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Biomedical subjects

A R Morton

Publications and source records attributed to A R Morton.

At least 55 records · Page 3Linked to original sources
PubMed1995

The haematological, biochemical and immunological profile of athletes suffering from the overtraining syndrome.

To help clarify the overtraining syndrome (OTS), a combination of parameters were measured in ten athletes who were suffering from OTS. Blood samples were obtained at rest and a range of haematological, biochemical and immunological tests were carried out on the samples. For each parameter, the mean value for the group was compared to an established normal range amongst age-matched controls. The subjects were also asked to complete a questionnaire to establish the severity of their condition. The data indicated that the debilitating fatigue experienced by the OTS sufferers was not related to any of the blood parameters traditionally associated with chronic exercise stress, since levels were normal in OTS. The only parameter measured which deviated significantly from the normal range for both the sedentary controls and the athletes was the plasma concentration of glutamine. Although the data in this study would suggest that plasma glutamine concentrations represented an objective, measurable difference between OTS subjects and normal controls, it remains to be shown that there is any correlation between glutamine concentrations and other clinical symptoms of OTS such as physical capability.

Adult↗
PubMed1995

Comparison of maximal oxygen consumption with oral and nasal breathing.

The major cause of exercise-induced asthma (EIA) is thought to be the drying and cooling of the airways during the 'conditioning' of the inspired air. Nasal breathing increases the respiratory system's ability to warm and humidity the inspired air compared to oral breathing and reduces the drying and cooling effects of the increased ventilation during exercise. This will reduce the severity of EIA provoked by a given intensity and duration of exercise. The purpose of the study was to determine the exercise intensity (%VO2 max) at which healthy subjects, free from respiratory disease, could perform while breathing through the nose-only and to compare this with mouth-only and mouth plus nose breathing. Twenty subjects (11 males and 9 females) ranging from 18-55 years acted as subjects in this study. They were all non-smokers and non-asthmatic. At the time of the study, all subjects were involved in regular physical activity and were classified, by a physician, as free from nasal polyps or other nasal obstruction. The percentage decrease in maximal ventilation with nose-only breathing compare to mouth and mouth plus nose breathing was three times the percentage decrease in maximal oxygen consumption. The pattern of nose-only breathing at maximal work showed a small reduction in tidal volume and large reduction in breathing frequency. Nasal breathing resulted in a reduction in FEO2 and an increase in FECO2. While breathing through the nose-only, all subjects could attain a work intensity great enough to produce an aerobic training effect (based on heart rate and percentage of VO2 max).

Adolescent↗
PubMed1995

Serum free cortisol responses to a standard exercise test among elite triathletes.

Eighteen elite male triathletes completed an incremental treadmill run to volitional exhaustion, followed by two maximal cycle ergometer sprints. Venous blood samples were obtained at rest (R), immediately post- (P) and one hour postexercise (H). Serum was analysed for total cortisol (TC) by a radioimmunoassay, and free cortisol (FC) by a temperature and time dependent ultrafiltration/dialysis method. Mean (+SE) resting cortisol levels were 627 + or - 23 (TC) and 12.5 + or - 2.5 nmol 1(-1)(FC). The mean percentage increase in TC (P vs. R) was 49.0 + 73%, accompanied by a 344 + or - 47% increase in FC. Significantly divergent (p<0.001) total cortisol responses (H vs. P) were observed within the group, and the athletes were divided into two subgroups (A and B) on this basis. In group A, both TC and FC returned to resting levels. In group B, there was a further slight increase in TC, accompanied by a significant (p<0.01) increase in FC reaching 851 + or - 268% of resting levels. These data suggest that exercise-induced increases in free cortisol, and hence its catabolic effect, are of much greater relative magnitude than TC changes. The relationship between TC and FC was best fitted to an exponential regression, with a clearcut change in slope at 700 nmol 1(-1)(TC) suggesting saturation of the binding protein. We suggest that the measurement of cortisol in athletes be reassessed, favouring determination of FC in the future.

Adult↗
PubMed1994

Psychological and immunological correlates of acute overtraining.

Five men undertook two intensive interval training sessions per day for 10 days, followed by 5 days of active recovery. Subjects supplied a venous blood sample and completed a mood-state questionnaire on days 1, 6, 11 and 16 of the study. Performance capabilities were assessed on days 1, 11 and 16 using a timed treadmill test to exhaustion at 18 kmh-1 and 1% grade. These individuals became acutely overtrained as indicated by significant reductions in running performance from day 1 to day 11. The overtrained state was accompanied by severe fatigue, immune system deficits, mood disturbance, physical complaints, sleep difficulties, and reduced appetite. Mood states moved toward baseline during recovery, but feelings of fatigue and immune system deficits persisted throughout the study.

Adaptation, Physiological↗
PubMed1993

The combined effects of aerobic exercise and alcohol restriction on blood pressure and serum lipids: a two-way factorial study in sedentary men.

OBJECTIVES: To determine whether vigorous exercise and alcohol restriction have additive and independent effects in reducing blood pressure in sedentary male alcohol drinkers. Also to assess whether 4 weeks of vigorous exercise could offset the fall in high-density lipoprotein cholesterol (HDL-cholesterol) usually observed after alcohol restriction. DESIGN: Seventy-five sedentary men were randomly assigned to drink low-alcohol beer or continue their normal drinking habits. Within these two groups subjects were further assigned either to a vigorous exercise programme of three 30-min sessions a week of cycling at 60-70% of maximum workload or to a control light-exercise programme. RESULTS: Seventy-two subjects completed the trial. Alcohol consumption fell by 85% in the low-alcohol group. Fitness increased by 10% following vigorous exercise, with a significant improvement in maximum oxygen uptake. After adjustment for weight loss, a significant effect of alcohol restriction in reducing both systolic and diastolic blood pressure was demonstrated. There was no effect of vigorous exercise on blood pressure. Serum total cholesterol, low-density lipoprotein cholesterol and apolipoprotein B were not influenced by alcohol restriction or vigorous exercise. However, alcohol restriction significantly reduced triglyceride, HDL-cholesterol, its subfractions HDL2-cholesterol and HDL3-cholesterol, and its major apolipoproteins apo A-I and apo A-II. These reductions were unaffected by moderate exercise. CONCLUSIONS: This study provides further evidence that alcohol restriction results in reductions in blood pressure in men who are regular alcohol drinkers. However, a simultaneous increase in fitness did not lead to lower blood pressures than those achieved with alcohol restriction alone, and was unable to offset alcohol-related falls in HDL-cholesterol, its subfractions and its major apolipoproteins.

Adult↗
PubMed1993

Nutritional status and efficiency of dialysis in CAPD and CCPD patients.

Renal patients are prone to malnutrition. This is of particular concern in patients undergoing peritoneal dialysis because of the loss of protein in the dialysate. Data comparing the adequacy of continuous cycling peritoneal dialysis (CCPD) and continuous ambulatory peritoneal dialysis (CAPD) are few. To compare nutritional status and dialysis adequacy, 32 patients were studied (19 CAPD, 13 CCPD). Weight change, dietary intake, degree of edema, and laboratory parameters (hemoglobin, albumin, urea, creatinine) were assessed. Dialysis efficiency was compared using urea and creatinine kinetics [KT/V(urea), normalized protein catabolic rate (PCRN), efficacy number, weekly creatinine clearance]. Age was similar in each group [CAPD 56.5 years (34-75 years); CCPD 53.5 years (14-76 years)]. There were no significant differences in hemoglobin, albumin [29 +/- 1.3 g/L CAPD; 32 +/- 1.5 g/L CCPD (mean +/- SEM)], urea, or creatinine between groups, nor in KT/V (1.72 +/- 0.15 CAPD; 1.93 +/- 0.17 CCPD) and PCRN (0.79 +/- 0.05 CAPD; 0.97 +/- 0.08 CCPD). The efficacy number was significantly higher in the CCPD patients (6.95 +/- 0.66 CAPD; 9.93 +/- 1.3 CCPD; p = 0.03). This study indicates that the nutritional status of CCPD patients at our center was similar to that of CAPD patients. Adequacy of dialysis was also similar in CCPD patients as compared with CAPD patients.

Adolescent↗
PubMed1993

Measuring and predicting outcomes in ESRD patients.

To test the feasibility of using general health status as a practical dialysis outcome measure, in a longitudinal pilot study, two well-validated instruments were administered to patients from our dialysis unit or clinic. The instruments were administered three times, at eight-week intervals for seven months to 41 hemodialysis (HD) patients. Forty-five transplant (Tx) patients were surveyed once as a validating control. Sociodemographic, imaging and biochemical data were tested as outcome predictors. Unexpected hospitalizations and adverse intercurrent events were used as additional outcome measures. Preliminary analysis shows HD patients scoring low, while Tx patients scored higher (healthier). These preliminary results suggest that assessment of general health status is a valid and practical outcome measure.

Health Status↗
PubMed1992

Cell numbers and in vitro responses of leucocytes and lymphocyte subpopulations following maximal exercise and interval training sessions of different intensities.

In vitro lymphocyte function and the mobilisation of peripheral blood leucocytes was examined in eight trained subjects who undertook an incremental exercise test to exhaustion and a series of interval training sessions. Venous blood samples were obtained before the incremental test, immediately after, and 30, 60, and 120 min after the test. Interval training sessions were undertaken on separate days and the exercise intensities for each of the different sessions were 30%, 60%, 90% and 120% of their maximal work capacity respectively, as determined from the incremental exercise test. There were 15 exercise periods of 1-min duration separated by recovery intervals of 2 min in each session. Venous blood samples were obtained immediately after each training session. Significant increases in lymphocyte subpopulations (CD3+, CD4+, CD8+, CD20+, and CD56+) occurred following both maximal and supramaximal exercise. This was accompanied by a significant decrease in the response of cultures of peripheral blood lymphocytes to Concanavalin A (ConA), a T-cell mitogen. The state of lymphocyte activation in vivo as measured by CD25+ surface antigen was not, however, affected by acute exercise. The total number of lymphocytes, distribution of lymphocyte subpopulations and in vitro lymphocyte response to ConA had returned to pre-exercise levels within half an hour of termination of exercise but serum cortisol concentrations had not begun to fall at this time. There was a significant decrease in the CD4+:CD8+ cell ratio following exercise; this was more the result of increases in CD3-CD8+ cells (CD8+ natural killer cells) than to CD3+CD8+ cells (CD8+ T-lymphocytes). Decreased responsiveness of T-cells to T-cell mitogens, postexercise, may have been the result of decreases in the percentage of T-cells in postexercise mixed lymphocyte cultures rather than depressed cell function. The cause of this was an increase in the percentage of natural killer cells which did not respond to the T-cell mitogen. The results indicated that while a substantial immediate in vitro "immunomodulation" occurred with acute exercise, this did not reflect an immunosuppression but was rather the result of changes in the proportions of reactive cells in mononuclear cell cultures. We have also demonstrated that the degree of the change in distribution of lymphocyte subpopulation numbers and responsiveness of peripheral blood mononuclear cells in in vitro mitogen reactions increased with increasing exercise intensity. Plasma volume changes may have contributed to some of the changes seen in leucocyte population and subpopulation numbers during and following exercise.

CD4-CD8 Ratio↗
PubMed1992

Biological responses to overload training in endurance sports.

Five subjects undertook 10 days of twice daily interval training sessions on a treadmill followed by 5 days of active recovery. On days 1, 6, 11, and 16 the subjects were required to undertake a test of submaximal and maximal work capacity on a treadmill combined with a performance test consisting of a run to exhaustion with the treadmill set at 18 km.h-1 and 1% gradient. Also on these days a pre-exercise blood sample was collected and analysed for a range of haematological, biochemical and immunological parameters. The subjects experienced a significant fall in performance on day 11 which had returned to pretraining levels on day 16. Serum ferritin concentrations were depressed significantly from pretraining concentrations at the conclusion of the recovery period while the expression of lymphocyte activation antigens (CD25+ and HLA-DR+) was increased both after the training phase and the recovery phase. The number of CD56+ cells in the peripheral circulation was depressed at the conclusion of the recovery period. Several parameters previously reported to change in association with overload training failing to reflect the decrease in performance experienced by subjects in this study, suggesting that overtraining may best be diagnosed through a multifactorial approach to the recognition of symptoms. The most important factor to consider may be a decrease in the level of performance following a regeneration period. The magnitude of this decreased performance necessary for the diagnosis of overtraining and the nature of an "appropriate" regeneration period are, however, difficult to define and may vary depending upon the training background of the subjects and the nature of the preceding training. It may or may not be associated with biochemical, haematological, physiological and immunological indicators. Individual cases may present a different range of symptoms and diagnosis of overtraining should not be excluded based on the failure of blood parameters to demonstrate variation. However, blood parameters may be useful to identify possible aetiology in each separate case report of over-training. An outstanding factor to emerge from this study was the difficulty associated with an objective diagnosis of overtraining and this is a possible reason why there have been new accounts of overtraining research in the literature.

Adult↗
PubMed1992

Infusion rate and pharmacokinetics of intravenous pamidronate in the treatment of tumour-induced hypercalcaemia.

We report the results of two consecutive randomized studies in the treatment of malignant hypercalcaemia with intravenous pamidronate. Overall normocalcaemia was achieved in greater than 90% of patients and a single infusion of 60 mg pamidronate given over 2 hours was as effective in restoring normocalcaemia as infusions given over 4, 8 or 24 hours. Similarly duration of normocalcemia after treatment with pamidronate and the control of the symptoms of hypercalcaemia were independent of infusion rate. Study of the pharmacokinetics of pamidronate in the treatment of hypercalcaemia show this drug to have a very high clearance due to calcified tissue retention and renal excretion. The initial half life of the drug in plasma is very short and most of the drug is cleared before distribution equilibrium is achieved. Short infusions of pamidronate are as safe and effective as infusions given over a longer time and are therefore to be preferred because of their greater convenience.

Adult↗
PubMed1992

Asthmatic drugs and competitive sport. An update.

Almost all asthmatics are prone to asthma triggered by moderate to severe exercise. Fortunately there are a number of pharmaceutical agents now available which can prevent and/or reverse exercise-induced asthma (EIA) and allow many asthmatics to participate in vigorous physical activities with minimum respiratory disadvantage. Regular exercise is an accepted part of the management of asthma and EIA can now be controlled so successfully that a number of elite sportspersons, in almost all types of sporting events, are asthmatic. This control of EIA, which is essential if asthmatics are to participate safely, requires that the patient and his/her doctor initiate a strategy to manage the disease during sport and other physical activities. In recent years the mortality and morbidity from asthma have been increasing and this has indicated the need to improve patient care. One of the most important innovations aiming to improve the control and treatment of asthma has been the recent development of the 6 point asthma management plan which is a strategy to simplify and optimise the long term management of asthma. It aims to improve the quality of life of most asthmatics and more importantly, prevent deaths due to asthma. Because antidoping controls operate in many high performance sports it is essential that the EIA management plan rely on those medications which are permitted. The list of allowable drugs is in continual flux as new ones are added and others are challenged on the grounds of possible ergogenicity. All aerosol beta 2-agonists except fenoterol, the khellin derivatives, theophylline, ipratropium bromide and the aerosol corticosteroids are currently permitted. Some nonasthmatic athletes who are aware of the improved performance of asthmatic athletes when using pre-exercise medication have been known to take antiasthma medication in the hope that it might improve their performance. Current evidence indicates, however, that the permitted medications are not ergogenic and do not give the asthmatic any advantage over the nonasthmatic athlete but merely removes the respiratory disadvantage under which he/she competes.

Administration, Inhalation↗
PubMed1992

Effects of nedocromil sodium, cromolyn sodium, and a placebo in exercise-induced asthma.

The incidence and severity of exercise-induced asthma were determined in nineteen asthmatic patients who performed eight minutes of exercise following four treatments administered in a random order. The treatments were nedocromil sodium, cromolyn sodium, placebo, and no treatment. It was concluded that nedocromil sodium (8 mg) and cromolyn sodium (4 mg) provide equal protection against exercise-induced asthma.

Adolescent↗
PubMed1992

Periodisation of training stress--a review.

Athletic performance improves as the athlete adapts to progressively increasing training loads. Empirical observations and studies investigating fluctuations in performance indicate that this adaptation occurs during periods of reduced training, termed regeneration periods. Thus it is essential that adequate regeneration time be included in training programmes so that adaptation can be achieved. In order to induce adaptation, heavy periods of training are used to provide a stimulus for adaptive processes to become functional. The literature and anecdotal accounts suggest that the cycling of light, medium, and heavy periods of training is an optimal method for combining the heavy periods of training with the periods of light training needed to allow adaptation and supercompensation.

Adaptation, Physiological↗
PubMed1992

Periodisation and the prevention of overtraining.

It may be essential for the athlete to train in cycles in order to induce optimal improvements and prevent overtraining. Without sufficient recovery time, adaptation may not occur and the athlete may develop the symptoms of overtraining due to continuous and/or excessive exposure to training stress. Training in cycles provides guidelines for the times in the training programme when regeneration should be complete, and therefore the times when the athlete can be screened for overtraining without confusing the fatigue of overload training with that of overtraining. A periodised training structure provides guidelines for conducting research into the mechanisms of training adaptation and overtraining.

Adaptation, Physiological↗
PubMed1992

Acute intensive interval training and T-lymphocyte function.

Immune suppression has been suggested to occur as a result of acute exercise although results of previous studies are variable, possibly due to the failure of some researchers to control exercise intensity and duration. Most of the studies so far have investigated immediate effects after bouts of exercise mainly in subjects undertaking lower body exercise (running or cycling), and the time course of recovery has rarely been determined. We chose two groups of athletes for our studies. One group represented subjects of a range of fitness levels from recreational runners to high-performance runners. The second group represented kayakists with a similar range of fitness levels. Following interval training designed to stress either the lower or upper body anaerobically, we have now shown that upper body exercise (kayaking) induces similar in vitro responses to those described for lower body exercise. There were no differences between the responses of low-fitness versus high-fitness subjects. In addition we have studied the in vitro responses of leukocytes following acute anaerobic exercise over a 24-h recovery period. The results showed that the reduced lymphocyte proliferative response, in vitro, to the T-cell mitogen CONA experienced immediately after exercise returned to normal levels within 2 h of recovery time. This suggests that the reduction in lymphocyte proliferative response is a short transient one.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗