Força muscular como determinante da eficiência do consumo de oxigênio e da máxima resposta metabólica ao exercício em pacientes com DPOC leve/moderada Muscle strength as a determinant of oxygen uptake efficiency and maximal metabolic response in patients with mild-to-moderate COPD

OBJETIVO: Comparar o comportamento de oxygen uptake efficiency slope (OUES, inclinação da eficiência do consumo de oxigênio) com o do consumo de oxigênio no pico do exercício (VO2pico). MÉTODOS: Estudo prospectivo transversal envolvendo 21 pacientes (15 homens) com DPOC leve/moderada que foram submetidos a espirometria, dinamometria de preensão palmar (DIN), teste cardiopulmonar de exercício e medida de lactato no pico do exercício (LACpico). RESULTADOS: A média de peso foi 66,7 ± 13,6 kg, e a de idade foi 60,7 ± 7,8 anos. Com exceção de VEF1 e relação VEF1/CVF (75,8 ± 18,6 do previsto e 56,6 ± 8,8, respectivamente), as demais variáveis espirométricas foram normais, assim como DIN. As médias, em % do previsto, para VO2pico (93,1 ± 15,4), FC máxima (92,5 ± 10,4) e OUES (99,4 ± 24,4), assim como a da taxa de troca respiratória (1,2 ± 0,1), indicaram estresse metabólico e hemodinâmico importante. A correlação entre o VO2pico e a OUES foi elevada (r = 0,747; p < 0,0001). A correlação entre DIN e VO2pico (r = 0,734; p < 0,0001) foi mais expressiva do que com aquela entre DIN e OUES (r = 0,453; p < 0,05). Resultados semelhantes ocorreram em relação às correlações de VO2pico e OUES com PImáx. Houve correlação significativa entre VO2pico e LACpico (r = -0,731; p < 0,0001), mas essa só ocorreu entre OUES e LACpico/potência máxima (r = -0,605; p = 0,004). CONCLUSÕES: Nossos resultados sugerem que, na DPOC leve/moderada, determinantes do VO2, além da força muscular global, têm um maior impacto na OUES do que no VO2pico.<br>OBJECTIVE: To compare the behavior of the oxygen uptake efficiency slope (OUES) with that of oxygen uptake at peak exertion (VO2peak). METHODS: This was a prospective cross-sectional study involving 21 patients (15 men) with mild-to-moderate COPD undergoing spirometry, handgrip strength (HGS) testing, cardiopulmonary exercise testing, and determination of lactate at peak exertion (LACpeak). RESULTS: Mean weight was 66.7 ± 13.6 kg, and mean age was 60.7 ± 7.8 years. With the exception of FEV1 and FEV1/FVC ratio (75.8 ± 18.6 of predicted and 56.6 ± 8.8, respectively), all spirometric variables were normal, as was HGS. The patients exhibited significant metabolic and hemodynamic stress, as evidenced by the means (% of predicted) for VO2peak (93.1 ± 15.4), maximum HR (92.5 ± 10.4), and OUES (99.4 ± 24.4), as well as for the gas exchange rate (1.2 ± 0.1). The correlation between VO2peak and OUES was significant (r = 0.747; p < 0.0001). The correlation between HGS and VO2peak (r = 0.734; p < 0.0001) was more significant than was that between HGS and OUES (r = 0.453; p < 0.05). Similar results were found regarding the correlations of VO2peak and OUES with MIP. Although LACpeak correlated significantly with VO2peak (r = -0.731; p < 0.0001), only LACpeak/maximum power correlated significantly with OUES (r = -0.605; p = 0.004). CONCLUSIONS: Our findings suggest that, in mild-to-moderate COPD, VO2 determinants other than overall muscle strength have a greater impact on OUES than on VO2peak

Efeitos de exercícios aquáticos sobre a aptidão cardiorrespiratória e a pressão arterial em hipertensas Effects of aquatic exercise on cardiorespiratory fitness and blood pressure in hypertensive women

O estudo visou avaliar a influência de um programa de exercícios aquáticos sobre a aptidão cardiorrespiratória e a pressão arterial em mulheres hipertensas. Dez hipertensas participaram do programa de exercícios aquáticos - aeróbicos, de fortalecimento, alongamento e relaxamento - duas vezes por semana durante 7 semanas, totalizando 14 sessões. Foram avaliadas pelo teste de esforço cardiorrespiratório antes e após o desenvolvimento do programa. A pressão arterial foi mensurada ao repouso e aos 10, 20 e 30 minutos após o exercício em cada sessão. As variáveis cardiorrespiratórias não apresentaram alterações significativas após o programa, tanto dos valores de limiar de anaerobiose quanto os do pico de esforço. As pressões arteriais sistólica, diastólica e média de repouso permaneceram estáveis no decorrer do programa. Entretanto, no período pós-exercício, os níveis da pressão arterial sistólica (PAS) e média (PAM) foram significativamente menores, quando comparados aos valores pré-exercício: houve redução média de 6,43 mmHg da PAS e 3,08 mmHg da PAM aos 30 minutos pós-exercício. Assim, o programa de exercícios aquáticos proposto não promove ganho aeróbico efetivo, mas os resultados sugerem que exercícios aquáticos como os propostos, em intensidade próxima ao limiar de anaerobiose, desencadeiam redução dos níveis de pressão arterial no período pós-exercício, em mulheres hipertensas.<br>The aim of this study was to assess the influence of an aquatic exercise program on cardiorespiratory fitness and blood pressure in hypertensive women. Ten hypertensive women took part in the study. The program consisted of aquatic aerobic, strengthening, and stretching exercises in intensity near the anaerobic threshold, besides relaxation, twice a week during 7 weeks, totalling 14 sessions. They were assessed by cardiorespiratory exercise testing before and after program development. Blood pressure was measured at rest before and at 10, 20, and 30 minutes after exercise, at the end of each session. After the hydrotherapy program, cardiorespiratory ranges did not show significant changes, neither at the anaerobic threshold nor at the effort peak. Systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure at rest remained stable all through the program. However, SBP and MBP levels at 30-minute rest after exercises, at the end of the program, were significantly lower when compared to pre-exercise ones: there was a mean 6,43 mmHg SBP decrease and a 3,08 mmHg MBP decrease. The hydrotherapy program thus did not promote effective aerobic increase, but results suggest that the proposed exercises, performed at near-anaerobic threshold, may reduce post-exercise SBP and MBP levels in hypertensive women

On being small: brain allometry in ants

Comparative neurobiologists have provided ample evidence that in vertebrates small animals have proportionally larger brains: in a double-logarithmic plot of brain weight versus body weight all data points conform quite closely to a straight line with a slope of less than one. Hence vertebrate brains scale allometrically, rather than isometrically, with body size. Here we extend the phylogenetic scope of such studies and the size range of the brains under investigation to the insects, especially ants. We show that the principle of (negative) allometry applies as well, but that ants have considerably smaller brains than any ant-sized vertebrate would have, and that this result holds even if the relatively higher exoskeleton weights of ants (as compared to endoskeleton weights of mammals) are taken into account. Finally, interspecific comparisons within one genus of ants, Cataglyphis, show that species exhibiting small colony sizes (of a few hundred individuals) have significantly smaller brains than species in which colonies are composed of several thousand individuals