Acute Low-Dose Capsiate Supplementation Improves Upper Body Resistance Exercise Performance in Trained Men: A Randomized, Crossover and Double-Blind Study.

Objectives: The purpose of this study was to compare the effects of two acute doses of Capsiate (CAP; 6 vs. 12 mg) on upper body resistance exercise performance in trained men. Methods: Using a randomized, crossover and double-blind design, 20 resistance-trained males were supplemented with low-dose CAP (6 mg), high-dose CAP (12 mg) or placebo 45 minutes before exercise. Subjects performed 4 sets of bench press with repetitions to failure at 70% 1 repetition maximum (1RM) and 2 minutes of rest between each set. The ratings of perceived exertion (RPE) and blood lactate were analyzed at baseline and after exercise. Results: Total weight lifted was greater in the low CAP (2,454.6 ± 448.6 kg) compared to placebo (2,354.7 ± 458.6 kg, p = 0.039) and high CAP (2,309.3 ± 428.1 kg, p = 0.001). There was no significant difference between conditions for RPE (p = 0.155) and blood lactate (p = 0.434). Conclusion: In summary, 6 mg CAP increased total weight lifted and repetitions to failure on bench press exercise in trained men, while 12 mg did not present any effect.

Anaerobic Contribution Determined in Free-Swimming: Sensitivity to Maturation Stages and Validity.

Evaluation of anaerobic contribution is important under swimming settings (training and modification through ages), therefore, it is expected to change during maturation. The accumulated oxygen deficit (AOD) method can be used to determine the contribution of nonoxidative energy during swimming; however, it requires several days of evaluation. An alternative method to estimate anaerobic contribution evaluation (ACALT), which can also be evaluated without snorkel (i.e., free-swimming, ACFS), has been proposed; however, these methods have never been compared. Thus, this study (i) analyzed the effect of maturation stage on ACFS during maximal 400 m swimming (Part I), and (ii) compared AOD with ACALT and ACFS, determined in a maximal 400 m effort (Part II). In Part I, 34 swimmers were divided into three groups, according to maturation stages (early-pubertal, middle-pubertal, and pubertal), and subjected to a maximal 400 m free-swimming to determine ACFS. In Part II, six swimmers were subjected to one 400 m maximal effort, and four submaximal constant efforts. The AOD was determined by the difference between the estimated demand and accumulated oxygen during the entire effort. The ACALT and ACFS (for Part I as well) was assumed as the sum of lactic and alactic anaerobic contributions. ACFS was higher in pubertal (3.8 ± 1.1 L) than early (2.1 ± 0.9 L) and middle pubertal group (2.4 ± 1.1 L). No difference was observed among absolute AOD (3.2 ± 1.3 L), ACALT (3.2 ± 1.5 L), and ACFS (4.0 ± 0.9 L) (F = 3.6; p = 0.06). Relative AOD (51.8 ± 12.2 mL·kg-1), ACALT (50.5 ± 14.3 mL·kg-1), and ACFS (65.2 ± 8.8 mL·kg-1) presented main effect (F = 4.49; p = 0.04), without posthoc difference. The bias of AOD vs. ACALT was 0.04 L, and AOD vs. ACFS was -0.74 L. The limits of agreement between AOD and ACALT were +0.9 L and -0.8 L, and between AOD and ACFS were +0.7 L and -2.7 L. It can be concluded that ACFS determination is a feasible tool to determine anaerobic contribution in young swimmers, and it changes during maturation stages. Also, ACFS might be useful to measure anaerobic contribution in swimmers, especially because it allows greater speeds.

Effects of Capsiate Supplementation on Maximal Voluntary Contraction in Healthy Men.

This study aimed to investigate the effects of acute capsaicin analog (Capsiate - CAP) supplementation on maximal voluntary isometric contraction (MVIC) performance in healthy young men. Thirteen subjects (25.2±3.2 yrs) participated in the present study. In two different days separated by one week, the subjects ingested capsiate (12 mg) or placebo (starch: 12 mg) 45 minutes before a MVIC test. The MVIC test consisted of five 10-second knee extension maximal isometric contractions with 45 seconds of recovery between efforts. The peak force, mean force, minimum force, fatigue index, and area under the curve of each contraction were calculated. Main condition effect was found, with higher values of peak force (+4.83%, F=6.867, p=0.02), fatigue index (+8.96%, F=5.228, p=0.041), and area under the curve (+4.19%, F=4.774, p=0.04) for CAP compared to placebo, however, no interaction effect was found for any variable (F=0.090 to 1.356, p≥0.276). In summary, healthy young men produced higher maximal isometric force and delayed fatigue in the CAP condition compared to placebo condition (condition effect) but without significant difference between each effort.

The Relevance of a Physical Active Lifestyle and Physical Fitness on Immune Defense: Mitigating Disease Burden, With Focus on COVID-19 Consequences.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a fast spreading virus leading to the development of Coronavirus Disease-2019 (COVID-19). Severe and critical cases are characterized by damage to the respiratory system, endothelial inflammation, and multiple organ failure triggered by an excessive production of proinflammatory cytokines, culminating in the high number of deaths all over the world. Sedentarism induces worse, continuous, and progressive consequences to health. On the other hand, physical activity provides benefits to health and improves low-grade systemic inflammation. The aim of this review is to elucidate the effects of physical activity in physical fitness, immune defense, and its contribution to mitigate the severe inflammatory response mediated by SARS-CoV-2. Physical exercise is an effective therapeutic strategy to mitigate the consequences of SARS-CoV-2 infection. In this sense, studies have shown that acute physical exercise induces the production of myokines that are secreted in tissues and into the bloodstream, supporting its systemic modulatory effect. Therefore, maintaining physical activity influence balance the immune system and increases immune vigilance, and also might promote potent effects against the consequences of infectious diseases and chronic diseases associated with the development of severe forms of COVID-19. Protocols to maintain exercise practice are suggested and have been strongly established, such as home-based exercise (HBE) and outdoor-based exercise (OBE). In this regard, HBE might help to reduce levels of physical inactivity, bed rest, and sitting time, impacting on adherence to physical activity, promoting all the benefits related to exercise, and attracting patients in different stages of treatment for COVID-19. In parallel, OBE must improve health, but also prevent and mitigate COVID-19 severe outcomes in all populations. In conclusion, HBE or OBE models can be a potent strategy to mitigate the progress of infection, and a coadjutant therapy for COVID-19 at all ages and different chronic conditions.

Correction to: Beta alanine supplementation effects on metabolic contribution and swimming performance.

An amendment to this paper has been published and can be accessed via the original article.

Beta alanine supplementation effects on metabolic contribution and swimming performance.

BACKGROUND: Investigations of ß-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of ß-alanine supplementation on metabolic contribution and performance during 400-m swim. METHODS: Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day- 1 of ß-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (∆[La-]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p > 0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFincl). RESULTS: No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ∆Lactate (p: 0.001; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89). CONCLUSIONS: Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and ß-alanine supplementation doesn't affect metabolic contribution and performance during 400-m freestyle.

Photobiomodulation 30 min or 6 h Prior to Cycling Does Not Alter Resting Blood Flow Velocity, Exercise-Induced Physiological Responses or Time to Exhaustion in Healthy Men.

PURPOSE: The aim of the current study was to investigate the effects of photobiomodulation therapy (PBMT) applied 30 min or 6 h prior to cycling on blood flow velocity and plasma nitrite concentrations at rest, time to exhaustion, cardiorespiratory responses, blood acid-base balance, and K+ and lactate concentrations during exercise. METHODS: In a randomized, crossover design, 13 healthy untrained men randomly completed four cycling bouts until exhaustion at the severe-intensity domain (i.e., above respiratory compensation point). Thirty minutes or 6 h prior to the cycling trials, participants were treated with PBMT on the quadriceps, hamstrings, and gastrocnemius muscles of both limbs using a multi-diode array (11 cm × 30 cm with 264 diodes) at doses of 152 J or a sham irradiation (with device turned off, placebo). Blood samples were collected before and 30 min or 6 h after treatments to measure plasmatic nitrite concentrations. Doppler ultrasound exams of the femoral artery were also performed at the same time points. Cardiorespiratory responses, blood acid-base balance, and K+ and lactate concentrations were monitored during exercise sessions. RESULTS: PBMT did not improve the time to exhaustion (p = 0.30). At rest, no differences were found in the peak systolic velocity (p = 0.97) or pulsatility index (p = 0.83) in the femoral artery, and in plasma nitrite concentrations (p = 0.47). During exercise, there were no differences for any cardiorespiratory response monitored (heart rate, p = 0.15; oxygen uptake, p = 0.15; pulmonary ventilation, p = 0.67; carbon dioxide output, p = 0.93; and respiratory exchange ratio, p = 0.32), any blood acid-base balance indicator (pH, p = 0.74; base excess, p = 0.33; bicarbonate concentration, p = 0.54), or K+ (p = 0.22) and lactate (p = 0.55) concentrations. CONCLUSIONS: PBMT at 152 J applied 30 min or 6 h before cycling at severe-intensity did not alter resting plasma nitrite and blood flow velocity in the femoral artery, exercise-induced physiological responses, or time to exhaustion in healthy untrained men.

Analysis of the heart rate deflection point as a tool for exercise prescription in subjects with COPD - a cross-sectional study.

Background: Prescription of exercise training in subjects with chronic obstructive pulmonary disease (COPD) remains a challenge in clinical practice. The heart rate deflection point (HRDP) is an option to reduce costs, reflects the anaerobic threshold and it is noninvasive; however its applicability in COPD is still unknown. Aim: To compare HRDP with gas exchange threshold values (GET) in subjects with COPD. Methods: Thirty-one subjects were evaluated in this cross-sectional study, diagnosed with COPD. The subjects performed an incremental exercise test on a treadmill to determine the GET, peak oxygen consumption (VO2PEAK), speed corresponding to VO2PEAK (sVO2PEAK), and peak values of heart rate (HRPEAK). To determine HRDP the heart rate values observed were plotted as a function of intensity. Results: The HRDP was visible in 96.77% of subjects. There was no difference between HRDP and GET (p = 0.07) and a moderate intraclass correlation coefficient (ICC): 0.74 [0.52-0.87] and high limits of agreements were presented (±1.1 km·h-1). Conclusion: The HRDP cannot be used to determine the limits between the physiological domains of these subjects. Thus, although significant correlation was found between HRDP and GET, their application for training prescription and monitoring in subjects with COPD proved to be limited.

Graded and ramp protocols present similar results in apparently healthy subjects / Protocolo escalonado e de rampa apresentam resultados similares em indivíduos aparentemente saudáveis

Abstract The aim of the study was to compare maximum oxygen uptake, maximum heart rate, speed corresponding to VO2max, time to exhaustion, and ventilatory thresholds between two maximal test protocols (scaled vs ramp) with equalized metabolic demand in apparently healthy young adults. Twenty-seven subjects of both sexes were analyzed and submitted to two maximum tests: 1) scaled test with 1.2 km∙h-1 every 2 min; 2) ramp test with 0.1 km∙h-1 every 0.18 min; both with 1% slope and maximum total duration of twenty minutes. Respiratory gas exchanges were directly analyzed, and ventilatory thresholds determined through visual inspection. Central tendency and dispersion measures were adopted, as well as paired t-test and effect size. Bland-Altman analysis verified the agreement among variables. Maximum speed showed significance difference (p < 0.01) for the scaled test (14.0 ± 1.9 km∙h-1) and ramp test (14.6 ± 2.3 km∙h-1). Even with small BIAS values, negative trend and high limits of agreement could be observed. Despite the non-difference presented for variables, except for maximum speed, it could be concluded that the scaled test is able to determine the analyzed variables similar to the ramp test, considering the same conditions of the present study.

Resumo O objetivo do estudo foi comparar o consumo máximo de oxigênio (VO2máx), frequência cardíaca (FC) máxima velocidade associada ao VO2máx, tempo até a exaustão e limiares ventilatórios entre dois protocolos de teste máximo (escalonado vs. rampa) com demanda metabólica equalizada em jovens adultos aparentemente saudáveis. Vinte e sete sujeitos de ambos os sexos foram analisados e submetidos à dois testes máximos: 1) escalonado com 1,2 km•h-1 a cada 2 min; 2) rampa com 0,1 km•h-1 a cada 0,18 min; ambos com 1% de inclinação e duração total máxima prevista de vinte minutos. As trocas respiratórias foram analisadas diretamente, e os limiares ventilatórios determinados por inspeção visual. Medidas de tendência central e dispersão foram adotadas, assim como um teste t pareado e tamanho do efeito. A análise de Bland-Altman verificou a concordância entre as variáveis. A única variável a apresentar diferença estatística (p < 0,01) foi a velocidade máxima (escalonado = 14,0 ± 1,9 km•h-1) e (rampa = 14,6 ± 2,3 km∙h-1). Mesmo com baixos valores de BIAS, é possível verificar uma tendência negativa assim como altos limites de concordância. Apesar da não diferença apresentada para as variáveis, exceto para a velocidade máxima, é possível afirmar que o teste escalonado é capaz de determinar as variáveis analisadas de modo semelhante ao teste rampa considerando as mesmas condições do presente estudo.

Development and validation of an equation to estimate body fat in elderly women / Desenvolvimento e validação de uma equação para estimar a gordura corporal em mulheres idosas

Abstract The purpose of this present study was to develop and validate a prediction equation for body composition assessment using anthropometric measures of elderly women. This is cross-sectional correlational study with 243 older women ± 64.5 years old and body mass index (BMI) ± 28.70 kg/m². For the development of the equation it was utilized the method of hold-out sample validation. The participants were randomly divided into equation development group (96 elderly women) and a group for validation (147 elderly women). Total body mass, height, waist and hip circumferences, ratio waist-hip ratio and BMI were measured. The whole-body dual-energy X-ray absorptiometry (DXA) assessed body composition (percentage of body fat, fat mass, and fat-free mass). The equations were developed using multiple linear regression, with validation by the stepwise method; the comparison of the equations was analyzed by the paired Student's t test and the analysis of residual scores by the method of Blant and Altman. The New Equation presents a strong correlation (R = 0.83) and (R² = 0.69), and a standard error of estimation equals to 3.21% for percentage body fat prediction. The mean difference between the estimations of percentage body fat from DXA and the New Equation was 0.11% (t(0,180); P = 0.850). Therefore, the New Equation had an accuracy of 93.5% and a total error of 1.8%. The body fat estimation in older women using this New Equation based on BMI and age is valid and accurate.

Resumo O objetivo do presente estudo foi desenvolver e validar uma equação de predição para avaliação da composição corporal utilizando-se medidas antropométricas de idosas. Este é um estudo transversal e correlacional com 243 idosas ± 64.5 anos de idade e índice de massa corporal (IMC) ± 28.70 kg/m². Para o desenvolvimento da equação utilizou-se o método de validação hold-out. As participantes foram divididas aleatoriamente em um grupo para desenvolvimento da equação (96 idosas) e um grupo para validação da equação (147 idosas). Massa corporal total, estatura, circunferências da cintura e quadril, relação cintura-quadril e IMC foram mensurados. A absorciometria por raios-X com dupla energia (DXA) para todo corpo foi utilizada para avaliação da composição corporal (percentual de gordura, massa gorda e massa livre de gordura). As equações foram desenvolvidas utilizando a regressão linear múltipla, com validação pelo método stepwise; a comparação das equações foi realizada pelo Teste T para amostras pareadas e análise dos escores residuais por meio do método de Bland e Waltman. A Nova Equação apresentou uma forte correlação (R = 0.83) e (R2 = 0.69), e uma estimativa de erro padrão de 3.21% para predição do percentual de gordura. A diferença média entre as estimativas de percentual de gordura pelo DXA e Nova Equação foi de 0.11% (t(0,180); P = 0.850). Assim, a Nova Equação teve uma precisão de 93.5% e um erro total de 1.8%. A estimativa do percentual de gordura em idosas usando a Nova Equação baseada no IMC e idade são válidos e precisos.

Anti-inflammatory response to acute exercise is related with intensity and physical fitness.

PURPOSE: The relationship between inflammatory markers and energetic metabolism has been explored. However, the relationship between exercise intensity and fitness status is unclear, and it is necessary to understand this relationship to apply specific exercise guidance. The purpose of the study was to analyze metabolic and inflammatory responses imposed by acute exercise sessions performed at moderate, heavy, and severe intensities and their relationship with the physical fitness status. METHODS: Nineteen healthy male volunteers performed three acute exercise sessions until exhaustion or up to 60 minutes on a cycle ergometer at moderate (90% of first ventilatory threshold [VT1]), heavy (midpoint between VT1 and second ventilatory threshold [VT2]), and severe (midpoint between VT2 and maximal aerobic power) intensities. Blood lactate, glucose, NEFA, endotoxin, and cytokines were determined for each exercise session. Peripheral and lipopolysaccharide (LPS)-stimulated release of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-10 was analyzed before, after, and 60 minutes after sessions. RESULTS: In peripheral blood, severe intensity increased lactate, endotoxin, and TNF-α immediately after exercise and glucose at 60 min after exercise. There was a trend for IL-10 increase at 60 minutes after exercise in peripheral blood. Immediately after exercise, LPS-stimulated TNF-α, IL-6, IL-6/IL-10 ratio, and lactate levels were higher in the severe intensity while nonester fatty acid levels decreased at this time. At 60 minute after exercise, higher concentrations of glucose and a trend for increased IL-10 were observed in severe intensity. A positive correlation was observed between maximal aerobic power and IL-10 ( r = 0.513; P = 0.042), and negative correlations between maximal aerobic power and endotoxin ( r = -0.531; P = 0.034) and lactate ( r = -0.538; P = 0.031) in heavy intensity. CONCLUSION: Our data show a novel finding that higher cytokine responses occur at higher intensities, mainly in severe intensity. However, the anti-inflammatory (IL-10) response was physical fitness-dependent.

Impact to short-term high intensity intermittent training on different storages of body fat, leptin and soluble leptin receptor levels in physically active non-obese men: A pilot investigation.

BACKGROUND & AIMS: Studies have postulated High Intensity Intermittent Training (HIIT) as a superior strategy to reduce body fat. The purpose of this study was to compare the effects HIIT and steady-state training (SST) on body composition, leptin, soluble leptin receptor (sOB-R) levels, and hunger perception in physically active non-obese men. METHODS: Twenty men performed five weeks of HIIT (5 km - 1 min running at 100% speed correspondent to VÈ©O2peak - v VÈ©O2peak - interspersed with 1-min passive recovery; n = 10) or SST (5 km at 70% of vVÈ©O2peak continuously; n = 10) three times a week. Body composition, and hunger perception were assessed at pre- and post-training and were compared by a two-way analysis (group and training period) with repeated measures in the second factor. A fasting time-course (baseline, 24 h, and 48 h after an experimental session of exercise) of leptin and sOB-R levels were measured at pre- and post-five weeks of training and assessed by a three-way analysis (group, period and time of measurement) with repeated measures in the second and third factors. RESULTS: There was no effect on body composition and hunger perception. Leptin was reduced in both groups, while sOB-R was increased post-five weeks of training in HIIT but not in the SST. CONCLUSIONS: Although both training groups exerted alterations in leptin levels, only HIIT was able increased sOB-R levels, this suggest a superior impact on central responses in physically active non-obese men.

Reliability and Validity of Tethered Swimming Lactate Minimum Test and Their Relationship With Performance in Young Swimmers.

PURPOSE: To test the reliability and validity of tethered swimming lactate minimum test in young swimmers. METHODS: Lactate minimum test was performed twice to test the reliability (experiment 1; n = 13). In addition, the validity was investigated through lactate minimum test relationships with tethered swimming lactate threshold and peak force obtained during graded exercise test (experiment 2; n = 11). Finally, the correlations with mean speeds observed during 200-m (s200m) and 30-minute continuous efforts (s30min) were also analyzed (experiment 3; n = 15). In all experiments, the lactate minimum test began with 3-minute all-out effort to induce lactatemia, followed by an exhaustive graded exercise test. RESULTS: The lactate minimum intensity and mean force during the entire 3-minute all-out effort (MF) showed high reliability (coefficient of variation < 8.9% and intraclass correlation coefficient > .93). The lactate minimum intensity was not different compared with lactate threshold (P = .22), presenting high correlations (r = .92) and agreement (95% limits of agreement = ±7.9 N). The mean force during the entire 3-minute all-out effort was similar to peak force obtained during graded exercise test (P = .41), presenting significant correlations (r = .88) and high indices of agreement (95% limits of agreement = ±11.3 N). In addition, lactate minimum test parameters correlated both with mean speeds observed during 200-m (r > .74) and 30-minute continuous efforts (r > .70). CONCLUSION: Thus, tethered swimming lactate minimum test can be used for training recommendations and to monitor aerobic adaptations in young swimmers.

Changes in HDL-c concentrations after 16 weeks of combined training in postmenopausal women: characteristics of positive and negative responders.

This study aimed to investigate the individual characteristics of body composition and metabolic profile that could explain interindividual variation in high-density lipoprotein cholesterol (HDL-c) concentrations in response to 16 weeks of combined strength plus aerobic (combined) training in postmenopausal women. The participants were divided into tertiles based on percentage of changes in HDL-c concentrations after combined training. Only women in the upper tertile (positive responders: Δ > 10.4%; n = 19) and lower tertile (negative responders: Δ < -1.4%; n = 19) were considered for analyses. The total body fat (BF), trunk fat (TF), android fat (AF), gynoid fat, and lean body mass were estimated by dual-energy X-ray absorptiometry. The metabolic profile - glucose, triacylglycerol, total cholesterol, HDL-c, low-density lipoprotein cholesterol, and very-low-density lipoprotein (VLDL) - were assessed. After 16 weeks, both positive and negative responders presented similar improvement in body composition, such as a decrease in percentage and kilograms of BF, TF, and AF, and increase in lean body mass (p value for time < 0.05). As expected, there was an effect of time and also a significant interaction (time vs. group) (p value < 0.001) in the improvement of HDL-c, with higher values for positive responders. Regarding metabolic profile, there were significant interactions (time vs. group) for triacylglycerol (p value = 0.032) and VLDL (p value = 0.027) concentrations, with lower values for positive responders. Our results suggests there is heterogeneity in combined training-induced HDL-c changes in postmenopausal women, and the positive responders were those who presented more pronounced decreases in triacylglycerol and VLDL concentrations.

Critical Velocity Determined by a Non-Exhaustive Method in Subjects With COPD.

BACKGROUND: Exercise training is an effective and low-cost tool for COPD rehabilitation. Thus, validating a non-exhaustive method to determine a patient's anaerobic threshold would be a very interesting tool in practical settings. We aimed to test the reproducibility of critical velocity values determined in a non-exhaustive manner (CVNE) and tolerance for exercise performed at this physiological marker in subjects with COPD. METHODS: Twelve subjects with COPD were evaluated in this cross-sectional study. The study was divided into 2 phases: Phase A consisted of reproducibility of CVNE for subjects with COPD, and Phase B determined the tolerance for exercise tests performed at this physiological marker. RESULTS: The proposed protocol for determining CVNE presented fair reproducibility according to blood lactate concentrations (intraclass correlation coefficient = 0.58). However, we cannot consider that the tests were reproducible due to the wide CI (0.03-0.85). Furthermore, moderate and strong correlations were observed between the CVNE determined by lactate concentration, by oxygen consumption (V̇O2 ) (r = 0.66), and by heart rate (r = 0.88). However, a high limit of agreement was observed ±1.45 km/h and ±1.55 km/h, respectively. In the tolerance for exercise test, none of the subjects presented lactate destabilization, whereas 3 tests were interrupted by oxygen saturation decline and 1 test was interrupted by hemodynamic instability. CONCLUSIONS: Although most of the subjects presented good tolerance for exercise at CVNE, fair levels of reproducibility were observed in subjects with COPD, even using lactate. Thus, the use of CVNE determined through double 3-min efforts should be considered with caution.

The Impact of Training Load on Bone Mineral Density of Adolescent Swimmers: A Structural Equation Modeling Approach.

PURPOSE: To investigate the mediating effect of muscle mass on the relationship between training load and bone density in adolescent swimmers. METHODS: A cross-sectional study involving 87 control and 22 swimmers aged 10-19 years (overall sample: n = 109). Swimmers had a minimum of 1 year of competition in regional and national championships, and control adolescents reported 1 year without any organized sport. Bone density was the main outcome (dual-energy X-ray absorptiometry), which was measured in upper limbs, lower limbs, spine, and whole body. Monthly training load was the independent variable, while the mediation effect of lean soft tissue was assessed. Maturity offset, age, inflammation, and vitamin D intake were treated as covariates. RESULTS: Swimmers had lower bone density than controls; there was a significant and positive relationship between training load and muscle mass. In boys, training load presented a negative correlation with bone density in lower limbs [r = -.293; 95% confidence interval (CI), -.553 to -.034]. In girls, training load was negatively related to bone mineral density in lower limbs (r = .563; 95% CI, -.770 to -.356) and whole body (r = -.409; 95% CI, -.609 to -.209). CONCLUSION: Training load had a negative relationship on bone density of swimmers of both sexes, independently of the positive effect of lean soft tissue on bone density.

High-Intensity Intermittent Exercise and Autonomic Modulation: Effects of Different Volume Sessions.

The aim of this study was to compare heart rate variability (HRV) recovery after 2 sessions of high-intensity intermittent exercise at different volumes (1.25 km [HIIE1.25] and 2.5 km [HIIE2.5]). 13 participants determined their maximal aerobic speed (MAS) and completed 2 HIIE (1:1 at 100% MAS) trials. The heart rate was recorded before and after each session. HRV indicators were calculated according to time (RMSSD and SDNN) and frequency (LF, HF and LF/HF ratio) domains. SDNN and RMSSD presented effect of test (F=20.97; p<0.01 and F=21.00; p<0.01, respectively) and moment (F=6.76; p<0.01 and F=12.30; p<0.01, respectively), without interaction. Even though we did not find an interaction effect for any HRV variables, the HIIE2.5 presented a delay of only 5 min in HRV recovery, when compared to HIIE1.25. However, the effects of the test (SDNN, RMSSD, LF-log, and HF-log) indicate higher autonomic stress during the entire recovery period. These findings may indicate that exercise volume interferes with HRV recovery. If so, physically active subjects may choose a lower volume exercise (i. e., HIIE1.25) in order to promote similar physical fitness adaptations with lower loading on autonomic modulation.

Modulation of inflammatory response arising from high-intensity intermittent and concurrent strength training in physically active males.

The purposes of this study were to determine: (i) the extent of an acute session of high-intensity intermittent exercise (HIIE) followed by a concurrent strength session (Conc) on the increase of systemic inflammatory cytokines and chemokines, and (ii) whether eight weeks of high intensity interval training plus concurrent strength training alters the acute inflammatory response and immune status. Ten recreationally active males (aged 26.9±4.3years) performed two experimental exercise sessions interspersed by eight weeks of HIIT plus concurrent strength training. The experimental exercise session was composed of a 5-km run on a treadmill (1:1 at 100% of maximal aerobic speed (MAS)), and after 10min of passive recovery, back squat exercises were performed (80% 1RM, four sets until exhaustion). Serum samples were collected after fasting, pre-HIIE, post-HIIE, Pre-Conc, Post-Conc, and 30 and 60min post-exercise session. The comparison between both concurrent exercise sessions was performed using repeated measure ANOVA, with the Bonferroni Post-hoc when necessary. Interleukin-6 (IL-6) presented a moment effect (F=6.72; p<0.05), with Post-Conc significantly higher than pre-HIIE, Post-HIIE, and 60min, only a tendency was found between pre-HIIE and post-HIIE (difference=-5.99; p=0.09). MCP-1 and IL-1ra did not present effects for condition, moment, or interaction. Interleukin-10 (IL-10) presented both moment and interaction effects (F=5.31 and 2.50; p=0.005 and 0.036). Pre-Conc and Post-Conc were significantly higher than Pre-HIIE. The interaction between before and after eight weeks of concurrent training probably occurred at Post-Conc (11.42±3.09pgmL-1 and 8.88±1.29pgmL-1). In addition, maintenance of immune function was observed. Therefore, HIIE and concurrent strength exercise lead to an increase in cytokines response, but eight weeks of training program promoted anti-inflammatory response after an acute session of concurrent exercise.

Reproducibility of Running Anaerobic Sprint Test for soccer players.

BACKGROUND: Although the Running Anaerobic Sprint Test (RAST) presents reliability when performed on firmer surfaces (i.e. athletic track), its application on less rigid surfaces can compromise the measure determinations. Thus, the aim of the present study was to evaluate the RAST reliability for soccer players performing on grass, and wearing soccer cleats. METHODS: Fourteen soccer players (16±1 years, 72.3±10.3 kg, 177.2±8.4 cm, 14.5±5.3% of fat mass, and VO2MAX of 52.0±5.1 mL∙kg-1∙min-1) performed six maximal 35-meter effort interspersed by 10s of passive rest (RAST). After 48h the RAST was repeated to test the reliability. The main variables analyzed were the peak power (PP), mean power (MP), fatigue indexes (FI), and impulse (ImP). The reproducibility of test and re-test was tested through the Student's t Test to paired samples, intraclass correlation (ICC), typical error (TE), and coefficient of variation (CV%). RESULTS: The PP (test=701.4±169.5 W; re-test 712.4±142.3 W), MP (test=538.6±111.4 W; re-test=551.9±101.1 W), and the ImP (test=2841.2±461.8 N∙s; re-test=2797.2±575.9 N∙s) were not different, presented significant correlation between the situations (ICC=0.88; 0.96 e 0.93; respectively), and low values of TE (71.9 W; 30.6 W e 191.1 N∙s, respectively) and CV% (10.2%; 5.9% e 6.8%, respectively). The FI (test=40.1±5.8; re-test=38.7±7.7%) were not significantly related between the test and re-test, and presented high TE (5.7%) and CV% (14.4%). CONCLUSIONS: We can conclude that RAST presents high reliability when performed on grass with soccer cleats, just as rigid surfaces. Besides, the ImP is more robust than the.