Flavia Meyer

Plasma metabolites, volume and electrolytes following 30-s high-intensity exercise in boys and men

It has been shown that boys recover faster than men following brief, high-intensity exercise. Better to understand this difference, plasma metabolite concenration, volume, electrolyte concentration [electrolyte], and hydrogen ion concentration [H+] changes were compared in five prepubescent boys [mean age 9.6 (SD 0.9) years] and 5 men [mean age 24.9 (SD 4.3) years] following 30-s, all-out cycling. Blood was collected prior to, at the end, and at the 1st, 3rd and 10th min following exercise. At the 10th min of recovery, the mens lactate concentration was 14.2 (SD 1.8) mmol · l−1 and [H+] was 66.1 (SD 5.9) nmol · l−1, compared with 5.7 (SD 0.7) mmol · l−1 and 47.5 (SD 1.2) nmol · l−1 respectively, in the boys (P < 0.01 for both). The glycerol concentration was higher in the boys at the end of exercise and until the 3rd min of recovery. Plasma volume (PV) decreased more in the men [16.9 (SD 3.0)%] than in the boys [9.4 (SD 2.8)%]. In both groups, [electrolyte] increased after exercise, tending to be higher in the men. Recovery of plasma [electrolyte] and PV started earlier in the boys (1st min) than in the men (3rd min). These findings would support the notion of a lesser reliance on glycolytic energy pathways in children and may explain the faster recovery of muscle power in boys compared to men.

Atividade física e saúde na infância e adolescência

Um estilo de vida ativo em adultos está associado a uma redução da incidência de várias doenças crônico-degenerativas bem como a uma redução da mortalidade cardiovascular e geral. Em crianças e adolescentes, um maior nível de atividade física contribui para melhorar o perfil lipídico e metabólico e reduzir a prevalência de obesidade. Ainda, é mais provável que uma criança fisicamente ativa se torne um adulto também ativo. Em conseqüência, do ponto de vista de saúde pública e medicina preventiva, promover a atividade física na infância e na adolescência significa estabelecer uma base sólida para a redução da prevalência do sedentarismo na idade adulta, contribuindo desta forma para uma melhor qualidade de vida. Nesse contexto, ressaltamos que a atividade física é qualquer movimento como resultado de contração muscular esquelética que aumente o gasto energético acima do repouso e não necessariamente a prática desportiva. Este documento, elaborado por médicos especialistas em exercício e esporte, baseia-se em conceitos científicos e na experiência clínica, tendo como objetivos: 1) estabelecer os benefícios da atividade física na criança e no adolescente; 2) caracterizar os elementos de avaliação e prescrição do exercício para a saúde nessa faixa etária; 3) estimular a recomendação e a prática da atividade física nas crianças e adolescentes, mesmo na presença de doenças crônicas, visto que são raras as contra-indicações absolutas.

Drink composition and the electrolyte balance of children exercising in the heat

Twelve 9- to 12-year-old children (6 boys, 6 girls) performed four exercise-in-heat (35 degrees C, 45% RH) trials which differed in the composition of the fluids they drank. In each trial, subjects cycled for one 20-min and two 15-min bouts at 50% peak VO2 with 10-min rest periods in between. In a fourth bout, they cycled at 90% peak VO2 until exhaustion. Drinks had the same grape flavor and were assigned in a double-blind design and in a Latin-square order. Subjects drank 7 ml.kg-1.h-1 to keep them euhydrated. Three of the drinks had 6% carbohydrates (CHO), with different [Na+]: 0, 8.8, 18.5 mmol.l-1 and one drink had neither CHO nor Na+ (WATER). Among drink trials, there were no differences in the increase in rectal temperature, HR, or performance time to exhaustion. Despite the larger Na+ deficit induced by the Na(+)-free drinks compared with the Na+ drinks (11.8 +/- 1.4 vs 5.7 +/- 0.9 mmol.h-1), neither plasma [Na+] nor osmolality were affected. These results suggest that electrolyte, as in the above conditions, did not affect electrolyte balance, thermoregulatory responses, or aerobic performance of children exercising in the heat. The greater Na+ deficit induced by ion-free drinks was of minor biological importance.

As equações de predição da taxa metabólica basal são apropriadas para adolescentes com sobrepeso e obesidade

The known predictive equations can present different values for basal metabolic rate (BMR) compared to those measured through indirect calorimetry. The objective of this study was to describe BMR through indirect calorimetry of overweight and obese boys (with ages between 12 and 17 years old) living in Porto Alegre, Brazil, and to compare the measured value with values estimated by predictive equations. Thirty-five volunteers had their BMR measured through indirect calorimetry in the morning, under standard conditions of fasting, rest and environment. The average (± standard deviation) of measured BMR was of 1,900.5 ± 248.8 kcal/24 hours. Estimated BMR were significantly greater, in three of four equations (6.5 to 9.5%), than measured BMR (p < 0.05). These results show that predictive equations are not suitable to estimate BMR in these groups of overweight and obese boys. The use of estimated BMR can lead, in most cases, to an overestimation of energy requirements for boys with similar characteristics.

Bone mineral density, milk intake and physical activity in boys who suffered forearm fractures

OBJECTIVE To compare boys with and without forearm fracture in terms of their bone mineral density, intake of milk and dairy products, and physical activity. METHODS There were 23 boys in each group (aged between 7 and 13 years). They were submitted to bone densitometry with dual-energy x-ray absorptiometry (DEXA) of the forearm (opposite side of the fracture). Participants answered questionnaires about their intake of milk and dairy products, and about their physical activity. RESULTS The mean+/-SD of the bone mineral density of the radial and ulnar distal diaphysis in the case group (0.430+/-0.038 g.cm(-2)) was significantly lower (p = 0.018) than that of the control group (0.458+/-0.039 g.cm(-2)). Likewise, the mean of the distal metaphysis of the forearm was 0.309+/-0.033 g.cm(-2) in the case group and 0.349+/-0.054 g.cm(-2) in the control group (p = 0.004). Milk intake (1.5+/-1.2 cups a day) was significantly lower in the case group (p = 0.001) than in the control group (2.7+/-1.2 cups a day). The number of boys who practiced after-school physical activity was significantly lower (p = 0.017) in the case group (six boys = 26%) than in the control group (15 boys = 53%). CONCLUSION Boys who suffered forearm fracture showed lower bone mineral density compared with the control group. In the case group, milk intake and physical activity were lower than in the control group.

Asma induzida pelo exercício: aspectos atuais e recomendações

Objective: To describe the mechanisms of Exercise-Induced Asthma (EIA) as well as the effect of different kinds of physical training on pulmonary function, anaerobic fitness, and aerobic fitness. We highlighted the importance of a correct diagnostic through exercise testing and, concerning treatment, the utilization of drugs such as beta-adrenergics and anticholinergics. Data source: The articles were chosen using the PubMed and Scielo databases, considering the year of publication and giving preference to clinical randomized trials with well-defined inclusion criteria. Summary of the findings: The medication used and the frequent symptoms during and after exercise appear as a limiting factor to the practice of exercises among subjects with EIA. This may result in a sedentary lifestyle. Conclusion: Subjects with EIA should be allowed to do exercise if well prescribed.

Are basal metabolic rate prediction equations appropriate for overweight and obese adolescents

The known predictive equations can present different values for basal metabolic rate (BMR) compared to those measured through indirect calorimetry. The objective of this study was to describe BMR through indirect calorimetry of overweight and obese boys (with ages between 12 and 17 years old) living in Porto Alegre, Brazil, and to compare the measured value with values estimated by predictive equations. Thirty-five volunteers had their BMR measured through indirect calorimetry in the morning, under standard conditions of fasting, rest and environment. The average (± standard deviation) of measured BMR was of 1,900.5 ± 248.8 kcal/24 hours. Estimated BMR were significantly greater, in three of four equations (6.5 to 9.5%), than measured BMR (p < 0.05). These results show that predictive equations are not suitable to estimate BMR in these groups of overweight and obese boys. The use of estimated BMR can lead, in most cases, to an overestimation of energy requirements for boys with similar characteristics.

Densidade mineral óssea, ingestão de leite e atividade física de meninos que sofreram fraturas no antebraço

OBJETIVO: O objetivo deste estudo foi comparar meninos com e sem fraturas de antebraco em relacao a densidade mineral ossea, consumo diario de produtos derivados de leite e atividade fisica. METODOS: Participaram do estudo 23 meninos (7 a 13 anos) em cada grupo (caso = 23, controle = 23). Eles foram submetidos a densitometria ossea (dual energy x-ray absorptiometry - DEXA) do antebraco oposto ao lado fraturado. Os participantes preencheram um questionario sobre o consumo diario de produtos contendo leite e suas atividades fisicas. RESULTADOS: A media±DP da densidade mineral ossea da diafise distal do radio e da ulna no grupo caso (0,430±0,038 g·cm-2) foi significativamente menor (p = 0,018) do que o grupo controle (0,458±0,039 g·cm-2). Da mesma forma, a media da metafise distal foi 0,309±0,033 g·cm-2 no grupo caso e 0,349±0,054 g·cm-2 no grupo controle (p = 0,004). O consumo de leite no grupo caso (1,5±1,2 copos por dia) foi significativamente menor (p = 0,001) do que no grupo controle (2,7±1,2 copos por dia). O numero de meninos que praticavam atividade fisica apos a escola foi significativamente menor (p = 0,017) no grupo caso (seis meninos = 26%) do que no grupo controle (15 meninos = 53%). CONCLUSAO: Meninos com fraturas no antebraco apresentaram menor densidade mineral ossea na regiao quando comparados com meninos que nunca sofreram fraturas. No grupo que sofreu fratura, o consumo de leite foi menor, e os meninos praticavam menos atividades fisicas extra-escolares do que os meninos que nunca tiveram fraturas.

Position statement of the Brazilian Society of Sports Medicine: physical activity and health in children and adolescents

Jose Kawazoe Lazzoli, Antonio Claudio Lucas da Nobrega, Tales de Carvalho,Marcos Aurelio Brazao de Oliveira, Jose Antonio Caldas Teixeira, Marcelo Bichels Leitao,Neiva Leite, Flavia Meyer, Felix Albuquerque Drummond, Marcelo Salazar da Veiga Pessoa,Luciano Rezende, Eduardo Henrique De Rose, Sergio Toledo Barbosa, Joao Ricardo Turra Magni,Ricardo Munir Nahas, Glaycon Michels and Victor Matsudo

Exercise-induced asthma: current aspects and recommendations

Objective: To describe the mechanisms of Exercise-Induced Asthma (EIA) as well as the effect of different kinds of physical training on pulmonary function, anaerobic fitness, and aerobic fitness. We highlighted the importance of a correct diagnostic through exercise testing and, concerning treatment, the utilization of drugs such as beta-adrenergics and anticholinergics. Data source: The articles were chosen using the PubMed and Scielo databases, considering the year of publication and giving preference to clinical randomized trials with well-defined inclusion criteria. Summary of the findings: The medication used and the frequent symptoms during and after exercise appear as a limiting factor to the practice of exercises among subjects with EIA. This may result in a sedentary lifestyle. Conclusion: Subjects with EIA should be allowed to do exercise if well prescribed.