such as tumors or inflammatory processes. 4 – 10 Changes in dynamic blood perfusion can be visualized in a contrast agent preset through signals from the gas-filled microbubble contrast agent, which will be eliminated as gas (sulfur hexafluoride) via the lungs. Regarding skeletal muscle tissue, CEUS
Marion Kellermann, Christoph Lutter and Thilo Hotfiel
Sarah J. Willis, Grégoire P. Millet and Fabio Borrani
the vascular and hemodynamic responses as well. The mechanisms controlled by blood pressure and muscle oxygen delivery 3 are particularly of interest during these hypoxic stimuli, specifically the muscle and respiratory pump, along with increased arteriovenous pressure gradient (perfusion pressure
Philippe Richard and François Billaut
possibility that they could also be ergogenic in sport. 4 Some of the ergogenic effects mediated via RIPC relate to a direct impact on the vasculature. IPC has been found to improve vascular function 5 , 6 and perfusion locally and in the contralateral limb, 5 , 6 thereby confirming the endothelial systemic
Cordial M. Gillette and Mark A. Merrick
and blood flow into the capillary through arteriole constriction. This would potentially limit fluid accumulation in the extremity. 4 If elevation alters capillary starling forces and potentially perfusion across the capillary bed, it may also impact cooling by altering the relative balance of heat
Florian J. Segerer, Johannes Biko, Christoph Reiners, Clemens Wirth and Helge Hebestreit
Exercise-induced arterial hypoxemia (EIAH) has been reported in patients with juvenile thyroid cancer treated with radioiodine for lung metastases. This retrospective study tested the hypothesis that EIAH is due to ventilation-perfusion-mismatch in this rare pulmonary condition.
50 patients (age 13–23 years) treated for juvenile thyroid carcinoma and lung metastasis with 131I and 24 controls with thyroid cancer but without lung metastases and prior 131I-treatment were assessed in a state of acute hypothyroidism by com-puted tomography of the lungs, pulmonary function testing, cardiopulmonary exercise test with measurements of gas exchange, oxygen saturation, alveolar-arterial difference in pO2 (p(A-a)O2) and pCO2 (p(ET-a)CO2).
10 of the 50 patients with lung metastases showed EIAH. They had more pronounced pulmonary fibrosis on computed tomography, a widened p(A-a)O2, and p(ET-a)CO2, a lower DVE/DVCO2-slope, a lower respiratory rate and no increased dead space ventilation. A more pronounced EIAH was associated with male gender, younger age, lower diffusion capacity, higher p(ET-a)CO2 during exercise and a higher peak exercise tidal volume over vital capacity ratio.
EIAH in patients with thyroid carcinoma and pulmonary metastases is not related to ventilation-perfusion mismatch but to alveolar hypoventilation, possibly related to an increased work of breathing with pulmonary fibrosis.
Jennifer Rogers, Robert W. Summers and G. Patrick Lambert
The purpose of this study was to determine if lowering carbohydrate (CHO) concentration in a sport drink influences gastric emptying, intestinal absorption, or performance during cycle ergometry (85 min, 60% VO2peak). Five subjects (25 ± 1 y, 61.5 ± 2.1 mL · kg−1 · min−1 VO2peak) ingested a 3% CHO, 6% CHO, or a water placebo (WP) beverage during exercise. Gastric emptying was determined by repeated double sampling and intestinal absorption by segmental perfusion. Total solute absorption and plasma glucose was greater for 6% CHO; however, neither gastric emptying, intestinal water absorption, or 3-mi time trial performance (7:58 ± 0:33 min, 8:13 ± 0:25 min, and 8:25 ± 0:29 min, respectively, for 6% CHO, 3% CHO, and WP) differed among solutions. These results indicate lowering the CHO concentration of a sport drink from 6% CHO does not enhance gastric emptying, intestinal water absorption, or time trial performance, but reduces CHO and total solute absorption.
Xiaocai Shi and Dennis H. Passe
The purpose of this study is to summarize water, carbohydrate (CHO), and electrolyte absorption from carbohydrate- electrolyte (CHO-E) solutions based on all of the triple-lumen-perfusion studies in humans since the early 1960s. The current statistical analysis included 30 reports from which were obtained information on water absorption, CHO absorption, total solute absorption, CHO concentration, CHO type, osmolality, sodium concentration, and sodium absorption in the different gut segments during exercise and at rest. Mean differences were assessed using independent-samples t tests. Exploratory multiple-regression analyses were conducted to create prediction models for intestinal water absorption. The factors influencing water and solute absorption are carefully evaluated and extensively discussed. The authors suggest that in the human proximal small intestine, water absorption is related to both total solute and CHO absorption; osmolality exerts various impacts on water absorption in the different segments; the multiple types of CHO in the ingested CHO-E solutions play a critical role in stimulating CHO, sodium, total solute, and water absorption; CHO concentration is negatively related to water absorption; and exercise may result in greater water absorption than rest. A potential regression model for predicting water absorption is also proposed for future research and practical application. In conclusion, water absorption in the human small intestine is influenced by osmolality, solute absorption, and the anatomical structures of gut segments. Multiple types of CHO in a CHO-E solution facilitate water absorption by stimulating CHO and solute absorption and lowering osmolality in the intestinal lumen.
Roy J. Shephard
Aging leads to a progressive deterioration of lung function, including a decrease of vital capacity, an increase of residual volume, a tendency for the airways to collapse during expiration, enlargement of all components of the respiratory dead space, a poor mixing of inspired gas, poor matching of ventilation with perfusion, a decrease of pulmonary diffusing capacity, and a substantial increase in the work of breathing. Ventilatory demand is increased during most physical tasks, but arterial blood homeostasis is surprisingly well maintained when elderly persons undertake vigorous exercise because peak cardiac output declines in parallel with the loss of ventilatory function. However, dyspnea progressively restricts peak effort as one ages. The exercise specialist cannot restore aged or damaged pulmonary tissue but can attempt to reduce the rate of future functional loss by encouraging smoking cessation, avoiding air pollution, and controlling acute infections. Enhanced fitness, stronger skeletal muscles, and better coordination can reduce ventilatory demand. Resisted breathing exercises may also strengthen the chest muscles and allow a mechanically more efficient pattern of breathing.
Llion A. Roberts, Johnpaul Caia, Lachlan P. James, Tannath J. Scott and Vincent G. Kelly
Purpose: External counterpulsation (ECP) has previously been used to treat cardiac patients via compression of the lower extremities during diastole to increase venous return and coronary perfusion. However, the effects of ECP on exercise performance and markers of recovery in elite athletes are largely unknown. Methods: On 2 separate occasions, 48 h apart, 7 elite National Rugby League players performed an identical 60-min field-based conditioning session followed by a 30-min period of either regular ECP treatment or placebo. Power measures during repeated cycle bouts and countermovement jump height and contraction time derivatives were measured at rest and 5 h postexercise. Saliva samples and venous blood samples were taken at rest, postexercise, and 5 h postexercise to assess stress, inflammation, and muscle damage. Results: After ECP treatment, cycling peak power output (P = .028; 11%) and accumulated peak power (P = .027; 14%) increased compared with the placebo condition. Postexercise plasma interleukin 1 receptor antagonist only increased after ECP (P = .024; 84%), and concentrations of plasma interleukin 1 receptor antagonist tended to be higher (P = .093; 76%) 5 h postexercise. Furthermore, testosterone-to-cortisol ratio was increased above baseline and placebo 5 h postexercise (P = .017–.029; 24–77%). The ratio of postexercise salivary α-amylase to immunoglobulin A decreased after treatment (P = .013; 50%) compared with the placebo control. Conclusions: Exercise performance and hormonal indicators of stress were improved and inflammation markers were reduced following acute ECP.
Ilkka Heinonen, Jukka Kemppainen, Toshihiko Fujimoto, Juhani Knuuti and Kari K. Kalliokoski
-Czernik, 2012 ). Human bone marrow circulation responds to acute exercise ( Heinonen et al., 2013a , 2013b ) and local heat stress ( Heinonen et al., 2011a ), although to a lesser degree than in contracting skeletal muscles ( Heinonen et al., 2007 , 2010a , 2011b , 2015 ). In addition to its perfusion, the