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Biomedical subjects

C Foster

Publications and source records attributed to C Foster.

At least 55 records · Page 3Linked to original sources
PubMed1983

Time course of lung volume changes during prolonged treadmill exercise.

It has been known since the 1920s that runners completing marathon races have reduced forced vital capacity (FVC) values. To investigate the time course of these lung volume alterations, we measured FVC and residual volume (RV) in 11 runners before, after, and at 30-min intervals during a 2.5-h treadmill run at just under their marathon pace (70% VO2max). Mean distance run was 21.5 +/- 1.5 (SD) miles in the 2.5-h period. During the first 60 min, both RV and total lung capacity (TLC) decreased by 110 ml, however, this change was not significant (P greater than 0.05). A high correlation (r = 0.93) was observed between delta RV and delta TLC during the first 5 min, while FVC remained unchanged. From 60-90 min, all lung volumes remained constant. From 90-150 min, lung volumes changed in a direction similar to that observed after a marathon, i.e., FVC decreased significantly (5.51 to 5.37 liter between 90 and 150 min, P less than 0.05), TLC remained unchanged (7.41 vs 7.42 liter, P greater than 0.05), and RV showed a nonsignificant increase from 1.90 to 2.05 liter (P greater than 0.05). The data are consistent with multiple mechanisms playing a role in pulmonary function changes during prolonged exercise. The smaller mean decrease in FVC observed in this study, as compared to that found during a marathon, suggested that the marathon imposes a greater demand on the lungs than did treadmill exercise of the duration and relative intensity used in this study.

Adult↗
PubMed1982

Comparative analysis of physiologic responses to three different maximal graded exercise test protocols in healthy women.

The purpose of this study was to compare the three most commonly used maximal graded exercise test (GXT) protocols in healthy women. Submaximal and maximal metabolic and hemodynamic responses were determined from two treadmill protocols, Bruce and Balke, and a bicycle protocol, in 49 women. Maximum oxygen uptake (VO2 max) was significantly different among protocols (Bruce=40.3, Balke=38.4, and Bike=36.6 ml/kg . min -1). Maximum heart rate (HR max) was significantly lower during Bike (178 beats/min) than during Bruce (182) and Balke (183) protocols. No differences in rate of increase in HR or systolic blood pressure (BP) per increase in multiples of the rest metabolic (METs) were found between Bruce and Balke protocols. The rate of recovery of HR and systolic BP was not different among tests. Comparisons of active and sedentary groups showed differences in VO2 max and submaximal HR and recovery HR at common minutes; however, the rate of increase in HR and systolic BP during exercise and the rate of decrease during recovery were not significantly different. Prediction of VO2 max with Bruce and Balke protocols from treadmill time was r=0.91 (SEE +/- 2.7 ml/kg . min -1) and r=0.94 (SEE 2.2 ml/kg . min -1), respectively. These data suggest a difference between men and women in increased HR and systolic BP per METs increase in exertion.

Adipose Tissue↗
PubMed1982

Effect of habitual exercise on left ventricular response to exercise.

To evaluate the effects of chronic physical exercise on left ventricular ejection fraction (LVEF) and ejection rate (LVER), radionuclide angiography was performed at rest and during upright-bicycle exercise in 45 healthy men. The subjects varied widely in exercise habits and working capacity. They were divided into three subgroups on the basis of habitual physical activity. Aerobic training was done more than 7, 2-4, and less than 1 h/wk by subgroups of athletes, trained, and untrained men, respectively. The results indicate marked differences in work capacity (298, 233, and 181 W in the athletes, trained, and untrained groups, respectively). Resting LVEF (72, 69, and 68%) and LVER (4.1, 3.4, and 3.6 s-1) were not significantly different among the groups. With maximal exercise, however, small but statistically significant differences in LVEF (75, 69, and 68%; P less than 0.05 athletes vs. trained and athletes vs. untrained) and in LVER (7.5, 6.3, and 5.2 s-1; P less than 0.05 among all groups) were observed. Work capacity was, however, poorly correlated with exercise LVEF (r = 0.18) and LVER (r = 0.47). The results of this study indicate that the enhanced working capacity observed secondary to increases in habitual physical activity can be attributed to differences in LVEF and LVER only in the most general terms. Accordingly the results agree with previous suggestions based primarily on echocardiographic data that the primary cardiac adaptation to exercise is dimensional rather than functional in character.

Adult↗
PubMed1982

Effect of warm-up on left ventricular response to sudden strenuous exercise.

Sudden strenuous exercise (SSE) has been shown to produce ischemic electrocardiographic (ECG) responses, abnormalities of myocardial blood flow, and decreases in left ventricular ejection fraction. Prior exercise taken as warm-up has been shown to ameliorate the ECG and myocardial blood flow abnormalities induced by SSE. The purpose of this study was to determine whether warm-up would normalize the responses of the left ventricular ejection fraction to SSE. Twenty healthy male volunteers performed SSE (400-W bicycle exercise) either with (group A, n = 10) or without (group B, n = 10) warm-up. Ejection fraction was measured using first-pass radionuclide angiography under control conditions and during SSE. During SSE ejection fraction decreased from control values in both group A (70.5 +/- 6.3 to 64.8 +/- 8.2%) and group B (70.3 +/- 10.1 to 57.7 +/- 7.7%), although ejection fraction was significantly higher during SSE in group A. The results are consistent with the hypothesis that the abnormal responses to SSE are attributable to subendocardial ischemia secondary to a delay in autoregulation of myocardial blood flow. However, the decrease in ejection fraction during SSE even following warm-up suggests that the mechanism for the abnormal response to SSE is more complicated than previously hypothesized.

Cardiac Output↗
PubMed1982

Left ventricular function at rest, peak exercise and postexercise.

To determine whether the temporal sequence of imaging could influence the results of exercise radionuclide angiography, 15 healthy volunteers were studied at rest, during peak bicycle exercise and immediately postexercise using first pass radionuclide angiography. Responses at rest, peak and postexercise included: heart rate (67 to 174 to 170 bpm), double product (7.4 to 31.5 to 27.5 mm Hg X bpm X 10(3)), left ventricular ejection fraction (68 to 69 to 80%) and mean normalized left ventricular ejection rate (3.63 to 6.56 to 8.56 s-1). The results indicate that left ventricular ejection fraction and mean normalized ejection rate were different during exercise and immediately postexercise although heart rate and double product were not. The results indicate that the temporal sequence of imaging is a significant procedural variable in the conduct of exercise radionuclide angiography.

Adult↗
PubMed1982

Diagnostic capabilities of exercise testing soon after myocardial revascularization surgery.

The purpose of this investigation was to compare data on early exercise testing for variables known to be of diagnostic/prognostic value following myocardial infarction in post-myocardial revascularization surgery patients. 70 patients were evaluated soon after surgery, by cardiac catheterization, moderate-intensity treadmill exercise testing, and rest and exercise radionuclide angiography. The results indicated no significant differences among groups with satisfactory and unsatisfactory results by catheterization compared for METs, peak heart rate, double product, ST-segment change, angina pectoris, and dysrhythmias. Significant differences were found among groups when rest and exercise ejection fraction and exercise-induced regional wall motion abnormality were taken into account. It was concluded that the moderate-intensity treadmill exercise test was ineffective in differentiating current cardiac function and arterial/graft status among postmyocardial revascularization surgery patients. Exercise radionuclide angiographic studies were able to identify groups of patients with adequate or inadequate postoperative cardiac catheterization results.

Cardiac Catheterization↗
PubMed1982

Effects of propranolol on perceived exertion soon after myocardial revascularization surgery.

Effect of propranolol on perceived exertion soon after myocardial revascularization surgery. Med. Sci. Sports Exercise. Vol. 14, No. 4, pp. 276-280, 1982. This study evaluated the effects of propranolol on ratings of perceived exertion (RPE), heart rate (HR), and systolic blood pressure (SBP) during graded exercise testing of myocardial revascularization surgery patients before hospital discharge. Eighty-six men performed a symptom-limited, graded exercise test on a treadmill an average of 11 d after surgery. Patients were assigned to three groups: those not taking propranolol (no-propranolol group, N = 54), those taking propranolol (propranolol group, N = 22), and those exhibiting exertional hypotension during testing (hypotensive group, N = 10). Test results showed that estimated METs during peak exercise were similar for the three groups. The propranolol group demonstrated a lower HR for submaximal and peak exercise when compared with the no-propranolol group, but RPE was the same for matched exercise intensities. The hypotensive group failed to increase SBP during exercise, but perceived the matched exercise intensities to be the same as the other two groups. The HR response of the hypotensive group was similar to that of the no-propranolol group. Thus, an abnormal SBP response during exercise was not reflected in a changed RPE when compared with patients who increased SBP appropriately. It was concluded that propranolol does not affect RPE during graded exercise testing soon after cardiac surgery.

Adult↗
PubMed1981

Fifty years of training and competition in the marathon: Wally Hayward, age 70--a physiological profile.

A 70-year-old South African long-distance runner, holder of his age group's marathon record and former Olympic marathon runner, was studied to determine the effects of 52 years of regular training on functional capacity and health. Maximal treadmill exercise testing revealed no ischaemic ECG abnormalities and an excellent functional capacity (58,6 ml/kg/min). Submaximal testing showed that the subject ran at approximately 86% of maximum aerobic capacity when completing the marathon in his record time. The subject was very lean (13,6% fat) for his age. Muscles contained 82% slow-twitch fibres. Pulmonary function and blood chemical values were within normal limits. Although total cholesterol was somewhat high (247 mg/dl), high-density lipoprotein cholesterol was elevated (53 mg/dl). Twenty-four-hour Holter monitoring revealed no significant ventricular ectopic activity although frequent premature atrial contractions were noted. M-mode echocardiography revealed a normal heart with moderately hypertrophied left ventricular wall thickness. Radionuclide cine angiography showed a normal ejection fraction at rest (69%), followed by a slight drop at maximal exercise (62%). Left ventricular regional wall motion was considered normal at both rest and exercise. He had no significant orthopaedic abnormalities but showed normal flexibility and well-balanced muscular strength. Thickened heel pads were also noted. These results appear to indicate a beneficial effect of habitual physical activity upon the retention of functional capacity with ageing.

Aged↗
PubMed1981

Left ventricular function during sudden strenuous exercise.

Strenuous exercise without warm-up has been shown to produce ischemia-like electrocardiographic (ECG) abnormalities in 60-70% of healthy subjects. These abnormalities appeared to be related to the development of an unfavorable myocardial supply/demand balance and, in chronically instrumented dogs, to transient decreases in coronary blood flow. A mechanism involving subendocardial ischemia has been proposed to explain the response to sudden strenuous exercise (SSE). To determine whether the response to SSE included the development of changes in myocardial pump performance typical of ischemia, left ventricular (LV) function at rest, during graded exercise and during SSE was evaluated in nine young (26.6 +/- 3.4 years), well-trained male volunteers using first-pass radionuclide angiography. During graded exercise, the LV ejection fraction increased from 66.9 +/- 9.4% at rest to 73.0 +/- 7.1% during peak exercise, and the LV ejection rate increased from 3.36 +/- 0.67 sec-1 at rest to 6.58 +/- 1.10 sec-1 during peak exercise. Segmental wall motion was normal in all studies. During SSE, the LV ejection fraction decreased in very subject, from an average 72.2 +/- 8.6% at rst to 57.3 +/- 8.1% during exercise. The LV ejection rate remained relatively constant (3.98 +/- 0.92 sec-1 at rest vs 4.33 +/- 0.74 sec-1 during SSE). No segmental wall motion abnormalities were observed during SSE; however, LV wall motion appeared to be diffusely hypokinetic during SSE. In contrast to previous reports, few ECG abnormalities were observed during SSE. These results support the hypothesis that subendocardial ischemia is an important mechanism in the response to SSE. However, the lack of ECG changes and segmental wall motion abnormalities and the relatively high absolute value of the LV ejection fraction suggest that if subendocardial ischemia occurs during SSE, it is attributable to physiologic rather than pathologic mechanisms.

Adult↗
PubMed1980

Limb blood flow. The influence of temperature during halothane-nitrous oxide anesthesia.

Twenty adult patients were examined before anesthesia, during anesthesia, and at the end of surgery to determine the influence of body cooling on limb blood flow during prolonged halothane-nitrous oxide anesthesia. Measurements included temperature, mean arterial pressure, and leg blood flow. Cooling was prevented in ten patients by warmed anesthetic gases. The mean tympanic temperature at end of surgery was 37 degrees C for the warmed (W) and 35 degrees C for the unwarmed (UW) patients, a significant difference. The mean value for leg blood flow was significantly decreased in the UW patients (W = 5.0 vs UW = 3.1 mL/100 cc of tissue/min). These results indicate that body cooling during prolonged inhalation anesthesia was associated with a reduced limb blood flow. Therefore, pulmonary warming may be of potential benefit under similar conditions to help prevent intraoperative vascular complications.

Abdomen↗
PubMed1980

Particulate cancellous marrow crib graft reconstruction of mandibular defects.

Between 1969 and 1978 more than 1000 mandible fractures were treated by the otolaryngology services at the University of Minnesota and affiliated hospitals. Most were successfully treated but 17 patients had significant loss of mandibular bone resulting in a much more difficult management problem. The loss of bone was usually due either to the initial injury such as a gunshot wound or was secondary to the complications of non-union or osteomyelitis. Particulate cancellous marrow grafts within a Vitallium or titanium mesh crib (PCM crib graft) were used to reconstruct the mandibular defects. One patient had bilateral defects requiring 2 PCM crib grafts. Thus, 18 grafts spanning defects 2 to 12 cm were performed. Success was measured by a stable mandible with satisfactory occlusion and he ability to chew, swallow and articulate satisfactorally. Of 18 grafts, 15 met these requirements. Several factors important to successful mandibular reconstruction included adequate immobilization, intraoral soft tissue coverage, external skin cover and tension-free closure and optimal intraoral hygiene. The crib used to hold the particulate cancellous marrow in position during the healing phase has been removed in three otherwise successful cases because of intraoral mucosal tenting or dehiscence or to allow adequate fitting of dentures. In our experience, the use of autogenous cancellous bone and marrow in metallic mesh has been a successful means of restoring function and stability to mandibular defects.

Adolescent↗