Impaired Cardiac Autonomic Control in Women With Fibromyalgia Is Independent of Their Physical Fitness.

BACKGROUND/OBJECTIVE: Evidence has suggested abnormal cardiac autonomic responses to exercise in patients with fibromyalgia (FM). However, it is not clear whether the dysautonomia represents a reduced physical fitness rather directly related to FM pathogenesis. Thus, we aimed to verify the cardiac autonomic responses before, during, and after a maximal incremental exercise in women with FM and whether these hypothesized alterations would be dependent with their physical fitness. METHODS: This is a cross-sectional study with 23 FM women and 17 healthy women. The participants performed a maximal incremental cycling test to determine their maximal workload (Wmax) and were further matched by their Wmax (14 FM patients, Wmax: 128.6 ± 16.2 W; and 14 healthy women, Wmax: 131.9 ± 15.9 W). Beat-to-beat heart rate (HR) was continuously monitored to calculate HR variability indexes at rest, chronotropic reserve during exercise, and HR recovery. RESULTS: Heart rate variability indexes related to vagal modulation were significantly lower in FM patients than in healthy women (p < 0.05). The chronotropic reserve and the HR recovery at 30, 120, 180, 300, and 600 seconds after exercise were all lower in FM patients compared with those of healthy women (p < 0.05). Similar findings were found when analysis was performed using the matched physical fitness subgroup. CONCLUSIONS: The documented cardiac autonomic abnormalities at rest, during, and after exercise in FM patients persist even when physical fitness status is taken in account. Thus, strategies to attenuate the dysautonomia in FM patients must be considered.

Effects of Walking Training with Restricted Blood Flow on HR and HRV Kinetics and HRV Recovery.

The aim of this study was to investigate the effects of walking training with and without blood flow restriction (BFR) on heart rate (HR) and heart rate variability (HRV) kinetics and HRV recovery. Twenty-one men (53.5±3.2 years; 82.4±13.5 kg; 168.5±7.2 cm) were randomly assigned to two training groups: walk training group with (BFR-W; n=11) and without (NOR-W; n=10) BFR. Before and after training, all subjects underwent body composition evaluation, incremental test, and one constant load test. Walking training was performed 3 times/week, during 6 weeks. Each session was composed by 5 sets of 3-min walking and 1-min rest between the sets. All parameters of HR on- and off-kinetics and RMSSD15 0 parameter of HRV on-kinetics were improved for BFR-W group after training (p<0.05), with an interaction effect for HR on-kinetics parameters and RMSSD15 0 parameter (p<0.05). Also, parameters of time and frequency domain of HRV recovery were also improved in BFR-W after training (p<0.05), with no interaction effect (p>0.05). Additionally, in BFR-W group, RMSSD60s values were improved in some moments after training (p<0.05). Therefore, this study demonstrates that a 6-week walking training with BFR improved cardiac autonomic responses on the onset and recovery of exercise.

Cardiac autonomic responses and number of repetitions maximum after LED irradiation in the ipsilateral and contralateral lower limb.

The aim of this study was to verify the maximum number of repetitions, fatigue index, blood lactate concentration ([Lac]), and cardiac autonomic responses after LED irradiation (LEDI) in the ipsilateral and contralateral limb. Twelve male subjects (22.0 ± 3.86 years; weight 82.94 ± 12.58 kg; height 1.77 ± 0.05 m), physically active, took part in this study. The subjects underwent a one repetition maximum (1RM) test and performed four randomly experimental sessions in the horizontal leg press exercise, which consisted in four sets of maximum repetitions at 80% of 1RM. The subjects performed two experimental sessions applying LED active or placebo on ipsilateral limb and two experimental sessions applying LED active or placebo on contralateral limb prior exercise and in the interval of sets on quadriceps and hamstrings muscles. A number of repetitions and fatigue index were verified. [Lac] and heart rate variability (HRV) were collected during post-exercise recovery and analyzed. It was observed that active LEDI promoted an increase in maximal number of repetitions (LEDI = 44.4 ± 9.0 vs placebo = 39.9 ± 11.4; p < 0.05) and decreases the fatigue index (LEDI = 34.3 ± 21.8% vs placebo = 50.0 ± 26.6%; p < 0.05) comparing to placebo situation, only in the ipsilateral application. There were no differences on [Lac] and in HRV parameters comparing LEDI vs placebo on post-exercise recovery in both applications (p > 0.05). The LEDI improves performance only in the ipsilateral application, but there were no differences on [Lac] and cardiac autonomic responses after exercise for both the applications.

Caffeine Attenuates Exacerbated Central Fatigue during Moderate Intensity Cycling Exercise in Women with Fibromyalgia.

PURPOSE: To compare the development of fatigability during a moderate intensity cycling exercise between women with fibromyalgia (FM) and control women (CON) after acute ingestion of caffeine and placebo. METHODS: Ten FM and 10 CON women performed a 30-minute moderate intensity cycling exercise one hour after the ingestion of a capsule containing either caffeine or a placebo. Fatigability and its central and peripheral determinants were determined via changes from pre- to post-15 and post-30 minutes of exercise in maximal voluntary isometric contractions (MVIC), voluntary activation (VA), and quadriceps potentiated twitch torque (Q tw-pot ), respectively. Heart rate, muscle oxygen saturation, perceptive responses, mood state, localized and widespread pain, and sleepiness were also monitored during and after exercise. RESULTS: There was a time vs. group interaction for MVIC and VA (p < 0.001) but not for Q tw-pot (p = 0.363), indicating a greater rate of fatigability development, mainly caused by central mechanisms, in the FM than in the CON group. There was also a main effect of condition for VA (p = 0.011), indicating that caffeine attenuates central mechanisms of fatigability in both groups. Caffeine ingestion also increased muscle oxygenation, perceived vigor, and energy, and decreased leg muscle pain, sleepiness, and perceived fatigue in both groups. However, caffeine improved perceived pleasure/displeasure and exercise adherence likelihood only in the FM group. CONCLUSIONS: Compared to CON, women with FM present a greater rate of fatigability during exercise, mainly of central origin. Caffeine seems to be a promising bioactive to counteract the central mechanisms of fatigability and improve the exercise experience among FM women.

Similarity in physiological and perceived exertion responses to exercise at continuous and intermittent critical power.

The purpose of this study was to compare the physiological responses [oxygen uptake (VO(2)), heart rate (HR) and blood lactate concentrations ([BLa])] and the rating of perceived exertion (RPE) response until exhaustion (TTE) at the continuous (CP(c)) and intermittent (CP(i)) critical power workloads. Ten moderately active men (25.5 ± 4.2 years, 74.1 ± 8.0 kg, 177.6 ± 4.9 cm) participated in this study. The incremental test was applied to determine the highest values of oxygen uptake (VO(2max)), heart rate (HR(max)), blood lactate concentrations ([BLa(max)]), and maximal aerobic power (MAP). Continuous and intermittent exhaustive predictive trials were performed randomly. The hyperbolic relation between power and time was used to estimate CP(c) and CP(i). CP(i) was derived from predictive trial results at an effort and recovery ratio of 30:30 s. Exercise at CP(c) and CP(i) as well as the physiological and RPE responses were measured until exhaustion. The values of physiological variables during CP(c) and CP(i) did not differ in either TTE test and were lower than the VO(2max), HR(max) and [BLa(max)] values. RPE was maximal at the end of exercise at CP(c) and CP(i). There was a high correlation between VO(2max) (L min(-1)) and CP(c) and CP(i) intensities (r ≥ 0.90) and between MAP, CP(c) and CP(i) (r ≥ 0.95). Similar physiological and RPE responses were found at CP(c) and CP(i) for the times analyzed.

Acute Caffeine Intake Reduces Perceived Exertion But Not Muscle Pain during Moderate Intensity Cycling Exercise in Women with Fibromyalgia.

OBJECTIVE: Exacerbated perceived exertion and muscle pain responses during exercise might limit physical activity practice in fibromyalgia patients. Thus, nutritional strategies that can reduce perceived exertion and muscle pain during exercise in fibromyalgia patients would be useful. The purpose of this study was to investigate the effects of acute caffeine intake on the perceptions of exertion and muscle pain during a moderate intensity exercise in women with fibromyalgia. METHOD: Using a randomized, double-blinded, placebo-controlled and crossover experimental design, eleven sedentary women diagnosed with fibromyalgia (age: 44.6 ± 10.5 years; body mass index: 28.5 ± 4.5 kg.m-2) ingested a capsule containing either caffeine (5 mg per kg of body mass) or cellulose (placebo), 60 minutes before performing a 30-minute constant-load cycling exercise, with work rate fixed at 50% of their individual peak workload attained in an incremental exercise test. Ratings of perceived leg muscle pain and perceived exertion were assessed every 5 minutes of exercise. RESULTS: The perceived leg muscle pain was similar (F(1,10) = 1.18, p = 0.30, ŋ2 = 0.11) between caffeine (2.1 ± 1.2 arbitrary units) and placebo conditions (2.2 ± 0.9 arbitrary units). The perceived exertion, however, was on average 8 ± 6% lower (F(1,10) = 12.13; p = 0.006; ŋ2 = 0.55) during exercise in the caffeine condition (12.4 ± 1.3 arbitrary units) than in the placebo condition (13.1 ± 1.1 arbitrary units). CONCLUSIONS: These findings indicate that acute caffeine intake could be an attractive strategy to attenuate the exacerbated perceived exertion of fibromyalgia patients during moderate intensity exercise.

A comparative study of heart rate variability and physical fitness in women with moderate and severe fibromyalgia.

The aim of this study was to compare the physical fitness and cardiac autonomic activity among women with moderate and severe fibromyalgia (FM) and healthy women. This study included 35 women with FM (age: 46.2±8.9 years) and 17 healthy women (age: 44.3±9.9 years). Participants with FM were divided into moderate FM (n=15) and severe FM (n=20) according to the total score obtained in FM impact questionnaire. The heart rate variability was monitored using a portable cardiac monitor with participants resting in supine position during 10 min. Thereafter, the participants performed the chair sit and reach test, the chair stand test, and the 6-min walk test to measure the lower-body flexibility, lower-body muscle strength, and cardiorespiratory fitness, respectively. The lower-body muscle strength and cardiorespiratory fitness were both reduced in moderate and severe FM compared to healthy women (P<0.01), with greater reduction in severe FM when compared to moderate FM (P<0.05). In addition, the parasympathetic indexes of heart rate variability were all similarly decreased in both moderate and severe FM, when compared to healthy women (P<0.05). The cardiac parasympathetic activity is similarly decreased in women with both moderate and severe FM in comparison to healthy women, despite a greater physical deconditioning in severe FM.

Familiarization indexes in sessions of 1-RM tests in adult women.

The objective of this study was to evaluate the familiarization to the 1-repetition maximum (1-RM) test in adult women with previous experience in resistance training and to compare the statistical methods to analyze familiarization. Twenty-seven women, with previous experience in resistance training but detrained for 6 months, participated in the study (21.6 +/- 2.5 years; 59.1 +/- 6.7 kg; 1.65 +/- 0.04 m; 21.8 +/- 2.4 kg/m). The 1-RM test was used to verify the strength levels in 3 exercises: bench press, squat, and arm curl. Five 1-RM tests sessions were performed in distinct days. Analysis of variance (ANOVA) for repeated measures, intraclass correlation coefficient (ICC), and Bland-Altman plotting procedures were used to compare the 1-RM load between the familiarization sessions. The significance assumed was p < 0.05. All exercises presented good ICC between 1-RM familiarization sessions (0.97-0.98). However, there were significant increases in 1-RM load among the 5 sessions of 1-RM tests in the bench press (+5.7%), squat (+5.4%), and arm curl (+11.1%). In addition, there were different responses according to the statistical analyses used (ANOVA, higher 1-RM strength, and Bland-Altman plotting). The results of the present study suggest that familiarization sessions are important for an accurate assessment of 1-RM load even in subjects with previous experience in resistance training.

Improving Cycling Performance: Transcranial Direct Current Stimulation Increases Time to Exhaustion in Cycling.

The central nervous system seems to have an important role in fatigue and exercise tolerance. Novel noninvasive techniques of neuromodulation can provide insights on the relationship between brain function and exercise performance. The purpose of this study was to determine the effects of transcranial direct current stimulation (tDCS) on physical performance and physiological and perceptual variables with regard to fatigue and exercise tolerance. Eleven physically active subjects participated in an incremental test on a cycle simulator to define peak power output. During 3 visits, the subjects experienced 3 stimulation conditions (anodal, cathodal, or sham tDCS-with an interval of at least 48 h between conditions) in a randomized, counterbalanced order to measure the effects of tDCS on time to exhaustion at 80% of peak power. Stimulation was administered before each test over 13 min at a current intensity of 2.0 mA. In each session, the Brunel Mood State questionnaire was given twice: after stimulation and after the time-to-exhaustion test. Further, during the tests, the electromyographic activity of the vastus lateralis and rectus femoris muscles, perceived exertion, and heart rate were recorded. RM-ANOVA showed that the subjects performed better during anodal primary motor cortex stimulation (491 ± 100 s) compared with cathodal stimulation (443 ± 11 s) and sham (407 ± 69 s). No significant difference was observed between the cathodal and sham conditions. The effect sizes confirmed the greater effect of anodal M1 tDCS (anodal x cathodal = 0.47; anodal x sham = 0.77; and cathodal x sham = 0.29). Magnitude-based inference suggested the anodal condition to be positive versus the cathodal and sham conditions. There were no differences among the three stimulation conditions in RPE (p = 0.07) or heart rate (p = 0.73). However, as hypothesized, RM- ANOVA revealed a main effect of time for the two variables (RPE and HR: p < 0.001). EMG activity also did not differ during the test accross the different conditions. We conclude that anodal tDCS increases exercise tolerance in a cycling-based, constant-load exercise test, performed at 80% of peak power. Performance was enhanced in the absence of changes in physiological and perceptual variables.

Effect of walk training combined with blood flow restriction on resting heart rate variability and resting blood pressure in middle-aged men

Aim: To investigate the effects of low-intensity walk training with and without blood flow restriction (BRF) on resting heart rate variability (HRV) and blood pressure (BP) in middle-aged men. Methods: Twenty-one men were randomly assigned into the walk training group with (BRF-W; n = 11) and without (NOR-W; n = 10) BFR. The resting HRV and blood pressure were assessed pre- and post-6 weeks of the intervention [3 times/week, 5 sets of 3-min walking (6 km.h-1) with 1-min of rest, totalizing 18 sessions of training]. The BFR-W group received the occlusive stimulus before of training sessions though of a standard sphygmomanometer and performed the training sessions with the vascular occlusion (80-100 mmHg) in both the legs. Results: Only BRF-W group improved HRV on time domain indices (SDNN and RMSSD; p < 0.05) after training but it was not found differences on frequency domain indices. In addition, systolic blood pressure (SBP) improved after training (PRE: 128.5 ± 5.9 vs POST: 119.1 ± 8.6 mmHg; Cohen's d = -1.30; p < 0.01) only in BFR-W group. There was not a significant difference on diastolic blood pressure (DBP) after training, however, effect size was moderate for BFR-W (Cohen's d = -0.56; p > 0.05). Conclusion: Our results showed that walking training with blood flow restriction can improve health cardiovascular parameters in middle-aged men.(AU)

Cardiac autonomic responses during and after a single session of aerobic exercise with and without blood flow restriction

Aim: To verify the on and off heart rate (HR) and HR variability (HRV) kinetics during a high-load aerobic exercise and a low-load aerobic exercise, with and without blood flow restriction (BFR). Methods: Fourteen healthy male subjects performed three randomly assigned experimental sessions: 1) 10 minutes walking at 40% of maximal aerobic speed (MAS) (40LL); 2) 10 minutes walking at 40% of MAS with BFR (40LL+BFR); and 3) 10 minutes running at 70% of MAS (70HL). The HR and HRV measurements were taken at rest, during exercise and the recovery period after constant load sessions. Results: The HR on- and off- kinetics, and HRV on-kinetics were faster in 40LL than in 40LL +BFR and 70HL (p < 0.05). The time constant (τon) of HR on-kinetics was faster in 40LL+BFR than in 70HL (23.4 ± 9.5 s vs 42 ± 9.5 s, respectively, p < 0.01), and was accompanied by faster HRV on-kinetics (12.4 ± 9.6 s vs 20.3 ± 13.7 s, respectively, p < 0.01). Although HR off-kinetics was not different between 40LL+BFR and 70HL, the recovery of time and frequency HRV indices were delayed in 70HL when compared to 40LL and 40LL+BFR (p < 0.05). Conclusions: These findings indicate that 40LL promoted faster cardiac adjustments compared to 40LL+BFR and 70HL sessions. Additionally, 40LL+BFR promoted faster cardiac adjustment and better HRV recovery compared to the 70HL session. (AU)

O treinamento de força com e sem o uso da plataforma vibratória é capaz de modular a variabilidade da frequência cardíaca em repouso? / Strength training with and without a vibration platform is capable to modulate heart rate variability?

Esse trabalho comparou a variabilidade da frequência cardíaca (VFC) de repouso antes e após 10 semanas de treinamento de força de grupos que usaram e não usaram a plataforma vibratória. Dezessete homens saudáveis foram divididos nos grupos treinamento de força convencional (TF) ou treinamento de força sobre a plataforma vibratória a frequência de 30 Hz (TF+V30). As mensurações do desempenho de força dinâmica máxima (1-RM) no exercício meio agachamento e da VFC de repouso foram feitas antes e após o programa de treinamento. Ambos os grupos tiveram aumento significante da força no período pós (de 15,1% no grupo TF e de 16,4% no grupo TF+V30), no entanto esse aumento se alterou na mesma magnitude para os dois grupos, não havendo diferença entre eles no desempenho de 1-RM nos períodos pré e pós-treinamento. Não foi observada diferença nas comparações entre os grupos e nas situações pré e pós-treinamento nas análises da VFC de repouso, no entanto a magnitude do effect size foi moderada (ES = 0,50-0,80) para algumas variáveis (intervalo R-R, desvio-padrão da média de todos os intervalos R-R - SDNN, raiz quadrada da média dos quadrados das diferenças entre os intervalos R-R sucessivos - RMSSD, componente de baixa frequência ajustada por meio de logarítmico - InLF e componente de alta frequência ajustada por meio de logarítmico - InHF) no grupo TF+V30 após o período de treinamento. Conclui-se que 10 semanas de treinamento de força com e sem a presença da vibração proporcionou aumento semelhante no desempenho de 1-RM em ambos os grupos e, embora o estímulo adicional da vibração tenha dado indícios de maior atividade vagal analisado por meio do ES, nenhum dos grupos apresentou alteração significante da VFC.

The current research compared resting heart rate variability (VFC) before and after 10 weeks of strength training in groups that used and did not use a vibration platform. Seventeen healthy men were divided into conventional strength training (TF) or strength training using a vibration platform with a frequency of 30 Hz (TF+V30) training groups. One repetition maximum load (1-RM) on half squat exercise and VFC measurements were determined pre- and post-training program. Both groups had improved 1-RM load after the program (15.1% in TF group and 16.4% in TF+V30 group), although this increase was changed in the same extent for the two groups and there was no difference in 1-RM load between groups pre- and post-training program. No significant difference was observed in resting VFC measurements between groups pre and post-training program, however the magnitude of the effect size was moderated (ES = 0.50-0.80) for some variables (R-R interval, standard deviation of all R-R interval - SDNN, RMSSD, log-transformed of low frequency - InLF, and log-transformed of high frequency - InHF) in TF+V30 group. It was concluded that 10 weeks of strength training program with or without the vibration platform provided similar increase in 1-RM load in both groups, and although some evidences in this study indicate that vibration can increase vagal activity analyzed by ES, in neither groups the strength training was able to change VFC significantly.

Efeito da familiarização na estabilização dos valores e 1RM para homens e mulheres / Effect of familiarization on the stabilization of 1RM values for men and women

O objetivo deste estudo foi verificar o número de sessões de familiarização necessárias para estabilização da carga do teste de uma repetição máxima (1RM) no exercício agachamento em homens e mulheres. Oito homens (25 ± 4 anos) e oito mulheres (20 ± 1anos) foram submetidos a cinco sessões experimentais. ANOVA e plotagem de Bland-Altman foram utilizadas para comparar a carga de 1RM entre as sessões (p<0,05). A estabilização da carga ocorreu na quarta sessão para os homens e na terceira para as mulheres, com aumentos significantes da força absoluta e relativa da primeira à quarta (17kg e 19%) e da primeira à terceira (9kg e 14%) sessões, respectivamente. Porém, não houve diferença significante na força relativa entre os gêneros. De acordo com nossos resultados, indivíduos inexperientes em treinamento de força atingem alta reprodutibilidade ao teste de 1RM no exercício agachamento, após realizar três a quatro sessões de familiarização.

The purpose of this study was to determine the number of familiarization sessions for stabilizing the load of one repetition maximum (1RM) tests on the squat exercise in men and women. Eight men (25 ± 4 years) and eight women (20 ± 1 years) underwent five experimental sessions. ANOVA and Bland-Altman plotting were used to compare the 1RM load between the sessions (p<0.05). The stabilization of load occurred at the fourth session for men and at the third session for women, with significantly increased in relative and absolute strength from the first to the fourth (17kg and 19%) and from the first to the third (9kg and 14%) session, respectively. However, relative strength did not differ significantly between genders. According to our results, individuals not experienced with strength training can reach high reliability in the 1RM test in the squat exercise, after performing three or four familiarizations sessions.

Métodos de quantificação de carga de treinamento em exercício realizado no máximo estado estável de lactato / Methods of quantification of training load in exercise performed at maximal lactate steady state

O objetivo do presente estudo foi comparar e correlacionar as estimativas de impulso de treinamento (TRIMP) propostos por Banister (TRIMPBanister), Stagno (TRIMPStagno) e Manzi (TRIMPManzi). Os participantes foram submetidos a um teste progressivo em cicloergômetro, com registro da frequência cardíaca e da concentração de lactato sanguíneo. Em uma segunda ocasião, realizaram 30 min. de exercício na intensidade correspondente ao máximo estado estável de lactato, a partir do qual foram calculados o TRIMPBanister, TRIMPStagno e TRIMPManzi. Os valores médios de TRIMPBanister (56,5 ± 8,2 u.a.) e TRIMPStagno (51,2 ± 12,4 u.a.) não diferiram entre si (P > 0,05) e foram altamente correlacionados (r = 0,90), com boa concordância, ou seja, viés reduzido e limites de concordância relativamente estreitos. O TRIMPStagno e TRIMPManzi (73,4 ± 17,6 u.a.) apresentarem alta correlação (r = 0,93), mas com diferença significantes entre eles; ainda, se mostraram pouco concordantes. As estimativas de TRIMPBanister e TRIMPManzi não foram diferentes (P = 0,06) e apresentaram alta correlação (r = 0,82), com baixa concordância. Assim, conclui-se que os métodos de TRIMP não são equivalentes. Na prática, parece ser prudente monitorar o processo de treinamento assumindo apenas uma das estimativas.

The aim of the present study was to compare and correlate training impulse (TRIMP) estimates proposed by Banister (TRIMPBanister), Stagno (TRIMPStagno) and Manzi (TRIMPManzi). The subjects were submitted to an incremental test on cycle ergometer with heart rate and blood lactate concentration measurements. In the second occasion, they performed 30 min. of exercise at the intensity corresponding to maximal lactate steady state, and TRIMPBanister, TRIMPStagno and TRIMPManzi were calculated. The mean values of TRIMPBanister (56.5 ± 8.2 u.a.) and TRIMPStagno (51.2 ± 12.4 u.a.) were not different (P > 0.05) and were highly correlated (r = 0.90). Besides this, they presented a good agreement level, which means low bias and relatively narrow limits of agreement. On the other hand, despite highly correlated (r = 0.93), TRIMPStagno and TRIMPManzi (73.4 ± 17.6 u.a.) were different (P < 0.05), with low agreement level. The TRIMPBanister e TRIMPManzi estimates were not different (P = 0.06) and were highly correlated (r = 0.82), but showed low agreement level. Thus, we concluded that the investigated TRIMP methods are not equivalent. In practical terms, it seems prudent monitor the training process assuming only one of the estimates.

Relationship between vagal withdrawaland reactivation indices and aerobic capacityin taekwondo athletes / Relação entre a retirada e reativação vagal com a capacidade aeróbia em atletas de taekwondo

The aim of this study was to evaluate the relationship between vagal withdrawal and reactivation indices and maximal running velocity (Vmax) in taekwondo athletes. Eleven elite taekwondo athletes (seven men: 23.7±2.2 years, 72.4±7.0 kg, 178.8±7.5 cm, 51.9±2.9 ml.kg-1.min-1, and four women: 18.8±1.5 years, 61.8±1.8 kg, 168.0±4.4 cm, 41.6±2.4 ml.kg-1.min-1) performed a graded exercise test until exhaustion, with the last complete stage performed corresponding to Vmax. Heart rate variability (HRV) parameters were calculated at 1-minute intervals until 85% of maximum HR and plotted against time for the estimation of vagal withdrawal indices (?, amplitude (A) and area under the curve (AUC)). Vagal reactivation indices were determined based on HR recovery during the first 60 s (HRR60s) and negative reciprocal of the slope of the regression line obtained during the first 30 s of HRR (T30). The vagal withdrawal parameters A and AUC were moderately and significantly correlated with Vmax (r = 0.61-0.71, P < 0.05), whereas ? presented a low correlation (r = 0.22-0.40, P > 0.05). T30 and HRR60s were also significantly correlated with Vmax (r = -0.77 and 0.64, P < 0.05, respectively). The present results showed that vagal withdrawal (A and AUC) and vagal reactivation (T30 and HRR60s) indices were significantly correlated with Vmax, suggesting that these indices can be used for the evaluation and monitoring of aerobic fitness in taekwondo athletes.

O objetivo deste estudo foi verificar em atletas de taekwondo a relação entre a retirada e reativação vagal com a velocidade aeróbia máxima (Vmax). Onze atletas de elite de taekwondo (sete homens: 23,7±2,2 anos, 72,4±7,0 kg, 178,8±7,5 cm, 51,9±2,9 ml.kg-1.min-1; e quatro mulheres: 18,8±1,5 anos, 61,8±1,8 kg, 168,0±4,4 cm, 41,6±2,4 ml.kg-1.min-1) realizaram um teste progressivo até exaustão, sendo a Vmax considerada o último estágio completo realizado. Os parâmetros da variabilidade da freqüência cardíaca (VFC) foram calculados a cada minuto do teste até o atingimento de 85% da FC máxima, e plotados contra o tempo para a estimativa dos indicadores de retirada vagal (?, amplitude (A) e área sob a curva (ASC)). Os indicadores de reativação vagal foram determinados pela recuperação da FC nos primeiros 60 s (RFC60s) e recíproca negativa da reta de regressão linear obtida pela RFC dos primeiros 30 s (T30). Os parâmetros de retirada vagal A e ASC foram moderado e significativamente correlacionados à Vmax (r = 0,61-0,71, P < 0,05), enquanto o ? apresentou baixa correlação (r = 0,22-0,40, P > 0,05). O T30 e RFC60s apresentaram correlação significante com a Vmax (r = -0,77 e 0,64, P < 0,05, respectivamente). Os resultados do presente estudo mostraram que os indicadores da retirada (A e ASC) e reativação vagal (T30 e RFC60s) foram significativamente correlacionados com a Vmax, sugerindo que esses indicadores poderiam ser utilizados na avaliação aeróbia e monitoramento do treinamento de atletas de taekwondo.

Cinética do consumo de oxigênio durante exercícios supramáximos: aplicação de modelos matemáticos / Oxygen uptake kinetics during supra-maximal exercise: mathematical modelling

A correta estimativa dos parâmetros da cinética do consumo de oxigênio é fundamental para a interpretação deseus mecanismos de controle e/ou limitação. O objetivo deste estudo foi caracterizar a cinética do consumo de oxigênio em intensidades supra-máximas realizadas em cicloergômetro a partir da utilização de dois modelos matemáticos distintos. Onze indivíduos saudáveis do sexo masculino (idade = 25,4 ± 4,9 anos, estatura = 177,0 ± 4,0 cm, massa corporal = 77,1 ± 11,3 kg, VO2max = 40,3 ± 6,3 mL.kg-1.min-1) realizaram quatro testes retangulares exaustivos de intensidades correspondentes a 100, 113, 133 e 153%VO2max. As constantes de tempo do componente primário da cinética do VO2 foram estimadas a partir dos modelos exponencial e semi-logarítmico e comparadas através de ANOVA para medidas repetidas e post hocde Tukey, admitindo-se P<0,05. A estimativa da demanda de oxigênio, necessária para o cálculo da constante de tempo pelo modelo semi-logarítmico, foi realizada mediante procedimento de regressão. O modelo exponencial forneceu menores valores de constante de tempo (35,1 ± 8,0s; 32,5 ± 7,4s; 29,6 ± 11,3s; 25,3 ± 7,5s) em relação ao modelo semi-logarítmico (107,9 ± 27,1s; 104,5 ± 24,3s; 114,1 ± 30,4s; 125,3 ± 24,9s) para todas as intensidades, respectivamente. A observação de comportamento confl itante da cinética do consumo de oxigênio a partir da aplicação de modelos matemáticos distintossugere precaução na realização de inferências fi siológicas dos parâmetros obtidos em exercícios supra-máximos...

Precise estimation of oxygen uptake kinetics parameters is essential to understand its control and/or limit uptake mechanisms. The purpose of the present study was to characterize the oxygen uptake kinetics responses during supramaximal cycle ergometer exercise using two modeling techniques. Eleven male subjects (age = 25.4 ± 4.9 years, height = 177.0 ± 4.0 cm, mass = 77.1 ± 11.3 kg, VO2max = 40.3 ± 6.3 mL.kg-1.min-1) performed a series of square-wave exercise transitions to exhaustion at intensities equivalent to 100, 113, 133 and 153% of VO2max. The time constant of the primary component was estimated with an exponential and semi-logarithmic model, comparisons were made using repeated measuresANOVA and the Tukey post hoc tests, with statistical signifi cance accepted when p<0.05. In order to calculate the time constant by the semi-logarithmic model it is necessary to estimate oxygen demand, which was performed by means of a regression procedure. The exponential model resulted in lower values for the time constant (35.1 ± 8.0s; 32.5 ± 7.4s; 29.6 ± 11.3s; 25.3 ± 7.5s) compared to the semi-logarithmic model (107.9 ± 27.1s; 104.5 ± 24.3s; 114.1 ± 30.4s; 125.3 ± 24.9s)at all intensities. The observation of this confl icting oxygen uptake kinetics behavior depending upon which mathematical model is applied suggests that physiological inferences on the basis of parameters obtained during supra-maximal exercise should be made with caution...

Determinação da sobrecarga anaeróbia em exercício intermitente a partir domodelo de potência crítica / Determining anaerobic workload during intermittent exercise using critical power model

O objetivo do estudo foi estimar a sobrecarga anaeróbia em exercício intermitente, por meio do modelo de potência crítica (PC), manipulando as durações absolutas de esforços e pausas (30s:30s e 60s:60s), porém com a razão esforço: pausa (E:P) invariável. Sete indivíduos realizaram 4 testes retangulares exaustivos em ciclo ergômetro para determinação da PC e capacidade de trabalho anaeróbio (CTA). Em outras duas sessões, os participantes realizaram dez esforços com E:P de 30s:30s e cinco esforços de 60s:60s com intensidade 70% superior à PC, seguido por um esforço até a exaustão com duração conhecida para determinar a CTA reposta e remanescente. Também foram determinadas concentrações de lactato sanguíneo nos protocolos intermitentes. Houve maior sobrecarga anaeróbia no protocolo intermitente de 60s:60s devido à menor duração do exercício (59%), CTA reposta (84%) e CTA remanescente (57%) do que no protocolo de 30s:30s, além do lactato sanguíneo (66%) e CTA líquido (38%) serem maiores no protocolo 60s:60s. Além disso, o modelo de PC mostrou-se eficaz na determinação da sobrecarga anaeróbia em exercício intermitente.

This study aimed to estimate the anaerobic workload during intermittent exercise, using critical power (CP)model and manipulating the work and rest periods (30s:30s e 60s:60s), while the work: rest ratio was unchanged. Participants (n equal 7) cycled exhaustively during four different sessions in order to estimate de CP and the anaerobic workcapacity (AWC). The following two sessions, they performed 10 bouts using 30s:30s and five bouts using 60s:60s, with intensity 70% greater than CP. Thereafter, they performed another continuous bout until exhaustion the intensity with known duration to determine recovered and remaining AWC. Blood lactate concentration was also measured throughout intermittent exercise. The 60s:60s protocol induced greater anaerobic workload compared with 30s:30s one, due to there were lower exercise duration (59%), recovered AWC (84%) and remaining AWC (57%) on the former protocol. In addition, blood lactate (66%) and net AWC (38%) during 60s:60s protocol were greater than during the 30s:30s one. In addition, the anaerobic workload during intermittent exercise can be determined using the CP model.

Comparação entre limiar de esforço percebido e indicadores de máximo estado estável de lactato em exercício intermitente / Comparison between perceived exertion threshold and indicators of maximal lactate steady state in intermittent exercise

O limiar de esforço percebido contínuo (LEPc) pode ser considerado como ponto de transição metabólica entreos domínios intenso e severo, pois se relaciona com a potência crítica. Dessa forma, os objetivos do presente estudo foram: (1) verificar a possibilidade de estimativa do LEP e de um indicador de máximo estado estável de lactato em exercício intermitente (LEPi e MEELINDIC), (2) comparar o LEPi e MEELINDIC com o máximo estado estável de lactato intermitente(MEELi), e (3) verifi car a relação entre a PSE e as respostas de lactato sangüíneo ([La]) em esforços intermitentes de alta intensidade. Dez participantes foram submetidos a sessões de familiarização, teste de esforço progressivo, testes preditivosintermitentes e determinação do MEELi. O LEPi e o MEELINDIC foram estimados a partir dos testes preditivos, e o MEELifoi determinado a partir de testes de 30 minutos. As correlações entre as taxas de aumento da PSE e [La] (r=0,77), e osvalores absolutos de PSE e [La] (r=0,78) foram moderadas. Os altos valores de R2 das taxas de aumento da PSE e [La] e das regressões lineares para a estimativa do LEPi e do MEELINDIC sugerem que essas variáveis podem ser estimadas deforma acurada. As intensidades do LEPi, MEELINDIC e MEELi não foram diferentes entre si. O LEPi e MEELINDIC apresentaram altas correlações com o MEELi (r=0,90 e r=0,80, respectivamente). Portanto, a relação entre a PSE e [La] é moderada, etanto o LEPi quanto o MEELINDIC podem ser estimados e utilizados como indicadores de capacidade aeróbia...

The continuous perceived exertion threshold (PETc) is considered as a metabolic transition point between theheavy and severe domain, since it is related with critical power. Thus, the aims of this study were: (1) to verify the possibility to estimate PET and maximal lactate steady state index in intermittent exercises (PETi and MLSSINDEX), (2) compare the PETiand MLSSINDEX with intermittent exercise maximal lactate steady state (MLSSi), and (3) to verify the relationship between RPE and blood lactate response ([La]) in high intensity intermittent exercises. Ten subjects underwent familiarization sessions, progressive exercise test, predictive intermittent trials and MLSSi determination. The PETi and MLSSINDIC were estimated from predictive trials, and MLSSi was determined from 30-minute tests. The correlations between the increase rates of RPE and [La] (r=0.77), and the absolute values of RPE and [La] (r=0.78) were moderate. The high R2 values as related to the relationship between the increase rate of RPE and [La], and also to the linear regressions for the PETi andMLSSINDEX estimation suggest that these variables may be accurately estimated. The PETi, MLSSINDEX and MLSSi intensities were not different from each other. The correlations between PETi and MLSSINDEX, with MLSSi were strong (r=0.90 andr=0.80, respectively). Therefore, the relationship between RPE and [La] is moderate, while both PETi and MLSSINDEX can be estimated and utilized as aerobic capacity indicators...

Effects os previous severe exercise on two and three parameter critical power modeling

The purpose of this study was to apply the two and three-parameter critical power model equations after depletion of a fi xed amount of anaerobic work capacity (AWC), followed by a short rest period. Sixteen subjects underwent: (1) two practice trials for ergometer familiarization to severe exercise; (2) 4-5 exercise bouts on different days for the estimation ofcritical power (CP) and AWC using the two and three parameter models; (3) the same procedures as described in stage 2 were repeated after 30 s recovery from 180 s of exercise completed at an intensity that would have elicited exhaustionin around 300 s. The CP2parameter (130-174 W versus 131-170 W) and CP3parameter (108 versus 100 W) estimated after prior severe exercise followed by a short rest period remained stable compared to the fatigue-free tests. The AWC2parameter wasreduced in response to prior severe exercise. The AWC3parameter was not signifi cantly reduced. The correlations between CP2parameter derived from the same equation with and without prior AWC2parameter reduction were strong (r = 0.97-0.99, P <0.001). The correlation was merely moderate (r = 0.62, P = 0.01) when CP3parameter was analyzed. It can be concluded that the two-parameter critical power model provides a coherent mathematical description of the reduced mechanical output induced by a prior fatiguing task, since AWC2parameter was affected while CP2parameter estimates remained constant.

O propósito do presente estudo foi aplicar as equações do modelo de potência crítica de dois e três parâmetros após a depleção de uma quantia fi xa de capacidade de trabalho anaeróbio (AWC), seguido de um período curto de repouso.Dezesseis sujeitos realizaram: (1) duas familiarizações ao exercício severo no cicloergômetro; (2) 4-5 exercícios máximos em dias diferentes para a estimativa da CP e AWC por meio dos modelos de dois e três parâmetros; (3) os mesmos procedimentos descritos no #2 foram realizados após 30 s de repouso e de um exercício de 180 s a uma intensidade em que a exaustão provavelmente ocorreria em ~300 s. A CP2parameter (130-174 W versus 131-170 W) e CP3parameter (108 versus100 W) estimadas após o exercício prévio severo e seguido por um curto período de repouso permaneceu estável quando comparado às estimativas sem o exercício prévio. A AWC2parameter foi diminuída em resposta ao exercício prévio severo. A AWC3parameter não foi signifi cativamente reduzida. As correlações entre CP2parameter derivados da mesma equação com esem a redução prévia da WC2parameter foram fortes (r = 0,97-0,99; P < 0,001). Para a CP3parameter a correlação foi somente moderada (r = 0,62; P = 0,01). Assim, pode ser concluído que o modelo de potência crítica de dois parâmetros promovedescrições matemáticas coerentes quando é induzido um exercício prévio, sendo que a AWC2parameter foi alterada enquanto que a estimativa da CP2parameter permaneceu constante.