A5002404195- Cardiovascular and exercise physiology
- Heart Rate Variability and Autonomic Control
- Sports Performance and Training
- Cardiovascular Effects of Exercise
- Exercise and Physiological Responses
- Nitric Oxide and Endothelin Effects
- Cardiovascular Function and Risk Factors
- Muscle metabolism and nutrition
- Muscle activation and electromyography studies
- Adipose Tissue and Metabolism
- Chronic Obstructive Pulmonary Disease (COPD) Research
- High Altitude and Hypoxia
- Respiratory Support and Mechanisms
- Pulmonary Hypertension Research and Treatments
- Cardiac Ischemia and Reperfusion
- Thermoregulation and physiological responses
- Mitochondrial Function and Pathology
- Hemodynamic Monitoring and Therapy
- Diet and metabolism studies
- Veterinary Equine Medical Research
- Muscle Physiology and Disorders
- Bayesian Modeling and Causal Inference
- Ion channel regulation and function
- Neuroscience of respiration and sleep
- Sports injuries and prevention
Kansas State University
2016-2025
University of South Wales
2024
Iowa State University
2021
Ames National Laboratory
2021
Australian National University
2021
University of British Columbia
1991-2020
Poole Hospital
2002-2018
The University of Kansas Cancer Center
2017
Cancer Research Center
2017
University of California, San Diego
1988-2016
For high-intensity cycling, power (P) can be well described as a hyperbolic function of tolerable work duration (t): P=(W'/t) + P LL W' is constant and the lower limit (asymptote) for which shown to occur at an O2 uptake ([Vdot]O2) lying above estimated threshold sustained blood [lactate] increase (ΘIac) but below maximum [Vdot]O2 ([Vdot]O2max) obtained during incremental cycling. This relation suggests that, LL, only certain amount (W') accomplished regardless its rate performance, with max...
Muscle O2 uptake (VO2) kinetics in response to an augmented energetic requirement (on-transition) has never been directly determined humans. We have developed a constant-infusion thermodilution technique that allowed rapid measurements of leg blood flow (Qleg) and, conjunction with frequent serial measurement arteriovenous content difference across the [(Ca - Cv)O2leg], permitted determination VO2 (VO2leg) at 3- 4-s time intervals. VO2leg during on-transition was taken as close approximation...
We tested the hypothesis that asymptote of hyperbolic relationship between work rate and time to exhaustion during muscular exercise, "critical power" (CP), represents highest constant can be sustained without a progressive loss homeostasis [as assessed using (31)P magnetic resonance spectroscopy (MRS) measurements muscle metabolites]. Six healthy male subjects initially completed single-leg knee-extension exercise at three four different rates limit tolerance (range 3-18 min) for estimation...
Dietary nitrate (NO(3)(-)) supplementation, via its reduction to nitrite (NO(2)(-)) and subsequent conversion nitric oxide (NO) other reactive nitrogen intermediates, reduces blood pressure the O(2) cost of submaximal exercise in humans. Despite these observations, effects dietary NO(3)(-) supplementation on skeletal muscle vascular control during locomotory remain unknown. We tested hypotheses that beetroot juice (BR) would reduce mean arterial (MAP) increase hindlimb flow exercising rat....
Background— Inorganic nitrate (NO 3 − ), abundant in certain vegetables, is converted to nitrite by bacteria the oral cavity. Nitrite can be nitric oxide setting of hypoxia. We tested hypothesis that NO supplementation improves exercise capacity heart failure with preserved ejection fraction via specific adaptations exercise. Methods and Results— Seventeen subjects participated this randomized, double-blind, crossover study comparing a single dose -rich beetroot juice , 12.9 mmol) an...
Abstract The anaerobic threshold (AT) remains a widely recognized, and contentious, concept in exercise physiology medicine. As conceived by Karlman Wasserman, the AT coalesced increase of blood lactate concentration ([La − ]), during progressive test, with an excess pulmonary carbon dioxide output ( ). Its principal tenets were: limiting oxygen (O 2 ) delivery to exercising muscle→increased glycolysis, La H + production→decreased muscle pH→with increased buffered [HCO 3 ]→increased CO...
During conventional cycle ergometry, as work rate (WR) is increased toward maximum, O2 extraction increases hyperbolically, typically achieving values of 80–90% at peak uptake (VO2). In contrast, studies using isolated knee-extensor exercise report much higher mass-specific blood flows (Q) and lower maximal extractions (approximately 70%), which have been interpreted transit time limitation to movement out the muscle capillary. However, achievable WR levels during ergometry are generally...
To quantify the relative contributions of convective and peripheral diffusive components O2 transport to increase in leg uptake (VO2leg) at maximum (VO2max) after 9 wk endurance training, 12 sedentary subjects (age 21.8 +/- 3.4 yr, VO2max 36.9 5.9 ml.min-1.kg-1) were studied. VO2max, blood flow (Qleg), arterial femoral venous PO2, thus VO2leg, measured while breathed room air, 15% O2, 12% O2. The sequence three inspirates was balanced. After VO2leg increased each inspired concentration...
We studied O2 transport in the leg to determine if hyperoxia will increase maximal rate of uptake (VO2max) exercising muscle. An inspired fraction (FIO2) from 0.21 1.00 was postulated have following effects: 1) VO2max by approximately 5–10%, 2) delivery [arterial concentration.flow (CaO2.Q] 10%, and 3) raise proportion both femoral venous PO2 mean capillary PO2. To test these hypotheses, 11 men performed cycle exercise highest work rates (WRmax) they could achieve while breathing 100%...
In response to an elevated metabolic rate ((.-)V(O(2)), increased microvascular blood-muscle O(2) flux is the product of both augmented delivery ((.-)Q(O(2)), and fractional extraction. Whole body exercising limb measurements demonstrate that (.-)Q(O(2) extraction increase as linear hyperbolic functions, respectively, (.-)V(O(2). Given presence disparate vascular control mechanisms among different muscle fibre types, we tested hypothesis that, in contractions, would be lower (as assessed via...
The severe exercise intensity domain may be defined as that range of work rates over which .VO(2max) can elicited during constant-load exercise. purpose this study was to help characterize the .VO(2) response within domain.Eleven participants performed cycle ergometer tests fatigue at several discrete between 95% and 135% maximum power (P(max)) achieved an incremental test.As previously demonstrated, relationship time hyperbolic. asymptote (critical power, P(critical)) 198 +/- 44 W. rapidity...
Muscle contractions evoke an immediate rise in blood flow. Distribution of this hyperemia within the capillary bed may be deterministic for muscle O 2 diffusing capacity and remains unresolved. We developed exteriorized rat ( n = 4) spinotrapezius evaluation hemodynamics before (rest), during, immediately after (post) a bout twitch to resolve (second-by-second) alterations red cell velocity V RBC ) flux f ). Contractions increased (all P < 0.05) (rest: 270 ± 62 μm/s; post: 428 47 μm/s),...
Insights into muscle energetics during exercise (e.g., muscular efficiency) are often inferred from measurements of pulmonary gas exchange. This procedure presupposes that changes O2 (VO2) associated with increases external work reflect accurately the increased VO2. The present investigation addressed this issue directly by making simultaneous determinations and leg VO2 over a range rates calculated to elicit 20–90% maximum on basis prior incremental (25 or 30 W/min) cycle ergometry. for...