4 Clinical Trials for Various Conditions
Purpose: To determine the acute effects of a mushroom blend vs. placebo on oxygen kinetics, aerobic power and time to fatigue in healthy adults.
This study aims to compare the rate at which oxygen uptake adapts to submaximal, moderate intensity exercise (oxygen uptake kinetics) between adults with and without Down syndrome, to determine the contribution of oxygen uptake kinetics to exercise intolerance of adults with Down syndrome. Additionally, the study will investigate the role of oxygen delivery (by the cardiovascular circuit) and oxygen utilization (in the mitochondria) on the oxygen uptake kinetics of adults with Down syndrome to identify specific areas which adults with Down syndrome could benefit from targeting during exercise training. Overall, this study aims to contribute to the knowledge on the exercise capacity of adults with Down syndrome, in order to improve the way adults with Down syndrome participate in and benefit from exercise. Participants will perform a maximal exercise test on a treadmill, and walk on a treadmill at a submaximal, moderate intensity speed and incline, during which oxygen uptake at the lungs, cardiac output, and oxygen utilization in the muscle will be measured.
Measurements of dynamic changes in oxygen uptake (VO2 kinetics) during recovery from exercise may describe regulatory control of oxygen transport and utilization and have greater reliability and less inherent risk than assessment of maximal oxygen uptake (VO2max) in patients for whom exercise is limited by pain, excessive fatigue, dyspnea and motivation. The purpose of this pilot study is to evaluate the effect of exercise intensity on the time constant describing changes in VO2 (tauVO2) during recovery from one minute of constant work rate exercise. Five normal healthy volunteers ages 18 and older will perform a progressive maximal aerobic exercise test, using a cycle ergometer, to determine VO2max and lactate threshold (LT) estimated by gas exchange. Each subject will also complete a series of maximal constant work rate tests and submaximal constant work rate tests at 80% LT and 50% of the difference between LT and VO2max (50% delta). Breath by breath variability and VO2 span will be used to determine the number of constant work rate test repetitions, for each subject for each exercise intensity, needed to establish confidence in tauVO2. A mean response profile of VO2 recovery kinetics for each exercise intensity will be analyzed using non-linear regression to determine tauVO2. To examine the effect of exercise intensity on tauVO2, one way analysis of variance will be used to determine whether differences exist among maximal and submaximal (80% LT and 50% delta) time constants. We hypothesize that there will be no significant differences among time constants for VO2 during recovery from maximal and submaximal constant work rate exercise lasting one minute. The results of this study are expected to provide increased understanding of the measurement of VO2 kinetics during recovery.
During clinical anesthesia, it is astonishing that CO2 monitoring consists mainly of end-tidal PCO2 to confirm endotracheal intubation and to estimate ventilation, and O2 monitoring consists of a single PO2 measurement to detect a hypoxic gas mixture. Better understanding of how O2 and CO2 kinetics monitoring can define systems pathophysiology will greatly enhance safety in anesthesia by detecting critical events such as abrupt decrease in cardiac output (Q.T) by vena-caval compression during abdominal surgery, occurrence of CO2 pulmonary embolism during laparoscopy, rising tissue O2 consumption (V.O2) during light anesthesia, and onset of anaerobic metabolism (V.CO2 is disproportionately higher than V.O2).