Calcium supplementation and parathyroid hormone response to vigorous walking in postmenopausal women.

Introduction: Disruptions in calcium (Ca) homeostasis during exercise may influence skeletal adaptations to exercise training. In young men, vigorous cycling causes increases in parathyroid hormone (PTH) and bone resorption (C-terminal telopeptides of type I collagen [CTX]); responses are attenuated by Ca supplementation. The study aimed to determine whether vigorous walking causes similar increases in PTH and CTX in older women and how the timing of Ca supplementation before and during exercise influences these responses.

Bone loss over 1 year of training and competition in female cyclists.

Objective: To observe changes in hip, spine, and tibia bone characteristics in female cyclists over the course of 1 year of training.

Design: Prospective observational study.

Setting: Laboratory.

Effect of prior acute exercise on trafficking of dietary fat away from adipose tissue.

Objective: Increasing fat content in an isocaloric diet is associated with positive fat imbalance. Exercise attenuates this process, and the authors hypothesized the attenuation was a result of altered postprandial lipid trafficking.

Design: To investigate the effects of prior exercise and nutritional state on the metabolic fate of dietary fat, a study was designed with 4 treatment arms.

Acute calcium ingestion attenuates exercise-induced disruption of calcium homeostasis.

Purpose: Exercise is associated with a decrease in bone mineral density under certain conditions. One potential mechanism is increased bone resorption due to an exercise-induced increase in parathyroid hormone (PTH), possibly triggered by dermal calcium loss. The purpose of this investigation was to determine whether calcium supplementation either before or during exercise attenuates exercise-induced increases in PTH and C-terminal telopeptide of Type I collagen (CTX; a marker of bone resorption).

Prolonged maternal amino acid infusion in late-gestation pregnant sheep increases fetal amino acid oxidation.

Protein supplementation during human pregnancy does not improve fetal growth and may increase small-for-gestational-age birth rates and mortality. To define possible mechanisms, sheep with twin pregnancies were infused with amino acids (AA group, n = 7) or saline (C group, n = 4) for 4 days during late gestation. In the AA group, fetal plasma leucine, isoleucine, valine, and lysine concentrations were increased (P < 0.

Effects of modafinil and sleep loss on physiological parameters.

Objective: The purpose of this study was to determine the effects of modafinil administration on physical performance, thermoregulation, and total energy expenditure (TEE) during continued wakefulness in Air Force operators.

Methods: Participants (N = 12) were randomly assigned to the modafinil or placebo group. Participants performed physical performance and testing during 72 hours of wakefulness.

Exercise increases the proportion of fat utilization during short-term consumption of a high-fat diet.

Background: Increases in energy substrate oxidation occur at different rates after an increase in either fat or carbohydrate intake. Adaptations to increased fat intake are relatively slow and are influenced by activity level.

Objective: We tested the hypothesis that increased levels of daily activity, as influenced by added exercise, would have a graded effect on the rate of compensatory adjustment to a short-term high-fat diet.