Efeitos Agudos da Bebida Energética sobre Parâmetros Autonômicos e Cardiovasculares em Indivíduos com Diferentes Capacidades Cardiorrespiratórias: Um Ensaio Controlado, Randomizado, Crossover e Duplo Cego / Acute Effects of Energy Drink on Autonomic and Cardiovascular Parameters Recovery in Individuals with Different Cardiorespiratory Fitness: A Randomized, Crossover, Double-Blind and Placebo-Controlled Trial

Resumo Fundamento Tem-se sugerido que o consumo de bebidas energéticas (BEs) possa afetar a atividade cardiovascular. Objetivos Investigar os efeitos agudos da ingestão de BE sobre a variabilidade da frequência cardíaca (VFC) recuperação cardiovascular após exercício aeróbico moderado em homens de diferentes capacidades cardiorrespiratórias. Métodos Este é um estudo randomizado, duplo cego, crossover, controlado por placebo. Vinte e oito jovens adultos foram divididos em dois grupos de acordo com o pico de consumo de oxigênio (pico de VO2): (1) pico de VO2 alto (AO) - pico de VO2 > 52,15 mL/Kg/min, e (2) pico de VO2 baixo (BO) - pico de VO2 <52,15 mL/Kg/min. Os indivíduos de ambos os grupos foram submetidos a dois protocolos de exercícios em ordem aleatória: exercício moderado aeróbico (60% de pico de VO2) após a ingestão de 250 mL de água (protocolo placebo) ou 250 mL de BE (protocolo BE). Durante os testes de exercício, foram registrados valores de parâmetros cardiorrespiratórios e de VFC. Resultados Foram observadas diferenças significativas para o índice de LF (unidades normalizadas) entre "repouso" e "Rec1" nos grupos de AO e BO durante o protocolo BE. Para a razão LF/HF, foram observadas diferenças significativas entre "repouso" e Rec1 nos grupos AO e BO nos protocolos BE. Conclusão A ingestão aguda de BE retardou a recuperação da frequência cardíaca após o exercício em indivíduos com capacidade cardiorrespiratória baixa e indivíduos com capacidade cardiorrespiratória alta.

Abstract Background It has been suggested that the consumption of energy drinks (ED) may affect cardiovascular activity. Objectives to investigate the acute effects of ED intake on heart rate variability (HRV) and cardiovascular recovery after moderate aerobic exercise in males with different cardiorespiratory capacities. Methods This is a randomized, double-blind, crossover, placebo-controlled study. Twenty-eight young adults were split into two groups according to their peak oxygen consumption (VO2peak) values: (1) High VO2 peak (HO) - VO2 peak > 52.15 mL/kg/min, and (2) low VO2 peak (LO) - peak VO2 <52.15 mL/kg/min. Subjects of both groups underwent two exercise protocols in randomized order: moderate aerobic exercise (60% of VO2peak) following the intake of 250 mL of water (placebo protocol) or 250 mL of ED (ED protocol). During the exercise tests, values of cardiorespiratory and HRV parameters were recorded. Results Significant differences were observed for the LF (normalized units) index between rest and Rec1 in HO energy and LO groups during the ED protocol. For the LF/HF ratio, significant differences were seen between rest and Rec1 in HO and LO during ED protocols. Conclusion Acute ED intake delayed heart rate recovery after exercise in subjects with low and high cardiorespiratory fitness.

Acute Effects of Energy Drink on Autonomic and Cardiovascular Parameters Recovery in Individuals with Different Cardiorespiratory Fitness: A Randomized, Crossover, Double-Blind and Placebo-Controlled Trial. / Efeitos Agudos da Bebida Energética sobre Parâmetros Autonômicos e Cardiovasculares em Indivíduos com Diferentes Capacidades Cardiorrespiratórias: Um Ensaio Controlado, Randomizado, Crossover e Duplo Cego.

BACKGROUND: It has been suggested that the consumption of energy drinks (ED) may affect cardiovascular activity. OBJECTIVES: to investigate the acute effects of ED intake on heart rate variability (HRV) and cardiovascular recovery after moderate aerobic exercise in males with different cardiorespiratory capacities. METHODS: This is a randomized, double-blind, crossover, placebo-controlled study. Twenty-eight young adults were split into two groups according to their peak oxygen consumption (VO2peak) values: (1) High VO2 peak (HO) - VO2 peak > 52.15 mL/kg/min, and (2) low VO2 peak (LO) - peak VO2 <52.15 mL/kg/min. Subjects of both groups underwent two exercise protocols in randomized order: moderate aerobic exercise (60% of VO2peak) following the intake of 250 mL of water (placebo protocol) or 250 mL of ED (ED protocol). During the exercise tests, values of cardiorespiratory and HRV parameters were recorded. RESULTS: Significant differences were observed for the LF (normalized units) index between rest and Rec1 in HO energy and LO groups during the ED protocol. For the LF/HF ratio, significant differences were seen between rest and Rec1 in HO and LO during ED protocols. CONCLUSION: Acute ED intake delayed heart rate recovery after exercise in subjects with low and high cardiorespiratory fitness.

FUNDAMENTO: Tem-se sugerido que o consumo de bebidas energéticas (BEs) possa afetar a atividade cardiovascular. OBJETIVOS: Investigar os efeitos agudos da ingestão de BE sobre a variabilidade da frequência cardíaca (VFC) recuperação cardiovascular após exercício aeróbico moderado em homens de diferentes capacidades cardiorrespiratórias. MÉTODOS: Este é um estudo randomizado, duplo cego, crossover, controlado por placebo. Vinte e oito jovens adultos foram divididos em dois grupos de acordo com o pico de consumo de oxigênio (pico de VO2): (1) pico de VO2 alto (AO) ­ pico de VO2 > 52,15 mL/Kg/min, e (2) pico de VO2 baixo (BO) - pico de VO2 <52,15 mL/Kg/min. Os indivíduos de ambos os grupos foram submetidos a dois protocolos de exercícios em ordem aleatória: exercício moderado aeróbico (60% de pico de VO2) após a ingestão de 250 mL de água (protocolo placebo) ou 250 mL de BE (protocolo BE). Durante os testes de exercício, foram registrados valores de parâmetros cardiorrespiratórios e de VFC. RESULTADOS: Foram observadas diferenças significativas para o índice de LF (unidades normalizadas) entre "repouso" e "Rec1" nos grupos de AO e BO durante o protocolo BE. Para a razão LF/HF, foram observadas diferenças significativas entre "repouso" e Rec1 nos grupos AO e BO nos protocolos BE. CONCLUSÃO: A ingestão aguda de BE retardou a recuperação da frequência cardíaca após o exercício em indivíduos com capacidade cardiorrespiratória baixa e indivíduos com capacidade cardiorrespiratória alta.

Cardiac Autonomic Modulation in Subjects with Amyotrophic Lateral Sclerosis (ALS) during an Upper Limb Virtual Reality Task: A Prospective Control Trial.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. As a result of the rapid progression and severity of the disease, people with ALS experience loss of functionality and independence. Furthermore, it has already been described presence of autonomic dysfunction. Despite the increasing use of virtual reality (VR) in the treatment of different diseases, the use of virtual reality environment as an intervention program for ALS patients is innovative. The benefits and limitations have not yet been proven. Our objective was to evaluate the autonomic function of individuals with amyotrophic lateral sclerosis throughout the virtual reality task. The analysis of autonomic function was completed before, during, and after the virtual reality task using the upper limbs; also, all steps lasted ten minutes in a sitting position. Heart rate variability (HRV) was taken via the Polar® RS800CX cardiofrequencymeter. The following questionnaire was enforced: Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS) and Fatigue Severity Scale (FSS). Different types of HRV were revealed for the groups, indicating that the ALS group has reduced HRV, with most of the representative indices of the sympathetic nervous system. Besides, the physiological process of reducing parasympathetic activity from rest to VR activity (vagal withdrawal), with reduction in HF (ms2) and an increase in HR from rest to activity, and a further increase throughout recovery, with withdrawal of sympathetic nervous system, occurs just for the control group (CG), with no alterations between rest, activity, and recovery in individuals with ALS. We could conclude that patients with ALS have the reduction of HRV with the sympathetic predominance when equated to the healthy CG. Besides that, the ALS individuals have no capability to adapt the autonomic nervous system when likened to the CG during therapy based on VR and their recovery.

Effects of Circuit Weight-Interval Training on Physical Fitness, Cardiac Autonomic Control, and Quality of Life in Sedentary Workers.

Sedentary behaviors, those that involve sitting and low levels of energy expenditure, have been associated with several adverse cardiometabolic effects. This study evaluated the chronic effects of a combined circuit weight interval training (CWIT) on physical fitness, quality of life, and heart rate variability (HRV), and compared the effects of CWIT-induced autonomic adaptations on different postures in adult sedentary workers. Twenty-seven sedentary workers (age 36.9 ± 9.2 years old, 13 men and 14 women) were divided into two groups: control, who continued their sedentary behavior, and experimental, who were submitted to a CWIT for 12 weeks, completing two ~40 min sessions per week. Monitoring of 8th, 16th, and 24th sessions revealed a moderate training load during sessions. Participants exhibited an improved aerobic capacity (VO2max, 34.03 ± 5.36 vs. 36.45 ± 6.05 mL/kg/min, p < 0.05) and flexibility (22.6 ± 11.4 vs. 25.3 ± 10.1 cm, p < 0.05) after the training period. In addition, they showed greater quality of life scores. However, the CWIT did not change body composition. Interestingly, more HRV parameters were improved in the seated position. The CWIT used in the current study was associated with improvements in several fitness and quality of life parameters, as well as in cardiac autonomic control of HR in adult sedentary workers. Examination of different body positions when evaluating changes in HRV appears to be a relevant aspect to be considered in further studies. Future randomized controlled trials (RCTs) with larger samples of both sexes should confirm these promising results.

Appetite Is Suppressed After Full-Body Resistance Exercise Compared With Split-Body Resistance Exercise: The Potential Influence of Lactate and Autonomic Modulation.

ABSTRACT: Conrado de Freitas, M, Ricci-Vitor, AL, de Oliveira, JVNS, Quizzini, GH, Vanderlei, LCM, Silva, BSA, Zanchi, NE, Cholewa, JM, Lira, FS, and Rossi, FE. Appetite is suppressed after full-body resistance exercise compared with split-body resistance exercise: the potential influence of lactate and autonomic modulation. J Strength Cond Res 35(9): 2532-2540, 2021-The purposes of this study were to investigate the effects of full- vs. split-body resistance training on appetite and leptin response and to verify the potential involvement of lactate and autonomic modulation during this response in trained men. Twelve recreationally resistance-trained men (age = 26.1 ± 5.5 years) performed 3 randomized trials in 3 conditions: upper body (UB), lower body (LB), and full body (FB). The subjective rating of hunger was obtained through a visual analog scale. Leptin and lactate concentration were evaluated at rest, immediately after exercise, and during recovery. Heart rate variability in the time and frequency domains was recorded at baseline and during recovery (until 60 minutes after exercise) to assess autonomic modulation. The FB condition induced lower subjective hunger ratings than the UB at Post-1 hour (p < 0.05) and a significant difference in the area under the curve between conditions (p = 0.028) with lower hunger sensation for FB in relation to UB (p = 0.041). The FB presented greater lactate concentration and induced slower heart rate variability recovery in relation to UB and LB conditions (p < 0.05), and heart rate variability remained lower until 60 minutes after exercise compared with rest only in the FB condition. There was a significant negative correlation between subjective hunger ratings and lactate concentration only for the FB condition (r = -0.72, p = 0.028). Full-body resistance exercise induced lower subjective hunger ratings after exercise in relation to UB resistance exercise. The FB also induced higher lactate production and slower recovery of autonomic modulation compared with the UB and LB conditions. Future research is necessary to investigate a mechanistic relationship between lactate concentrations and hunger suppression after resistance exercise.

Influence of Acute and Chronic High-Intensity Intermittent Aerobic Plus Strength Exercise on BDNF, Lipid and Autonomic Parameters.

The purpose of the present study is two-fold. First, we evaluated whether 8-weeks of combined training (high-intensity intermittent plus strength training) may change brain derived neurotropic factor (BDNF) and lipid parameters (triacylglycerol, HDL-c and non-HDL) in a fasted state. Second, we investigated the effect of an acute session of high-intensity intermittent exercise followed by strength training on systemic BDNF and lipid parameters pre- and post 8-weeks of training. Twenty-one healthy and physically active men were divided into two groups: high-intensity intermittent exercise combined with strength training (HSG; n = 11) and control (CG; n = 10). The HSG exercised for one minute at 100% of speedVO2max (sVO2max) interspersed with one minute of passive recovery followed by strength training (8 exercises with 8-12 repetition maximum loads) for 8-weeks. Heart rate variability, blood pressure, lipid profile, and BDNF concentrations were measured in the fasted state pre- and post-exercise and before and after the 8-week training period. After 8-weeks of exercise training, there was an increase in spectral high frequency component (ms2) and RR interval (p < 0.05), a decreased spectral low frequency component (nu) and heart rate values (p < 0.05), an increase in HDL-c (p < 0.001), and lower BDNF concentrations (p < 0.001). These results suggest that 8-weeks of high-intensity intermittent exercise combined with strength exercise is an effective protective cardio-metabolic strategy capable of increasing HDL-c and BDNF concentrations after an acute exercise session. In the long-term, the modulation on BDNF and HDL-c concentrations may be a determining factor for protection against neurological and cardiovascular diseases.

Involvement of Cardiorespiratory Capacity on the Acute Effects of Caffeine on Autonomic Recovery.

Background and objectives: As a result of ergogenic properties, caffeine has been increasingly taken prior to physical exercise, yet its effects on post-exercise recovery, considering the differences in the cardiorespiratory capacity of the individuals, has not yet been studied or fully elucidated. Optimizing the post-exercise recovery can convey advantages to physical activity practitioners. We evaluated the acute effects of caffeine on heart rate (HR) autonomic control recovery following moderate aerobic exercise in males with different cardiorespiratory capacities. Materials and Methods: We split young adult men into two groups based on their various oxygen consumption peaks (VO2 peak): (1) Higher VO2 (HO): Sixteen volunteers, peak VO2 > 42.46 mL/kg/min and (2) Low VO2 (LO): Sixteen individuals, VO2 < 42.46 mL/kg/min). The volunteers were submitted to placebo and caffeine protocols, which entailed 300 mg of caffeine or placebo (starch) in capsules, followed by 15 min of rest, 30 min of moderate exercise on a treadmill at 60% of the VO2 peak, followed by 60 min of supine recovery. Heart rate variability (HRV) indexes in the time and frequency domains were examined. Results: Effect of time for RMSSD (square root of the average of the square of the differences between normal adjacent RR intervals) and SDNN (standard deviation of all normal RR intervals recorded in a time interval) was achieved (p < 0.001). Significant adjustments were observed (rest versus recovery) at the 0 to 5th min of recovery from exercise for the LO during the placebo protocol and at the 5th at 10th min of recovery for the caffeine protocol. For the HO in both procedures we found significant alterations only at the 0 to 5th min of recovery. Conclusion: Caffeine delayed parasympathetic recovery from exercise in individuals with lower cardiorespiratory capacity.

Impact of functional training on geometric indices and fractal correlation property of heart rate variability in postmenopausal women.

BACKGROUND: To evaluate the influence of functional training on the geometric indices of heart rate variability (HRV) and fractal correlation properties of the dynamics of heart rate in menopausal women. METHODS: Of 39 women who were in the period of menopause for more than a year and who did not practice any regular physical activity were divided into: Functional training group (FTG = 50 ± 4.5 years; 67.64 ± 11.64 kg; 1.5 ± 0.05 m) that executed the functional training (FT) and all proposals by reviews and the Control group (58.45 ± 4.8 years; 66.91 ± 13.24 kg; 1.55 ± 0.05 m) who performed all assessments but not FT. The training consisted of 18 weeks (three times a week) and the volunteers performed three sets of 11 functional exercises followed by a walk in each of the sessions. The autonomic nervous system modulation was evaluated by analysis of HRV and the indices obtained were: RR intervals, RRTRI, TINN, SD1, SD2, SD1/SD2, qualitative analysis of Poincaré plot and DFA (alfa-1, alfa-2 and alfa-1/alfa-2). The Student's t-test for unpaired samples (normal data) or Mann-Whitney test nonnormal data) were used to compare the differences obtained between the final moment and the initial moment of the studied groups (p < .05). CONCLUSION: Were observed in the FTG: increased SD1 (CG 0.13 ± 4.00 vs. 3.60 ± 8.43), beat-to-beat global dispersion much greater as an increased in the dispersion of long-term RR intervals and increased fractal properties of short-term (α1) (CG -0.04 ± 0.13 vs. 0.07 ± 0.21). FT promoted a beneficial impact on cardiac autonomic modulation, characterized by increased parasympathetic activity and short-term fractal properties of the dynamics of the heart rate.

Agreement analysis of oscillometric devices in the measure of resting heart rate in breast cancer survivors.

OBJECTIVE: The aim of this study was to verify the reproducibility of an oscillometric device in the measurement of resting heart rate (RHR) in breast cancer survivors. METHODS: This study included 85 breast cancer survivors with a mean age of 58.87±10.03 years. For the RHR evaluation, the equipment used was the Omron HEM 742, electronic and digital arm device, for measurement of blood pressure and heart rate (HR), with automatic cuff inflation and deflation. At the same time as the oscillometric measurement, HR was measured by the HR monitor Polar RS800 CX, which has been validated previously for HR uptake. The HR value obtained by the cardiofrequency meter was registered at the same time that the Omron device measured blood pressure and HR values. RESULTS: It was observed that the RHR values were very close in both devices and that the correlation values and intraclass correlation coefficient were high. These results were replicated when the female breast cancer survivors were stratified by age group. The agreement values presented by the Bland-Altman analysis showed good values; both for the entire sample and stratified by age, few cases were outside beyond 95% confidence interval range. CONCLUSION: The present study showed that the oscillometric device used presented good values of reproducibility in the detection of RHR values in breast cancer survivors compared with a cardiac monitor.

Association of cardiac autonomic modulation with physical and clinical features of young people with type 1 diabetes.

OBJECTIVE: The objective of this study was to verify possible associations between heart rate variability indices and physical activity, body composition, and metabolic and cardiovascular parameters in individuals with type 1 diabetes. METHOD: A total of 39 young patients with type 1 diabetes were included. Body composition, physical activity, cardiovascular parameters, and metabolic parameters were assessed. For the heart rate variability analysis, heart rate was recorded beat-by-beat using a Polar S810i heart rate monitor for 30 minutes, with the volunteers in the supine position; subsequently, the following indices were considered: standard deviation of all normal RR intervals; root-mean square of differences between adjacent normal RR intervals in a time interval; percentage of adjacent RR intervals with a difference of duration >50 ms; high frequency component in milliseconds squared; high frequency component in normalised units; standard deviation of the instantaneous variability beat-to-beat; and standard deviation of the long-term variability. The association between the heart rate variability indices and independent variables was verified through linear regression in unadjusted and adjusted models (considering gender and age). The statistical significance was set at 5% and the confidence interval at 95%. RESULTS: High values of at-rest heart rate were associated with reduced parasympathetic activity and global heart rate variability, and higher values of waist-to-hip ratio were related to lower parasympathetic activity, independent of age or gender. CONCLUSION: For young patients with type 1 diabetes, increases in at-rest heart rate values are associated with reduced parasympathetic activity and global heart rate variability, whereas higher waist-to-hip ratio values are related to lower parasympathetic activity, both independent of age and gender.

Changes in body fatness affect cardiovascular outcomes more than changes in physical activity.

OBJECTIVE: The aim of this study was to analyse whether changes in physical activity and body fatness are related to modifications in cardiovascular risk factors among adolescents. Material and methods A sample of 89 healthy adolescents was recruited for this study. We assessed habitual physical activity, body fat percentage, arterial thickness, blood sample, and biological maturation. Multivariate models were used to analyse the relationships between independent and dependent variables. RESULTS: Physical activity (mean difference: 429.4 steps [95% confidence interval=-427 to 1286]) and body fatness (mean difference: -0.7% [95% confidence interval=-1.6-0.2]) remained stable during the study period. Independent of changes in physical activity, for each percentage increase in body fatness, femoral intima-media thickness increased by 0.007 mm (ß=0.007 [95% confidence interval=0.001-0.013]). Longitudinal relationships were found for high-density lipoprotein-cholesterol (ß=-0.477 mg/dl [95% confidence interval=-0.805 to -0.149]) and triacylglycerol (ß=2.329 mg/dl [95% confidence interval=0.275-4.384]). CONCLUSION: Changes in body fatness are more important than the amount of physical activity on cardiovascular and metabolic risks.

Analysis of agreement between cardiac risk stratification protocols applied to participants of a center for cardiac rehabilitation.

BACKGROUND: Cardiac risk stratification is related to the risk of the occurrence of events induced by exercise. Despite the existence of several protocols to calculate risk stratification, studies indicating that there is similarity between these protocols are still unknown. OBJECTIVE: To evaluate the agreement between the existing protocols on cardiac risk rating in cardiac patients. METHOD: The records of 50 patients from a cardiac rehabilitation program were analyzed, from which the following information was extracted: age, sex, weight, height, clinical diagnosis, medical history, risk factors, associated diseases, and the results from the most recent laboratory and complementary tests performed. This information was used for risk stratification of the patients in the protocols of the American College of Sports Medicine, the Brazilian Society of Cardiology, the American Heart Association, the protocol designed by Frederic J. Pashkow, the American Association of Cardiovascular and Pulmonary Rehabilitation, the Société Française de Cardiologie, and the Sociedad Española de Cardiología. Descriptive statistics were used to characterize the sample and the analysis of agreement between the protocols was calculated using the Kappa coefficient. Differences were considered with a significance level of 5%. RESULTS: Of the 21 analyses of agreement, 12 were considered significant between the protocols used for risk classification, with nine classified as moderate and three as low. No agreements were classified as excellent. Different proportions were observed in each risk category, with significant differences between the protocols for all risk categories. CONCLUSION: The agreements between the protocols were considered low and moderate and the risk proportions differed between protocols.

Analysis of agreement between cardiac risk stratification protocols applied to participants of a center for cardiac rehabilitation

ABSTRACT Background Cardiac risk stratification is related to the risk of the occurrence of events induced by exercise. Despite the existence of several protocols to calculate risk stratification, studies indicating that there is similarity between these protocols are still unknown. Objective To evaluate the agreement between the existing protocols on cardiac risk rating in cardiac patients. Method The records of 50 patients from a cardiac rehabilitation program were analyzed, from which the following information was extracted: age, sex, weight, height, clinical diagnosis, medical history, risk factors, associated diseases, and the results from the most recent laboratory and complementary tests performed. This information was used for risk stratification of the patients in the protocols of the American College of Sports Medicine, the Brazilian Society of Cardiology, the American Heart Association, the protocol designed by Frederic J. Pashkow, the American Association of Cardiovascular and Pulmonary Rehabilitation, the Société Française de Cardiologie, and the Sociedad Española de Cardiología. Descriptive statistics were used to characterize the sample and the analysis of agreement between the protocols was calculated using the Kappa coefficient. Differences were considered with a significance level of 5%. Results Of the 21 analyses of agreement, 12 were considered significant between the protocols used for risk classification, with nine classified as moderate and three as low. No agreements were classified as excellent. Different proportions were observed in each risk category, with significant differences between the protocols for all risk categories. Conclusion The agreements between the protocols were considered low and moderate and the risk proportions differed between protocols.

Dynamics of heart rate variability analysed through nonlinear and linear dynamics is already impaired in young type 1 diabetic subjects.

BACKGROUND: Autonomic diabetic neuropathy is one of the most common complications of type 1 diabetes mellitus, and studies using heart rate variability to investigate these individuals have shown inconclusive results regarding autonomic nervous system activation. Aims To investigate the dynamics of heart rate in young subjects with type 1 diabetes mellitus through nonlinear and linear methods of heart rate variability. METHODS: We evaluated 20 subjects with type 1 diabetes mellitus and 23 healthy control subjects. We obtained the following nonlinear indices from the recurrence plot: recurrence rate (REC), determinism (DET), and Shanon entropy (ES), and we analysed indices in the frequency (LF and HF in ms2 and normalised units - nu - and LF/HF ratio) and time domains (SDNN and RMSSD), through analysis of 1000 R-R intervals, captured by a heart rate monitor. RESULTS: There were reduced values (p<0.05) for individuals with type 1 diabetes mellitus compared with healthy subjects in the following indices: DET, REC, ES, RMSSD, SDNN, LF (ms2), and HF (ms2). In relation to the recurrence plot, subjects with type 1 diabetes mellitus demonstrated lower recurrence and greater variation in their plot, inter-group and intra-group, respectively. CONCLUSION: Young subjects with type 1 diabetes mellitus have autonomic nervous system behaviour that tends to randomness compared with healthy young subjects. Moreover, this behaviour is related to reduced sympathetic and parasympathetic activity of the autonomic nervous system.

Characteristics and associated factors with sports injuries among children and adolescents

BACKGROUND: The participation of children and adolescents in sports is becoming increasingly common, and this increased involvement raises concerns about the occurrence of sports injuries. OBJECTIVES: To characterize the sports injuries and verify the associated factors with injuries in children and adolescents. METHOD: Retrospective, epidemiological study. One thousand three hundred and eleven children and adolescents up to 18 years of age enrolled in a sports initiation school in the city of Presidente Prudente, State of São Paulo, Brazil. A reported condition inquiry in interview form was used to obtain personal data and information on training and sports injuries in the last 12 months. Injury was considered any physical complaint resulting from training and/or competition that limited the participation of the individual for at least one day, regardless of the need for medical care. RESULTS: The injury rate per 1000 hours of exposure was 1.20 among the children and 1.30 among the adolescents. Age, anthropometric data, and training characteristics only differed with regard to the presence or absence of injuries among the adolescents. The most commonly reported characteristics involving injuries in both the children and adolescents were the lower limbs, training, non-contact mechanism, mild injury, asymptomatic return to activities, and absence of recurrence. CONCLUSIONS: The injury rate per 1000 hours of exposure was similar among children and adolescents. Nevertheless, some peculiarities among adolescents were observed with greater values for weight, height, duration of training, and weekly hours of practice. .

The influence of resistance exercise with emphasis on specific contractions (concentric vs. eccentric) on muscle strength and post-exercise autonomic modulation: a randomized clinical trial.

BACKGROUND: Compared to eccentric contractions, concentric contractions result in higher cardiovascular stress. However, we do not know how these two types of contractions influence cardiac autonomic modulation during the post-exercise recovery period. OBJECTIVE: to compare the effect of resistance training that is performed with concentric vs. eccentric emphasis on muscle strength and on post-exercise recovery which was assessed by examining heart rate variability (HRV), for the knee extensor muscle group in young healthy adults. METHODS: For this study, 105 men between 18 and 30 years of age were randomized into 4 groups: concentric control (CONCC), eccentric control (ECCC), concentric training (CONCT) and eccentric training (ECCT). The CONCC and ECCC groups underwent one session of resistance exercise (RE) using the knee extensor muscle group (3 sets of 1 repetition at 100% of the maximal repetition [1MR]) and the CONCT and ECCT groups performed 10 training sessions. The HRV was analyzed at baseline and across four recovery periods (T1, T2, T3 and T4). RESULTS: The ECCT group exhibited increased muscle strength at the end of the study. Regarding cardiac autonomic modulation, the CONCC and ECCC groups exhibited increases in overall variability (SDNN and SD2) at T1 compared to baseline, and the ECCT group demonstrated increases in variables reflecting vagal modulation and the recovery process (RMSSD, SD1 and HF [ms2]) at T1, T2 and T4 compared to baseline. CONCLUSIONS: Resistance training with emphasis on eccentric contractions promoted strength gain and an increase in cardiac vagal modulation during recovery compared to baseline.

The influence of resistance exercise with emphasis on specific contractions (concentric vs. eccentric) on muscle strength and post-exercise autonomic modulation: a randomized clinical trial / Influência de exercício resistido com ênfase em contrações específicas (concêntrica vs excêntrica) sobre a força muscular e a modulação autonômica pós-esforço: ensaio clínico randomizado

Background: Compared to eccentric contractions, concentric contractions result in higher cardiovascular stress. However, we do not know how these two types of contractions influence cardiac autonomic modulation during the post-exercise recovery period. Objective: to compare the effect of resistance training that is performed with concentric vs. eccentric emphasis on muscle strength and on post-exercise recovery which was assessed by examining heart rate variability (HRV), for the knee extensor muscle group in young healthy adults. Methods: For this study, 105 men between 18 and 30 years of age were randomized into 4 groups: concentric control (CONCC), eccentric control (ECCC), concentric training (CONCT) and eccentric training (ECCT). The CONCC and ECCC groups underwent one session of resistance exercise (RE) using the knee extensor muscle group (3 sets of 1 repetition at 100% of the maximal repetition [1MR]) and the CONCT and ECCT groups performed 10 training sessions. The HRV was analyzed at baseline and across four recovery periods (T1, T2, T3 and T4). Results: The ECCT group exhibited increased muscle strength at the end of the study. Regarding cardiac autonomic modulation, the CONCC and ECCC groups exhibited increases in overall variability (SDNN and SD2) at T1 compared to baseline, and the ECCT group demonstrated increases in variables reflecting vagal modulation and the recovery process (RMSSD, SD1 and HF [ms2]) at T1, T2 and T4 compared to baseline. Conclusions: Resistance training with emphasis on eccentric contractions promoted strength gain and an increase in cardiac vagal modulation during recovery compared to baseline. .

Contextualização: Ações concêntricas apresentam maior estresse cardiovascular quando comparadas às excêntricas. Entretanto, não se sabe a influência desses tipos de ações no comportamento da modulação autonômica cardíaca durante o processo de recuperação pós-esforço. Objetivo: Comparar o efeito de um treinamento resistido para o grupo extensor do joelho realizado com ênfase concêntrica vs excêntrica sobre a força muscular e a recuperação pós-exercício considerando índices de variabilidade de frequência cardíaca (VFC) em jovens saudáveis. Método: Cento e cinco homens, com idades entre 18 e 30 anos, foram randomizados em quatro grupos: controle concêntrico (CCONC), controle excêntrico (CEXC), treinamento concêntrico (TCONC) e treinamento excêntrico (TEXC). Os grupos CCONC e CEXC realizaram uma sessão de exercício reduzido (ER) para o grupo extensor do joelho [três séries de uma repetição a 100% de uma repetição máxima (1RM)], e os grupos TCONC e TEXC realizaram dez sessões de treinamento. A VFC foi analisada no momento basal e na recuperação após as sessões (T1, T2, T3 e T4). Resultados: Observou-se aumento da força muscular para o grupo TEXC. Em relação à modulação autonômica cardíaca, observou-se, em comparação ao momento basal, aumento dos índices SDNN e SD2 no momento T1 nos grupos CCONC e CEXC e aumento dos índices RMSSD, SD1 e AF (ms2) nos momentos T1, T2 e T4 no grupo TEXC. Conclusões: Conclui-se que o treinamento resistido realizado com ênfase em contrações excêntricas promoveu ganho de força e aumento da modulação vagal cardíaca durante o processo de recuperação ...

Autonomic modulation and its relation with body composition in swimmers.

This study compared autonomic modulation in swimmers and non-athletes in relation to body composition. A total of 28 athletes with a mean age of 19.7 ± 2.9 years were evaluated who had at least 2 years of swimming training, trained approximately 7,000 m per day, with a frequency of 5 days per week, and who competed at national level. The control group was made up of 21 volunteers (23.0 ± 2.5 years), who did not practice regular physical activity (<2 hours per week). Body composition was estimated using dual-energy x-ray absorptiometry, and autonomic modulation was assessed by heart rate variability (HRV). The results show that there were significant differences in autonomic modulation and body composition between the groups, and that the athletes had a higher overall variability (standard deviation of all normal intervals between consecutive heart beats [SDNN]: 78.1 [72.5-93.5] × 61.1 [56.4-75.7], p = 0.022) and greater autonomic balance (LF/HF: 0.96 [0.88-1.35] × 0.71 [0.56-0.93], p = 0.023), compared with the non-athletes, respectively. In addition, a moderate and positive relation was obtained between fat-free mass and the square root of the squared differences between consecutive heartbeat intervals (RMSSD: r = 0.526, p = 0.004 × r = 0.456, p = 0.038), (SDNN: r = 0.617, p = 0.001 × r = 0.571, p = 0.007) and low frequency (LFms: r = 0.517, p = 0.005 × r = 0.600, p = 0.004) in the athletes and non-athletes, respectively, without a correlation between fat mass (FM). The conclusion is that young highly trained swimmers had lower FM, increased fat-free mass, and better HRV than young adult non-athletes and suggests that a lower quantity of FM and, especially, a greater fat-free mass (FFM) are linked to better autonomic modulation. Thus, this study could contribute to coaches and trainers establishing greater performance by better autonomic modulation and greater quantity of FFM.

Characteristics and associated factors with sports injuries among children and adolescents.

BACKGROUND: The participation of children and adolescents in sports is becoming increasingly common, and this increased involvement raises concerns about the occurrence of sports injuries. OBJECTIVES: To characterize the sports injuries and verify the associated factors with injuries in children and adolescents. METHOD: Retrospective, epidemiological study. One thousand three hundred and eleven children and adolescents up to 18 years of age enrolled in a sports initiation school in the city of Presidente Prudente, State of São Paulo, Brazil. A reported condition inquiry in interview form was used to obtain personal data and information on training and sports injuries in the last 12 months. Injury was considered any physical complaint resulting from training and/or competition that limited the participation of the individual for at least one day, regardless of the need for medical care. RESULTS: The injury rate per 1000 hours of exposure was 1.20 among the children and 1.30 among the adolescents. Age, anthropometric data, and training characteristics only differed with regard to the presence or absence of injuries among the adolescents. The most commonly reported characteristics involving injuries in both the children and adolescents were the lower limbs, training, non-contact mechanism, mild injury, asymptomatic return to activities, and absence of recurrence. CONCLUSIONS: The injury rate per 1000 hours of exposure was similar among children and adolescents. Nevertheless, some peculiarities among adolescents were observed with greater values for weight, height, duration of training, and weekly hours of practice.