Application of the allometric scale for the submaximal oxygen uptake in runners and rowers

Background: The aim of the current study was to determine the allometric exponents for runners and rower’s metabolic cost, while also verifying the relation of performance with and without the allometric application. Methods: Eleven runners (age: 22.3±10.4 years; height: 174±8.8 cm; body mass: 61.7±9.3 kg; maximum oxygen uptake ( •VO2max): 56.3±3.9 ml.kg[sup]-1[/sup].min[sup]-1[/sup]) and fifteen rowers (age: 24±5.4 years; height: 185.5±6.5 cm; body mass: 83.5±7.2 kg; •VO2max: 61.2±3.4 ml.kg[sup]-1[/sup].min[sup]-1[/sup]) carried out a specific progressive maximum test. The allometric exponent was determined from the logarithmic equation Log y = Log b Log x, where x is the mass, y is the VO2max (l.min[sup]-1[/sup]), a is one constant and b is the allometric exponent. The data were analyzed using descriptive and comparative statistics (independent T test of the Student), with p<0.05 (SPSS version 13.0). Results: The allometric exponent of the rowers was 0.70 and that of the runners was 1.00. Significant differences were found between the fat mass percentage, with higher value for rowers, suggesting that this variable may influence the behavior of the allometric exponent and consequently of the basal metabolic rate. Conclusions: Scaling may help in understanding variation in aerobic power and in defining the physiological limitations of work capacity

A slow V&#775;O2 on-response allows comfortable adoption of aerobically unaffordable walking and running speeds on short stair ascents

The aim of this study was to investigate the mechanical and metabolic reasons for the spontaneous gait/speed choice when ascending a short flight of stairs, where walking on every step or running on every other step are frequently interchangeable options. The kinematics, oxygen uptake (V\u307O2 ), ventilation and heart rate of 24 subjects were sampled during climbing one and two flights of stairs while using the two gaits. Although motor acts were very short in time (5-22\u2005s), metabolic kinetics, extending into the 250\u2005s after the end of climbing, consistently reflected the (metabolic equivalent of the) required mechanical energy and allowed comparison of the two ascent choices: despite a 250% higher mechanical power associated with running, measured [Formula: see text], ventilation and heart rate peaked at only +25% with respect to walking, and in both gaits at much lower values than [Formula: see text] despite predictions based on previous gradient locomotion studies. Mechanical work and metabolic cost of transport, as expected, showed a similar increase (+25%) in running. For stairs up to a height of 4.8\u2005m (30 steps at 53% gradient), running makes us consume slightly more calories than walking, and in both gaits with no discomfort at all. The cardio-respiratory-metabolic responses similarly delay and dampen the replenishment of phosphocreatine stores, which were depleted much faster during the impulsive, highly powered mechanical event, with almost overlapping time courses. This discrepancy between mechanical and metabolic dynamics allows us to afford climbs ranging from almost to very anaerobic, and to interchangeably decide whether to walk or run up a short flight of stairs

Cardiorespiratory responses during deep water running with and without horizontal displacement at different cadences

AbstractObjectiveTo compare the cardiorespiratory responses during deep water running with and without displacement at different cadences.MethodsTwelve young women performed deep water running with and without displacement during 4min at three separate cadences: (a) 60bpm; (b) 80bpm; and (c) 100bpm. The heart rate (HR), ventilation (Ve) and oxygen uptake (VO2) were collected in the last minute of each test. Two-way ANOVA for repeated measures was used with Bonferroni's post hoc test (p<0.05) to compare variables.ResultsThe results showed a significant increase in all variables as the cadence increased (HR: p<0.001; Ve: p<0.001; VO2: p<0.001). In addition, the VO2 and Ve values were significantly higher for deep water running with displacement compared to running without displacement (VO2: p=0.047; Ve: p=0.007). However, there was no significant difference in HR with and without displacement (p=0.065).ConclusionsThe results indicate that the increase in both cadence and displacement results in significant cardiorespiratory responses as a result of deep water running. This finding is important for adapting exercise prescription to the goals of participants

Analysis Of Maximal Isometric Force And Emg Signal In Lower Limb Exercise [análise Da Força Isométrica Máxima E Do Sinal De Emg Em Exercícios Para Os Membros Inferiors]

The aim of this study was to compare maximal isometric force (MIF) and the electrical activity of the vastus medialis, vastus lateralis, rectus femoris, gluteus maximus and biceps femoris long head muscles between maximal voluntary contractions (MVC) performed at different joint angles, and to identify the most suitable positions to normalize the electromyography (EMG) signals from each of these muscles when they are activated under dynamic conditions. Ten men ranging in age from 20 to 30 years, who were familiar with strength training exercise, were studied. MVC at different joint angles of the knee extensors and flexors (0°, 60°, 90°) and hip extensors (-30°, 0°, 60°) and flexors (90°, 120°) were tested. The MIF values differed significantly between the 60° knee flexion and 60° and 90° knee extension positions (p0.05). Significantly higher EMG values were only observed for the rectus femoris muscle at 90° knee extension (p0.05). 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Comparação das respostas cardiorrespiratórias de um exercício de hidroginástica com e sem deslocamento horizontal nos meios terrestre e aquático Comparisons of cardiorrespiratory responses in a hydrogymnastics exercise with and without horizontal movement on land and in aquatic environment

O objetivo do estudo foi comparar as respostas cardiorrespiratórias de um exercício de hidroginástica (corrida estacionária) realizado com e sem deslocamento horizontal no meio terrestre (MT), em piscina funda (PF) e em piscina rasa (PR). Seis mulheres jovens realizaram os exercícios durante 4 min numa cadência de 80 bpm. O exercício consistia em flexão e extensão de quadril com os braços simulando um movimento de corrida. A frequência cardíaca (FC) e o consumo de oxigênio (VO2 ) foram coletados no último minuto de exercício e a percepção de esforço (PE) foi coletada ao término do exercício. Para a comparação das variáveis utilizou-se ANOVA two-way para medidas repetidas com fatores meio e forma de execução (p < 0,05). Para todas as variáveis analisadas foram encontrados valores menores no exercício em PR comparado ao exercício no MT. Porém, nenhuma diferença foi observada entre o exercício no MT e em PF, exceto para a FC, que foi menor no exercício em PF. Em relação à forma de execução, para a FC, foram encontrados valores maiores no exercício com deslocamento quando comparado ao exercício sem deslocamento somente na PF. Estes achados sugerem a possibilidade de executar o exercício analisado em PF com gasto energético (GE) similar e FC menor quando comparado ao mesmo exercício no MT. Fato de grande relevância para populações que querem obter um GE semelhante ao exercício no MT, mas que necessitam de uma menor sobrecarga cardiovascular.<br>The aim of the study was to compare the cardiorespiratory responses during an hydrogymnastics exercise performed with and without horizontal movement on land environment (LE) and in a deep (DS) and in a shallow swimming pool (SS). Six YOUNG women performed the exercise during four minutes in each environment (LE, DS and SS) and situation (with and without horizontal movement) in a cadence of 80 bpm. The exercise consisted in a hip flexion/extension while the arms simulating a running movement. The heart rate (HR) and oxygen uptake (VO2 ) were veriefied during the last minute in each exercise and the rate of perceived exertion (RPE) was collected in the ending of the exercise. To variables comparisons was used ANOVA two-way for repeated measures with factors environment and situation (p < 0,05). For all cardiorespiratory variables analyzed, SS exercise were lower than that found on LE. Although, no difference was observed in the exercise performed on LE or in DS, except for the HR, that was lower during DS. Acording to the different situations, higher HR value was found during the exercise with horizontal movement when compared with the exercise without horizontal movement in the DS. These findings suggest the possibility to perform the exercise analyzed with similar energy expenditure and lower FC in DS when compared with exercise in LE. It is very important for people that need similar energy expenditure and lower cardiovascular overload during aquatic exercise