Association of Endogenous Testosterone with Physical Fitness Measures during Firefighter Occupational Health Evaluations.

Firefighting is a physically demanding profession associated with unacceptably high on-duty cardiovascular mortality. Low endogenous total testosterone (TT) is an emerging cardiometabolic (CM) risk factor in men, but limited data exists on its interactions with physical fitness (PF). Data from occupational health and fitness assessments of 301 male career firefighters (FFs) were analyzed. TT was categorized as low (<264 ng/dL), borderline (264-399 ng/dL), and reference (400-916 ng/dL). PF tests included cardiorespiratory fitness (submaximal treadmill), body fat percentage (BF%), push-ups, plank, and handgrip strength assessments. In the crude analyses, FFs in the low TT group had worse muscular and cardiorespiratory fitness measures compared to the referent group. However, after adjusting for age and BF%, none of the PF differences remained statistically significant. Similarly, the odds of less-fit FFs (PF performance below median values) having low TT were higher compared to the fitter ones only before adjusting for age and BF%. Therefore, in the final adjusted model, there was no significant association between TT and PF. Our data suggest that age and body fat confound the association between PF and TT. Low TT and poor PF are important components of FFs' CM risk profile, and there is potential benefit to considering TT screening as part of a comprehensive occupational health program that manages performing medical evaluations and provides education and preventative programming.

Post-exercise heart rate recovery and its speed are associated with resting-reactivity cardiovagal modulation in healthy women.

The present study sought to expand upon prior investigations of the relationship between post-exercise heart rate recovery (HRR) and cardiovagal resting-reactivity modulation. HRR from 1st to 5th min after maximal exercise test was correlated with a cardiovagal index of heart rate variability (SD1) at resting (supine and orthostatic positions) and its reactivity after the orthostatic stress test in 34 healthy women. Statistical analysis employed non-parametric tests with a p-value set at 5%. HRR, ∆%HRR, and coefficient of HRR (CHRR) at the 3rd and 5th min correlated with SD1 and SD1n (normalized units) in the supine position (rs = 0.36 to 0.47; p = < 0.01). From the 1st to 5th min, HRR, ∆%HRR, and CHRR correlated with SD1 and SD1n in the orthostatic position (rs = 0.29 to 0.47; p = ≤ 0.01 to 0.05), except for HRR at 5th min with SD1n (p = 0.06). Following the orthostatic stress test, HRR at 3rd and HRR, %∆HRR at 5th min correlated with ∆absSD1 (rs = 0.28 to 0.35; p = 0.02 to 0.05). All HRR measurements at 1st min correlated with ∆absSD1n (rs = 0.32 to 0.38; p = 0.01 to 0.03), and the CHRR at 1st min correlated with ∆%SD1(rs = 0.37; p = 0.01). After the sample was divided into high and low cardiovagal modulation subgroups, the subgroup with high modulation at rest (supine and orthostatic) and higher cardiovagal reactivity (reduction) showed faster HRR (p = ≤ 0.01 to 0.05; ES:0.37 to 0.50). HRR throughout the 1st to 5th min positively correlates with cardiovagal modulation in the orthostatic position, and the 3rd and 5th min positively correlate with cardiovagal modulation in both postures at rest. Faster HRR following the maximal exercise test is associated with high resting-reactivity cardiovagal modulation in healthy women.

Longitudinal changes in cardiorespiratory fitness among firefighters based on a fixed 12.0 MET standard and an age-adjusted fitness standard.

BACKGROUND: Firefighting is a physically demanding profession. Firefighters (FFs) need adequate physical fitness (PF) to perform duty tasks efficiently. While FFs' work demands are constant throughout their career, there is an expected age-related decline in PF. OBJECTIVE: To describe longitudinal changes in cardiorespiratory fitness (CRF) based on a fixed (12.0 METs) and an age-adjusted standard and compare the prevalence of fit/unfit firefighters (FFs) over eight years. METHODS: 297 Brazilian male firefighters were randomly selected. CRF was assessed by the 12-minute Cooper test. To compare the prevalence's of fit/unfit FFs depending on the standard (12 METs vs. age-adjusted), the McNemar test was used. RESULTS: The reduction in the prevalence of fit firefighters was 4.4-fold higher when the analysis did not consider age. CONCLUSION: After eight years, the prevalence of fit FFs decreased by 30.5% based on the fixed standard, while this reduction was only 7% when using an age-adjusted standard.

Physical activity and health: a historical and conceptual approach / A relação entre atividade física e saúde: uma abordagem histórica e conceitual

This theoretical essay reflects on physical activity (PA) and health and the development of this study area, particularly in Brazil. A historical review is presented based on major research themes in the area since the 1950s and the evolution of PA recommendations for health. Crucial conceptual and operational definitions in the area that have gone through recent updates are addressed. The pa-per highlights relevant institutions and documents, as well as reflects on future perspectives and challenges in the field. Finally, this essay highlights the need to reduce the gap between the robust scientific knowledge already produced about the health benefits of PA and the real action in the field, especially in the primary health care setting

A partir de uma abordagem histórica, conceitual, crítica e didática, este ensaio teórico propõe uma reflexão sobre a relação entre atividade física (AF) e saúde e o desenvolvimento desta área de estudo, com um olhar especial sobre o Brasil. Apresenta-se revisão histórica a partir de grandes temas de pesquisa na área desde os anos 1950 e da evolução das recomendações de AF para a saúde. São abordadas definições conceituais e operacionais que passaram por atualizações recentes e que são cruciais na área. Faz-se destaque a instituições e documentos relevantes, além de reflexões sobre perspectivas e desafios futuros para a área. Por fim, destaca a necessidade da redução na distância entre a solidez do conhecimento já produzido sobre os benefícios da AF para a saúde e os desejados avanços no contexto da promoção da saúde, em especial na atenção primária à saúde

Can resting heart rate explain the heart rate and parasympathetic responses during rest, exercise, and recovery?

The effect of resting heart rate (RHR) on the heart rate (HR) dynamics and parasympathetic modulation at rest, exercise, and recovery remain to be clarified. This study compares HR and parasympathetic responses at rest, during submaximal exercise testing and recovery in young, physically active men with different RHR average values. HR and parasympathetic responses were compared between two groups: bradycardia group-RHR < 60 bpm (BG, n = 20) and normocardia group-RHR ≥ 60 ≤ 100 bpm (NG, n = 20). A Polar RS800® was used to record the RR-interval series and HR at rest in the supine position, following the postural change (from supine to orthostatic position) and in the orthostatic position for 5 minutes, as well as during and after a submaximal exercise testing. Statistical analysis employed the MANOVA, Mann-Whitney, and Simple Linear regression test with a two-tailed p-value set at ≤ 0.05. BG at rest showed lower HR in the orthostatic position, higher parasympathetic activity in the supine and orthostatic positions, and higher parasympathetic reactivity than NG (p ≤ 0.01) after the postural change. BG before exercise showed lower HR and higher values of the chronotropic reserve and parasympathetic withdrawal than NG (p ≤ 0.01) throughout the exercise. Following the exercise, BG showed higher values of HR recovery (HRR) and parasympathetic reactivation in the 3rd and 5th minutes of recovery than NG (p ≤ 0.01). Lastly, the RHR can explain the variance of the HR at rest, during exercise testing, and recovery from 11 to 48%. We concluded that BG (RHR < 60 bpm) showed higher chronotropic and parasympathetic modulation at rest, higher chronotropic reserve, parasympathetic withdrawal during the submaximal exercise test, and faster HRR and parasympathetic reactivation after effort in young physically active men.

Modelo Lógico do Programa Tribunal Superior do Trabalho em Movimento: uma construção de 15 anos de experiência / Logic Model of the Tribunal Superior do Trabalho em Movimento Program: a construction of 15 years of experience

Na perspectiva de promover saúde no local de trabalho, com ênfase na atividade física (AF), em 2004 o Tribunal Superior do Trabalho (TST), em Brasília, Distrito Federal, criou o Programa TST em Movimento. O objetivo deste estudo foi descrever o modelo lógico (ML) do Programa, a partir de sua construção histórica. O ML foi desenvolvido seguindo as diretrizes do Centers of Disease Control and Prevention, descrevendo objetivo, recursos, atividades, produtos, metas, fatores influenciadores e público-alvo. Sua construção incluiu a análise de documentos do Programa, como o relatório de resultados de 2019. O Programa é composto por profissionais de educação física, fisioterapia e estagiários, oferecendo atividades como educação em saúde, práticas de AF, eventos e monitoramento de indicadores em saúde. O ML apresentado é fruto de 15 anos de experiência e passa a compor os processos avaliativos e o acompanhamento das metas, iluminando a sustentabilidade do Programa em bases sólidas

From the perspective of promoting health in the workplace, with an emphasis on physical activity (PA), in 2004 the Tribunal Superior do Trabalho (TST), in Brasília, Distrito Federal, created the TST em Mo­vimento Program. The aim of this study was to describe the logical model (LM) of the Program, based on its historical construction. The LM was developed following the Centers of Disease Control and Prevention guidelines, describing objective, resources, activities, products, goals, influencing factors, and target audience. Its construction included the analysis of Program documents, such as the 2019 results report. The Program is composed of physical education professionals, physiotherapy, and trainees, offering activities such as health education, PA practices, events, and monitoring of health indicators. The LM presented is the result of 15 years of experience and becomes part of the evaluation processes and monitoring of goals, illuminating the Program's sustainability on solid foundations

The experience of a training course for physical activity promotion at the primary health care setting / A experiência de curso de capacitação para promoção da atividade física na atenção primária à saúde

Evidence demonstrates the importance of physical activity (PA) promotion strategies in primary health care (PHC) as well as the lack of professional qualification in this area. We aimed to report the experience of a basic training course to conduct group classes in a pilot study of the Program Brasil em Movimento from Brazilian Ministry of Health (PBM). The course covered eight topics within 22 hours delivered remotely. In 21 days of publicity, 630 people signed up, with an average of 439 views for each class. Students evaluated the course positively (95%) and would recommend it (93%). We observed that: 1- the number of subscribers and off-line classes views demonstrate the existence of a demand for this type of qualification; 2- the remote course offering was adequate to reach professionals from all regions of Brazil; 3- offering this type of training seems essential, given the background heterogeneity of the target audience.

Evidências demonstram a importância de estratégias de promoção da atividade física no contexto da atenção primária à saúde (APS) e a carência de qualificação profissional específica nesta área. Objetivou-se relatar a experiência de um curso básico de capacitação para condução de aulas coletivas junto ao estudo piloto do Programa Brasil em Movimento, do Ministério da Saúde (PBM). O curso abrangeu oito temas com carga de 22 horas oferecidas remotamente. Em 21 dias de divulgação inscreveram-se 630 pessoas, com média de 439 visualizações das aulas. Os discentes avaliaram o curso positivamente (95%) e o recomendariam (93%). Observou-se que: 1- o número de inscritos e de visualizações das aulas indicam interesse por este tipo de qualificação; 2- a oferta do curso de modo remoto foi adequada para atingir interessados de todas regiões do Brasil; 3- a oferta desse tipo de capacitação parece ser fundamental, frente à heterogeneidade de formação do público alvo

High-Intensity Interval Training Combined with Different Types of Exercises on Cardiac Autonomic Function. An Analytical Cross-Sectional Study in CrossFit® Athletes.

It is well established that endurance exercise has positive effects on cardiac autonomic function (CAF). However, there is still a dearth of information about the effects of regular high-intensity interval training combined with different types of exercises (HIITCE) on CAF. OBJECTIVE: The aim of this study is to compare CAF at rest, its reactivity, and reactivation following maximal exercise testing in HIITCE and endurance athletes. METHODS: An observational study was conducted with 34 male athletes of HIITCE (i.e., CrossFit®) [HG: n = 18; 30.6 ± 4.8 years] and endurance athletes (i.e., triathlon) [TG.: n = 16; 32.8 ± 3.6 years]. We analyzed 5 min of frequency-domain indices (TP, LF, HF, LFn, HFn, and LF/HF ratio) of heart rate variability (HRV) in both supine and orthostatic positions and its reactivity after the active orthostatic test. Post-exercise heart rate recovery (HRR) was assessed at 60, 180, and 300 s. Statistical analysis employed a non-parametric test with a p-value set at 5%. RESULTS: The HG showed reduced HFn and increased LFn modulations at rest (supine). Overall cardiac autonomic modulation (TP) at supine and all indices of HRV at the orthostatic position were similar between groups. Following the orthostatic test, the HG showed low reactivity for all HRV indices compared to TG. After the exercise, HRR does not show a difference between groups at 60 s. However, at 180 and 300 s, an impairment of HRR was observed in HG than in TG. CONCLUSION: At rest (supine), the HG showed reduced parasympathetic and increased sympathetic modulation, low reactivity after postural change, and impaired HRR compared to TG.

Low testosterone and cardiometabolic risks in a real-world study of US male firefighters.

Low serum total testosterone (TT) is associated with increased cardiovascular risk and metabolic derangements, with fatty liver (FL) emerging as an additional cardiometabolic threat. We investigated the associations between TT and cardiometabolic (CM) health in 298 US male firefighters. Cross-sectional data from occupational health examination were analyzed. TT was categorized as low (< 264 ng/dL), borderline (264-399 ng/dL), and reference (400-916 ng/dL). Conventional CM risk factors were compared among TT categories, and between firefighters with and without FL. 81% of firefighters were obese/overweight; almost 40% had FL. In the low-TT group, only 3.1% had normal BMI, while 78.1% had FL. The low-TT group had a worse CM profile, independently of age and BMI, and a fourfold higher adjusted odds of having FL. FL was associated with lower TT, regardless of age, BMI and HbA1c. Having a FL, HbA1c ≥ 5.7% or triglycerides ≥ 150 mg/dL increased the odds for low-TT by 4.1, 2.7 and 6.6 times, respectively. These real-world data reveal strong associations between low-TT and CM risk factors and support a call for action towards screening for low-TT and FL, regardless of age, BMI or dysmetabolic conditions in firefighters. Recognizing cardiometabolic risks in firefighters provides an opportunity to lessen cardiovascular diseases burden.

Cardiorespiratory fitness assessment among firefighters: Is the non-exercise estimate accurate?

BACKGROUND: Minimum cardiorespiratory fitness (CRF) has been recommended for firefighters due to job requirements. Thus, it is important to identify accurate and readily available methods to assess CRF in this population. Non-exercise CRF estimates (NEx-CRF) have been proposed but this approach requires validation in this population. OBJECTIVE: To evaluate the accuracy of a NEx-CRF, as compared to a field maximum exercise test, among career military firefighters of both genders using a comprehensive agreement analysis. METHODS: We evaluated the accuracy of a NEx-CRF estimate compared to the Cooper 12 min running test among 702 males and 106 female firefighters. RESULTS: Cooper and NEx-CRF tests yielded similar CRF in both genders (differences <1.8±4.7 ml/kg-1.min-1; effect size <0.34). However, NEx-CRF underestimated Cooper-derived CRF among the fittest firefighters. NEx-CRF showed moderate to high sensitivity/specificity to detect fit or unfit firefighters (71.9% among men and 100% among women). Among men, the NEx-CRF method correctly identified most firefighters with less than 11 METs or greater than 13 METs, but showed lower precision to discriminate those with CRF between 11-13 METs. CONCLUSIONS: The NEx-CRF method to estimate firefighters' CRF may be considered as an alternative method when an exercise-based method is not available or may be used to identify those who require more traditional testing (CRF 11-13 METs).

Physical activity and the coronavirus pandemic: an urgent time to change the recommendation focus / Atividade física e a pandemia de coronavirus: um momento urgente para mudança no foco das recomendações

The COVID-19 pandemic is disrupting the routine daily life of millions of people. The pandemic associated restrictive measures impose unprecedented challenges, including the need to stay physically active in a social distancing scenario that drastically reduces access to physical activity (PA) spaces and opportunities. Therefore, we aimed to discuss the need for an urgent change in the main focus of PA recommendations. The total of PA needed for health promotion has been focused on the minimum of 150min/moderate-to-vigorous PA/week. It is time for a call for action toward shifting the focus of PA recommendations. Instead of the traditional "doing at least 150min/week of PA, and less than that if you can't reach that goal", recommendations should emphasize the idea of "move more, sit less and, if possible, accumulate 150min/PA/week. The coronavirus pandemic, its associated social distancing and impacts on PA opportunities impose an urgent change in PA recommendation main focus

A pandemia de COVID-19 alterou a rotina de milhões de pessoas. Medidas restritivas associadas à pandemia impõem desafios sem precedentes, incluindo a necessidade de nos mantermos fisicamente ativos em um cenário de distanciamento social que reduz drasticamente o acesso a espaços e oportunidades de atividade física (ATF). Discutimos a necessidade urgente de mudança no foco das recomendações de ATF. O total de ATF necessária para promoção da saúde tem sido centrado no mínimo de 150min de ATF moderada-vigorosa/sem. É momento para uma chamada de ação em direção à mudança no foco das recomendações. Ao invés do tradicional "acumule pelo menos 150min/ATF/sem, e menos que isso caso não consiga atingir esta meta", as recomendações deveriam enfatizar a ideia de "mexa-se mais ­ sente-se menos, podendo, acumule 150min/ATF/sem. A pandemia de coronavírus, o distanciamento social e os impactos nas oportunidades de ATF impõem uma mudança urgente no foco das recomendações de ATF

Borderline-low testosterone levels are associated with lower left ventricular wall thickness in firefighters: An exploratory analysis.

BACKGROUND: Low endogenous testosterone has been associated with increased cardiovascular risk in men. OBJECTIVES: To determine the prevalence of low serum testosterone level (TT) in a cohort of male US career firefighters and to examine its relation with left ventricular wall thickness (LVWT). MATERIALS AND METHODS: We conducted a cross-sectional study among 341 career firefighters, (age: 37.5 ± 10.3 years; BMI: 28.9 ± 4.5 kg/m2 ), who underwent an occupational medical screening examination. TT quartiles were determined, and LVWT distribution among them was plotted. Then, TT values were categorized as low (<264 ng/dL), borderline (264-399 ng/dL), reference range (400-916 ng/dL), and high (>916 ng/dL). To further investigate the association of mildly decreased TT on LVWT, we divided the borderline group into borderline-low (264-319 ng/dL) and borderline-high (320-399 ng/dL) ranges. LVWT values were classified as low LVWT when <0.6 cm. A multivariate model was used to compare LVWT, age, BMI, systolic blood pressure (SBP), and HbA1c among groups by TT values. RESULTS: The prevalence of low TT was 10.6% and of borderline was 26.4%, while 58.7% had levels in the reference range. The low-TT group was older and had higher BMI and SBP as compared to the reference group (P < .01). LVWT values were different among groups (P = .04) and significantly lower in firefighters with borderline-low TT as compared to the reference group (P < .05). This finding also occurred within obese firefighters (P = .03). The borderline-low group had a higher adjusted risk for a low LVWT as compared to the reference group [OR: 4.11 (95% CI: 1.79-9.43)]. DISCUSSION: Our findings highlight the possible relationship between a mild reduction in testosterone levels (borderline) and lower LVWT. CONCLUSIONS: A high prevalence of subnormal TT levels (low and borderline: 37%) was observed in this relatively homogeneous cohort of career firefighters. Mildly decreased TT levels and lower LVWT might represent a preclinical condition and a window of opportunity for cardiovascular preventive interventions in firefighters.

Nível insuficiente de atividade física se associa a menor qualidade de vida e ao estudo noturno em universitários do Distrito Federal / Insufficient level of physical activity is associated with reduced quality of life and night-time studying in Brazilian undergraduate students / Nivel insuficiente de actividad física está asociado a menor calidad de vida y al estudio nocturno en universitarios del Distrito Federal

Resumo A prática de atividade física (AF) é essencial à saúde e à qualidade de vida (QV). Objetivo: Avaliar o nível de atividade física (NAF), a QV, fatores antropométricos e socioeconômicos em universitários do Distrito Federal. Métodos: Foram avaliados aleatoriamente 392 voluntários (43,6% homens). Empregaram-se os questionários IPAQ, WHOQOL e de tempo sentado (TS). Foram avaliados preditores do NAF com o emprego de regressão logística, assim como da QV estratificada por sexo, turno, NAF e renda. Resultados: Dos pesquisados, 51,4% eram insuficientemente ativos (IA) e mostraram menor QV do que os ativos (AT), nos domínicos físico (DOMF) e psicológico (DOMPS) (p < 0,05). Não houve associação do NAF com gênero, idade, estado civil, tabagismo e renda (p > 0,05). Menor NAF associou-se com maior TS e com aulas no turno noturno. A proporção de universitários IA foi elevada e se mostrou associada com menor QV no DOMF e DOMPS, elevado TS e com estudo noturno.

Abstract Physical activity (PA) practice is an essential issue for health and quality of life (QOL). Objective: We analyzed the level of physical activity (LPA) and QOL in association with anthropometric and socioeconomics factors among undergraduate students from the Distrito Federal - Brazil. Methods: We randomly evaluated 392 volunteers (43.6% men). We employed the IPAQ + reported siting time (ST), and WHOQOL questionnaires. Logistic regression was used to evaluate LPA predictors. QOL was compared between sex, class period (day vs night), LPA and income. Results: Two hundred and one volunteers (51.4%) were insufficiently active (IA) and showed lower QOL than the active (AT) ones on physical (PHD) and psychological (PSD) domains (p< 0.05). Lower LPA was associated with greater ST and with the night shift study. We found a high proportion of IA students that was associated with lower QOL on PHD and PSD, higher ST and nightshift study.

Resumen La práctica de actividad física (AF) es esencial para la salud y la calidad de vida (CV). Objetivo: Analizamos el nivel de la actividad física (NAF) y CV asociados con factores antropométricos y socio-económicos entre universitarios del Distrito Federal - Brasil. Metodología: Evaluamos 392 voluntarios aleatorios (43,6% hombres). Aplicamos los cuestionarios IPAQ + tiempo sentado (TS) informado y WHOQOL. Se utilizó una regresión logística para evaluar los predictores de NAF. CV fue comparado por sexo, turno de cursada (día vs noche), NAF e ingresos. Resultados: Doscientos un voluntarios (51,4%) eran insuficientemente activos (IA) y mostraron menor CV que los activos (AT) en los dominios físicos (DOMF) y psicológicos (DOMPS) (p˂0,05). Menor NAF se asoció con mayor TS y con clases en turno noche. Encontramos una alta proporción de universitarios IA asociada con menor CV en DOMF y DOMPS, alto TS y con estudio nocturno.

Questionnaire-Based Prevalence of Physical Activity Level on Adults According to Different International Guidelines: Impact on Surveillance and Policies.

BACKGROUND: The World Health Organization recommends 150 minutes of moderate to vigorous physical activity (PA) throughout the week. However, the weekly frequency of PA and how to combine moderate and vigorous PA to define who reaches the recommended PA are controversial. PA level might be highly different based on the recommendation and/or the criteria employed. METHODS: Demographic data and PA level evaluated by International Physical Activity Questionnaire from 3 random and representative samples from 1 state, 1 city, and 1 local organization in Brazil were analyzed (n = 2961). Nine criteria from different recommendations were used to define PA level. Prevalence estimates and 95% confidence intervals of sufficient PA were calculated for each criterion and compared with the referent (World Health Organization guideline). Total agreement, sensitivity, and specificity were also calculated with 95% confidence interval. RESULTS: When a weekly frequency of PA was required, the prevalence of sufficient PA decreased by 11% (P < .05). For all criteria, doubling the vigorous PA minutes was similar to simply adding them to moderate PA. These findings are consistent regardless of sex, age, and educational level. CONCLUSION: Prevalence estimates and agreement between different PA recommendations were significantly affected when a minimum frequency was required but did not change when vigorous PA minutes were doubled.

Impact of heart rate on reproducibility of heart rate variability analysis in the supine and standing positions in healthy men.

OBJECTIVE: The reliability of heart rate variability (HRV) analysis is not yet fully understood, especially considering different body positions and the mathematical influence of heart rate. The aim of this study was to evaluate the reliability of HRV in supine and standing positions, with and without mathematical adjustment of HRV by the average R-R interval (iRR). METHODS: We evaluated 37 young males (23.1±4 years; 25.1±3 kg/m2). A 5-min segment of the iRR was collected in the supine and standing positions on three occasions separated by 48-hour intervals. Absolute and relative reliability of temporal and spectral indices were assessed by the coefficient of variation (CV) and the intraclass correlation coefficient (ICC), respectively. RESULTS: We did not observe differences in HRV indices in the three occasions in the supine or standing position (p>0.05). Moderate to good reproducibility was observed for temporal and spectral indices of HRV in the supine position (ICC: 0.65-0.89; CV: 0.9-19.8). In the orthostatic position, low to good reproducibility was observed (ICC: 0.35-0.89; CV: 1.1-34.8), with higher ICCs for temporal indices. After mathematical adjustment, only a small modification in HRV reliability was observed in both positions. CONCLUSIONS: In young adult males, the mathematical adjustment of HRV by the average iRR led to a nonsignificant effect on HRV reliability. Additionally, HRV reliability is dependent on body position and the index analyzed. Promising measures in both supine and standing positions include r-MSSD and the HF band (parasympathetic indices).

Impact of heart rate on reproducibility of heart rate variability analysis in the supine and standing positions in healthy men

OBJECTIVE: The reliability of heart rate variability (HRV) analysis is not yet fully understood, especially considering different body positions and the mathematical influence of heart rate. The aim of this study was to evaluate the reliability of HRV in supine and standing positions, with and without mathematical adjustment of HRV by the average R-R interval (iRR). METHODS: We evaluated 37 young males (23.1±4 years; 25.1±3 kg/m2). A 5-min segment of the iRR was collected in the supine and standing positions on three occasions separated by 48-hour intervals. Absolute and relative reliability of temporal and spectral indices were assessed by the coefficient of variation (CV) and the intraclass correlation coefficient (ICC), respectively. RESULTS: We did not observe differences in HRV indices in the three occasions in the supine or standing position (p>0.05). Moderate to good reproducibility was observed for temporal and spectral indices of HRV in the supine position (ICC: 0.65-0.89; CV: 0.9-19.8). In the orthostatic position, low to good reproducibility was observed (ICC: 0.35-0.89; CV: 1.1-34.8), with higher ICCs for temporal indices. After mathematical adjustment, only a small modification in HRV reliability was observed in both positions. CONCLUSIONS: In young adult males, the mathematical adjustment of HRV by the average iRR led to a nonsignificant effect on HRV reliability. Additionally, HRV reliability is dependent on body position and the index analyzed. Promising measures in both supine and standing positions include r-MSSD and the HF band (parasympathetic indices).

Is a short-stage protocol during an incremental exercise test reliable for heart rate variability threshold analysis?

Aim: Heart rate variability threshold (HRVT) is a valid method to determine parasympathetic depression during an incremental exercise test (IET). However, HRVT is usually assessed using the last 60s of each 180s stage of an IET, resulting in longer and demotivating tests. This study aimed to evaluate the agreement of HRVT analysis adopting the first and second minute of R-R interval (iRR) segment comparatively to a standard third-minute segment obtained at each 3-min stage on IET. Methods: Seventeen young male subjects (22.2 ± 3.1 years; 23.4 ± 2.3 kg/m2) underwent IET on a cycle ergometer. HRVT was considered the load corresponding to the point of stabilization of the SD1 index (HRVTV), or the first load with SD1 value < 3ms (HRVT<3), both assessed by the 1st (HRVT1V, HRVT1<3), 2nd (HRVT2V, HRVT2<3) and standard 3rd (HRVT3V, HRVT3<3) 60s iRR segment analyzed at each stage of IET. Agreement and reliability were assessed by the Bland-Altman analysis and the intraclass correlation coefficient (ICC), respectively. Results: High reliability and non-significant bias were observed considering HRVT1V vs HRVT3V (ICC = 0.92; p = 0.18) or HRVT2V vs HRVT3V (ICC = 0.94; p = 0.99). However, lower reliability was observed for HRVT1<3 vs HRVT3<3 (ICC = 0.79; p = 0.75) and for HRVT2<3 vs HRVT3<3 (ICC = 0.91; p = 0.33). Conclusion: HRVT can be similarly assessed by the 1st, 2nd or 3rd 60 seconds iRR segment, mainly when assessed by a visual method.(AU)

Resting Bradycardia, Enhanced Postexercise Heart Rate Recovery and Cardiorespiratory Fitness in Recreational Ballroom Dancers.

PURPOSE: In a cross-sectional study design, we evaluated the resting heart rate (HRbaseline) and exercise and postexercise stress test-related chronotropic responses in male practitioners of recreational ballroom dancing (BD; n = 25, Mage = 26.6 ± 6.1 years) compared to a control group of insufficiently active nondancers (CG; n = 25, Mage = 25.9 ± 4.5 years). METHOD: All participants underwent a submaximal exercise test. At 85% of the maximal predicted HR, the recovery protocol was started, and heart rate recovery (HRR) was recorded during 1-min intervals for 5 min. RESULTS: Compared with CG, BD showed lower HRbaseline (70 beats per minute [bpm] vs. 62 bpm, respectively, U = 143, p < .05, ES = .46), lower preexercise HR (94 bpm vs. 86 bpm, U = 157, p < .05, ES = .42), longer exercise test duration (346 s vs. 420 s, U = 95.5, p < .05, ES = .59), and higher HRR for 5 min postexercise (U = 1.29-1.89, p < .05, ES = .33-.50) as follows: 1st min (32 bpm vs. 40 bpm), 2nd min (45 bpm vs. 53 bpm), 3rd min (51 bpm vs. 58 bpm), 4th min (55 bpm vs. 59 bpm), and 5th min (59 bpm vs. 63 bpm). The coefficient of HRR from the 1st min to the 5th min postexercise was similar in both groups (U = 229-311, p > .05, ES = < .10-.22). CONCLUSION: Heightened cardiovascular functional status characterized by favorable enhanced chronotropic dynamics appears to occur in practitioners of recreational ballroom dancing, which suggests that this modality of exercise may result in health benefits.