Changes in body fluids during endurance rowing training

A Temperature-Based Bioimpedance Correction for Water Loss Estimation During Sports

The amount of total body water (TBW) can be estimated based on bioimpedance measurements of the human body. In sports, TBW estimations are of importance because mild water losses can impair muscular strength and aerobic endurance. Severe water losses can even be life threatening. TBW estimations based on bioimpedance, however, fail during sports because the increased body temperature corrupts bioimpedance measurements. Therefore, this paper proposes a machine learning method that eliminates the effects of increased temperature on bioimpedance and, consequently, reveals the changes in bioimpedance that are due to TBW loss. This is facilitated by utilizing changes in skin and core temperature. The method was evaluated in a study in which bioimpedance, temperature, and TBW loss were recorded every 15 min during a 2-h running workout. The evaluation demonstrated that the proposed method is able to reduce the error of TBW loss estimation by up to 71%, compared to the state of art. In the future, the proposed method in combination with portable bioimpedance devices might facilitate the development of wearable systems for continuous and noninvasive TBW loss monitoring during sports.

Monitoring change of body fluids during physical exercise using bioimpedance spectroscopy

During physical exercise body muscles are activated and heat is generated. In intensive physical activity, heat will be released by sweating to protect the body of overheating. Sweating and convection implies a water loss which can lead to dehydration. To avoid health problems as a result of dehydration, the body water content can be monitored to detect changes early in order to rehydrate in time. Bioimpedance Spectroscopy (BIS) is a comfortable measurement method to monitor the body composition under controlled conditions, that is used for different applications, like monitoring dialysis. Unfortunately, the physiological changes due to sportive activities can influence the BIS and complicate the measurement. In this article, a study is presented in which the fluid content of five test persons is monitored during physical exercise, whereas all test persons did not drink anything before and during sport. During training not only the body composition was measured using a BIS device but also the skin temperature was monitored with an infrared camera. As a result, it could be shown that such a combination of measurement systems allow to use BIS devices also during sport as significant monitoring systems for detecting a person's body fluid loss.

Antioxidant enzymes show adaptation to oxidative stress in athletes and increased stress in hemodialysis patients

The aim of the study is to compare oxidative stress in hemodialysis patients in controls and in rowers. The patients are a model of decreased antioxidant capacity, and the athletes (rowers) are a model of the highest antioxidant capacity due to their chronic adaptation to demanding training. Thirty-five subjects participated in the study, 9 patients with end-stage renal disease treated by hemodialysis, 12 healthy young subjects from the normal population, and 14 rowers. The antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as non-transferrin-bound iron as a promoter of free radical damage, were determined. Blood analysis was taken in dialysis patients in the morning, before the dialysis procedure. There was significantly higher activity of catalase in dialysis patients (catalase 4.26 +/- 0.35 mkat/g Hb) compared to the controls (catalase 2.73 +/- 0.38 mkat/g Hb) and rowers (catalase 1.71 +/- 0.30 mkat/g Hb). Superoxide dismutase activity was significantly lower (10.42 +/- 1.46 microkat/g Hb) than in the controls (11.94 +/- 1.18 microkat/g Hb) and rowers (14.09 +/- 0.92 microkat/g Hb). There was no significant differences between glutathione peroxidase activities in the three groups. Superoxide dismutase and Se were higher in rowers than in dialysis patients (P < 0.05). The concentrations of both non-transferrin-bound iron and ferritin were significantly higher in dialysis patients. Hemodialysis patients might have increased oxidative stress, which is characterized by significantly higher erythrocyte enzyme activity of catalase and lower activity of superoxide dismutase. Top rowers had increased superoxide dismutase and glutathione peroxidase, perhaps because of adaptation during training, which was not the case in dialysis patients and controls.

Extracellular bicarbonate and non-bicarbonate buffering against lactic acid during and after exercise

Defense of extracellular pH constancy against lactic acidosis can be estimated from changes (Delta) in lactic acid ([La]), [HCO(3)(-)], pH and PCO(2) in blood plasma because it is equilibrated with the interstitial fluid. These quantities were measured in earlobe blood during and after incremental bicycle exercise in 13 untrained (UT) and 21 endurance-trained (TR) males to find out if acute and chronic exercise influence the defense. During exercise the capacity of non-bicarbonate buffers (beta(nbi) = -Delta[La] . DeltapH(-1) - Delta[HCO(3)(-)] . DeltapH(-1)) available for the extracellular fluid (mainly hemoglobin, dissolved proteins and phosphates) amounted to 32 +/- 2(SEM) and 20 +/- 2 mmol l(-1) in UT and TR, respectively (P < 0.02). During recovery beta(nbi) decreased to 14 (UT) and 12(TR) mmol l(-1) (both P < 0.001) corresponding to values previously found at rest by in vivo CO(2) titration. Bicarbonate buffering (beta(bi)) amounted to 44-48 mmol l(-1) during and after exercise. The large exercise beta(nbi) seems to be mainly caused by an increasing concentration of all buffers due to shrinking of the extracellular volume, exchange of small amounts of HCO(3)(-) or H(+) with cells and delayed HCO(3)(-) equilibration between plasma and interstitial fluid. Increase of [HCO(3)(-)] during titration by these mechanisms augments total beta and thus the calculated beta(nbi) more than beta(bi) because it reduces DeltapH and Delta[HCO(3)(-)] at constant Delta[La]. The smaller rise in exercise beta(nbi) in TR than UT may be caused by an increased extracellular volume and an improved exchange of La(-), HCO(3)(-) and H(+) between trained muscles and blood.

Avaliação nutricional de remadores competitivos

O remo teve início como um meio de sobrevivência, transporte ou forma de atuar em guerras. Atualmente, é uma modalidade esportiva que utiliza membros superiores e inferiores para a propulsão do barco, sendo utilizadas vias aeróbicas e anaeróbicas. Tem-se como objetivo revisar os fatores dietéticos, antropométricos e bioquímicos que possam auxiliar na avaliação e orientação nutricional de remadores, visando melhorar o desempenho desses atletas. Por ser uma atividade de alta intensidade (aproximadamente 85% do volume máximo de oxigênio) e curta duração (cinco a oito minutos), ressalta-se a importância do consumo adequado de carboidratos, embora estudos demonstrem que remadores ingerem menos carboidratos que o recomendado, podendo comprometer estoques de glicogênio muscular bem como a imunidade. As categorias são divididas em função do sexo, faixa etária e massa corporal, o que faz da antropometria um método de seleção de remadores para competições no nível nacional e internacional. Devido ao elevado volume e à intensidade de treinamento, o atleta está susceptível a alterações plasmáticas de alguns metabólitos, como a uréia e creatinina, podendo ser diagnosticadas por meio da avaliação bioquímica. Logo, qualquer fator que contribua para a otimização da avaliação nutricional e conseqüente orientação de um remador deve ser estudado.

Bioelectrical impedance spectroscopy for the assessment of body fluid volumes of term neonates

The assessment of fluid volume in neonates by a noninvasive, inexpensive, and fast method can contribute significantly to increase the quality of neonatal care. The objective of the present study was to calibrate an acquisition system and software to estimate the bioelectrical impedance parameters obtained by a method of bioelectrical impedance spectroscopy based on step response and to develop specific equations for the neonatal population to determine body fluid compartments. Bioelectric impedance measurements were performed by a laboratory homemade instrument. The volumes were estimated in a clinical study on 30 full-term neonates at four different times during the first month of life. During the first 24 hours of life the total body water, extracellular water and intracellular water were 2.09 +/- 0.25, 1.20 +/- 0.19, and 0.90 +/- 0.25 liters, respectively. By the 48th hour they were 1.87 +/- 0.27, 1.08 +/- 0.17, and 0.79 +/- 0.21 liters, respectively. On the 10th day they were 2.02 +/- 0.25, 1.29 +/- 0.21, and 0.72 +/- 0.14 liters, respectively, and after 1 month they were 2.34 +/- 0.27, 1.62 +/- 0.20, and 0.72 +/- 0.13 liters, respectively. The behavior of the estimated volume was correlated with neonatal body weight changes, leading to a better interpretation of such changes. In conclusion, this study indicates the feasibility of bioelectrical impedance spectroscopy as a method to help fluid administration in intensive care neonatal units, and also contribute to the development of new equations to estimate neonatal body fluid contents.