José Luiz Dantas

The relationship between rating of perceived exertion and muscle activity during exhaustive constant-load cycling.

The aims of this study were to verify the relationship between rating of perceived exertion (RPE) and electromyography (EMG) increases during exhaustive constant-load cycling bouts and, to compare and to correlate the power outputs corresponding to perceived exertion threshold (PET) and neuromuscular fatigue threshold (NFT). 11 men completed 3-4 different exhaustive constant-load cycling bouts on a cycle ergometer, being RPE and EMG measured throughout the bouts. The linear regression of the RPEslope and EMGslope against the power output identified the PET and NFT intensity, respectively. There was a significant relationship between RPEslope and EMGslope (R(2)=0.69; P<0.01). However, the linearity of RPEslope (R(2)=0.93±0.07) was significantly higher (P<0.001) than EMGslope (R(2)=0.63±0.25). In addition, the RPEslope and EMGslope were related to time to exhaustion (r=-0.59 and r=-0.60; P<0.001). There was no significant difference (P=0.42) between PET (201.5±27.9W) and NFT (210.3±22.6W) and they were significantly correlated (r=0.78; P=0.005). Therefore, the RPE and EMG increases during exhaustive constant-load cycling bouts are related and, PET and NFT intensities are similar and closely associated.

Electromyographic activity and rate of muscle fatigue of the quadriceps femoris during cycling exercise in the severe domain.

Camata, TV, Altimari, LR, Bortolotti, H, Dantas, JL, Fontes, EB, Smirmaul, BPC, Okano, AH, Chacon-Mikahil, MPT, and Moraes, AC. Electromyographic activity and rate of muscle fatigue of the quadriceps femoris during cycling exercise in the severe domain. J Strength Cond Res 25(9): 2537-2543, 2011—This study compared the activation pattern and the fatigue rate among the superficial muscles of the quadriceps femoris (QF) during severe cycling exercise. Peak oxygen consumption (&OV0312;o2peak) and maximal accumulated oxygen Deficit (MAOD) were established by 10 well-trained male cyclists (27.5 ± 4.1 years, 71.0 ± 10.3 kg, 173.4 ± 6.6 cm, mean &OV0312;o2peak 56.7 ± 4.4 ml·kg−1·min−1, mean MAOD 5.7 ± 1.1 L). Muscle activity (electromyographic [EMG] signals) was obtained during the supramaximal constant workload test (MAOD) and expressed by root mean square (RMS) and median frequency (MF slope). The RMS of the QF, vastus lateralis (VL) and vastus medialis (VM) muscles were significantly higher than at the beginning after 75% of exercise duration, whereas for the rectus femoris (RF), this was observed after 50% of exercise duration (p ≤ 0.05). The slope of the MF was significantly higher in the RF, followed by the VL and VM (−3.13 ± 0.52 vs. −2.61 ± 0.62 vs. −1.81 ±0.56, respectively; p < 0.05). We conclude that RF may play an important role in limiting performance during severe cycling exercise.

Resposta da frequência cardíaca durante sessão de treinamento de karatê

Karate practice can promote beneficial adaptations on the health-related components of physical fitness. Among the components, the maximum oxygen uptake (VO2max) is an important indicator of cardiorespiratory fitness, as it is also a strong and independent predictor of the risk of death from cardiovascular disease and all other causes. Previous studies have evaluated the heart rate (HR) responses in the karate modality during protocols elaborated by researchers who simulated training. However, the results should be carefully interpreted, since elaborated protocols can compromise the ecological validity of the HR behavior. Thus, the aim of the study was to monitor the HR to investigate the distribution of intensity during a karate training session (TS) with ecological validity preserved. Nine athletes (M (SD) = 22 (5.2) years; 60.3 (12.9) weight; 170.0 (0.10) height; 170.0 (0.10) cm; 11.6 (5.7) % fat) performed a maximal incremental test (IT) and one TS with continuous HR monitoring, subsequently distributed by Edward´s method. The mean TS duration was 91.3 (11.9) min (IC95% = 82.0 - 100.5). The values of average and maximum HR of the TS were equivalent to 72 % (IC95% = 66 - 78 %) and 94 % (IC95% = 89 - 99 %) respectively, of maximum HR reached in the incremental test (HRmax). During 79.9 % (IC95% = 65.7 - 94.1 %) of the total time of TS the athletes remained at intensity above 60% of HRmax. Thus, it was concluded that the TS lies within the ACSM recommendations concerning intensity, duration and weekly frequency, presenting itself as an interesting alternative of exercise to promote cardiorespiratory fitness.

Fourier and wavelet spectral analysis of EMG signals in isometric and dynamic maximal effort exercise

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 isometric and dynamic exercise. The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in isometric and dynamic exercise (P>0.05). However, the results of the variance was lower for both types of exercise 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.

Influence of music and its moments of application on performance and psychophysiological parameters during a 5km time trial

ABSTRA C T Objective. The purpose of this study was to verify the influence of music introduced in different moments in a 5-km time-trial cycling (TT5KM) on psychophysical variables. Methods. Ten trained cyclists participated in this study (24 ± 1 years; 73.5 ± 10.4 kg; 180 ± 12 cm). The participants performed the TT5KM in three distinct conditions: music during warm-up (MW), music during the protocol (MP) and control (C). During all conditions the time (T), power output (W), heart rate (HR) and rating of perceived exertion (RPE) was evaluated and the mood state was assessed with the BRUMS questionnaire. After descriptive statistics, data normality was confirmed using the Shapiro-Wilk’s test. Mean performance, performance at each 500m, RPE at each 1000m and mood state were compared with ANOVA two way for repeated measures (moment x condition). The significance level was set at p 0.05), but there is a possibility of RPE to be smaller when the subject listen music during (90%) or before (93%) the test compared with control condition. Conclusion. Our results showed that regardless the time of application (i.e., before or during exercise), music did not affect performance and psychophysiological parameters during the TT5KM.

O nível de treinamento não influencia a percepção subjetiva de esforço durante um teste incremental

Different training levels, combined with experience in performing exhaustive exercise, may produce different sensations of fatigue. The objective of this study was to compare the rating of perceived exertion (RPE) between cyclists and non-cyclists during a maximal incremental test (ITMAX). Twenty-three subjects were recruited and divided into a cyclist group (CG) (n = 12; age: 26.5 ± 4.7 years, body weight: 68.2 ± 11kg, height: 176 ± 8.6 cm) and a non-cyclist group (NCG) (n = 11; 25.2 ± 4.0 years, body weight: 72.9 ± 9 kg, height: 175.1 ± 6.3 cm). All subjects performed an ITMAX until exhaustion on a cycling simulator, starting at 0 W and with increments of 20 W.min-1. RPE was measured at 30-second intervals during ITMAX and the maximal power output (PMAX) of each subject was also recorded. The total time of each test was normalized to the percentage of completed trial (10% to 100%, intervals of 10%), and the corresponding RPE was recorded. PMAX was 368 ± 12.7 W and 256 ± 11.2 W for CG and NCG, respectively (P < 0.01). No significant difference in median RPE was observed between groups at any time point. In conclusion, RPE responses did not differ between CG and NCG during ITMAX, suggesting that training level does not influence RPE.

Respostas neuromusculares dos membros inferiores durante protocolo intermitente de saltos verticais em voleibolistas

The purpose of this study was to analyze the performance and the electromyographic responses of the muscles Rectus Femoris, Biceps Femoris and Gastrocnemius Medialis during vertical jumping protocol. Participated 13 female volleyball players (15,6 ± 0,9 years). Initially was performed a protocol of maximum power (three maximum jumps), followed by resistance jumps protocol (cycles of three maximum jumps in about 10 seconds (s) - one jump every three s, with recovery of 15s. The duration of resistance protocol was 20 minutes. Technique used was countermovement jump without the aid of arms on a mat of contact. The data collected during the jumps were divided into four periods containing 12 cycles each. The results showed a decrease in the height of the jumps of about 1,3cm between the periods from 1 to 4, and this decrease was more significant in the 3rd and 4th periods compared with the 1st and 2nd. However, with respect to the variables RMS and FM, a change did not occur in the electromyographic responses between muscles and periods. It was concluded that fatigue may depend of the psychophysiological variables, the level of the CNS, which also influence the performance.

O nível de treinamento não influencia a percepção subjetiva de esforço durante um teste incremental DOI:10.5007/1980-0037.2010v12n3p159

Different training levels, combined with experience in performing exhaustive exercise, may produce different sensations of fatigue. The objective of this study was to compare the rating of perceived exertion (RPE) between cyclists and non-cyclists during a maximal incremental test (ITMAX). Twenty-three subjects were recruited and divided into a cyclist group (CG) (n = 12; age: 26.5 ± 4.7 years, body weight: 68.2 ± 11kg, height: 176 ± 8.6 cm) and a non-cyclist group (NCG) (n = 11; 25.2 ± 4.0 years, body weight: 72.9 ± 9 kg, height: 175.1 ± 6.3 cm). All subjects performed an ITMAX until exhaustion on a cycling simulator, starting at 0 W and with increments of 20 W.min-1. RPE was measured at 30-second intervals during ITMAX and the maximal power output (PMAX) of each subject was also recorded. The total time of each test was normalized to the percentage of completed trial (10% to 100%, intervals of 10%), and the corresponding RPE was recorded. PMAX was 368 ± 12.7 W and 256 ± 11.2 W for CG and NCG, respectively (P < 0.01). No significant difference in median RPE was observed between groups at any time point. In conclusion, RPE responses did not differ between CG and NCG during ITMAX, suggesting that training level does not influence RPE.

Training level does not influence the rating of perceived exertion during an incremental test

Different training levels, combined with experience in performing exhaustive exercise, may produce different sensations of fatigue. The objective of this study was to compare the rating of perceived exertion (RPE) between cyclists and non-cyclists during a maximal incremental test (ITMAX). Twenty-three subjects were recruited and divided into a cyclist group (CG) (n = 12; age: 26.5 ± 4.7 years, body weight: 68.2 ± 11kg, height: 176 ± 8.6 cm) and a non-cyclist group (NCG) (n = 11; 25.2 ± 4.0 years, body weight: 72.9 ± 9 kg, height: 175.1 ± 6.3 cm). All subjects performed an ITMAX until exhaustion on a cycling simulator, starting at 0 W and with increments of 20 W.min-1. RPE was measured at 30-second intervals during ITMAX and the maximal power output (PMAX) of each subject was also recorded. The total time of each test was normalized to the percentage of completed trial (10% to 100%, intervals of 10%), and the corresponding RPE was recorded. PMAX was 368 ± 12.7 W and 256 ± 11.2 W for CG and NCG, respectively (P < 0.01). No significant difference in median RPE was observed between groups at any time point. In conclusion, RPE responses did not differ between CG and NCG during ITMAX, suggesting that training level does not influence RPE.

Training level does not influence the rating of perceived exertion during an incremental test DOI:10.5007/1980-0037.2010v12n3p159

Different training levels, combined with experience in performing exhaustive exercise, may produce different sensations of fatigue. The objective of this study was to compare the rating of perceived exertion (RPE) between cyclists and non-cyclists during a maximal incremental test (ITMAX). Twenty-three subjects were recruited and divided into a cyclist group (CG) (n = 12; age: 26.5 ± 4.7 years, body weight: 68.2 ± 11kg, height: 176 ± 8.6 cm) and a non-cyclist group (NCG) (n = 11; 25.2 ± 4.0 years, body weight: 72.9 ± 9 kg, height: 175.1 ± 6.3 cm). All subjects performed an ITMAX until exhaustion on a cycling simulator, starting at 0 W and with increments of 20 W.min-1. RPE was measured at 30-second intervals during ITMAX and the maximal power output (PMAX) of each subject was also recorded. The total time of each test was normalized to the percentage of completed trial (10% to 100%, intervals of 10%), and the corresponding RPE was recorded. PMAX was 368 ± 12.7 W and 256 ± 11.2 W for CG and NCG, respectively (P < 0.01). No significant difference in median RPE was observed between groups at any time point. In conclusion, RPE responses did not differ between CG and NCG during ITMAX, suggesting that training level does not influence RPE.