Kinematic analysis and self-perceived exertion during the walking gait with a backpack in Brazilian scholars

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.

Ratings of perceived exertion at anaerobic threshold in patients with coronary artery disease / Percepción subjetiva del esfuerzo en el liminar anaeróbico en pacientes con enfermedad arterial coronaria / Percepção subjetiva do esforço no limiar anaeróbio em pacientes com doença arterial coronariana

The study aimed to identify and compare the ratings of perceived exertion (RPE) at the ventilatory anaerobic threshold (VAT) in healthy subjects and patients with coronary artery disease (CAD). A total of 30 male subjects took part in the study and were divided into three groups: a control group (CG) composed of 10 healthy participants; a group composed of 10 participants diagnosed with CAD beta-blocker user (G-DACb); and a group composed of 10 participants with CAD non-beta-blocker user (G-DAC). The participants performed a cardiopulmonary exercise test (CPET) with continuous type ramp protocol to determine the VAT, through the visual graphical analysis (loss of parallelism between the oxygen uptake and the carbon dioxide output). During CPET, before the end of each one-minute period, the subjects were asked to rate dyspnea (RPE-D) and leg fatigue (RPE-L) on the Borg CR-10 scale. After the VAT was determined, the score that the participants gave on the Borg CR10 scale was verified. CG participants showed higher workload, oxygen uptake, carbon dioxide output, ventilation and heart rate at the VAT compared to the G-DAC and G-DACb (p<0.05). However, regarding the RPE-L and the RPE-D, no significant difference between the groups were observed (p<0.05). Values between five and six on Borg CR-10 scale matched the VAT in the subjects studied. However, other parameters must be concomitantly used for prescribing exercise intensity in physical training protocols, at levels close to the VAT for patients with CAD.

El objetivo del estudio fue identificar y comparar la percepción subjetiva del esfuerzo (PSE) en el liminar anaeróbico ventilatorio (LAV) en sujetos sanos y con enfermedad arterial coronaria (EAC). Fueron estudiados 30 hombres siendo10 sanos que constituyeron el grupo control (GC) y 20 diagnosticados con EAC, de los cuales 10 utilizaban medicamento betabloqueante (G-DACb) y 10 no utilizaban (G-DAC). Los voluntarios fueron sometidos a una prueba de ejercicio cardiopulmonar (TECP) con protocolo continuo tipo rampa para la determinación del LAV, a través del análisis gráfico visual (pérdida del paralelismo entre el consumo de oxígeno y producción de dióxido de carbono). Durante la realización del TECP, se pidió a los voluntarios que informaran al final de cada minuto la percepción subjetiva del esfuerzo de los miembros inferiores (PSE-M) y la percepción subjetiva del esfuerzo respiratorio (PSE-R) a través de la escala de Borg CR-10. El GC presentó mayores valores de potencia, consumo de oxígeno, producción de dióxido de carbono, ventilación y frecuencia cardiaca en el LAV comparado con los grupos G-DAC y G-DACb (p<0,05). La PSE-M fue menor en el G-DACb comparado con el GC (p<0,05). Después del ajuste por la covariable potencia, no hubo diferencia significativa entre los grupos para PSE-M y PSE-R (p>0,05). Los valores entre cinco y seis en la escala CR-10 de Borg correspondieron al LAV en la muestra estudiada. Sin embargo, otros parámetros deben ser utilizados simultáneamente para la prescripción de la intensidad del ejercicio en los protocolos de entrenamiento físico, en niveles cercanos al LAV para pacientes con EAC.

O objetivo do estudo foi identificar e comparar a percepção subjetiva do esforço (PSE) no limiar anaeróbio ventilatório (LAV) em indivíduos saudáveis e com doença arterial coronariana (DAC). Foram estudados 30 homens, sendo 10 saudáveis que constituíram o grupo controle (GC) e 20 diagnosticados com DAC, dos quais 10 faziam uso de medicamento betabloqueador (G-DACb) e 10 não faziam uso (G-DAC). Os voluntários foram submetidos a um teste de exercício cardiopulmonar (TECP) com protocolo contínuo tipo rampa para determinação do LAV, através da análise visual gráfica (perda do paralelismo entre o consumo de oxigênio e a produção de dióxido de carbono). Durante a realização do TECP, foi solicitado aos voluntários que relatassem ao final de cada minuto a percepção subjetiva do esforço de membros inferiores (PSE-M) e a percepção subjetiva do esforço respiratório (PSE-R), através da escala CR-10 de Borg. O GC apresentou maiores valores de potência, consumo de oxigênio, produção de dióxido de carbono, ventilação e frequência cardíaca no LAV comparado aos grupos G-DAC e G-DACb (p<0,05). A PSE-M foi menor no G-DACb comparado ao GC (p<0,05). Após ajuste pela covariável potência, não houve diferença significativa entre os grupos para PSE-M e PSE-R (p>0,05). Valores entre cinco e seis na escala CR-10 de Borg correspondeu ao LAV na amostra estudada. Entretanto, outros parâmetros devem ser utilizados concomitantemente para a prescrição da intensidade de exercício nos protocolos de treinamento físico, em níveis próximos ao LAV para pacientes com DAC.

Change in heart rate at double product break point and validity of utilizing age-predicted heart rate at 50%VO₂max due to improvement of cardiovascular fitness / 体力科学

Previously, we have reported that age-predicted heart rate at 50%VO₂max (HR@50%VO₂max) is an effective index of adjusting appropriate exercise intensity for health promotion exercise. Thus, the aim of this study is to elucidate the change in HR at double product break point (HR@DPBP) and the validity of HR@50%VO₂max due to improvement of cardiovascular fitness. Ninety two healthy adults (57 +/- 9 years old), who participated in the health exercise training course, were studied. Participants were instructed how to control the intensity of physical activity for DPBP during their daily life. DPBP was determined with the use of incremental exercise test, and METs at DPBP (METs@DPBP), HR@DPBP, ratings of perceived exertion at DPBP (RPE@DPBP) were measured before and after the course. HR@50%VO₂max was calculated with the following formula; 138 - age/2 (bpm). METs@DPBP significantly increased (p<0.001) after 10 weeks of the course, whereas HR@DPBP did not change. Interestingly, however, there was a significantly positive correlation (p<0.001) between amount of change in METs@DPBP and that in HR@DPBP (ΔHR@DPBP). Multiple linear regression analysis indicated this correlation was independent from sex, age and amount of change in HR at rest (p<0.001). Before and after the course, proportion of study subjects’ %ΔHRs ((HR@50%VO₂max - HR@DPBP) / HR@DPBP x 100) within -10% ~ +10% were both 48.9%, and proportion of study subjects’ RPEs@DPBP within 11~13 were 92% and 85%, respectively. In this study, it was identified that significantly positive relation between amount of change in cardiovascular fitness and that of ΔHR@DPBP. This finding was independent from potentially affecting factors. In conclusion, this longitudinal study could suggest that HR@50%VO₂max and RPE were valuable indexes of determining exercise intensity for health promotion exercise.

Monitoramento do treinamento no judô: comparação entre a intensidade da carga planejada pelo técnico e a intensidade percebida pelo atleta / Training load monitoring in judo: comparison between the training load intensity planned by the coach and the intensity experienced by the athlete

O objetivo do presente estudo foi comparar a percepção referente à intensidade da carga de treinamento planejada pelos técnicos com a percepção de intensidade reportada pelos atletas de Judô. A amostra foi composta por quatro técnicos e 40 atletas da Seleção Brasileira de Judô. A comparação entre a intensidade planejada e a intensidade experienciada foi realizada através da aplicação do método da percepção subjetiva do esforço (PSE) da sessão durante um training camp. Também foram realizadas coletas de sangue para determinação da concentração de lactato sanguíneo. A intensidade da carga de treinamento reportada pelos atletas superou a intensidade planejada pelos técnicos em todas sessões de treinamento. Com relação à concentração de lactato, houve aumento no período pós-treino em todas as sessões do training camp, não havendo diferença entre as sessões. Os resultados do presente estudo demonstram que, embora o programa de treinamento tenha sido elaborado por técnicos experientes, foi detectada diferença entre a intensidade da carga externa planejada pelo técnico e a intensidade da carga interna percebida pelos atletas. Estes dados reforçam a importância do constante monitoramento do treinamento, a fim de maximizar o desempenho de atletas de elite.

The aim of this study was to compare the perception concerning of the training load intensity of Judo coaches and athletes. The sample consisted of 4 coaches and 40 athletes of the Brazilian National Judo Team. The comparison between the intensity planned by the coach and the intensity experienced by the athletes was determined by the Session RPE method during a "Training camp". In order to assess lactate responses to training, blood samples were collected pre- and post training session. The intensity experienced by athletes was higher than the intensity planned by coaches in all training sessions. Regarding lactate concentration, it was observed an increase at post-training as compared to pre-training in all sessions, with no differences between sessions. The results of this study demonstrate that although the training session has been developed by experienced coaches, significant differences were detected between the intensity of external training load planned by the coach and the intensity of the internal training load experienced by the athletes. These data reinforce the relevance of training monitoring in order to maximize performance of elite athletes.

DEVELOPMENT OF PREDICTION EQUATIONS FOR CARDIORESPIRATORY FITNESS USING RATINGS OF PERCEIVED EXERTION IN JAPANESE MEN AND WOMEN / 体力科学

A study was conducted to develop prediction equations for cardiorespiratory fitness (maximal oxygen uptake : VO<SUB>2max</SUB> and oxygen uptake at anaerobic threshold : VO<SUB>2AT</SUB>) in Japanese adult men and women. Eighty-three healthy men and 86 healthy women, aged 20-64 years (41.1±13.5 and 41.5±13.5, respectively), were recruited as subjects. Mean (±SD) of VO<SUB>2max</SUB> and VO<SUB>2AT</SUB> measured during a cycling test were 37.2±6.4 and 20.5±4.7 ml/kg/min, respectively, in men and 32.7±7.3 and 17.8±4.1 ml/kg/min, respectively, in women. In this study 36 kinds of equations applicable to each sex were developed using all the subjects (n=169) . These equations consisted of independent variables such as work rate divided by body weight (W/Wt), age and body fat percentage (%Fat), which were signficantly correlated with measured VO<SUB>2max</SUB> and VO<SUB>2AT</SUB>. Multiple correlation coefficients (R) and standard errors of estimate (SEE) of the equations ranged from 0.641 to 0.830 (<I>P</I><0.05) and from 3.66 to 4.98 ml/kg/min, respectively, for VO<SUB>2max</SUB> and from 0.661 to 0.815 (<I>P</I><0.05) and from 2.77 to 3.20 ml/kg/min, respectively, for VO<SUB>2AT</SUB>. Reliability coefficients (r) between the first and second tests were 0.911 in men and 0.873 in women for VO<SUB>2max</SUB>, and 0.869 in men and 0.770 in women for VO<SUB>2AT</SUB>, all of which were statistically significant (<I>P</I><0.05) . It is concluded that the equations developed in the present study have the merits of simplicity, economy, accuracy and reliability. Furthermore, from the viewpoint of safety and convenience, the following prediction equations are recommended.<BR>(Male)<BR>VO<SUB>2max</SUB> (ml/kg/min) =6.57 W<SUB>RPE-legs 15</SUB>/Wt-0.19 Age-0.36%Fat+41.29<BR>(R=0.830, SEE=3.66 ml/kg/min)<BR>VO<SUB>2AT</SUB> (ml/kg/min) =7.35 W<SUB>RPE-legs 14</SUB>/Wt-0.06Age-0.23%Fat+15.62<BR>(R=0.815, SEE=2.77 ml/kg/min)<BR>(Female)<BR>VO<SUB>2max</SUB> (ml/kg/min) =7.30 W<SUB>RPE-legs 15</SUB>/Wt-0.12 Age-0.46%Fat+37.32<BR>(R=0.828, SEE =4.16 ml/kg/min)<BR>VO<SUB>2AT</SUB> (ml/kg/min) =5.03 W<SUB>RPE-legs 14</SUB>/Wt-0.01 Age-0.16%Fat+14.15<BR>(R=0.680, SEE=3.06 ml/kg/min)