during incremental treadmill test in dyslipidaemic patients. Methods: Twenty-seven dyslipidaemic patients (61.50 ± 10.46 years) performed an incremental treadmill test, in which the AT was determined using both methods. Bland-Altman statistics was adopted in order to verify the agreement between the methods. Results: Agreement in AT determination between the VT and HRDP methods was observed (p < 0.05) for heart rate (138.00 ± 23.80 and 136.26 ± 22.18 bpm, respectively), oxygen uptake (31.00 ± 10.33 and 31.00 ± 11.17 ml.kg−1.min−1), and treadmill velocity (7.67 ± 1.71 km.h-1and 8.00 ± 1.75 km.h-1). Conclusion: Our results suggest that the HRDP method can be adopted for the determination of the AT in dyslipidaemic patients, showing agreement with the VT method.(AU)

Apolipoprotein B and angiotensin-converting enzyme polymorphisms and aerobic interval training: randomized controlled trial in coronary artery disease patients

Physical training has been strongly recommended as a non-pharmacological treatment for coronary artery disease (CAD). Genetic polymorphisms have been studied to understand the biological variability in response to exercise among individuals. This study aimed to verify the possible influence of apolipoprotein B (ApoB: rs1042031 and rs693) and angiotensin-converting enzyme (ACE-ID: rs1799752) genotypes on the lipid profile and functional aerobic capacity, respectively, after an aerobic interval training (AIT) program in patients with CAD and/or cardiovascular risk factors. Sixty-six men were randomized and assigned to trained group (n=32) or control group (n=34). Cardiopulmonary exercise test was performed to determine the ventilatory anaerobic threshold (VAT) from cardiorespiratory variables. The AIT program, at an intensity equivalent to %VAT (70-110%), was conducted three times a week for 16 weeks. ApoB gene polymorphisms (−12669C>T (rs1042031) and −7673G>A (rs693)) were identified by real-time polymerase chain reaction (PCR). I/D polymorphism in the ACE gene (rs1799752) was identified through PCR and fragment size analysis. After 16 weeks, low-density lipoprotein (LDL) levels increased in the trained and control groups with the GA+AA genotype (−7673G>A) of the ApoB gene. Trained groups with ACE-II and ACE-ID genotypes presented an increase in oxygen consumption (VO2VAT) and power output after the AIT program. The presence of the ACE I-allele was associated with increased aerobic functional capacity after the AIT program. Increased LDL levels were observed over time in patients with the −7673G>A polymorphism of the ApoB gene. Trial Registration Information: ClinicalTrials.gov: NCT02313831

Running economy in elite soccer and futsal players: differences among positions on the field / Economia de corrida em jogadores de futebol e futsal de elite: diferenças entre as posições em campo

OBJECTIVE: To determine running economy in a large sample of elite soccer and futsal players to obtain benchmarks in different positions. METHODS: Running Economy is the energy demand at a submaximal running velocity. Players were divided into 6 subgroups. Soccer: defenders, midfielders, and strikers; futsal: defenders, wingers, and pivots. Elite soccer players (n=129) and elite futsal players n=72 performed an incremental running test starting at 8.4 km.h-1 with increments of 1.2 km.h-1 every two minutes on a treadmill until exhaustion. Running Economy was determined by interpolation between ventilatory thresholds 1 and 2 (VT1 and VT2). RESULTS: Running Economy (measured as mL.kg-1.km-1) was compared between the playing positions in the two team sports. In soccer, running economy was 222.7 (defenders), 227.0 (midfielders), and 219.8 (strikers) mL.kg-1.km-1, respectively. In futsal, the corresponding values were 198.5 (defenders), 196.9 (wingers), and 190.5 (pivots) mL.kg-1.km-1, respectively. We no found significantly differences between the three positions in both sports. The Running Economy of futsal players was 12.5% better than that of soccer players. Running Economy correlated positively with oxygen uptake at VT2 in both sports and in all positions. CONCLUSION: Futsal players exhibited better Running Economy than soccer players; this should be considered as a factor in the athlete's training plan.

OBJETIVO: Determinar a Economia de Corrida numa grande amostra de jogadores de futebol e futsal de elite em diferentes posições do campo. METODOS: Os jogadores foram subdivididos em três subgrupos: futebol (jogadores de defesa, meio-campistas e atacantes) e futsal (jogadores de defesa, alas e pivôs). Foram 129 jogadores de futebol e 72 jogadores de futsal, que competem nas respectivas primeiras divisões do Brasil. Os jogadores foram submetidos a teste de esforço em esteira (8,4 km-1.h+1,2km-1.h a cada dois minutos) até a exaustão. Consumo máximo de oxigênio, limiares ventilatórios e Economia de Corrida foram registrados por análise de troca gasosa respiratória. A Economia de Corrida foi determinada por interpolação utilizando as velocidades dos limiares ventilatórios 1 e 2 e o consume de oxigênio nas duas velocidades. RESULTADOS: Os valores de Economia de Corrida entre as posições nos dois esportes foram os seguintes: Futebol, jogadores de defesa (222,7±16,7mL.kg-1.km-1), meio-campistas (227±19,9mL.kg-1.km-1), e atacantes (219,8±17,2mL.kg-1.km-1). Futsal, jogadores de defesa (198,5±10,8mL.kg-1.km-1), alas (196,9±16,2mL.kg-1.km-1), e pivôs (190,5±11,8mL.kg-1.km-1). Não foram encontradas diferenças significativas entre as três posições em ambos os esportes. A Economia de Corrida dos jogadores de futsal foi 12,5% melhor do que dos jogadores de futebol. Neste estudo, os jogadores da posição pivô no futsal tiveram os melhores valores de Economia de Corrida (custo de oxigênio mais baixo). Embora o consumo máximo de oxigênio (VO2max) e o limiar ventilatório 2 (LV2) fosse maior nos jogadores de futebol, a Economia de Consumo foi pior. Esta correlacionou-se positivamente com o VO2 no LV2 em ambos os esportes e em todas as posições CONCLUSÃO: Futsal tem melhor Economia de Consumo do que futebol. O presente estudo aponta a importância dos índices Economia de Consumo no plano de treinamento físico dos atletas.

Evaluation of anaerobic threshold in non-pregnant and pregnant rats

ABSTRACT Several studies present different methodologies and results about intensity exercise, and many of them are performed in male rats. However, the impact of different type, intensity, frequency and duration of exercise on female rats needs more investigation. From the analysis of blood lactate concentration during lactate minimum test (LacMin) in the swimming exercise, the anaerobic threshold (AT) was identified, which parameter is defined as the transition point between aerobic and anaerobic metabolism. LacMin test is considered a good indicator of aerobic conditioning and has been used in prescription of training in different exercise modalities. However, there is no evidence of LacMin test in female rats. The objective was to determine AT in non-pregnant and pregnant Wistar rats. The LacMin test was performed and AT defined for mild exercise intensity was from a load equivalent to 1% of body weight (bw), moderate exercise as carrying 4% bw and severe intensity as carrying 7% bw. In pregnant rats, the AT was reached at a lower loading from 5.0% to 5.5% bw, while in non-pregnant the load was from 5.5% to 6.0% bw. Thus, this study was effective to identify exercise intensities in pregnant and non-pregnant rats using anaerobic threshold by LacMin test.

Cinética de la inmunoglobulina-A salival (IgAs) en adultos jóvenes con capacidad aeróbica promedio o excelente antes y después de una prueba de esfuerzo máximo / Salivary immunoglobulin A (sIgA) kinetics in young adults with an average or excellent aerobic capacity before and after a cardiopulmonary graded exercise test

Background: Aim: To compare the concentration of secretory immunoglobulin-A (sIgA) in young adults with average or excellent aerobic capacity before and after a cardiopulmonary graded exercise test. Methods: Participants were nine apparently healthy physically active males (Mean age = 21.3 ± 2.1 yr.), randomly allocated in two groups based on their VO2max: a) average aerobic capacity (AEC, n = 5) or b) excellent aerobic capacity (EAC, n = 4). Participants performed the Bruce protocol to determine their aerobic capacity. The sIgA was measured before the test, immediately after the test and 60-, 120-, 240-, and 1440-min after the test. Results: Mixed factorial 2 x 6 ANOVA indicated no significant interactions between groups and measurements (p = 0.956), and main effect groups on sIgA (AEC = 85.4 ± 19.3 μg/mL vs. EAC = 79.2 ± 21.5 μg/mL, p = 0.836). Tukey's post hoc analysis revealed significant differences measurement obtained immediately after the test and between the initial measurement (p = 0.020), 60-min (p = 0.030), 240-min (p = 0.016), and 1440-min (p = 0.028) following the test. Conclusion: There is no change in sIgA kinetics depending on the aerobic capacity of the participants following an aerobic capacity cardiopulmonary graded exercise test.

Introducción. Objetivo: Comparar la cinética en la concentración de inmunoglobulina A salival (IgAs) en adultos jóvenes con capacidad aeróbica promedio (n: 5) o excelente (n: 4) antes y después de una prueba de esfuerzo. Método: 9 adultos jóvenes (edad 21,3 ± 2,1), divididos de acuerdo su VO2máx, realizaron una prueba de esfuerzo mediante el protocolo de Bruce. La concentración de IgAs fue determinada mediante el Salimetrics IgA Kit®, evaluando inicial, inmediatamente finalizada la prueba, +60, +120, +240, +1.440 min. Resultados: La prueba ANOVA 2x6 mixta indicó que no existieron interacciones significativas entre grupos y mediciones (p = 0,956). Tampoco se encontró una diferencia significativa en la media de IgAs en los grupos (Promedio = 85,4 ± 19.3 μg/mL vs Excelente=79,2 ± 21.5 μg/mL, p = 0,836). Independientemente de las mediciones, el análisis post hoc de Tukey indicó que las diferencias se encontraron en la medición obtenida inmediatamente después de la prueba y entre la medición inicial (p: 0,020), la medición obtenida 60 min (p: 0,030), 240 min (p: 0,016) y 1.440 min (p = 0,028) posteriores a la prueba. Conclusión: Los datos encontrados sugieren que no hay un cambio en la concentración de IgAs a través del tiempo en función de la capacidad aeróbica de los participantes.

Relationship between aerobic capacity and pelvic floor muscles function: a cross-sectional study

The objective of this study was to evaluate the relationship between aerobic capacity and pelvic floor muscles (PFM) function in adult women. Women aged 18 or over and without urinary dysfunction or other chronic diseases were eligible to participate. They completed the habitual physical activity (HPA) questionnaire, underwent a PFM functional evaluation by palpation and perineometry, and performed a submaximal (between 75 and 85% of maximum heart rate) cardiopulmonary exercise (CPX) test to determine the ventilatory anaerobic threshold (VAT). Forty-one women were included (35±16 years, 75% physically active, 17% very active, and 8% sedentary and 17% presented grade 1 PFM contraction, 31.8% grade 2, 26.8% grade 3, and 24.4% grade 4, according to the modified Oxford Scale). The average PFM contraction pressure obtained by perineometer was 53±26 cmH2O and the average oxygen consumption at VAT (VO2VAT) obtained from CPX was 14±2 mL·kg-1·min-1. Significant correlations were found between PFM contraction pressure and VO2VAT (r=0.55; P<0.001); between PFM contraction pressure and HPA score (r=0.38; P=0.02); between age and VO2VAT (r=-0.25; P=0.049); and between VO2VAT and HPA score (r=0.36; P=0.02). An age-adjusted multiple linear regression equation (R2=0.32) was derived to estimate VO2VAT from the contraction value obtained by perineometer, so that the PFM contraction pressure was able to predict VO2VAT. The equation was validated using data from another group of 20 healthy women (33±12 years; PFM contraction: 49±23 cmH2O) and no significant difference was found between actual VO2VAT and predicted VO2VAT (13.1±1.9 vs 13.8±2.0 mL·kg-1·min-1). In conclusion, PFM function is associated with aerobic capacity in healthy women and PFM contraction pressure may be used to estimate VO2VAT in this population.

Post-analysis methods for lactate threshold depend on training intensity and aerobic capacity in runners. An experimental laboratory study / Métodos de pós-análise do limiar do lactato dependem da intensidade de treinamento e da capacidade aeróbica dos corredores. Um estudo laboratorial experimental

ABSTRACT CONTEXT AND OBJECTIVE: This study aimed to evaluate different mathematical post-analysis methods of determining lactate threshold in highly and lowly trained endurance runners. DESIGN AND SETTING: Experimental laboratory study, in a tertiary-level public university hospital. METHOD: Twenty-seven male endurance runners were divided into two training load groups: lowly trained (frequency < 4 times per week, < 6 consecutive months, training velocity ≥ 5.0 min/km) and highly trained (frequency ≥ 4 times per week, ≥ 6 consecutive months, training velocity < 5.0 min/km). The subjects performed an incremental treadmill protocol, with 1 km/h increases at each subsequent 4-minute stage. ­Fingerprint ­blood-lactate analysis was performed at the end of each stage. The lactate threshold (i.e. the running velocity at which blood lactate levels began to exponentially increase) was measured using three different methods: increase in blood lactate of 1 mmol/l at stages (DT1), absolute 4 mmol/l blood lactate concentration (4 mmol), and the semi-log method (semi-log). ANOVA was used to compare different lactate threshold methods and training groups. RESULTS: Highly trained athletes showed significantly greater lactate thresholds than lowly trained runners, regardless of the calculation method used. When all the subject data were combined, DT1 and semi-log were not different, while 4 mmol was significantly lower than the other two methods. These same trends were observed when comparing lactate threshold methods in the lowly trained group. However, 4 mmol was only significantly lower than DT1 in the highly trained group. CONCLUSION: The 4 mmol protocol did not show lactate threshold measurements comparable with DT1 and semi-log protocols among lowly trained athletes.

RESUMO CONTEXTO E OBJETIVO: O objetivo do presente estudo é avaliar modelos matemáticos de pós-análise do limiar de lactato em grupos de corredores de longa distância muito ou pouco treinados. TIPO DE ESTUDO E LOCAL: Estudo laboratorial experimental. Hospital Público Universitário Terciário. MÉTODO: Vinte e sete corredores homens foram divididos em: pouco treinados (frequência < 4 vezes por semana, < 6 meses, velocidade ≥ 5,0 minutos/km) e muito treinados (frequência ≥ 4 vezes por semana, ≥ 6 meses, velocidade < 5,0 minutos/km). Os participantes foram submetidos a protocolo de esteira escalonado (1% inclinação) = 1 km/h por fase (4 minutos). Ao fim de cada estágio, análise da "impressão digital" metabolômica foi realizada. O limiar do lactato (i.e. velocidade em que o lactato sanguíneo aumenta exponencialmente) foi medido utilizando-se três métodos: aumento de 1 mmol/l da concentração, concentração absoluta de 4 mmol e método semi-log. ANOVA foi utilizada para comparar os diferentes limiares de lactato e grupos. RESULTADO: Atletas muito treinados apresentaram limiares de lactato maiores que os corredores pouco treinados, independentemente do método de cálculo utilizado. Comparando todos os corredores juntos, as análises de aumento de 1 mmol/l e semi-log não foram diferentes, enquanto a concentração absoluta de 4 mmol/l foi significativamente mais baixa que as dos dois outros métodos. Essas mesmas tendências foram observadas ao se compararem os métodos de limiar de lactato no grupo menos treinado. Entretanto, a análise absoluta de 4 mmol/l foi menor do que a do aumento de 1 mmol/l no grupo muito treinado. CONCLUSÃO: O método concentração absoluta de 4 mmol não mostrou mensurações comparáveis de limiar do lactato quando comparado com os protocolos aumento de 1 mmol/l e semi-log nos atletas pouco treinados.

Effects of continuous vs interval exercise training on oxygen uptake efficiency slope in patients with coronary artery disease

The oxygen uptake efficiency slope (OUES) is a submaximal index incorporating cardiovascular, peripheral, and pulmonary factors that determine the ventilatory response to exercise. The purpose of this study was to evaluate the effects of continuous exercise training and interval exercise training on the OUES in patients with coronary artery disease. Thirty-five patients (59.3±1.8 years old; 28 men, 7 women) with coronary artery disease were randomly divided into two groups: continuous exercise training (n=18) and interval exercise training (n=17). All patients performed graded exercise tests with respiratory gas analysis before and 3 months after the exercise-training program to determine ventilatory anaerobic threshold (VAT), respiratory compensation point, and peak oxygen consumption (peak VO2). The OUES was assessed based on data from the second minute of exercise until exhaustion by calculating the slope of the linear relation between oxygen uptake and the logarithm of total ventilation. After the interventions, both groups showed increased aerobic fitness (P<0.05). In addition, both the continuous exercise and interval exercise training groups demonstrated an increase in OUES (P<0.05). Significant associations were observed in both groups: 1) continuous exercise training (OUES and peak VO2 r=0.57; OUES and VO2 VAT r=0.57); 2) interval exercise training (OUES and peak VO2 r=0.80; OUES and VO2 VAT r=0.67). Continuous and interval exercise training resulted in a similar increase in OUES among patients with coronary artery disease. These findings suggest that improvements in OUES among CAD patients after aerobic exercise training may be dependent on peripheral and central mechanisms.

Effects of a physical fitness program on memory and blood viscosity in sedentary elderly men

The aim of this study was to investigate the effects of a 6-month exercise program on cognitive function and blood viscosity in sedentary elderly men. Forty-six healthy inactive men, aged 60–75 years were randomly distributed into a control group (n=23) and an experimental group (n=23). Participants underwent blood analysis and physical and memory evaluation, before and after the 6-month program of physical exercise. The control group was instructed not to alter its everyday activities; the experimental group took part in the fitness program. The program was conducted using a cycle ergometer, 3 times per week on alternate days, with intensity and volume individualized at ventilatory threshold 1. Sessions were continuous and maximum duration was 60 min each. There was significant improvement in memory (21%; P<0.05), decreased blood viscosity (−19%; P<0.05), and higher aerobic capacity (48%; P<0.05) among participants in the experimental group compared with the control group. These data suggest that taking part in an aerobic physical fitness program at an intensity corresponding to ventilatory threshold-1 may be considered a nonmedication alternative to improve physical and cognitive function.

Influence of exercise modality on agreement between gas exchange and heart rate variability thresholds

The main purpose of this study was to investigate the level of agreement between the gas exchange threshold (GET) and heart rate variability threshold (HRVT) during maximal cardiopulmonary exercise testing (CPET) using three different exercise modalities. A further aim was to establish whether there was a 1:1 relationship between the percentage heart rate reserve (%HRR) and percentage oxygen uptake reserve ( % V ˙ O 2  R ) at intensities corresponding to GET and HRVT. Sixteen apparently healthy men 17 to 28 years of age performed three maximal CPETs (cycling, walking, and running). Mean heart rate and V ˙ O 2 at GET and HRVT were 16 bpm (P<0.001) and 5.2 mL·kg-1·min-1 (P=0.001) higher in running than cycling, but no significant differences were observed between running and walking, or cycling and walking (P>0.05). There was a strong relationship between GET and HRVT, with R2 ranging from 0.69 to 0.90. A 1:1 relationship between %HRR and % V ˙ O 2  R was not observed at GET and HRVT. The %HRR was higher during cycling (GET mean difference=7%; HRVT mean difference=11%; both P<0.001), walking (GET mean difference=13%; HRVT mean difference=13%; both P<0.001), or running (GET mean difference=11%; HRVT mean difference=10%; both P<0.001). Therefore, using HRVT to prescribe aerobic exercise intensity appears to be valid. However, to assume a 1:1 relationship between %HRR and % V ˙ O 2  R at HRVT would probably result in overestimation of the energy expenditure during the bout of exercise.

Comparison of maximal lactate steady state with V2, V4, individual anaerobic threshold and lactate minimum speed in horses / Comparação da máxima fase estável do lactato com a V2, V4, o limiar anaeróbio individual e lactato mínimo em equinos

The anaerobic threshold is a physiologic event studied in various species. There are various methods for its assessment, recognized in the human and equine exercise physiology literature, several of these involving the relationship between blood lactate concentration (LAC) and exercise load, measured in a standardized exercise test. The aim of this study was to compare four of these methods: V2, V4, individual anaerobic threshold (IAT) and lactate minimum speed (LMS) with the method recognized as the gold standard for the assessment of anaerobic threshold, maximal lactate steady-state (MLSS). The five tests were carried out in thirteen trained Arabian horses, in which velocities and associated LAC could be measured. The mean velocities and the LAC associated with the anaerobic threshold for the five methods were respectively: V2 = 9.67±0.54; V4 = 10.98±0.47; V IAT = 9.81±0.72; V LMS = 7.50±0.57 and V MLSS = 6.14±0.45m.s-1 and LAC IAT = 2.17±0.93; LAC LMS = 1.17±0.62 and LAC MLSS = 0.84±0.21mmol.L-1. None of the velocities were statistically equivalent to V MLSS (P<0.05). V2, V4 and V LMS showed a good correlation with V MLSS , respectively: r = 0.74; r = 0.78 and r = 0.83, and V IAT did not significantly correlate with V MLSS. Concordance between the protocols was relatively poor, i.e., 3.28±1.00, 4.84±0.30 and 1.43±0.32m.s-1 in terms of bias and 95% agreement limits for V2, V4 and LMS methods when compared to MLSS. Only LAC LMS did not differ statistically from LAC MLSS. Various authors have reported the possibility of the assessment of anaerobic threshold using rapid protocols such as V4 and LMS for humans and horses. This study corroborates the use of these tests, but reveals that adjustments in the protocols are necessary to obtain a better concordance between the tests and the MLSS.

O limiar anaeróbio é um evento fisiológico estudado em várias espécies. Sua mensuração possui vários métodos reconhecidos na literatura da fisiologia do exercício humano e equino, muitos deles envolvendo a relação entre a concentração sanguínea de lactato (LAC) e a carga de exercício. O objetivo do presente estudo foi comparar quatro desses métodos: V2 , V4 , limiar anaeróbio individual (LAI) e o teste do lactato mínino (LM) com o método reconhecido na literatura como o padrão ouro para a mensuração do limiar anaeróbio, a máxima fase estável do lactato (MFEL). Os cinco testes foram realizados em treze equinos árabes treinados, nos quais as velocidades e suas respectivas LAC puderam ser quantificadas. As velocidades médias e LAC associadas ao limiar anaeróbio aferido pelos cinco métodos foram respectivamente: V2 = 9,67±0,54; V4 = 10,98±0,47; V LAI = 9.81±0.72; V LM = 7,50±0,57 e V MFEL = 6,14±0,45m.s-1 ; e LAC LAI = 2,17±0,93; LAC LM = 1,17±0,62 e LAC MFEL = 0,84±0,21mmol.L-1. Nenhuma dessas velocidades foi estatisticamente igual à V MFEL (P<0,05). A V2 , a V4 e a V LM mostraram uma boa correlação com a V MFEL , respectivamente r = 0,74; r = 0,78 e r = 0,83, e a V LAI não se correlacionou significativamente com a V MFEL. A concordância entre os protocolos foi relativamente fraca, sendo 3,28±1,00; 4,84±0,30 e 1,43±0,32m.s-1 em termos de viés e limites de concordância a 95% para os métodos V2 , V4 e LM comparados à MFEL. Muitos autores relataram a possibilidade da mensuração do limiar anaeróbio pelo uso de protocolos rápidos, como a V4 e o LM, para humanos e equinos. O presente estudo corrobora a utilização desses testes, mas revela que ajustes nos protocolos são necessários para se obter uma melhor concordância entre os mesmos e a MFEL.

Determination of anaerobic threshold through heart rate and near infrared spectroscopy in elderly healthy men

BACKGROUND: Aging leads to low functional capacity and this can be reversed by safe and adequate exercise prescription. OBJECTIVE: The aim of this study was to identify the anaerobic threshold (AT) obtained from the V-slope method as well as visual inspection of oxyhemoglobin ( O2Hb) and deoxyhemoglobin (HHb) curves and compare findings with the heteroscedastic (HS) method applied to carbon dioxide production ( CO2), heart rate (HR), and HHb data in healthy elderly men. A secondary aim was to assess the degree of agreement between methods for AT determination. METHOD: Fourteen healthy men (61.4±6.3 years) underwent cardiopulmonary exercise testing (CPX) on a cycle ergometer until physical exhaustion. Biological signals collected during CPX included: ventilatory and metabolic variables; spectroscopy quasi-infrared rays - NIRS; and HR through a cardio-frequency meter. RESULTS: We observed temporal equivalence and similar values of power (W), absolute oxygen consumption (O2 - mL/min), relative O2 ( mL.Kg - 1.min -1), and HR at AT by the detection methods performed. In addition, by the Bland-Altman plot, HR confirmed good agreement between the methods with biases between -1.3 and 3.5 beats per minute. CONCLUSIONS: (i) all detection methods were sensitive in identifying AT, including the HS applied to HR and (ii) the methods showed a good correlation in the identification of AT. Thus, these results support HR as valid and readily available parameter in determining AT in healthy elderly men. .

Efeito das cargas de treinamento sobre parâmetros fisiológicos de futebolistas / Effect of training loads on physiological parameters of soccer players

O objetivo desse estudo foi verificar os efeitos de três semanas de treinamentos com intensidades monitoradas sobre a capacidade aeróbia de futebolistas profissionais. Quatorze futebolistas integrantes de equipe da primeira divisão do Campeonato Brasileiro de 2010, foram avaliados pré e pós três semanas de treinamento. O limiar anaeróbio (LAn) foi determinado pelo método bi-segmentado, para isso quatro esforços submáximos de 800 metros com intensidades de 10, 12, 14 e 16 km/h foram aplicados. Trinta três sessões de treinamentos foram quantificadas em zonas de acordo com frequência cardíaca referente ao LAn (FC LAn): Z1 - 10% abaixo, Z2 - 90-100% e Z3 - acima da FC LAn. Durante os treinamentos os jogadores permaneceram 31,17±14,86%, 42,96±14,90% e 25,87±16,67% em Z1, Z2 e Z3, respectivamente. Não foram encontradas diferenças significativas no LAn (pré = 13,29 ± 0,71 km∙h-1; pós=12,85 ± 0,90 km∙h-1), percepção subjetiva de esforço correspondente ao LAn (pré = 11,53 ± 1,45 u.a; pós=11,23 ± 1,53 u.a) e FC LAn (pré = 166,64 ± 10,69 bpm; pós = 174,50 ± 10,89 bpm), indicando que três semanas de treinamento são insuficiente para gerar adaptações positivas no LAn de futebolistas.

The aim of this study was to investigate the effects of three weeks of training with intensity monitored on the aerobic capacity of professional soccer players. Fourteen players, members of a first division Brazilian Championship team in 2010, aged 22.78 ± 3.06 years were evaluated pre and post three weeks of training. The anaerobic threshold intensity LAn was determined by bi-segmented method, for this four submaximal efforts of 800 meters with intensities 10, 12, 14 and 16 km/h were applied. Thirty three training sessions were quantified in zones according to heart rate related to the LAn (FC LAn): Z1 - 10% below, Z2 - 90-100% and Z3 - above the FC LAn. During training participants remained 31.17 ± 14.86%, 42.96% and 25.87 ± 14.90 ± 16.67% in Z1, Z2, and Z3 respectively. There were no significant differences in the LAn (pre = 13,29 ± 0,71 km∙h-1; post = 12,85 ± 0,90 km∙h-1), perceived exertion (pre = 11,53 ± 1,45 u.a; post = 11,23 ± 1,53 u.a) and FC LAn (pre = 166,64 ± 10,69 bpm; post = 174,50 ± 10,89 bpm) between conditions before and after training, indicating that three weeks of training are insufficient to generate positive changes in soccer players LAn.

Reliability and validity of heart rate variability threshold assessment during an incremental shuttle-walk test in middle-aged and older adults

Studies on the assessment of heart rate variability threshold (HRVT) during walking are scarce. We determined the reliability and validity of HRVT assessment during the incremental shuttle walk test (ISWT) in healthy subjects. Thirty-one participants aged 57 ± 9 years (17 females) performed 3 ISWTs. During the 1st and 2nd ISWTs, instantaneous heart rate variability was calculated every 30 s and HRVT was measured. Walking velocity at HRVT in these tests (WV-HRVT1 and WV-HRVT2) was registered. During the 3rd ISWT, physiological responses were assessed. The ventilatory equivalents were used to determine ventilatory threshold (VT) and the WV at VT (WV-VT) was recorded. The difference between WV-HRVT1 and WV-HRVT2 was not statistically significant (median and interquartile range = 4.8; 4.8 to 5.4 vs 4.8; 4.2 to 5.4 km/h); the correlation between WV-HRVT1 and WV-HRVT2 was significant (r = 0.84); the intraclass correlation coefficient was high (0.92; 0.82 to 0.96), and the agreement was acceptable (-0.08 km/h; -0.92 to 0.87). The difference between WV-VT and WV-HRVT2 was not statistically significant (4.8; 4.8 to 5.4 vs 4.8; 4.2 to 5.4 km/h) and the agreement was acceptable (0.04 km/h; -1.28 to 1.36). HRVT assessment during walking is a reliable measure and permits the estimation of VT in adults. We suggest the use of the ISWT for the assessment of exercise capacity in middle-aged and older adults.

Association between muscle strength and the cardiopulmonary status of individuals living with HIV/AIDS

OBJECTIVE: The purpose of this study was to compare aerobic function [anaerobic threshold (%VO2-AT), respiratory compensation point (%VO2-RCP) and peak oxygen uptake (VO2peak)] between physically active patients with HIV/AIDS and matched controls and to examine associations between disease status, poor muscle strength, depression (as estimated by the profile of mood states questionnaire) and the aerobic performance of patients. METHODS: Progressive treadmill test data for %VO2-AT (V-slope method), RCP and (VO2peak) were compared between 39 male patients with HIV/AIDS (age 40.6±1.4 years) and 28 male controls (age 44.4±2.1 years) drawn from the same community and matched for habitual physical activity. Within-patient data were also examined in relation to CD4+ counts (nadir and current data) and peak isokinetic knee torque. RESULTS: AT, RCP and (VO2peak) values were generally similar for patients and controls.Within the patient sample, binary classification suggested that AT, RCP and (VO2peak) values were not associated with either the nadir or current CD4+ count, but treadmill test variables were positively associated with peak isokinetic knee torque. CONCLUSION: The aerobic performance of physically active patients with HIV/AIDS is generally well conserved. Nevertheless, poor muscle strength is observed in some HIV/AIDS patients, which is associated with lower anaerobic power and (VO2peak), suggesting the possibility of enhancing the aerobic performance of patients with weak muscles through appropriate muscle-strengthening activities.

Método do limiar de variabilidade da frequência cardíaca aplicado em pré-adolescentes obesos e não obesos / Method of heart rate variability threshold applied in obese and non-obese pre-adolescents / Método del umbral de variabilidad de la frecuencia cardíaca aplicado en preadolescentes obesos y no obesos

FUNDAMENTO: A detecção do limiar anaeróbico (LA) pela análise da variabilidade da frequência cardíaca (LiVFC) pode significar uma nova maneira de avaliação da capacidade funcional cardiorrespiratória (CFCR) em pré-adolescentes. OBJETIVO: Testar o método de LiVFC para detecção do LA em pré-adolescentes não obesos (NO), obesos (O) e obesos mórbidas (OM), a fim de determinar diferenças em sua CFCR. MÉTODOS: Foram estudados 30 pré-adolescentes, com idades entre 9 e 11 anos, divididos em três grupos de 10: a) grupo NO - índice de massa corpórea (IMC) com percentil do National Center for Chronic Disease Prevention and Health Promotion entre 5 e 85; b) grupo O - IMC de percentil entre 95 e 97 e c) grupo OM - IMC com percentil acima de 97. Todos foram submetidos a um protocolo incremental realizado em esteira rolante e registraram-se os batimentos cardíacos para detecção do LiVFC, que foi determinado pelo valor de 3,0 ms do índice do desvio-padrão 1 (SD1), extraído dos intervalos RR. RESULTADOS: Os valores médios no momento do LiVFC mostraram maiores valores para o grupo NO, destacando-se: a) VO2 (ml/kg/min) NO = 27,4 ± 9,2; O = 13,1 ± 7,6 e OM = 11,0 ± 1,7; b) FC (bpm): NO = 156,3 ± 18,0; O =141,7 ± 11,4 e OM = 137,7 ± 10,4; e c) distância percorrida (metros): NO = 1.194,9 ± 427,7; O = 503,2 ± 437,5 e OM = 399,9 ± 185,1. CONCLUSÃO: O LiVFC se mostrou efetivo para avaliação da CFCR e poderá vir a ser aplicado como método alternativo à ergoespirometria em determinadas situações.

BACKGROUND: The detection of anaerobic threshold (AT) by heart rate variability analysis (HRVt) may mean a new way to assess the cardiorespiratory capacity (CRC) in pre-adolescents. OBJECTIVE: To test the method of HRVt to detect AT in non-obese (NO), obese (O) and morbidly obese (MO) pre-adolescents in order to determine differences in their CRC. METHODS: Were studied 30 pre-adolescents, aged between 9 and 11 years, divided into three groups of ten pre-adolescents each: a) NO group - body mass index (BMI) between 5 and 85 percentiles of the chart of National Center for Chronic Disease Prevention and Health Promotion.; b) O group - BMI between 95 and 97 of the same chart; c) MO group - BMI with percentile over 97. All were submitted to an incremental protocol conducted on a treadmill, and the heart rate was recorded for the detection of the HRVt when the beat-to-beat variability (SD1), extracted from the RR intervals, reached the value of 3 ms. RESULTS: The mean values obtained at HRVt were higher for the NO group, which included: a) VO2 (ml/kg/min) NO = 27.4 ± 9.2; O = 13.1 ± 7.6, and MO = 11.0 ± 1.7 b) HR (bpm): NO = 156.3 ± 18.0, O = 141.7 ± 11.4 and 137.7 ± 10.4 MO; c) distance (m): NO = 1,194.9 ± 427.7, O = 503.2 ± 437.5 and MO = 399.9 ± 185.1. CONCLUSION: HRVt was effective for evaluation of CRC and could be applied as an alternative method to ergoespirometry in certain situations.

BACKGROUND: La detección del umbral anaeróbico (UA) por el análisis de la variabilidad de la frecuencia cardíaca (LiVFC) puede significar una nueva manera de evaluación de la capacidad funcional cardiorrespiratoria (CFCR) en preadolescentes. OBJECTIVE: Testear el método de LiVFC para detección del UA en preadolescentes no obesos (NO), obesos (O) y obesos mórbidos (OM), a fin de determinar diferencias en su CFCR. METHODS: Fueron estudiados 30 preadolescentes, con edades entre 9 y 11 años, divididos en tres grupos de 10: a) grupo NO - índice de masa corporal (IMC) con percentil del National Center for Chronic Disease Prevention and Health Promotion entre 5 y 85; b) grupo O - IMC de percentil entre 95 y 97 y c) grupo OM - IMC con percentil encima de 97. Todos fueron sometidos a un protocolo incremental realizado en cinta rodante y se registraron los latidos cardíacos para detección del LiVFC, que fue determinado por el valor de 3,0 ms del índice de desviación-estándar 1 (SD1), extraído de los intervalos RR. RESULTS: Los valores medios en el momento del LiVFC mostraron mayores valores para el grupo NO, destacándose: a) VO2 (ml/kg/min) NO = 27,4 ± 9,2; O = 13,1 ± 7,6 y OM = 11,0 ± 1,7; b) FC (lpm): NO = 156,3 ± 18,0; O =141,7 ± 11,4 y OM = 137,7 ± 10,4; y c) distancia recorrida (metros): NO = 1.194,9 ± 427,7; O = 503,2 ± 437,5 y OM = 399,9 ± 185,1. CONCLUSION: El LiVFC se mostró efectivo para evaluación de la CFCR y podrá comenzar a ser aplicado como método alternativo a la ergoespirometría en determinadas situaciones.

Cardiopulmonary exercise testing in evaluation of patients of chronic obstructive pulmonary disease.

Background. Objective assessment of severity in patients with chronic obstructive pulmonary disease (COPD) is mainly limited to pulmonary function testing performed at rest. But, accurate assessment of exercise capacity in patients with COPD may be possible with cardiopulmonary exercise testing (CPET). Methods. Forty-three patients with stable COPD were included and were divided into three groups based upon the spirometry data as per the Global Initiative for Obstructive Lung Disease (GOLD) guidelines as follows: Group A: mild COPD, Group B: moderately severe COPD and Group C: severe COPD. Symptom-limited CPET was performed using treadmill on incremental continuous ramp protocol in all of them. Results. Five patients (11.6%) had mild COPD; 16 (37.2%) had moderately severe COPD and the remaining 22 (51.6%) patients had severe COPD. Anaerobic threshold was attained in all the 43 patients. The dominant symptom at peak exercise were dyspnoea (n=19) and both dyspnoea and leg fatigue (n=7). The other causes of exercise limitation included dyspnoea with significant oxygen desaturation (n=6); and dyspnoea with severe oxygen desaturation (n=2). Six patients complained only of leg fatigue at peak exercise. A significant correlation between forced expiratory volume in the first second (FEV1) percent predicted and the predicted maximum oxygen uptake (VO2 max % predicted) was observed in all the three groups (r=0.39, p=0.011) but with marked variability of peak VO2 for a given degree of airflow obstruction. Twenty-three (53.5%) patients with low anaerobic threshold (<30%) were identified as potential group likely to benefit from exercise training for pulmonary rehabilitation. Conclusions. Cardiopulmonary exercise testing is useful to determine the causes of exercise limitation and to assess the maximal exercise capacity of patients with COPD.