Purpose:The aim of this study was to verify the influence of aerobic fitness (VO 2 max) on internal training loads, as measured by the session rating of perceived exertion (session-RPE) method. Methods: Nine male professional outfield futsal players were monitored for 4 wk of the in-season period with regards to the weekly accumulated session-RPE, while participating in the same training sessions. Single-session-RPE was obtained from the product of a 10-point RPE scale and the duration of exercise. Maximal oxygen consumption was determined during an incremental treadmill test. Results: The average training load throughout the 4 wk period varied between 2,876 and 5,035 arbitrary units. Technical-tactical sessions were the predominant source of loading. There was a significant correlation between VO 2 max (59.6 ± 2.5 mL • kg -1 • min -1 ) and overall training load accumulated over the total period (r = -0.75). Conclusions: The VO 2 max plays a key role in determining the magnitude of an individual's perceived exertion during futsal training sessions.

The aim of this study was to investigate the heart rate variability (HRV) following resistance training with and without vascular occlusion. It was hypothesized that low intensity with vascular occlusion would elicit comparable post-exercise HRV responses to that of high intensity without vascular occlusion. Nine subjects undertook four experimental sessions of leg press exercise on different days: 1) one repetition maximum (1RM) test, 2) 4 sets of 8 repetitions + one set until exhaustion at 80% of 1RM without vascular occlusion (HI), 3) 4 sets of 16 repetitions + one set until exhaustion at 40% of 1RM with vascular occlusion (LIO), and 4) 4 sets of 16 repetitions + one set with the number of repetition equal to the last set of LIO but at 40% of 1RM without vascular occlusion (LI). HRV was analyzed 10min, 20min, 30min, 1h, 5h and 24h after HI, LIO and LI sessions. The HI session increased heart rate (HR) and reduced the root mean square of successive difference of R-R intervals (RMSSD) and log-transformed high frequency (lnHF) power during prolonged recovery (HR=5h; RMSSD=30 min; lnHF=1h) at a greater magnitude when compared with LIO and LI. Despite the same intensity of exercise for LIO and LI, the occlusion delayed the recovery of HR and HRV variables. Post-exercise blood lactate concentration was moderate to strongly correlated with peak HR (r=0.87), RMSSD (r=-0.64) and lnHF (r=-0.68). The present study has demonstrated that LIO was able to reduce cardiac autonomic stress when compared with HI.

We tested the hypothesis that maximal oxygen uptake and ventilatory threshold (VT), and their respective speeds (S(VO2max) and S(VT)) could discriminate the competitive level of futsal players. The outfield players of a high-level Brazilian professional futsal team (N = 9; age 22.6 ± 4.2 years; body mass 70.6 ± 6.4 kg; height 174.3 ± 6.0 cm), and a semiprofessional team (N = 11; age 17.2 ± 0.8 years; body mass 70.4 ± 6.5 kg; height 175.0 ± 4.0 cm), volunteered for participation in this study. Subsequently, they were evaluated during an incremental treadmill test for the determination of cardiorespiratory variables, S(VO2max), and S(VT). Both teams exhibited a similar body mass and VO2max (p = 0.542 and p = 0.427), whereas the S(VO2max) and the S(VT) were significantly higher in the professional team (p = 0.001 and p = 0.030, respectively). Additionally, the professional team exhibited both lower HR at VT (p = 0.046) and HRmax (p = 0.002). However, the %HRmax at VT did not differ between groups (p = 0.912). These results remained similar after adjusting for the age differences between groups (p = 0.106). It was concluded that both S(VO2max) and S(VT) were sensitive for detecting differences in the competitive level of futsal players, whereas VO2max and VT were not.

Pedro, RE, Guariglia, DA, Okuno, NM, Deminice, R, Peres, SB, and Moraes, SMF. Effects of 16 weeks of concurrent training on resting heart rate variability and cardiorespiratory fitness in people living with HIV/AIDS using antiretroviral therapy: a randomized clinical trial. J Strength Cond Res 30(12): 3494-3502, 2016-The study evaluated the effects of concurrent training on resting heart rate variability (HRVrest) and cardiorespiratory fitness in people living with HIV/AIDS undergoing antiretroviral therapy (ART). Fifty-eight participants were randomized into 2 groups (control and training group); however, only 33 were analyzed. The variables studied were HRVrest indices, submaximal values of oxygen uptake (V[Combining Dot Above]O2sub) and heart rate (HR5min), peak speed (Vpeak), and peak oxygen uptake (V[Combining Dot Above]O2peak). The training group performed concurrent training (15-20 minutes of aerobic exercise plus 40 minutes of resistance exercise), 3 times per week, for 16 weeks. Posttraining V[Combining Dot Above]O2peak and Vpeak increased, and HR5min decreased. Resting heart rate variability indices did not present statistical differences posttraining; however, the magnitude-based inferences demonstrated a "possibly positive effect" for high frequency (HF) and low frequency (LF) plus high frequency (LF + HF) and a "likely positive effect" for R-Rmean posttraining. In conclusion, concurrent training was effective at improving cardiorespiratory fitness and endurance performance. Moreover, it led to probably a positive effect on HF and a likely positive effect on R-Rmean in people living with HIV/AIDS undergoing ART.

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Resumo -O objetivo deste estudo foi analisar se a variabilidade da frequência cardíaca (VFC) analisada no período inicial da pré-temporada de futebol apresenta relação com a melhora do desempenho físico ao longo deste período. Dez jogadores de futebol fizeram parte da amostra. O desempenho foi analisado através dos seguintes testes: Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1), sprint de 30 m e salto vertical, aplicados antes e após seis semanas da pré-temporada. As medidas de VFC foram realizadas em repouso, na posição supina, durante dez minutos. O teste de Spearman foi usado para investigar as possíveis relações entre VFC e melhora no desempenho e o teste T de Student para verificar as mudanças no desempenho e na VFC. A inferência prática baseada em magnitudes (analise qualitativa) foi aplicada para verificar as chances dos valores encontrados serem positivos, irrelevantes e negativos. Houve melhora significante do desempenho para o Yo-Yo IR1 (P< 0,001) e Sprint de 30 m (P< 0,001). A análise qualitativa revelou que a mudança do desempenho no Yo-Yo IR1 foi "muito provavelmente positiva", para o Sprint de 30 m foi "quase certamente positiva" e para o salto vertical foi "inconclusiva". Houve forte correlação entre um índice parassimpático da VFC e a variação no desempenho [r = 0,85; P = 0,003 (IC95% =0,49 -0,97)]. Em conclusão, esse estudo mostrou uma correlação forte entre índices parassimpáticos da VFC analisados antes do treinamento, com a melhora do desempenho no Yo-Yo IR1 durante a pré-temporada em atletas de futebol. Palavras-chave: Atletas; Esporte; Fisiologia cardiovascular; Testes de aptidão. ]. In conclusion, this study revealed a strong correlation between parasympathetic indices of HRV (analyzed before the training) with the performance improvement in Yo-Yo IR1 in football athletes during pre-season. Abstract -The aim of this study was to analyze whether the heart rate variability (HRV), assessed at the beginning of a soccer preseason, reveals a correlation with the improvement of physical performance over this training period. Ten soccer players took part in the study

Frequency domain analyses of changes in electromyographic (EMG) signals over time are frequently used to assess muscle fatigue. Fourier based approaches are typically used in these analyses, yet Fourier analysis assumes signal stationarity, which is unlikely during dynamic contractions. Wavelet based methods of signal analysis do not assume stationarity and may be more appropriate for joint time-frequency domain analysis. The purpose of this study was to compare Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) in assessing muscle fatigue in maximal constant load dynamic exercise (100% W(max)). The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in maximal constant load dynamic exercise (P>0.05). However, the results of the variance was significantly lower for at least one of the muscles studied in CWT compared to STFT (P〈0.05) indicating more variability in the EMG signal analysis using STFT. Thus, the stationarity assumption may not be the sole factor responsible for affecting the Fourier based estimates.

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