Abstract:
:We present a computer simulation of a two-compartment model of the systemic circulation which demonstrates how this model can be used to understand the mechanism(s) for the maximal exercise cardiac output (Q). The model consists of two parallel vascular channels, the splanchnic channel (all blood draining through the hepatic veins) and the peripheral channel (all other vascular beds). The distinguishing characteristic of each channel is the product of its venous compliance and venous resistance. Model parameters for the human circulation were estimated from similar parameters obtained directly from animal experiments. "Exercise" was achieved by decreasing the compliance of both channels to 40% of their initial value and by redistributing the Q such that the fraction of Q perfusing the splanchnic channel fell from 38 to 5%, while that perfusing the peripheral channel (skeletal muscles) increased from 62 to 95%. These combined changes increased Q from 4.4 to 22.0 l X min-1 and suggest that maximal adjustments of the two-compartment model parameters lead to a prediction of a maximal Q that approaches the maximal Q usually obtained by humans during exercise.
journal_name
Med Sci Sports Exercjournal_title
Medicine and science in sports and exerciseauthors
Green JF,Jackman APsubject
Has Abstractpub_date
1984-06-01 00:00:00pages
299-305issue
3eissn
0195-9131issn
1530-0315journal_volume
16pub_type
杂志文章abstract:PURPOSE:This study aimed to determine whether competitive intermittent exercise in the heat affects recovery, aggravates markers of muscle fiber damage, and delays the recovery of performance and muscle glycogen stores. METHODS:Plasma creatine kinase, serum myoglobin, muscle glycogen, and performance parameters (sprin...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0b013e31827ded04
更新日期:2013-05-01 00:00:00
abstract:PURPOSE:Aerodynamic drag plays an important role in performance for athletes practicing sports that involve high-velocity motions. In giant slalom, the skier is continuously changing his/her body posture, and this affects the energy dissipated in aerodynamic drag. It is therefore important to quantify this energy to un...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0b013e3182443315
更新日期:2012-06-01 00:00:00
abstract::Increased vertical impact loading during running has been associated with a variety of running related injuries including stress fractures, patellofemoral pain, and plantar fasciitis. PURPOSE:The purpose of this study was to examine the acute and long-term effect of a gait retraining program aimed at teaching runners...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000001710
更新日期:2018-12-01 00:00:00
abstract:PURPOSE:The main purpose of the present study was to measure the total oxygen consumed, accumulation of blood metabolites, and performance during alternating intensity exercise before and after a period of creatine (Cr) loading in well-trained humans. METHODS:Fourteen males were randomly assigned to two groups of seve...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1097/00005768-200002000-00018
更新日期:2000-02-01 00:00:00
abstract:PURPOSE:The purpose of this study was to determine the effects of early outpatient exercise on muscle mass, function, and fractional synthetic rate in severely burned children. METHODS:Forty-seven children with ≥40% total body surface area burn performed a 12-wk standard of care rehabilitation (SOC, n = 23) or rehabil...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章,随机对照试验
doi:10.1249/MSS.0000000000000296
更新日期:2014-09-01 00:00:00
abstract:PURPOSE:To quantify the relationship between total training load and running performance during the most important competitions of the season (national cross-country championships, 4.175- and 10.130-km races). METHODS:Eight well-trained, subelite endurance runners (age (mean+/-SD): 23+/-2 yr; VO2max: 70.0+/-7.3 mL.kg....
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章
doi:10.1249/01.mss.0000155393.78744.86
更新日期:2005-03-01 00:00:00
abstract:PURPOSE:Carnosine is a dipeptide composed of β-alanine and L-histidine and is present in skeletal muscle. Chronic oral β-alanine supplementation can induce muscle carnosine loading and is therefore seen as the rate-limiting factor for carnosine synthesis. However, the effect of L-histidine supplementation on carnosine ...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000001213
更新日期:2017-03-01 00:00:00
abstract:PURPOSE:This study examines the usefulness of complementing accelerometry-based physical activity measurement with spatial data from portable global positioning system (GPS) units to determine where physical activity occurs. METHODS:First, using the geographic distribution of data points and Bland-Altman plots, we exa...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/01.mss.0000185297.72328.ce
更新日期:2005-11-01 00:00:00
abstract::The relationships between physical activity, physical fitness, and coronary heart disease risk factors measured in a large community sample were evaluated. Self-reported physical activity using a single question, maximal oxygen consumption estimates derived from the Pawtucket Heart Health Step Test, blood pressure, no...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:
更新日期:1995-03-01 00:00:00
abstract:PURPOSE:To validate the 7-d Physical Activity Recall (PAR) telephone interview version and its activity intensity categories. METHODS:Seventy-four adults (47 women, 27 men), ranging in age (18-67) and activity levels, were interviewed by phone and in-person using the same PAR protocol. Each participant wore a TriTrac-...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/01.MSS.0000064941.43869.4E
更新日期:2003-05-01 00:00:00
abstract:INTRODUCTION/PURPOSE:The goal of this program was to determine the feasibility of a novel noninvasive, highly miniaturized optomechanical earbud sensor for accurately estimating total energy expenditure (TEE) and maximum oxygen consumption (VO2max). The optomechanical sensor module, small enough to fit inside commercia...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000000183
更新日期:2014-01-01 00:00:00
abstract::The effects of a 7% carbohydrate-electrolyte drink (CE) and an artificially sweetened placebo (P) on performance and physiological function were compared during a 40-km run in the heat. Eight highly trained male runners completed two runs on a measured outdoor course. The first 35 km of each run was performed at self-...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章
doi:
更新日期:1992-08-01 00:00:00
abstract:INTRODUCTION:Slow gait predicts many adverse clinical outcomes in old adults, but the mechanisms of how power training can minimize the age-related loss of gait velocity is unclear. We examined the effects of 10 wk of lower extremity power training and detraining on healthy old adults' lower extremity muscle power and ...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000001082
更新日期:2017-01-01 00:00:00
abstract:PURPOSE:The purpose of this investigation was to determine heart rate (HR)/oxygen consumption (VO2) calibration curves for exercising and sedentary women during pregnancy and the postpartum periods. METHODS:Fifty-two women were studied at three time points: 20 wk gestation, 32 wk gestation, and 12 wk postpartum. Subje...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1097/00005768-200205000-00004
更新日期:2002-05-01 00:00:00
abstract::Regression analysis is often used to demonstrate associations among variables believed to be biologically related. Failure to demonstrate a "significant" relationship may be due to two factors: 1) the variables are truly unrelated, or 2) a relationship exists but goes undetected due to inadequate statistical power. In...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:
更新日期:1988-12-01 00:00:00
abstract:PURPOSE:Circulating angiogenic cells (CAC) comprise multiple subpopulations of exercise-inducible peripheral blood mononuclear cells (PBMC) that promote angiogenesis and maintain endothelial integrity. We examined the effect of acute maximal exercise on CD31, CD62E, CD14/CD31, CD34/VEGFR2, CD3/CD31, and CD3 PBMC in you...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000001029
更新日期:2016-12-01 00:00:00
abstract:PURPOSE:It is unclear how muscle strength in tibial rotation and knee abduction change following anterior cruciate ligament (ACL) injury and reconstruction. Such strength changes are likely, considering the oblique orientation of the ACL and the constraint provided by the ACL at various tibial rotation and adduction po...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章
doi:10.1097/00005768-200201000-00002
更新日期:2002-01-01 00:00:00
abstract:PURPOSE:The effect of quantified resistance and high impact exercise training on bone mass as modified by age and oral contraceptive (OCont) use in young women was studied. METHODS:Women were categorized by age (18-23 vs 24-31 yr) and OCont use, and were then randomized into either three sessions of resistance exercis...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1097/00005768-200106000-00004
更新日期:2001-06-01 00:00:00
abstract::The effects of the potent opioid, sufentanil, were studied in 11 athletes. Sufentanil was administered intravenously (up to 0.5 microgram.kg-1 over 10 min) to the subjects while they ran at 14 km.hr-1 on a level treadmill. Prior to, and after, the drug infusion, the treadmill was inclined by 6% for 4 min and CO2 was i...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:
更新日期:1988-12-01 00:00:00
abstract::To determine the effects of anabolic steroids on myocardial structure, VO2max, and body composition, experienced age-matched male weight trainers (M age 26.5 yr) who either used (U) (N = 11) or did not use (NU) (N = 13) anabolic steroids were evaluated. Steroid users were tested while off cycle (U-OFF) for at least 8 ...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:
更新日期:1993-11-01 00:00:00
abstract::This study assessed body density (BD) in an ethnically diverse sample of women (African American, Caucasian, Mexican American and Native American) (N = 139) who were between 20 and 30 or 40 and 50 yr of age and of normal weight for their height. BD was assessed using three methods: hydrostatically determined density (...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1097/00005768-199701000-00013
更新日期:1997-01-01 00:00:00
abstract:PURPOSE:The effects of chronic eccentric-only versus concentric-only exercise on muscle physiology and blood biochemistry were investigated. METHODS:Twenty women performed on an isokinetic dynamometer a concentric (n = 10;mean ± SEM: age = 21.0 ± 0.4 yr, body fat = 22.0% ± 0.9%) or an eccentric (n = 10, age = 20.0 ± 0...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章,随机对照试验
doi:10.1249/MSS.0b013e3181e91d90
更新日期:2011-01-01 00:00:00
abstract:UNLABELLED:High-speed auto racing has been demonstrated to produce accelerated heart rate (HR) during competition. However, it has not been determined whether the increase in HR was due to physical work efforts or a result of emotional stress. PURPOSE:The purpose of this investigation was to examine the physiological ...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1097/00005768-200212000-00033
更新日期:2002-12-01 00:00:00
abstract::To study effort tolerance in elderly women with different physical activity backgrounds, 52 physically active (PA) and 42 sedentary control women (CO) aged 66-85 yr were assigned to perform cycle ergometer exercise to their volitional maximum. Oxygen uptake, respiratory exchange ratio (RER), heart rate, work power, an...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1097/00005768-199801000-00024
更新日期:1998-01-01 00:00:00
abstract:INTRODUCTION:Recent studies suggested that muscle mass and muscle strength may independently or synergistically affect aging-related health outcomes in older adults; however, prospective data on mortality in the general population are sparse. METHODS:We aimed to prospectively examine individual and joint associations ...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0000000000001448
更新日期:2018-03-01 00:00:00
abstract::Although no conclusive evidence exists to suggest that vitamin supplementation improves athletic performance in nutritionally adequate individuals, exercise may increase requirements for certain vitamins in individuals with marginal vitamin stores. This review summarizes results from recent research studies of vitamin...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:
更新日期:1987-10-01 00:00:00
abstract::Twenty subjects were randomly assigned to: 1) prophylactic ibuprofen (N = 5) [400 mg TID initiated 4 h before collection of baseline data and strenuous eccentric exercise bout], 2) therapeutic ibuprofen (N = 5) [400 mg TID initiated 24 h after baseline], 3) placebo (N = 5), or 4) control (N = 5). Muscle soreness perce...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1249/00005768-199301000-00003
更新日期:1993-01-01 00:00:00
abstract:INTRODUCTION:Dementia caregivers have an increased risk of cardiovascular disease, and it is possible that metabolic disturbances contribute to this risk. Regular physical exercise reduces cardiometabolic risk, but caregivers may have less opportunity to engage in such activity. We hypothesized that regular physical ac...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章
doi:10.1249/MSS.0b013e3181e6d478
更新日期:2011-01-01 00:00:00
abstract:PURPOSE:The purpose of the present study was to examine the effect of increased protein intake on short-term decrements in endurance performance during a block of high-intensity training. METHODS:Trained male cyclists (VO(2max) = 64.2 ± 6.5 mL·kg(-1)·min(-1)) completed two 3-wk trials both divided equally into normal ...
journal_title:Medicine and science in sports and exercise
pub_type: 临床试验,杂志文章
doi:10.1249/MSS.0b013e3181f684c9
更新日期:2011-04-01 00:00:00
abstract::Canine skeletal muscle preparations in situ contain varying mixtures of fast and slow fatigue resistant fibers. All vessels on the arterial side of the vascular bed in these preparations from the conduit arteries to the arterioles contribute to the vascular resistance. The vascular beds autoregulate at rest and during...
journal_title:Medicine and science in sports and exercise
pub_type: 杂志文章,评审
doi:10.1249/00005768-198810001-00004
更新日期:1988-10-01 00:00:00