Reduced Body Flexibility Is Associated With Poor Survival in Middle-Aged Men and Women: A Prospective Cohort Study.

OBJECTIVES: Flexibility is recognized as one of the components of physical fitness and commonly included as part of exercise prescriptions for all ages. However, limited data exist regarding the relationship between flexibility and survival. We evaluated the sex-specific nature and magnitude of the associations between body flexibility and natural and non-COVID-19 mortality in a middle-aged cohort of men and women. DESIGN: Prospective cohort study. METHODS: Anthropometric, health and vital data from 3139 (66% men) individuals aged 46-65 years spanning from March 1994 to October 2022 were available. A body flexibility score, termed Flexindex, was derived from a combination of 20 movements (scored 0-4) involving seven different joints, resulting in a score range of 0-80. Kaplan-Meier survival curves were obtained, and unadjusted and adjusted hazard ratios (HRs) for mortality estimated. RESULTS: During a mean follow-up of 12.9 years, 302 individuals (9.6%) comprising 224 men/78 women died. Flexindex was 35% higher in women compared to men (mean ± SD: 41.1 ± 9.4 vs. 30.5 ± 8.7; p < 0.001) and exhibited an inverse relationship with mortality risk in both sexes (p < 0.001). Following adjustment for age, body mass index, and health status, the HR (95% CI) for mortality comparing upper and bottom of distributions of Flexindex were 1.87 (1.50-2.33; p < 0.001) for men and 4.78 (1.23-31.71; p = 0.047) for women. CONCLUSIONS: A component of physical fitness-body flexibility-as assessed by the Flexindex is strongly and inversely associated with natural and non-COVID-19 mortality risk in middle-aged men and women. Future studies should assess whether training-induced flexibility gains are related to longer survival.

Cardiorespiratory optimal point during exercise testing and sudden cardiac death: A prospective cohort study.

BACKGROUND: Cardiorespiratory optimal point (COP) during exercise, a potentially useful submaximal cardiopulmonary exercise testing (CPET) variable, may be an independent risk factor for cardiovascular disease outcomes. However, the relationship of COP with risk of sudden cardiac death (SCD) has not been previously investigated. We sought to evaluate the association between COP during exercise and SCD risk and determine whether COP improves SCD risk prediction. METHODS: COP, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was ascertained in 2190 men who underwent clinical exercise testing. Hazard ratios (HRs) (95% confidence intervals [CIs]) and measures of risk discrimination for SCD were calculated. RESULTS: A total of 240 SCDs death occurred during a median follow-up of 28.8 years. COP was linearly associated with SCD in a dose-response manner. In a multivariable model comprising several established and emerging CVD risk factors, the HR (95% CI) for SCD was 2.51 (1.36-4.62) per standard deviation increase in COP. This was minimally attenuated to 2.36 (1.27-4.37) on further adjustment for high sensitivity C-reactive protein. The association did not vary importantly in several relevant clinical subgroups. Addition of COP to a SCD risk score was associated with a C-index change of 0.0086 (0.0005 to 0.0167; p = .038) and difference in -2 log likelihood (p = .017). CONCLUSIONS: COP during exercise is strongly, inversely and independently associated with SCD in a graded fashion. COP during exercise may potentially be used for the prediction of the long-term risk for SCD beyond established CVD risk factors.

Handgrip strength is inversely associated with fatal cardiovascular and all-cause mortality events.

Purpose: We aimed to assess the associations of handgrip strength (HS) with cardiovascular and all-cause mortality and whether adding data on HS to cardiovascular disease (CVD) risk factors is associated with improvement in CVD mortality prediction.Design: Handgrip strength was assessed in a population-based sample of 861 participants aged 61-74 years at baseline. Relative HS was obtained by dividing the absolute value by body weight.Results: During a median (interquartile range) follow-up of 17.3 (12.6-18.4) years, 116 fatal coronary heart diseases (CHDs), 195 fatal CVDs and 412 all-cause mortality events occurred. On adjustment for several risk factors, the hazard ratios (95% confidence intervals (CIs)) for fatal CHD, fatal CVD and all-cause mortality were 0.59 (0.37-0.95), 0.59 (0.41-0.86) and 0.66 (0.51-0.84), respectively, comparing extreme tertiles of relative HS. Adding relative HS to a CVD mortality risk prediction model containing established risk factors did not improve discrimination or reclassification using Harrell's C-index (C-index change: 0.0034; p = .65), integrated-discrimination-improvement (0.0059; p = .20) and net-reclassification-improvement (-1.31%; p = .74); however, there was a significant difference in -2 log likelihood (p < .001).Conclusions: Relative HS is inversely associated with CHD, CVD and all-cause mortality events. Adding relative HS to conventional risk factors improves CVD risk assessment using sensitive measures of discrimination.KEY MESSAGESHandgrip strength (HS) assessment is simple, inexpensive and it takes only a few minutes to measure in clinical practice; however, its prognostic role for fatal cardiovascular outcomes on top of traditional risk factors in apparently healthy populations is uncertain.In a population-based prospective cohort study, good HS adjusted for body weight was associated with lower risk of fatal cardiovascular outcomes and the associations remained consistent across several clinically relevant subgroups.Handgrip strength may be a useful prognostic tool for fatal CHD and CVD events, in the general population.

CLINIMEX Aerobic Fitness Questionnaire: Proposal and Validation

Cardiorespiratory (aerobic) fitness is strongly and directly related to major health outcomes, including all-cause mortality. Maximum oxygen uptake (VO2max), directly measured by maximal cardiopulmonary exercise test (CPET), represents the subject's aerobic fitness. However, as CPET is not always available, aerobic fitness estimation tools are necessary. Objectives: a) to propose the CLINIMEX Aerobic Fitness Questionnaire (C-AFQ); b) to validate C-AFQ against measured VO2max; and c) to analyze the influence of some potentially relevant variables on the error of estimate. Methods: We prospectively studied 1,000 healthy and unhealthy subjects (68.6% men) aged from 14 to 96 years that underwent a CPET. The two-step C-AFQ describes physical activities with corresponding values in metabolic equivalents (METs) - ranging from 0.9 to 21 METs. Results: Application of C-AFQ took less than two minutes. Linear regression analysis indicated a very strong association between estimated (C-AFQ) and measured (CPET) maximal METs - r2 = 0.83 (Sy.x = 1.63; p < .001) - with median difference of only 0.2 METs between both values and interquartile range (percentiles 25 and 75) of 2 METs. The difference between estimated and measured METs was not influenced by age, sex, body mass index, clinical condition, ß-blocker use or sitting-rising test scores. Conclusion: C-AFQ is a simple and valid tool for estimating aerobic fitness when CPET is unavailable and it is also useful in planning individual ramp protocols. However, individual error of estimate is quite high, so C-AFQ should not be considered a perfect substitute for CPET's measured VO2max

Recovery from sauna bathing favorably modulates cardiac autonomic nervous system.

OBJECTIVE: Sauna bathing is becoming a common activity in many countries and it has been linked to favorable health outcomes. However, there is limited data on the heart rate (HR) and heart rate variability (HRV) responses to an acute sauna exposure. DESIGN: We conducted a single-group, longitudinal study utilizing a pre-post design to examine acute effects of sauna bathing on the autonomic nervous system as reflected by HRV. A total of 93 participants (mean [SD] age: 52.0 [8.8] years, 53.8% males) with cardiovascular risk factors were exposed to a single sauna session (duration: 30 min; temperature: 73 °C; humidity: 10-20%) and data on HRV variables were collected before, during and after sauna. RESULTS: Time and frequency-domain HRV variables were significantly modified (p < 0.001) by the single sauna session, with most of HRV variables tending to return near to baseline values after 30 min recovery. Resting HR was lower at the end of recovery (68/min) compared to pre-sauna (77/min). A sauna session transiently diminished the vagal component, whereas the cooling down period after sauna decreased low frequency power (p < 0.001) and increased high frequency power in HRV (p < 0.001), favorably modulating the autonomic nervous system balance. CONCLUSIONS: This study demonstrates that a session of sauna bathing induces an increase in HR. During the cooling down period from sauna bathing, HRV increased which indicates the dominant role of parasympathetic activity and decreased sympathetic activity of cardiac autonomic nervous system. Future randomized controlled studies are needed to show if HR and HRV changes underpins the long-term cardiovascular effects induced by regular sauna bathing.

Relative peak exercise oxygen pulse is related to sudden cardiac death, cardiovascular and all-cause mortality in middle-aged men.

Background Preliminary evidence suggests that peak exercise oxygen pulse - peak oxygen uptake/heart rate-, a variable obtained during maximal cardiopulmonary exercise testing and a surrogate of stroke volume, is a predictor of mortality. We aimed to assess the associations of peak exercise oxygen pulse with sudden cardiac death, fatal coronary heart disease and cardiovascular disease and all-cause mortality. Design A prospective study. Methods Peak exercise oxygen pulse was assessed in a maximal cycling test at baseline in 2227 middle-aged men of the Kuopio Ischaemic Heart Disease cohort study using expired gas variables and electrocardiograms. Relative peak exercise oxygen pulse was obtained by dividing the absolute value by body weight. Results During a median follow-up of 26.1 years 1097 subjects died; there were 220 sudden cardiac deaths, 336 fatal coronary heart diseases and 505 fatal cardiovascular diseases. Relative peak exercise oxygen pulse (mean 19.5 (4.1) mL per beat/kg/102) was approximately linearly associated with each outcome. Comparing extreme quartiles of relative peak exercise oxygen pulse, hazard ratios (95% confidence intervals) for sudden cardiac death, fatal coronary heart disease and cardiovascular disease, and all-cause mortality on adjustment for cardiovascular risk factors were 0.55 (0.36-0.83), 0.58 (0.42-0.81), 0.60 (0.46-0.79) and 0.59 (0.49-0.70), respectively ( P < 0.001 for all). The hazard ratios were unchanged on further adjustment for C-reactive protein and the use of beta-blockers. The addition of relative peak exercise oxygen pulse to a cardiovascular disease mortality risk prediction model significantly improved risk discrimination (C-index change 0.0112; P = 0.030). Conclusion Relative peak exercise oxygen pulse measured during maximal exercise was linearly and inversely associated with fatal cardiovascular and all-cause mortality events in middle-aged men. In addition, relative peak exercise oxygen pulse provided significant improvement in cardiovascular disease mortality risk assessment beyond conventional risk factors.

A reference equation for maximal aerobic power for treadmill and cycle ergometer exercise testing: Analysis from the FRIEND registry.

Background Maximal oxygen uptake (VO2max) is a powerful predictor of health outcomes. Valid and portable reference values are integral to interpreting measured VO2max; however, available reference standards lack validation and are specific to exercise mode. This study was undertaken to develop and validate a single equation for normal standards for VO2max for the treadmill or cycle ergometer in men and women. Methods Healthy individuals ( N = 10,881; 67.8% men, 20-85 years) who performed a maximal cardiopulmonary exercise test on either a treadmill or a cycle ergometer were studied. Of these, 7617 and 3264 individuals were randomly selected for development and validation of the equation, respectively. A Brazilian sample (1619 individuals) constituted a second validation cohort. The prediction equation was determined using multiple regression analysis, and comparisons were made with the widely-used Wasserman and European equations. Results Age, sex, weight, height and exercise mode were significant predictors of VO2max. The regression equation was: VO2max (ml kg-1 min-1) = 45.2 - 0.35*Age - 10.9*Sex (male = 1; female = 2) - 0.15*Weight (pounds) + 0.68*Height (inches) - 0.46*Exercise Mode (treadmill = 1; bike = 2) ( R = 0.79, R2 = 0.62, standard error of the estimate = 6.6 ml kg-1 min-1). Percentage predicted VO2max for the US and Brazilian validation cohorts were 102.8% and 95.8%, respectively. The new equation performed better than traditional equations, particularly among women and individuals ≥60 years old. Conclusion A combined equation was developed for normal standards for VO2max for different exercise modes derived from a US national registry. The equation provided a lower average error between measured and predicted VO2max than traditional equations even when applied to an independent cohort. Additional studies are needed to determine its portability.

Cardiorespiratory optimal point during exercise testing as a predictor of all-cause mortality.

INTRODUCTION AND AIM: The cardiorespiratory optimal point (COP) is a novel index, calculated as the minimum oxygen ventilatory equivalent (VE/VO2) obtained during cardiopulmonary exercise testing (CPET). In this study we demonstrate the prognostic value of COP both independently and in combination with maximum oxygen consumption (VO2max) in community-dwelling adults. METHODS: Maximal cycle ergometer CPET was performed in 3331 adults (66% men) aged 40-85 years, healthy (18%) or with chronic disease (81%). COP cut-off values of <22, 22-30, and >30 were selected based on the log-rank test. Risk discrimination was assessed using COP as an independent predictor and combined with VO2max. RESULTS: Median follow-up was 6.4 years (7.1% mortality). Subjects with COP >30 demonstrated increased mortality compared to those with COP <22 (hazard ratio [HR] 6.86, 95% confidence interval [CI] 3.69-12.75, p<0.001). Multivariate analysis including gender, age, body mass index, and the forced expiratory volume in 1 s/vital capacity ratio showed adjusted HR for COP >30 of 3.72 (95% CI 1.98-6.98; p<0.001) and for COP 22-30 of 2.15 (95% CI 1.15-4.03, p<0.001). Combining COP and VO2max data further enhanced risk discrimination. CONCLUSIONS: COP >30, either independently or in combination with low VO2max, is a good predictor of all-cause mortality in community-dwelling adults (healthy or with chronic disease). COP is a submaximal prognostic index that is simple to obtain and adds to CPET assessment, especially for adults unable or unwilling to achieve maximal exercise.

Influence of age in estimating maximal oxygen uptake.

OBJECTIVE: To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO2max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. METHODS: 1850 adults (68% men), aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness (CRF) was assessed relative to sex and age [younger (18 to 35 years), middle-aged (36 to 60 years) and older (> 60 years)]. VO2max [mL·(kg·min)(-1)] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO2max and related EE were compared among the three age- and sex-specific groups. RESULTS: Directly measured VO2max of men and women were 29.5 ± 10.5 mL·(kg·min)(-1) and 24.2 ± 9.0 mL·(kg·min)(-1) (P < 0.01). EE [mL·(kg·min)(-1)] and percent errors (%E) for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL·(kg·min)(-1), and -0.8 ± 13.1% and -1.7 ± 15.4% (P > 0.05), respectively. EE and %E for each age-group were, respectively, for men: younger = 1.9 ± 4.1 mL·(kg·min)(-1) and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL·(kg·min)(-1) and 0.4 ± 10.3%, older = -0.2 ± 2.7 mL·(kg·min)(-1) and -4.2 ± 16.6% (P < 0.01); and for women: younger = 1.2 ± 3.1 mL·(kg·min)(-1) and 2.7 ± 10.0%, middle-aged = 0.7 ± 2.8 mL·(kg·min)(-1) and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL·(kg·min)(-1) and -9.5 ± 22.4% (P < 0.01). CONCLUSION: VO2max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO2max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured.

Sexual Activity and Heart Patients: A Contemporary Perspective.

Sexual activity (SA) encompasses several behaviors such as kissing (Ki), touching (T), oral (O) stimulation, masturbation (M), and vaginal/anal intercourse (I). The acronym KiTOMI is proposed here to represent these behaviors. SA, particularly coitus, is a major aspect of health-related quality of life and is often considered the most pleasant and rewarding exercise performed during an entire lifetime. Although several studies have been conducted on sexuality, relatively limited information is available regarding SA in patients with heart disease. Moreover, the level of evidence of this limited information is nearly always B or C. This article provides a comprehensive and updated review of the relevant literature and offers evidence and expert-based practical messages regarding SA in patients with heart disease. Considering the rationale for exercise prescription, SA is typically well tolerated by most clinically stable patients with heart disease. Even in more debilitated and sicker individuals, KiT activities would most likely be feasible and desirable. The absolute risk of major adverse cardiovascular events during SA is typically very low. Even lower death rates have been reported for specific groups, such as women in general, aerobically fit men, and asymptomatic young adults with congenital heart disease. Finally, we emphasize the relevance of sexual counselling for patients and their partners, including the proper use of medications to treat erectile dysfunction. Counselled patients will be reassured and adequately informed regarding how to gradually resume habitual SA after a major cardiac event or procedure, starting with KiT and progressively advancing to KiTOM until all KiTOMI activities are allowed.

Sex-Specific Equations to Estimate Maximum Oxygen Uptake in Cycle Ergometry.

BACKGROUND: Aerobic fitness, assessed by measuring VO2max in maximum cardiopulmonary exercise testing (CPX) or by estimating VO2max through the use of equations in exercise testing, is a predictor of mortality. However, the error resulting from this estimate in a given individual can be high, affecting clinical decisions. OBJECTIVE: To determine the error of estimate of VO2max in cycle ergometry in a population attending clinical exercise testing laboratories, and to propose sex-specific equations to minimize that error. METHODS: This study assessed 1715 adults (18 to 91 years, 68% men) undertaking maximum CPX in a lower limbs cycle ergometer (LLCE) with ramp protocol. The percentage error (E%) between measured VO2max and that estimated from the modified ACSM equation (Lang et al. MSSE, 1992) was calculated. Then, estimation equations were developed: 1) for all the population tested (C-GENERAL); and 2) separately by sex (C-MEN and C-WOMEN). RESULTS: Measured VO2max was higher in men than in WOMEN: -29.4 ± 10.5 and 24.2 ± 9.2 mL.(kg.min)-1 (p < 0.01). The equations for estimating VO2max [in mL.(kg.min)-1] were: C-GENERAL = [final workload (W)/body weight (kg)] x 10.483 + 7; C-MEN = [final workload (W)/body weight (kg)] x 10.791 + 7; and C-WOMEN = [final workload (W)/body weight (kg)] x 9.820 + 7. The E% for MEN was: -3.4 ± 13.4% (modified ACSM); 1.2 ± 13.2% (C-GENERAL); and -0.9 ± 13.4% (C-MEN) (p < 0.01). For WOMEN: -14.7 ± 17.4% (modified ACSM); -6.3 ± 16.5% (C-GENERAL); and -1.7 ± 16.2% (C-WOMEN) (p < 0.01). CONCLUSION: The error of estimate of VO2max by use of sex-specific equations was reduced, but not eliminated, in exercise tests on LLCE.

Sex-Specific Equations to Estimate Maximum Oxygen Uptake in Cycle Ergometry / Equações Específicas por Sexo para Estimativa do Consumo Máximo de Oxigênio em Cicloergometria

AbstractBackground:Aerobic fitness, assessed by measuring VO2max in maximum cardiopulmonary exercise testing (CPX) or by estimating VO2max through the use of equations in exercise testing, is a predictor of mortality. However, the error resulting from this estimate in a given individual can be high, affecting clinical decisions.Objective:To determine the error of estimate of VO2max in cycle ergometry in a population attending clinical exercise testing laboratories, and to propose sex-specific equations to minimize that error.Methods:This study assessed 1715 adults (18 to 91 years, 68% men) undertaking maximum CPX in a lower limbs cycle ergometer (LLCE) with ramp protocol. The percentage error (E%) between measured VO2max and that estimated from the modified ACSM equation (Lang et al. MSSE, 1992) was calculated. Then, estimation equations were developed: 1) for all the population tested (C-GENERAL); and 2) separately by sex (C-MEN and C-WOMEN).Results:Measured VO2max was higher in men than in WOMEN: -29.4 ± 10.5 and 24.2 ± 9.2 mL.(kg.min)-1 (p < 0.01). The equations for estimating VO2max [in mL.(kg.min)-1] were: C-GENERAL = [final workload (W)/body weight (kg)] x 10.483 + 7; C-MEN = [final workload (W)/body weight (kg)] x 10.791 + 7; and C-WOMEN = [final workload (W)/body weight (kg)] x 9.820 + 7. The E% for MEN was: -3.4 ± 13.4% (modified ACSM); 1.2 ± 13.2% (C-GENERAL); and -0.9 ± 13.4% (C-MEN) (p < 0.01). For WOMEN: -14.7 ± 17.4% (modified ACSM); -6.3 ± 16.5% (C-GENERAL); and -1.7 ± 16.2% (C-WOMEN) (p < 0.01).Conclusion:The error of estimate of VO2max by use of sex-specific equations was reduced, but not eliminated, in exercise tests on LLCE.

ResumoFundamento:A condição aeróbica, avaliada pela medida do VO2máx no teste cardiopulmonar de exercício máximo (TCPE) ou estimada por equações no teste de exercício, é preditora de mortalidade. Porém, o erro obtido pela estimativa em um dado indivíduo pode ser alto, afetando decisões clínicas.Objetivo:Determinar o erro de estimativa do VO2máx em cicloergometria em população atendida nos serviços de ergometria e propor equações específicas por sexo para minimizar o erro na estimativa do VO2máx.Métodos:Foram avaliados 1715 adultos (18 a 91 anos) (68% homens) submetidos a TCPE máximo em cicloergômetro de membros inferiores (CMI) com protocolo de rampa. Calculou-se o erro percentual (E%) entre o VO2máx medido e o estimado pela equação ACSM modificada (Lang e col. MSSE, 1992). A seguir, foram desenvolvidas equações de estimativa: 1) para toda a amostra testada (C-GERAL) e 2) separadamente por sexo (C-HOMENS e C-MULHERES).Resultados:O VO2máx medido foi maior em homens do que em mulheres - 29,4 ± 10,5 e 24,2 ± 9,2 mL.(kg.min)-1 (p < 0,01) -. As equações de estimativa do VO2máx foram mL.(kg.min)-1: C-GERAL = [carga final (W)/peso (kg)] x 10,483 + 7; C‑HOMENS = [carga final (W)/peso (kg)] x 10,791 + 7; e C-MULHERES = [carga final (W)/peso (kg)] x 9,820 + 7. Os E% em homens foram -3,4 ± 13,4% (ACSM modificada), 1,2 ± 13,2% (C-GERAL) e -0,9 ± 13,4% (C-HOMENS) (p < 0,01). Em mulheres, obtivemos: -14,7 ± 17,4% (ACSM modificada), -6,3 ± 16,5% (C-GERAL) e -1,7 ± 16,2% (C-MULHERES) (p < 0,01).Conclusão:O erro de estimativa do VO2máx através de equações específicas por sexo foi reduzido, porém não eliminado, nos testes de exercício em CMI.

Anxiety, panic disorder and coronary artery disease: issues concerning physical exercise and cognitive behavioral therapy.

Psychological factors such as stress and depression have already been established as primary and secondary cardiovascular risk factors. More recently, the role of anxiety in increasing cardiac risk has also been studied. The underlying mechanisms of increased cardiac risk in panic disorder patients seem to reflect the direct and indirect effects of autonomic dysfunction, as well as behavioral risk factors associated with an unhealthy lifestyle. Implications of the comorbidity between panic and cardiovascular disease include higher morbidity, functional deficits, increased cardiovascular risk, and poor adherence to cardiac rehabilitation or exercise programs. This article probes the most recent evidence on the association between coronary artery disease, anxiety and panic disorder, and discusses the potential role of incorporating regular physical exercise and cognitive behavioral therapy in the treatment of this condition.

Variability of cardio-respiratory, electromyographic, and perceived exertion responses at the walk-run transition in a sample of young men controlled for anthropometric and fitness characteristics.

The cardio-respiratory (heart rate, HR; oxygen uptake, VO(2;) expired carbon dioxide, VCO(2); ventilation, VE), electromyographic (EMG; medial gastrocnemius, vastus lateralis, rectus femoralis, and anterior tibialis), and perceived exertion (PE) responses during a protocol for the determination of the walk-run transition speed (WRTS) were investigated. From an initial sample of 453 volunteers, 12 subjects matched for age, anthropometric characteristics [height, weight, lower limb length (LLL)], cardio-respiratory fitness (peak oxygen consumption, VO(2peak); ventilatory threshold, VT; maximal HR), and habitual physical activity levels were selected (age = 18.6 ± 0.5 years; height = 174.5 ± 1.4 cm; weight = 66.4 ± 1.1 kg; LLL = 83.3 ± 1.2 cm, VO(2peak) = 52.2 ± 2.2 ml kg(-1) min(-1); VT = 39.8 ± 2.6 ml kg(-1) min(-1)). The highly reproducible WRTS determination protocol (ICC = 0.92; p < 0.0001) consisted in 2-min warm-up at 5.5 km h(-1) followed by increments of 0.1 km h(-1) every 15 s. Between-subjects variability of the measured variables during 24 walking and 12 running velocities (from 80 to 120% of WRTS) was compared to WRTS variation. The coefficient of variation for WRTS was 7.8%, which was within the range of variability for age, anthropometric variables, VO(2peak), and maximal HR (from 5 to 12%). Cardio-respiratory responses at WRTS had a greater variation (VO(2) about 50%; VE/VCO(2) about 35%; VE/VO(2) about 45%; HR about 30%). The highest variation was found for PE (from 70 to 90%) whereas EMG variables showed the lowest variation (from 25 to 30%). Linear regression between EMG series and VO(2) data showed that VO(2) reflected the increase in muscle activity only before the WRTS. These results support the hypothesis that the walk-run transition phenomenon is determined by mechanical variables such as limb length and its relationship to biomechanical model rather than by metabolic factors.

Cardiac vagal withdrawal and reactivation during repeated rest-exercise transitions.

It is not known whether subjects that have higher cardiac vagal reactivation (CVR) during repeated exercise transitions also have higher cardiac vagal withdrawal (CVW) at the onset of exercise, which would lead to better heart rate (HR) regulation during exercise transitions. Therefore, our aims were to investigate: (a) the influence of CVR on CVW during repeated rest-exercise transitions; and (b) the influence of the sympathetic activity on CVR and CVW. Fifty-eight healthy men (22 ± 4 years) performed 20 rest-exercise transitions interspaced by 30 s. In addition, nine healthy men (24 ± 3 years) ingested either 25 mg of atenolol or placebo, on a crossover, double-blind, randomized design, then performed 20 rest-exercise transitions interspaced by 30 s. Cardiac vagal reactivation was assessed by a HR variability index (RMSSD) and CVW by the HR increase at the onset of a valid and reliable cycling protocol. The CVR and CVW responses were associated (partial r ranged from 0.60 to 0.66; p < 0.05). Participants with higher CVR over transitions maintained their CVW over repeated transitions [first transition (mean ± SEM) = 1.59 ± 0.04 vs. 20th = 1.50 ± 0.03 (a.u.), p = 0.24], while participants with lower CVR had a CVW decrease over repeated transitions [first transition (mean ± SEM) = 1.38 ± 0.04 vs. 20th = 1.19 ± 0.03 (a.u.), p < 0.01). In addition, the CVR and CVW over the rest-exercise transitions were similar during atenolol and placebo (ANCOVA interaction p = 0.12 and p = 0.48, respectively). In conclusion, the CVR among repeated rest-exercise transitions influenced the CVW at the onset of exercise, which was not affected by a partial ß(1) cardioselective adrenoceptor blockade.

Normotensos com resposta pressórica exagerada ao exercício possuem tônus vagal cardíaco aumentado / Normotensive individuals with exaggerated exercise blood pressure response have increased cardiac vagal tone

FUNDAMENTO: Valores exagerados da pressão arterial sistólica (PAS) durante um teste cardiopulmonar de exercício máximo (TCPE) são classicamente considerados como inapropriados e associados a um maior risco para desenvolvimento de doenças cardiovasculares. Sabe-se que o sistema nervoso autônomo modula a PA no exercício. Contudo, não está claramente estabelecido o comportamento do tônus vagal cardíaco (TVC) em indivíduos saudáveis com uma resposta pressórica exagerada no TCPE. OBJETIVO: Analisar o comportamento do TVC em homens adultos saudáveis que apresentam uma resposta pressórica exagerada no TCPE. MÉTODOS: De 2.505 casos avaliados entre 2002-2009, foram identificados criteriosamente 154 casos de homens, entre 20-50 anos de idade, saudáveis e normotensos. A avaliação incluía exame clínico, medidas antropométricas, testes de exercício de 4 segundos (tônus vagal cardíaco) e TCPE realizado em cicloergômetro, com medidas de pressão arterial a cada minuto pelo método auscultatório. Baseado no valor máximo de PAS obtido no TCPE, a amostra foi dividida em tercis, comparando-se o TVC, a carga máxima e o VO2 máximo. RESULTADOS: Os valores de TVC diferiram entre os indivíduos que se apresentavam nos tercis inferior e superior para a resposta da PAS ao TCPE, respectivamente, 1,57 ± 0,03 e 1,65 ± 0,04 (média ± erro padrão da média) (p = 0,014). Os dois tercis também diferiam quanto ao VO2 máximo (40,7 ± 1,3 vs 46,4 ± 1,3 ml/kg-1.min-1; p = 0,013) e a carga máxima (206 ± 6,3 vs 275 ± 8,7 watts; p < 0,001). CONCLUSÃO: Uma resposta pressórica exagerada durante o TCPE em homens adultos saudáveis é acompanhada de indicadores de bom prognóstico clínico, incluindo níveis mais altos de condição aeróbica e de tônus vagal cardíaco.

BACKGROUND: Exaggerated systolic blood pressure (SBP) levels during a maximal cardiopulmonary exercise test (CPET) are classically considered as inappropriate and associated with a higher risk for the development of cardiovascular diseases. It is known that the autonomic nervous system modulates the BP during exercise. However, the behavior of the cardiac vagal tone (CVT) has not been fully established in healthy individuals with an exaggerated BP response to CPET. OBJECTIVE: To analyze the behavior of the CVT in healthy adult males presenting an exaggerated BP response to CPET. METHODS: Of the 2,505 cases evaluated between 2002-2009, 154 cases were thoroughly identified, consisting of healthy male normotensive subjects aged 20-50 years. The evaluation included clinical assessment, anthropometric measurements, 4-second exercise test (cardiac vagal tone) and cardiopulmonary exercise test (CPET) performed in a cycle-ergometer, with BP measurements being taken every minute through auscultation. Based on the maximum SBP value obtained at the CPET, the sample was divided in tertiles, comparing CVT, maximum workload and VO2 max. RESULTS: The CVT results differed between individuals in the lower tertile and upper tertile for the SBP response to the CPET, respectively: 1.57 ± 0.03 and 1.65 ± 0.04 (mean ± standard error of mean) (p = 0.014). The two tertiles also differed regarding the VO2 max (40.7 ± 1.3 vs 46.4 ± 1.3 ml/kg-1.min-1; p = 0.013) and the maximum workload (206 ± 6.3 vs 275 ± 8.7 watts; p < 0.001). CONCLUSIOn: An increased BP response during the CPET in healthy adult males is accompanied by indicators of good clinical prognosis, including higher levels of aerobic fitness and cardiac vagal tone.

Cardiac arrhythmias triggered by sudden and dynamic efforts.

BACKGROUND: Some arrhythmias are triggered only during exercise. The aim of this study is to describe the frequency and type of arrhythmia induced by a standardized protocol of sudden and dynamic exercise, which tends to reflect routine situations of efforts (e.g., climbing stairs), and compare with those found on maximal cardiopulmonary exercise test (CPET). METHODS: A total of 2329 subjects (1594 men) aged 9-91 years (mean 52 years, SD +/- 16) were submitted to a standardized protocol of sudden and dynamic exercise (4-second exercise test [4sET]) prior to a CPET. A continuous digital electrocardiogram (ECG) was recorded during 4sET and CPET, and later reviewed and interpreted by the same physician (who supervised all the procedures). RESULTS: A total of 1125 subjects (43%) had cardiac arrhythmias during one or both procedures. About 57% of the arrhythmias were supraventricular, but 47 subjects (2% of all subjects) presented more complex arrhythmias including 43 cases of nonsustained supraventricular tachycardia and four nonsustained ventricular tachycardia. While arrhythmias were more often exposed by the CPET (P < 0.01), in 221 cases (10% of the total sample) of arrhythmias they were only induced by 4sET; these included four cases of nonsustained supraventricular tachycardia. CONCLUSION: 4sET-induced arrhythmias tend to be simple and were always short-lasting. In some cases, ECG recording during 4sET showed arrhythmias that would not be induced by a progressive maximal exercise test. Different situations of exercise, sudden and short versus maximal and progressive, tend to generate different arrhythmic responses and possibly complementary clinical implications.