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Search Results: 1 - 10 of 22619 matches for " Leandro Ricardo Altimari "
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Fourier and Wavelet Spectral Analysis of EMG Signals in 1-km Cycling Time-Trial  [PDF]
Marcelo Bigliassi, Paulo Rogério Scalassara, Thiago Ferreira Dias Kanthack, Taufik Abr?o, Antonio Carlos de Moraes, Leandro Ricardo Altimari
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.513181
Abstract: Frequency domain analyses in electromyographic (EMG) signals are frequently applied to assess muscle fatigue and similar variables. Moreover, Fourier-based approaches are typically used for investigating these procedures. Nonetheless, Fourier analysis assumes the signal as stationary which is unlikely during dynamic contractions. As an alternative method, wavelet-based treatments do not assume this pattern and may be considered as more appropriate for joint time-frequency domain analysis. Based on the previous statements, the purpose of the present study was to compare the application of Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) to assess muscle fatigue in dynamic exercise of a 1-km of cycling (time-trial condition). The results of this study indicated that CWT and STFT analyses have provided similar fatigue estimates (slope) (p> 0.05). However, CWT application represents lesser dispersion (p< 0.05) for vastus medialis (189.9 ± 82.1 for STFT vs 148.6 ± 60.2 for CWT) and vastus lateralis (151.6 ± 49.6 for STFT vs 103.5 ± 27.9 for CWT). In conclusion, despite the EMG signal did not change (p> 0.05) according to different methods, it is important to note that these responses seem to show greater values for CWT compared to STFT for 2 superficial muscles. Thereby, we are capable of considering CWT as a reliable and useful method to take into consideration when non-stationary or oscillating exercise models are evaluated.
Correla??es entre protocolos de determina??o do limiar anaeróbio e o desempenho aeróbio em nadadores adolescentes
Altimari, Juliana Melo;Altimari, Leandro Ricardo;Gulak, Andréia;Chacon-Mikahil, Mara Patricia Traina;
Revista Brasileira de Medicina do Esporte , 2007, DOI: 10.1590/S1517-86922007000400007
Abstract: the purpose of this study was to correlate the anaerobic threshold speeds (ats) obtained from fixed lactate blood concentration (ats 4 e ats 3.5 mm), lactate minimum speed (lacmins) and the critical speed (cs) determined from different distances and number of coordinates: cs1 (50/100/200 m), cs2 (100/200/400 m), cs3 (50/100/200/400 m) and cs4 (200/400 m) with the performance in 400 meters (s) in adolescent swimmers. the sample was constituted by 15 swimmers (10 boys and five girls = 14.7 ± 0.7 years; 61.9 ± 8.5 kg; 171.1 ± 8.8 cm) of national level, with five to seven years of experience in competitive swimming. the correlation between the indexes and the performance in 400 m (s) was made using pearson correlation coefficients. significance was set at p < 0.01. the correlations between ats 4 mm, ats 3.5 mm, lacmins and the performance in 400 m (s) were: r = -0.63, r = -0.90 e r = 0.91, respectively (p < 0.01). the correlations between cs1 (50/100/200 m), cs2 (100/200/400 m), cs3 (50/100/200/400 m), cs4 (200/400 m) and the performance in 400 m (s) were: r = -0.62, r = -0.97, r = -0.98 e r = -0.94, respectively (p < 0.01). we suggest that ats obtained from fixed lactate blood concentration of 3.5 mm, as well as lacmins and the cs obtained through larger distances seem to be the most fitted indexes of prediction of the aerobic performance in the studied adolescent swimmers. additionally, the number of coordinates seems no influencing the relation between cs and aerobic performance.
Determination of the critical power and anaerobic work capacity of canoeists on an arm ergometer, using two linear equations
Juliana Melo Altimari,Leandro Ricardo Altimari,Alexandre Hideki Okano,Edilson Serpeloni Cyrino
Revista Brasileira de Cineantropometria e Desempenho Humano , 2007,
Abstract: The objective of the present study was to investigate the infl uence of two linear models on the determination of critical potential (CP) and anaerobic work capacity (AnWC) of canoeists evaluated on an arm ergometer. Eight male canoeists (17.1 ± 1.1 years; 63.3 ± 6.5 kg; 173.4 ± 4.3 cm) volunteered to take part in the study. Two different linear equations were employed to calculate CP and AnWC: power-1/time and work-time, using three different power levels (Wlim) and their respective times to exhaustion (tlim). The athletes underwent six test sessions on an arm ergometer at 70 rpm until voluntary exhaustion, with and interval of 24 hours between sessions, at two different intensities each day, with a minimum interval of 90 minutes. The statistical analysis employed descriptive statistics, Student’s t test and Pearson’s linear correlation (P < 0.05). The power-1/time equation produced a signifi cantly higher CP than the work-time equation (144.6 ± 17.3 W vs. 141.9 ± 16.5 W, respectively; P < 0.05), whereas AnWC was signifi cantly greater when calculated by work-time than when calculated by power-1/time (12.8 ± 2.9 kJ vs. 13.9 ± 3.2 kJ; respectively, P < 0.05). The coefficient of correlation between power-1/time and work-time for CP and AnWC was r=0.98 and r=0.92, respectively (P < 0.05). Despite this high level of correlation between the models in terms of CP and AnWC, the results suggest that adopting different models appears to interfere in the calculation of CP and AnWC of exercise on an arm ergometer. RESUMO O objetivo do presente estudo foi verifi car a infl uência de dois modelos lineares na determina o da potência crítica (PC) e da capacidade de trabalho anaeróbio (CTAn), em erg metro de bra o, em atletas de canoagem. Para tanto, oito canoístas do sexo masculino (17,1 ± 1,1 anos; 63,3 ± 6,5 kg; 173,4 ± 4,3 cm), participaram voluntariamente desta investiga o. A PC e a CTAn foram obtidas por meio de duas equa es lineares: potência-1/tempo e trabalho-tempo, utilizando três potências (Wlim) e seus respectivos tempos até a exaust o (tlim). Os atletas foram submetidos a seis sess es de testes em erg metro de bra o a 70 rpm até a exaust o voluntária, com intervalo de 24 horas entre cada sess o, a duas intensidades diferentes a cada dia, com intervalo mínimo de 90 minutos. Para o tratamento estatístico utilizou-se a estatística descritiva, teste t de Student e correla o linear de Pearson (P < 0,05). A PC da equa o potência-1/tempo foi significativamente maior que da equa o trabalho-tempo (144,6 ± 17,3 W vs 141,9 ± 16,5 W, respectivamente; P < 0,05),
Varia??o do equilíbrio muscular durante uma temporada em jogadores de futebol categoria sub-20
Goulart, Luiz Fernando;Dias, Raphael Mendes Ritti;Altimari, Leandro Ricardo;
Revista Brasileira de Medicina do Esporte , 2008, DOI: 10.1590/S1517-86922008000100003
Abstract: the objective of the present study was to evaluate the muscular balance of knee flexors and extensors (rfe) in under-20 soccer players during a training season. 15 under-20 subjects from the ponte preta athletic association of campinas participated in a 29 week macrocycle preparation (mp), composed of preparatory and competitive periods which were divided into four mesocycles: general stage (m1), special stage (m2), pre-competitive stage (m3) and competitive stage (m4). rfe of both members was determined with the torque peak (tp) obtained in isokinetic dynamometer in three consecutive sets of five repetitions of 60 degrees/s. isokinetic evaluation was accomplished in four stages along the mp at the end of each mesocycle (m1, m2, m3, and m4). statistic analysis was performed using the friedman test with repeated measures, followed by wilcoxon test and mann-whitney u test, with significance level of p<0.05. tp of knee flexors muscles in both members were greater in m2 and m3 than in m1 and m4. tp of knee extensors in m1 was significantly inferior than the other stages of the study (m2, m3, and m4), in both members. rfe, in both members, was inferior in m1 when compared to m2 and m3. rfe comparison among members did not reveal significant differences in any moment of the study (m1, m2, m3, and m4). the results indicated the existence of alterations in the size of rfe; within normality though, and maintenance of the proportionality among members along the mp. these results suggest that there are not sensitive periods to the occurrence of injuries due to muscular imbalances along mp in under-20 soccer players.
Isokinetic force of under-twenties soccer players: comparison of players in different field positions
Luiz Fernando Goulart,Raphael Mendes Ritti Dias,Leandro Ricardo Altimari
Revista Brasileira de Cineantropometria e Desempenho Humano , 2007,
Abstract: During a soccer match, countless movements involving muscular force are performed. While some studies have analyzed the force exerted by soccer players, their results have been divergent, particularly when force has been analyzed with respect to fi eld positions. The objective of this study was to compare peak torque, total muscular work, maximum power and isokinetic fatigue index of the knee fl exor and extensor muscles of soccer players in a variety of fi eld positions. Seventy-eight under-twenty soccer players were classifi ed according to the position they play: goalkeepers (n=7), full backs (n=14), wingers (n=16), defensive midfi elders (n=11), center midfi elders (n=14) and forwards (n=16). The concentric isokinetic force of knee fl exor and extensor muscles was evaluated using an isokinetic dynamometer, Cybex brand Norm 6000 model (CSMI, USA). Data was analyzed in terms of non-parametric statistics and results expressed in medians and semi-interquartile range. The Kruskal-Wallis test was applied and when results were signifi cant to p<0.05, the Mann-Whitney U test was used. Full backs’ knee fl exor muscles exhibited lower peak torque, total muscular work and maximum power, when compared with the other positions, and defensive midfi elders’ fl exor muscles had a greater fatigue index than the forwards’. Goalkeepers’ knee extensor muscles exerted lower peak torque and had a higher fatigue index, when compared to results for the other positions. The results of this study indicate that there are differences in strength between players of different positions, especially full backs, defensive midfi elders and goalkeepers. This suggests that the soccer players’ field positions have an infl uence on their levels of isokinetic force. RESUMO Durante uma partida de futebol s o realizados inúmeros movimentos que envolvem a for a muscular. Embora alguns estudos tenham analisado a for a de jogadores de futebol, os resultados encontrados têm sido controversos, principalmente quando analisada a for a em fun o da posi o de jogo. O objetivo deste estudo foi comparar o pico de torque, trabalho muscular total, potência máxima e índice de fadiga isocinético dos músculos fl exores e extensores de joelho de jogadores de futebol que atuam em diferentes posi es de jogo. Foram incluídos 78 atletas de futebol, pertencentes à categoria Sub-20, foram agrupados de acordo com a posi o em campo de jogo: goleiros (n=7), zagueiros (n=14), laterais (n=16), volantes (n=11), meio campo (n=14) e atacantes (n=16). Foi realizada avalia o da for a isocinética concêntrica dos múscu
Leandro Ricardo Altimari,Eduardo Bodnariuc Fontes,Alexandre Hideki Okano,Ricardo Okada Triana
Brazilian Journal of Biomotricity , 2008,
Abstract: ALTIMARI, L. R.; FONTES, E. B.; OKANO, A. H.; TRIANA, R. O.; CHACON-MIKAHIL, M. P. T.; MORAES, A. C. The caffeine ingestion increases time to neuromuscular fatigue and performance during supramaximal cycling exercise. Brazilian Journal of Biomotricity, v. 2, n. 3, p. 195-203, 2008.The purpose of this study was to investigate the effect of the caffeine ingestion (CAF) on the neuromuscular fatigue (NMF) and performance during supramaximal cycling exercise. Nine male cyclists (27.2 ± 3.9 yr; 73.7 ± 12.3 kg and 174.2 ± 6.1 cm), trained, were subjected to two tests of constant load (Tcons) separated by 72 h intervals in intensity of 110% wmax until exhaustion conducted randomly in CAF and PL conditions. CAF (6 mg.kg-1) or PL (maltodextrin) were administred in a double-blind procedure 60 min before the start of Tcons. During the Tcons were obtained the time of exhaustion (TE) and time of onset of neuromuscular fatigue (TONMF) (s) through electromyographic activity (EMG) of the vastus lateralis (VL), vastus medialis (VM) e rectus femoris (RF) muscles. Normality of the data distribution was confirmed using the Shapiro-Wilk test, and this was followed by Student t-tests with level of significance set at P<0.05. The TE was 15% higher on condition CAF compared to PL (132.3 ± 8.4 and 116.7 ± 7.6 s, P<0.05, respectively). Significant difference was found between the TONMF of VL, VM and RF muscles when compared to CAF and PL conditions (P<0.05). According to these results, it can be concluded that the ingestion of 6 mg.kg-1 of caffeine increases time to neuromuscular fatigue and performance during supramaximal in cycling exercise.
Enxágue bucal com carboidrato: recurso ergogênico capaz de otimizar o desempenho físico
Bortolotti, Henrique;Altimari, Leandro Ricardo;Vitor-Costa, Marcelo;Cyrino, Edilson Serpeloni;
Revista Brasileira de Cineantropometria & Desempenho Humano , 2011, DOI: 10.5007/1980-0037.2011v13n2p158
Abstract: studies have shown that the mere presence of carbohydrate in the human mouth promotes the activation of some specific brain regions, with a positive impact on physical performance. thus, the strategy of carbohydrate mouth rinse has been recently adopted with success in strenuous exercise (> 70% vo2max) lasting approximately 60 min. in this respect, the objective of this study was to discuss, based on literature data, the efficacy of this strategy to improve physical performance, as well as the possible mechanisms involved. the results produced, although still preliminary, are promising and led us to believe that carbohydrate mouth rinse is an interesting strategy, especially because of its easy application, low cost and good efficacy in improving physical performance during intense and prolonged physical exercise.
Cafeína e performance em exercícios anaeróbios
Altimari, Leandro Ricardo;Moraes, Antonio Carlos de;Tirapegui, Julio;Moreau, Regina Lúcia de Moraes;
Revista Brasileira de Ciências Farmacêuticas , 2006, DOI: 10.1590/S1516-93322006000100003
Abstract: the ergogenic effects of caffeine on performance in anaerobic activites are not clear yet, so are the mechanisms involved in this type of physical effort. the theories that have been trying to explain the ergogenic effects of caffeine during anaerobic activities are related to the effect of caffeine in some portion of the central nervous system (cns), the propagation of neural signs between brain and neuromuscular junction, and also to the effect of caffeine on the skeletal muscle, facilitating the stimulation-contraction of the skeletal muscle. some studies have been indicating increases of muscular strength accompanied by greater resistance to the installation of the process of muscular fatigue after caffeine ingestion. it has been suggested that it happens much more by the direct action of caffeine in cns than by its action at peripherical level. regarding maximum and submaximum exercises of short duration, the studies have been controversial, although most of them indicates that caffeine seems to improve the performance significantly in maximum exercises of short duration (<5 min), when not preceded by sub maximum prolonged exercises. however, these results need to be confirmed, as well as the mechanisms of action of caffeine in these types of efforts.
Efeito de oito semanas de suplementa??o com creatina monoidratada sobre o trabalho total relativo em esfor?os intermitentes máximos no cicloerg?metro de homens treinados
Altimari, Leandro Ricardo;Okano, Alexandre Hideki;Trindade, Michele Caroline de Costa;Cyrino, Edilson Serpeloni;Tirapegui, Julio;
Revista Brasileira de Ciências Farmacêuticas , 2006, DOI: 10.1590/S1516-93322006000200008
Abstract: this study investigated the effect of long-term supplementation with creatine monohydrate (crm) on relative total work (rtw) in intermittent maximal efforts in the cycle ergometer of trained men. twenty six individuals were randomly divided in creatine group (cr, n=13) and placebo group (pl, n=13). the subjects received in a double-blind manner, doses of crm or placebo-maltodextrin (20 g.d-1 for 5 days and 3 g.d-1 for 51 subsequent days). the groups had their alimentary habits and physical fitness controlled previously. for determination of the rtw the subjects were submitted to exercise protocol in cycle ergometer comprised three 30s anaerobic wingate test interspersed with two minutes recovery, before and after the supplementation period. anova, followed by the tukey post hoc test, when p<0.05, were used for data treatment. there was a significant time effect for rtw (f1,24=8.00; p<0.05), with the cr group demonstrating significant greater (3%) on the rtw production compared to pl group after the supplementation period (690.54 ± 46.83 vs 655.71 ± 74.34 j.kg-1 respectively; p<0.05). the results of the present study suggest that crm supplementation improve the performance in repeated efforts of high intensity and short duration.
Can neuromuscular fatigue threshold bedetermined by short and non-exhaustive bouts?. DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p254
Eduardo Bodnariuc Fontes,Alexandre Hideki Okano,Bruno de Paula Smirmaul,Leandro Ricardo Altimari
Revista Brasileira de Cineantropometria e Desempenho Humano , 2012,
Abstract: The present study determined the neuromuscular fatigue threshold (NFT) using four different time-periods of analysis of the electromyographic signal and compared these estimations with critical power (CP). Fifteen healthy young men (73.6 ± 5.1 kg, 177.8 ± 7.0 cm, 23.4 ± 5.2 years) performed 3-4 different severe constant workload trials until exhaustion on a cycle ergometer with simultaneous SEMG signals acquisition. The obtained data permitted NFT estimation with four different periods of analysis as follows: initial 30s (T30), 1min (T1), 2min (T2) and total time (TT), as well as CP. T30 and T1 were significantly higher than TT and CP and, T2 and TT did not differ between each other, and both were significantly higher than CP. In addition, TT was significantly correlated to CP (0.72; P < 0.05) and to T2 (0.58; P < 0.05). We conclude that NFT overestimates CP, independent of the time-period analysis used for its determination.
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