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Biomedical subjects

C Foster

Publications and source records attributed to C Foster.

At least 91 records · Page 5Linked to original sources
PubMed1988

Normalization of the blood lactate profile in athletes.

The power output-blood lactate or velocity-blood lactate relationship, the lactate "profile", is a widely used method for the evaluation of athletes. Recent observations have suggested a shift in the blood lactate profile when athletes are fatigued, as at training camps. This study was designed to determine whether the blood lactate profile could be corrected for progressive muscle glycogen depletion by normalizing for the peak exercise blood lactate concentration. Ten well-trained subjects performed incremental cycle ergometer exercise followed by supramaximal exercise (Wingate test) following 3 days of usual and 3 days of heavier than usual training. Following heavier than usual training, blood lactate accumulation was reduced during submaximal exercise such that the power output associated with a lactate concentration of 4 mM was significantly increased (3.08 vs 3.51 W/kg). The maximal blood lactate concentration was also reduced (14.8 vs 12.7 mM) although average supramaximal power output was unchanged (9.03 vs 8.92 W/kg). When the submaximal blood lactate concentrations were normalized for the maximal blood lactate concentration, there were no significant differences in the power output associated with 20% (2.6 vs 2.7 W/kg), 25% (3.1 vs 3.2 W/kg), or 30% (3.3 vs 3.5 W/kg) of maximal lactate. The results suggest that normalization based on peak exercise blood lactate may be a useful strategy for circumventing one of the primary practical barriers to the use of the blood lactate profile in athletes.

Adult↗
PubMed1988

Potential for strength and endurance training to amplify endurance performance.

The impact of adding heavy-resistance training to increase leg-muscle strength was studied in eight cycling- and running-trained subjects who were already at a steady-state level of performance. Strength training was performed 3 days/wk for 10 wk, whereas endurance training remained constant during this phase. After 10 wk, leg strength was increased by an average of 30%, but thigh girth and biopsied vastus lateralis muscle fiber areas (fast and slow twitch) and citrate synthase activities were unchanged. Maximal O2 uptake (VO2max) was also unchanged by heavy-resistance training during cycling (55 ml.kg-1.min-1) and treadmill running (60 ml.kg-1.min-1); however, short-term endurance (4-8 min) was increased by 11 and 13% (P less than 0.05) during cycling and running, respectively. Long-term cycling to exhaustion at 80% VO2max increased from 71 to 85 min (P less than 0.05) after the addition of strength training, whereas long-term running (10 km times) results were inconclusive. These data do not demonstrate any negative performance effects of adding heavy-resistance training to ongoing endurance-training regimens. They indicate that certain types of endurance performance, particularly those requiring fast-twitch fiber recruitment, can be improved by strength-training supplementation.

Adenosine Triphosphate↗
PubMed1987

Effect of age and training on aerobic capacity and body composition of master athletes.

Maximum oxygen uptake (VO2max) and body composition have been shown to deteriorate with age. How much of the decline is attributable to aging and how much is affected by reduced physical activity is not known. The purpose of this investigation was to determine the aerobic capacity and body composition of 24 master track athletes and to evaluate the relationship to age and maintenance of training over a 10-yr period. The subjects (50-82 yr of age) were retested after a 10.1-yr follow-up (T2). All continued their aerobic training, but only 11 were still highly competitive (COMP) and continued to train at the same intensity. The other 13 athletes studied became noncompetitive (post-COMP) and reduced their training intensity. The results showed the COMP group to maintain its VO2max and maximum O2 pulse while the post-COMP group showed a significant decline (54.2-53.3 vs. 52.5-45.9 ml X kg-1 X min-1; 20.7-20.8 vs. 22.4-20.0 ml/beat from test one (T1) to T2 for the COMP vs. post-COMP groups, respectively). Maximum heart rate declined 7 beats/min for both groups. Body composition showed no difference between groups from T1 to T2. For both groups body weight declined slightly (70.0-68.9 kg), percent fat increased significantly (13.1-15.1%), and fat-free weight decreased significantly (61.0-59.0 kg). Thus, when training was maintained, aerobic capacity remained unchanged over the follow-up period. Body composition changed for both groups and may have been related to aging and/or the type of training performed.

Aged↗
PubMed1986

Functional translation of exercise responses from graded exercise testing to exercise training.

This study attempts to develop a quantitative approach to the prescription of absolute exercise intensity during level ground ambulation (min/mile) or cycle ergometry (kpm) from responses observed during GXT. A total of 345 subjects performed GXT and exercise training sessions with either the Bruce treadmill protocol and level ground ambulation (N = 154) or cycle ergometry (N = 191). Responses from 90% of each group were used to generate equations for predicting training pace (or power output) from the time (or power output) during the GXT when target HR was achieved. FAI was also included in the prediction of training pace (or power output). The remaining 10% of subjects in each group were used to cross-validate the prediction equations. The correlation between the time (or power output) during GXT when the training HR was observed and the pace of ambulation (or power output) was 0.70 for treadmill walking and 0.88 for cycle-cycle. Correlations were increased by the addition of FAI to the prediction equation. The results of this investigation suggest that the absolute intensity of exercise for training can be predicted accurately from GXT results.

Cardiac Rehabilitation↗
PubMed1986

Tryptic digestion of myosin light chain kinase produces an inactive fragment that is activated on continued digestion.

Trypsin digestion of chicken gizzard myosin light chain kinase at limiting trypsin concentrations proceeds in stages. In the first stage, catalytic activity in the presence or absence of calcium and calmodulin decreases. In the second stage, activity in the absence of calcium increases, and the calcium-calmodulin complex no longer stimulates activity. The initial loss of activity is associated with the appearance of a 59,000-Da peptide that has been isolated and shown to have low catalytic activity. This peptide was further digested to a 55,000-Da peptide that has calcium-independent catalytic activity. This peptide has been isolated, and its affinities for the peptide substrate Kemptamide (Lys-Lys-Arg-Pro-Gln-Arg-Ala-Thr-Ser-Asn-Val-Phe-Ser-NH2) and ATP have been shown to be the same as those of the intact enzyme. Neither the 59,000-Da nor the 55,000-Da fragment binds calmodulin.

Calcium↗
PubMed1986

The NIH experience with precocious puberty: diagnostic subgroups and response to short-term luteinizing hormone releasing hormone analogue therapy.

Between 1979 and 1983, 129 children (95 girls) with precocious puberty were referred to the National Institutes of Health and received treatment for at least 6 months with the long-acting LHRH analogue D-Trp6-Pro9-NEt-LHRH. The majority (107 of 129) of the children had central precocious puberty mediated by activation of the hypothalamic-pituitary-gonadal axis in association with hypothalamic hamartomas (24 of 107) or other central nervous system lesions (21 of 107), or idiopathic precocious puberty (62 of 107). Hypothalamic hamartomas or other central nervous system lesions were a frequent cause of central precocious puberty in girls (27 of 87), but idiopathic precocious puberty was still the most frequent diagnosis (63%). Idiopathic precocious puberty was uncommon in boys (6%). The patients with peripheral precocious puberty included six girls with McCune-Albright syndrome and six boys with familial male precocious puberty. These children had peripheral sex steroid secretion in the absence of hypothalamic-pituitary-gonadal axis maturation. The children with combined peripheral and central precocious puberty included nine children with congenital adrenal hyperplasia and one girl with a virilizing adrenal tumor. In the patients with central precocious puberty or combined peripheral and central precocious puberty, LHRHa therapy caused suppression of gonadotropin and sex steroid levels (P less than 0.001), stabilization or regression of secondary sexual characteristics, and decreases in growth rate and in the rate of bone age maturation (P less than 0.005). Patients with peripheral precocious puberty, however, had no significant change in gonadotropin or sex steroid levels, growth rate, or the rate of bone age maturation, and no improvement in secondary sexual characteristics. Thus, LHRHa is an effective treatment of central precocious puberty and combined peripheral and central precocious puberty, but is ineffective in the therapy of peripheral precocious puberty.

Adrenal Hyperplasia, Congenital↗
PubMed1986

Exercise training following cardiovascular surgery.

The patient following cardiovascular surgery is a special, and probably somewhat easier, problem for the rehabilitation team than post-MI or angina patients. These patients may generally be viewed as somewhat more stable than post-MI patients. Rehabilitation thus focuses on minimization of bed rest, treatment of the sequale of sternotomy, and surveillance for new or changing medical problems. Physiological adaptations to training are likely to parallel those observed with post-MI patients, except that evidence of improved myocardial perfusion is less likely to be observed. Although GXT may be useful to evaluate progress in rehabilitation, it is unlikely to yield meaningful information regarding the adequacy of the surgical result. The possibility for exercise programs/risk factor modification as a vehicle for secondary prevention following CABGS is about as likely, and as well supported by the available literature, as it is following MI. Secondary prevention studies following other types of cardiovascular surgery are not available.

Angioplasty, Balloon↗
PubMed1986

Central circulatory adaptations to exercise training in health and disease.

Cross-sectional and longitudinal studies are reviewed that address the effects of training on several measures of central circulatory function, including gas exchange, cardiac output, left ventricular structure, and left ventricular function. Responses to training in healthy individuals, athletes, and patients with ischemic cardiovascular disease are compared.

Adult↗
PubMed1985

Reduced training intensities and loss of aerobic power, endurance, and cardiac growth.

Twelve subjects participated in an exercise program of cycling and running 40 min/day, 6 days/wk. After 10 wk, they continued to train with either a one-third or two-thirds reduction in work rates for an additional 15 wk. Frequency and duration for the additional training remained the same as during the 10 wk of training. The average increases in maximum O2 uptake (VO2 max) were between 11 and 20% when measured during cycling and treadmill running after 10 wk of training. VO2 max was not maintained at the 6-day/wk training levels with a one-third reduction in training intensity but was still higher than pretraining levels. With a two-thirds reduction in intensity, VO2 max declined to an even greater extent than with the one-third reduction. Short-term endurance (approximately 5 min) was maintained in the one-third reduced group but was markedly reduced in the two-thirds reduced group. Long-term endurance was decreased significantly from training by 21% in the one-third reduced group (184-145 min) and by 30% in the two-thirds reduced group (202-141 min). Calculated left ventricular mass, obtained from echocardiographic measurements, increased approximately 15% after training but returned to control levels after reduced training in both groups. These results demonstrate that training intensity is an essential requirement for maintaining the increased aerobic power and cardiac enlargement with reduced training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1985

Screening for developmental disabilities.

Developmental disabilities are responsible for a combination of severe physical, mental, psychological and social deficits. They develop before age 22 years and involve a little more than 1% of the population. Screening for developmental disabilities is the first step in their prevention. Various screening instruments are available for use throughout the developmental years that are designed to detect the wide variety of developmental problems that interfere with a developing person's optimal adaptation to his or her environment. The screening instruments must be inexpensive, reproducible, widely available and cost effective to the child, family and society.

Adult↗
PubMed1984

Peak exercise and immediate postexercise imaging for the detection of left ventricular functional abnormalities in coronary artery disease.

Eleven patients without significant coronary artery disease (CAD) (group A), 22 patients with significant CAD and no prior myocardial infarction (MI) (group B), and 10 patients with CAD and a previous MI (group C) were imaged at rest, at peak exercise and immediately after exercise by first-pass radionuclide angiography. At peak exercise, mean left ventricular (LV) ejection fraction (EF) did not change significantly in group A or C and decreased significantly in group B. However, in all groups mean LVEF increased significantly immediately after exercise. Examination of potential criteria for an abnormal LVEF response showed that changes from rest to peak exercise were sensitive for detection of CAD but were not specific. Postexercise criteria were more specific but relatively insensitive: 15 of 32 patients (47%) with CAD showed a normal (greater than 5% increase over rest) response after exercise. Similarly, a regional abnormality at peak exercise was 100% sensitive, compared with a sensitivity of 78% after exercise for the whole group, and only 68% in patients without prior MI. Seven patients would have been misclassified as normal if postexercise imaging alone had been performed. The likelihood of an abnormal postexercise EF response was related to the extent of CAD: No patient with 1-vessel, 8 of 17 with 2-vessel and 9 of 12 with 3-vessel CAD showed such a response. Peak exercise imaging is necessary to achieve maximal sensitivity for the detection of CAD, and a high false-negative rate will be obtained if postexercise imaging only is used. The combination of peak exercise and postexercise imaging may be of value in assessing the severity of CAD.

Adult↗
PubMed1984

Work capacity and left ventricular function during rehabilitation after myocardial revascularization surgery.

A prospective randomized trial was conducted to evaluate the effects of exercise-based cardiac rehabilitation after myocardial revascularization surgery (MRS) on work capacity (measured in mets) and left ventricular function as determined from ejection fraction (LVEF). Twenty-eight patients undergoing MRS were randomly assigned to experimental (aerobic exercise, n = 19) or control (muscle relaxation and low-level exercise, n = 9) groups. Patients were studied before surgery (T1) and 2 (T2), 8 (T3), and 24 (T4) weeks after surgery with first-pass radionuclide angiography both while they were at rest and during maximal upright cycle ergometric exercise. Subsets of patients were also studied at T2, T3, and T4 at a standard workload of 75 W, and during maximal exercise 1 year after surgery (T5). Work capacity improved in both groups although significantly more so in the experimental group (3.9, 3.8, 6.0, and 7.3 mets and 3.7, 3.7, 4.9, and 5.7 mets at T1, T2, T3, and T4 in the experimental and control groups, respectively). The differences between groups were significant by T3. Peak exercise LVEF increased significantly in both groups from T1 to T2 then decreased at T3 and remained unchanged through T5. Peak exercise LVEF at T3 to T5 remained significantly above that observed at T1. LVEF responses were not related to the exercise program. During a standard workload, heart rate decreased, blood pressure increased, and LVEF did not change in either group. After conclusion of the formal protocol (T4), work capacity and LVEF did not change for either group throughout an additional 6 months (T5).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗
PubMed1984

The use of immunohistochemical probes in the study of benign and malignant breast disease.

A review is presented of the use of immunohistochemical probes in the study of the cellular pathology of the breast. Using a combination of monoclonal and polyclonal antisera it has been possible to investigate the relationship between myoepithelial cells and basement membrane components in benign breast disease and the disturbance of this relationship in early invasive and infiltrating ductal carcinomas. The use of immunohistochemical techniques at the ultrastructural level provides the methodology for future detailed analyses. The heterogeneous expression of antigenic determinants characteristic of epithelial cells in the normal breast is considered in conjunction with its relevance to the heterogeneity seen in the invasive tumours.

Animals↗
PubMed1983

Effect of exercise protocol on the left ventricular response to exercise.

The purpose of this study was to determine whether the left ventricular response during exercise radionuclide angiography would be influenced by exercise protocol. One hundred twenty healthy volunteers (aged 18 to 40 years) performed upright bicycle exercise using 1 of 5 protocols. Ejection fraction was measured using first-pass radionuclide angiography. Exercise protocols were as follows: (1) graded exercise (25 W increase every 2 minutes) to fatigue, heart rate greater than 85% of age-predicted maximum, n = 53; (2) graded exercise to 85% of age-predicted maximal heart rate or to fatigue with heart rate less than 85% of age-predicted maximum, n = 26; (3) graded exercise to fatigue, with "exercise" imaging performed immediately after exercise, n = 15; (4) abrupt presentation of a supermaximal work load (400 W), n = 10; (5) graded exercise to a work load of 75 W preceding the abrupt presentation of a supermaximal work load (300 to 400 W), n = 16. Protocols 2 and 3, representing less than maximal stress, yield higher ejection fractions than Protocol 1 and may reduce the sensitivity of exercise radionuclide angiography. Protocols 4 and 5, representing supermaximal stress, yield lower ejection fractions than Protocol 1 and may reduce the specificity of exercise radionuclide angiography. Thus, exercise protocol has a significant influence on the left ventricular response during exercise radionuclide angiography.

Adolescent↗