Abstract Aim: The present study aimed to investigate the effects of different backpack loads on the walking gait kinematics and ratings of perceived exertion (RPE) in Brazilian scholars. Methods: The sample was composed of 25 male children and adolescents, from 10 to 14 years. The mean body mass and height were 45.3 kg ± 10.6 kg and 1.51 m ± 0.08 m, respectively. For the walking gait assessment, a tridimensional analysis system was used. In the backpack conditions, loads of 5%, 10%, 15%, and 20% were applied according to the body weight of everyone. Kinematic variables and angular amplitudes of head, shoulders, thorax, pelvis, and knees in the sagittal plane were collected. The OMNI scale was used to assess the RPE. Results: The loads of 5%, 10%, 15%, and 20% promoted postural adjustments and alterations in the walking gait, in which the RPE presented a correlation with those alterations. The step in the left cycle altered from the baseline in the 5% (p = 0.006). The stride length altered from baseline in the 5% (p = 0.030) and 10% (p < 0.001) load conditions. The single support time was different from baseline in all conditions (p = 0.003; p = 0.012; p = 0.005; p = 0.006). The walking gait cadence was different in the comparison between baseline in the 5% (p = 0.003). Thorax amplitude altered in the 10% (p = 0.023), 15% (p = 0.033) and 20% (p = 0.005) load conditions in the left cycle. Conclusion: We concluded that the posture, RPE, and the gait kinematic altered according to the increase in the backpack load.

Abstract Aim: This study aimed to verify the acute effect of photobiomodulation (PBM) on maximal lactate production rate (VLamax) in front crawl swimmers. Methods: Fifteen male swimmers (20.9 ± 2.4-year-old) participated in this study. Three sets of front crawls were performed at distances of 100-, 200- and 400-m under three experimental conditions: PBM (420 J), placebo (PLA) and control (C) in this randomized, crossover, double-blind and placebo-controlled study. PBM or PLA were applied or simulated before performance tests. One-way Anova for repeated measurements were used for statistical analyses. Results: The results showed that the prior PBM application did not affect VLamax in front crawl swimmers: VLamax 100-m (PBM = 0.20 ± 0.05 mmol·L-1·s-1; PLA = 0.20 ± 0.04 mmol·L-1·s-1 and C = 0.21 ± 0.04; mmol·L-1·s-1); 200-m (PBM = 0.09 ± 0.03 mmol·L-1·s-1; PLA = 0.08 ± 0.02 mmol·L-1·s-1 and C = 0.08 ± 0.02 mmol·L-1·s-1) and 400-m (PBM = 0.04 ± 0.01 mmol·L-1·s-1; PLA = 0.04 ± 0.01 mmol·L-1·s-1 and C = 0.03 ± 0.01 mmol·L-1·s-1). Nor effect swim time (ST) performance: ST 100 m (PBM = 65.5 ± 6.3 s; PLA = 65.2 ± 5.6 s; C = 66.0 ± 5.9 s); ST 200 m (PBM = 148.5 ± 17.9 s; PLA = 149.4 ± 16.4 s; C = 150.1 ± 17.9 s); ST 400 m (PBM = 327.7 ± 38.2 s; PLA = 321.6 ± 47.7 s; C = 329.5 ± 41.2 s). Conclusions: PBM application prior front crawl swimming tests did not significantly modify the VLamax on swimmers covering distances of 100-, 200- and 400-m.

Abstract Aims: The study aimed to evaluate the effects of a backward running (BR) training program prescribed by the peak backward running velocity (Vpeak_BR) on physiological variables and a 3 km forward running (FR) performance. Methods: Eight untrained running male adults in running took place in the study. All the participants underwent five weeks of BR training prescribed based on Vpeak_BR. They performed a maximal incremental test on the treadmill to determine the maximal oxygen uptake (V̇O2max) and the velocity associated with V̇O2max (vV̇O2max). The participants were also tested on the track field to determine the Vpeak_BR and undertook a 3 km FR performance. All initial assessments were also performed after the training period. Results: The results showed statistically significant improvements in 3 km FR performance (14.2 ± 1.2 min vs. 13.5 ± 1.0 min) and Vpeak_BR (8.0 ± 0.8 km·h−1 vs. 8.5 ± 0.5 km·h−1) after the training period. Conclusion: BR training effectively improved 3 km FR performance and Vpeak_BR, demonstrating that Vpeak_BR determined according to the protocol proposed in this study can be used for the prescription of BR training. Further, BR training represents an effective training method that can be inserted into an FR running training program.

Resumo Esse estudo objetivou gerar uma equação de frequência cardíaca máxima (FCmax) baseada na idade para corredores aerobiamente treinados. Trinta e quatro corredores homens realizaram três testes incrementais em esteira motorizada, com início a 8 km·h-1 e incrementos de 1 km·h-1 a cada um, dois ou, três minutos. A FCmax foi definida como o valor mais alto de frequência cardíaca registrado em cada teste. As análises de post hoc indicaram que a FCmax de cada teste foi significativamente menor que o valor mais elevado de FCmax para cada participante. A FCmax predita pela equação "206 - 0,7 x idade" subestimou a mais alta FCmax em 8,6 batimentos·min-1. Logo, a equação gerada baseada em idade "218 - 0,8 x idade" deveria ser usada para predizer a FCmax em corredores aerobiamente treinados.

Abstract This study aimed to generate an age-based maximum heart rate (HRmax) equation for endurance-trained runners. Thirty-four male runners performed three tests on a motorized treadmill, starting at 8 km h-1 with increments of 1 km h-1 every 1, 2 or, 3 min. HRmax was defined as the highest heart rate value recorded during each test. Post hoc analyses indicated that the HRmax derived from each test was significantly lower than the highest HRmax value, for each participant. HRmax predicted by "206 - 0.7 × age" underestimated the highest HRmax by 8.6 beats min-1. Thus, the generated age-based "218 - 0.8 × age" equation should be used to predict HRmax in endurance-trained runners.

Resumen El objetivo de este estudio fue generar una ecuación de la frecuencia cardíaca máxima (FCmáx) basada en la edad en corredores entrenados en resistencia. Treinta y cuatro corredores de sexo masculino realizaron 3 pruebas en una cinta ergométrica motorizada, comenzando con la velocidad de 8 km/h-1 con incrementos de 1 km/h-1 cada uno, 2 o 3 min. La FCmáx fue definida como el valor de la frecuencia cardíaca más elevada registrada durante cada prueba. Los análisis posteriores indicaron que la FCmáx derivada de las pruebas fue considerablemente más baja que el valor más alto de la FCmáx de cada participante. La FCmáx pronosticada por la ecuación «206-0,7 × edad», subestimada la más alta FCmás por 8,6 lat/min-1. Así, la ecuación generada basada en la edad «218-0,8 × edad» debería utilizarse para pronosticar la FCmáx en corredores entrenados en resistencia.

ResumoExaminou-se a reprodutibilidade do desempenho em provas de corrida de 5 e 10 km em pista de atletismo. Trinta e um corredores recreacionistas, do gênero masculino, fizeram duas provas de 5 e duas de 10 km em uma pista oficial de atletismo. Não houve diferença significativa entre os testes-retestes para ambas as provas com o uso do teste t pareado (p > 0,05). Os coeficientes de correlação intraclasse e de variação foram de 0,94/3,44% (5 km) e de 0,97/2,43% (10 km), respectivamente. A reprodutibilidade de ambas as provas em pista de atletismo foi semelhante às reprodutibilidades reportadas na literatura para testes em laboratório. Além disso, a prova de 10 km se mostrou mais reprodutível do que a prova de 5 km para a amostra estudada e necessitou de aproximadamente metade da amostra necessária para se detectarem aumentos significativos durante teste-reteste em provas de 5 km.

AbstractWe examined the reproducibility of performance in running events of 5 and 10 km in running track. Thirty-one recreational, male, runners performed two tests of 5 and two tests of 10 km in an official running track. There was no significant difference in time between the test-retest for both tests using the paired t test (P > 0.05). The intraclass coefficient of correlation and the coefficient of variation were 0.94/3.44% (5 km) and 0.97/2.43% (10 km), respectively. The reproducibility of both running events in running track was similar to that reported in the literature for laboratory tests. In addition, the 10 km test was more reproducible than the 5 km test for this studied sample, requiring approximately half the sample needed to detect significant increases during test-retest in running events of 5 km.

ResumenHemos examinado la reproducibilidad del desempeño en pruebas de carrera de 5 y 10 km en pista de atletismo. Treinta y un corredores recreativos, género masculino, realizaron dos pruebas de 5 y dos de 10 km en una pista oficial de atletismo. No hubo diferencia significativa en el tiempo test-retest entre ambas pruebas mediante la prueba de t para muestras apareadas (P > 0,05). Los coeficientes de correlación intraclase y de variación fueron de 0,94/3,44% (5 km) y 0,97/2,43% (10 km), respectivamente. Se encontró que la reproducibilidad de las dos pruebas de carrera en pista de atletismo fue similar a la descrita en la literatura para pruebas de laboratorio. Además, la prueba de 10 km fue más reproducible que la prueba de 5 km para la muestra estudiada, lo que requiere aproximadamente la mitad de la muestra necesaria para detectar un aumento significativo en test-retest en pruebas de 5 km.

Poucos estudos verificaram a influência do ambiente de teste (campo e laboratório) sobre o ritmo de corrida e variáveis fisiológicas obtidas durante o desempenho em corrida de endurance. Portanto, o objetivo deste estudo foi comparar o comportamento da velocidade média (VM), ritmo de corrida, frequência cardíaca (FC) e percepção subjetiva de esforço (PSE) obtidas durante os desempenhos de corrida em provas time trial de uma hora realizados em pista de atletismo e em esteira. Dezoito homens corredores recreacionais (25,4 ± 3,3 anos) realizaram duas performances de uma hora de corrida: uma em esteira e outra em pista de atletismo de 400 m. A PSE e a FC foram registradas a cada 10 minutos, e a VM a cada 15 minutos para a determinação do ritmo de corrida. As variáveis relacionadas aos desempenhos foram comparadas pelo teste t de Student para amostras pareadas. Os valores de VM, FC e PSE obtidos durante diferentes momentos das provas foram comparados pela Anova de dois fatores para medidas repetidas seguido do post hoc de Bonferroni. Para todas as análises, foi adotado nível de significância de P< 0,05. A VM da prova realizada em pista (12,2 ± 0,8 km·h-1) foi superior à prova em esteira (11,8 ± 0,8 km·h-1). Além disso, foram encontradas diferenças entre os dois desempenhos para os valores de frequência cardíaca média e máxima, e para o ritmo de corrida. A partir dessas diferenças, conclui-se que os desempenhos foram influenciados pelo ambiente onde as provas de uma hora foram realizadas.

Few studies have investigated the influence of test environment (field vs. laboratory) on pacing strategy and on physiological variables measured during endurance running performance tests. The objective of this study was therefore to compare the behavior of mean velocity (MV), pacing strategy, heart rate (HR) and rating of perceived exertion (RPE) during one-hour running time trials conducted on an athletics track with the behavior of the same variables during one-hour running time trials conducted on a treadmill. Eighteen male recreational runners (25.4 ± 3.3 years) performed two one-hour time trials; the first running on a treadmill and the second on a 400 m athletics track. Rating of perceived exertion and HR were recorded every 10 minutes and MV was calculated every 15 minutes for analysis of pacing strategy (0-15min; 15-30min; 30-45min; and 45-60min). These performance variables were compared using Student's t test for paired samples. Figures for MV, HR and RPE measured at different points during the trials were compared using two-factor ANOVA for repeated measures, followed by Bonferroni's post hoc test. A significance level of P < 0.05 was adopted for all analyses. Mean velocity was higher for the trials on the running track (12.2 ± 0.8 km·h-1) than for the trials on the treadmill (11.8 ± 0.8 km·h-1). Additionally, there were also differences between the two test environments for mean and maximum heart rate, and in terms of pacing strategy. On the basis of these differences, it can be concluded that performance was influenced by the environment in which the one-hour time trials were conducted.

O objetivo do estudo foi comparar equipamentos de impedância bioelétrica bipolar (IB2) (frequência: 50Hz) e octapolar (IB8) (frequência: 5, 50 e 500Hz) para a estimativa da massa livre de gordura (MLG) e da gordura relativa (G%), antes e após 16 semanas de intervenção, em adolescentes com sobrepeso e obesidade. A MLG e a G% foram medidas por meio da IB2 e da IB8, antes e após 16 semanas de intervenção multiprofissional focada na mudança de comportamento alimentar e atividade física. A MLG e a G% obtidas nas IBs foram comparadas pela ANOVA de medidas repetidas e correlacionadas através da Correlação de Pearson. Foram observadas diferenças (p<0,05) entre os equipamentos para a estimativa da MLG e G% apenas no momento pré intervenção nas meninas. Concluiu-se que as estimativas da MLG e da G% não foram estatisticamente diferentes pelos dois equipamentos (octapolar e bipolar), bem como a variação dessas duas variáveis.

The aim of this study was to compare bipolar (BI2) (frequency: 50Hz) and octapolar (BI8) (frequency: 5, 50 e 500Hz) bioelectrical impedance analyzers to estimate fat-free mass (FFM) and relative body fat (BF%) before and after 16 weeks of intervention in overweight and obese adolescents. The FFM and BF% were measured by BI2 and BI8 before and after 16 weeks of multidisciplinary intervention focused on changing eating and exercise habits. FFM and BF% obtained in the IBs were compared by ANOVA for repeated measures and correlated by Pearson Correlation Coefficient. Differences (p<0.05) were observed between the analyzers for the estimation of FFM and BF% only in the pre intervention moment for the girls. We conclude that the estimations of FFM and BF% were not significantly different between the two BI (octapolar and bipolar), especially for the variation of these two variables.

O objetivo deste estudo foi comparar as velocidades de corrida no limiar de lactato (vLL) determinadas pelos métodos objetivos e individuais Dmax (vLL Dmax) e log-log (vLLlog-log) sendo esperado uma relação entre eles melhor do que a relação deles com o método de concentração fixa de lactato sanguíneo em 3,5 mM (vLL3,5mM). Participaram deste estudo 17 corredoras recreacionais com experiência em provas de rua de 10 km (idade: 42,1 ± 6,7 anos; estatura: 1,63 ± 0,03 m; massa corporal 57,2 ± 4,9 kg) que realizaram um teste incremental em esteira ergométrica, com velocidade inicial de 7 km/h e incrementos de 1 km/h a cada três minutos. Amostras de sangue foram coletadas nas pausas de 30 segundos entre cada estágio. As vLL foram 10,3 ± 1,4 (vLLlog-log), 10,9 ± 0,8 (vLL Dmax) e 11,6 ± 1,2 km/h (vLL3,5mM) sendo a vLL3,5mM significantemente superior à vLLlog-log (P <0,001) e à vLL Dmax (P = 0,024). Apesar disso, a amplitude dos limites de concordância (±1,96 DP) entre as vLL foi semelhante, variando entre ±1,48 e ±1,77 km/h e a correlação entre a vLL3,5mM e as velocidades vLLlog-log (r = 0,70) e vLL Dmax (r = 0,78) foi maior que a correlação daquelas velocidades entre si (r = 0,65). Em suma, as velocidades vLLlog-log e vLL Dmax não apresentaram uma melhor relação entre si do que a relação delas com a vLL3,5mM.

The aim of this study was to compare the running speed at lactate threshold (sLT) determined by the objective and individual methods Dmax (sLT Dmax) and log-log (sLTlog-log) being expected a better relationship between them than the relationship of them to the fixed lactate concentration method at 3.5 mM (sLT3.5mM). Seventeen amateur women runners, with experience of 10 km road races (age: 42.1 ± 6.7 year; height: 1.63 ± 0.03 m; body mass 57.2 ± 4.9 kg), participated in this study. They performed an incremental exercise test on a motorized treadmill, which the initial speed was 7 km/h, with increments of 1km/h every 3-min. Blood samples were collected between the stages, during a rest of 30-s. The sLT were 10.3 ± 1.4 (sLTlog-log), 10.9 ± 0.8 (sLT Dmax) and 11.6 ± 1.2 km/h (sLT3.5mM) being the sLT3.5mM significantly higher than sLTlog-log (P <0.001) and sLT Dmax (P = 0.024). Despite that, the limits of agreement range (±1.96 SD) among the sLT was similar, varying between ±1.48 and ±1.77 km/h and the correlation between sLT3.5mM and the speeds sLTlog-log (r = 0.70) and sLT Dmax (r = 0.78) was higher than the correlation between sLTlog-log and sLT Dmax (r = 0.65). In summary, the sLTlog-log and sLT Dmax speeds did not show a better relationship between themselves than the relationship of them to the sLT3.5mM.

Comparou-se a velocidade de corrida no limiar de lactato (vLL) determinada pelo método Dmax utilizando-se os ajustes de curva exponencial mais constante (vLLexp) e polinomial de terceira ordem (vLLpol). Dezessete corredoras recreacionais realizaram um teste incremental descontínuo em esteira rolante até a exaustão voluntária com coleta de sangue entre os estágios para análise do lactato. A vLL Exp (10,9 ± 0,8 km/h) foi estatisticamente diferente (P < 0,05) da vLL Pol (10,4 ± 1,1 km/h) utilizando-se o teste t de Student pareado. A correlação entre a vLL Exp e a vLL Pol foi de r = 0,84. As correlações entre a velocidade pico e as vLL foram r = 0,94 (vLLexp) e r = 0,69 (vLLpol). Foi concluído que a escolha da curva de regressão do lactato sanguíneo influi no valor da vLL, sendo a vLLpol consistentemente inferior à vLLexp.

The running speed at lactate threshold (vLT) determined by the Dmax method was compared using the exponential plus constant (vLTexp) and third level polynomial (vLTpol) curve fitting. Seventeen female recreational runners underwent a treadmill incremental test until voluntary exhaustion. Blood samples were collected between the stages for lactate analysis. The vLTexp (10.9 ± 0.8 km/h) was statistically different (P < 0.05) from vLTpol (10.4 ± 1.1 km/h) using paired Student's t test. The correlation between vLTexp and vLTpol was r = 0.84. The correlations between peak speed and vLT were r = 0.94 (vLTexp) and r = 0.69 (vLTpol). It was concluded that the choice of the blood lactate regression curve influences the vLT value, in which the vLTpol was consistently lower than the vLTexp.

Se comparó la velocidad de carrera en el umbral de lactato (vLL) determinado por el método Dmax utilizando la curva exponencial más constante (vLLexp) y polinómica de tercer grado (vLLpol). Diecisiete corredoras recreativas ejecutaron una prueba incremental discontinua en la cinta rodante hasta la extenuación voluntaria con la extracción de sangre entre las etapas para el análisis de lactato. La vLL Exp (10,9 ± 0,8 km/h) fue estadísticamente diferente (P < 0,05) de la vLL Pol (10,4 ± 1,1 km/h) mediante la prueba t de Student pareado. La correlación entre vLL Exp y vLL Pol fue de r = 0,84. Las correlaciones entre el pico de velocidad y las vLL fueron de r = 0,94 (vLLexp) y r = 0,69 (vLLpol). Fue concluido que la elección de la curva de regresión de lactato sanguíneo influye en el valor de la vLL, siendo la vLLpol sistemáticamente inferior a la vLLexp.

O objetivo deste estudo foi comparar os valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx determinados diretamente por um sistema de ergoespirometria com os valores preditos indiretamente pelo sistema ErgoPC durante um teste de esforço máximo realizado por mulheres corredoras. Participaram 20 mulheres corredoras treinadas (42,7 ± 6,4 anos; 1,64 ± 0,04m; 58,3 ± 5,8kg; IMC 21,7 ± 1,9kg/m² e 22,3 ± 3,5%G). Os sujeitos foram submetidos à avaliação da composição corporal e a um teste de esforço progressivo em esteira ergométrica (Inbrasport, Porto Alegre, RS, Brasil) para mensuração da aptidão aeróbia (<img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx). A velocidade inicial foi de 7km/h com incrementos de 1km/h a cada três minutos, sendo mantida uma inclinação constante durante todo o teste equivalente a 1%. As participantes foram fortemente estimuladas a permanecerem no teste o maior tempo possível, até a exaustão voluntária. Para a mensuração direta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx, foi utilizado um sistema de ergoespirometria de circuito aberto (analisador de gases Espirômetro <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" />2000 Inbrasport, Porto Alegre, Brasil). A predição indireta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx foi realizada através do programa ErgoPC que utiliza a fórmula de Foster (1996) para tal predição. Para a análise estatística, foi realizado o teste t de Student (p < 0,05), para a comparação dos valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx obtidos de forma direta e indireta, e o teste de correlação de Pearson, para correlacionar essas duas variáveis. A medida direta do <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx apresentou valor de 51,8 ± 6,8ml/kg/min, e o indireto, 42,8 ± 3,7ml/kg/min. Na comparação entre os dois resultados foi encontrada diferença estatisticamente significante entre as variáveis. A correlação encontrada entre os valores de <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx foi de r = 0,67. Portanto, os resultados mostram que o <img src="/img/revistas/rbme/v17n4/a12cr01.jpg" align="absmiddle" />2máx obtido de forma indireta subestima o valor da medida direta.

The aim of this study was to compare the values of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max directly determined by an ergospirometry system, with values indirectly predicted by the ErgoPC system during maximal exercise test underwent by female runners. Twenty trained female runners participated in the study (42.7 ± 6.4 years-old, height 1.64 ± 0.04m, body mass 58.3 ± 5.8kg, body mass index (BMI) 21.7 ± 1.9kg/m² and body fat percentage 22.3 ± 3.5. The subjects were evaluated for body composition and underwent a progressive exercise test on treadmill (Inbrasport, Porto Alegre, RS, Brazil) to measure the aerobic fitness (<img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max ). The initial speed was 7km/h with increments of 1km/h every three minutes and constant inclination of 1% was kept throughout the test. The participants were encouraged to remain in the test as long as possible until voluntary exhaustion. The gas analyzer VO2000 Inbrasport Spirometer, Porto Alegre, Brazil was used for the direct measurement of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max , while for the indirect measurement of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max the ErgoPC program with the prediction formula from Foster (1996) was used. Statistical analysis was performed by Student's t test for the comparison of the values of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max obtained in the direct and indirect test, and Pearson's correlation was applied to correlate these two variables. Direct measurement of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max showed a value of 51.8 ± 6.8ml/kg/min and indirect one of 42.8 ± 3.7ml/kg/min. The comparison between both results was significantly different. The correlation between the values of <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max was r = 0.67. Thus, the results show that the obtained <img src="/img/revistas/rbme/v17n4/en_a12cr01.jpg" align="absmiddle" />2max by an indirect way underestimates the value of the direct measurement.