Biomedical subjects

M S el-Sayed

Publications and source records attributed to M S el-Sayed.

At least 19 recordsLinked to original sources

PubMed1999

The effect of moderate alcohol ingestion on blood coagulation and fibrinolysis at rest and in response to exercise.

The effect of alcohol ingestion before exercise on blood haemostasis is not known. The present study examined the effects of moderate alcohol ingestion on blood haemostatic variables at rest and in response to exercise. Eleven normal healthy individuals randomly performed two tests separated by 7 days. A moderate dose of ethanol (0.5 g.kg-1) was administered before one test, whereas an equal volume of an alcohol-free drink was administered before the other. Forty-five minutes after the ingestion of either drink, the participants cycled at 65% VO2max for 30 min followed by a 5-min all-out performance. Venous blood samples were obtained before and 45 min after the ingestion of both drinks, and also immediately after exercise. Exercise induced a significant increase in tissue-type plasminogen activator activity and antigen, and factor VIII procoagulant activity. The post-exercise data also showed a significant decrease in plasminogen activator inhibitor activity and soluble fibrin, with a significant shortening in prothrombin time and activated partial thromboplastin time, but not thrombin time. No significant changes were observed in antithrombin III. Although no significant differences were found between trials in the haemostatic and fibrinolytic variables at rest, a significant decrease in fibrinogen concentration was observed after exercise in the alcohol trial. This suggests that ingesting a moderate dose of alcohol does not alter blood coagulation and fibrinolysis at rest. Apart from fibrinogen concentration, which was significantly decreased after exercise in the alcohol trial, most of the haemostatic and fibrinolytic variables were not affected by alcohol. The mechanism responsible for the decrease in fibrinogen following exercise in the alcohol trial remains unknown, but might be related to inhibition of fibrinogen synthesis by the liver or an enhanced rate of its catabolism.

Adult↗

PubMed1997

Exogenous carbohydrate utilisation: effects on metabolism and exercise performance.

It is generally recognized that a decrease in carbohydrate availability can lead to the development of fatigue during prolonged exercise in humans. Administration of glucose or other carbohydrates before or during exercise has been shown to postpone fatigue, conserve muscle glycogen and improve performance. Carbohydrates can be categorised according to their ability to increase blood glucose concentration (known as glycaemic index) and by the extent they stimulate the release of insulin. The glycaemic index is reflected in the rate at which consumed carbohydrate is made available in the blood. Glucose is the only type of carbohydrate that can readily be oxidised by skeletal muscle for energy production. Gastric emptying is the primary factor limiting the rate of carbohydrate delivery to the blood and therefore influences the utilisation of exogenous carbohydrate ingested before or during exercise. Various methods have been used to assess the oxidation of exogenous carbohydrates during exercise. Peak rates of CHO oxidation during exercise have been reported between 0.4 and 1.0 g/min, and the rates of oxidation do not appear to be influenced to a major extent by the use of multiple drinking schedule in comparison with a single bolus schedule. Previous studies also suggest that the ingestion of fructose during exercise does not offer any additional benefits over ingestion of glucose or glucose polymer solutions of similar concentration. The hormones insulin, glucagon and adrenaline together with cortisol and growth hormone play key roles in the regulation of carbohydrate metabolism during exercise. Ingestion of moderately concentrated carbohydrate solutions (4-8%) enhances prolonged exercise performance and is appropriate for optimising energy and fluid delivery without causing adverse effects. The ergogenic effects of carbohydrate ingestion on performance during intermittent exercise such as competitive sports are less well established, although the evidence to date suggests diminished performance when carbohydrate are limiting.

Biological Transport, Active↗

PubMed1997

Carbohydrate ingestion improves endurance performance during a 1 h simulated cycling time trial.

This study examined the effect of carbohydrate ingestion on metabolic and performance-related responses during and after a simulated 1 h cycling time trial. Eight trained male cyclists (VO2 peak = 66.5 ml kg-1 min-1) rode their own bicycles mounted on a windload simulator to imitate real riding conditions. At a self-selected maximal pace, the cyclists performed two 1 h rides (separated by 7 days) and were fed either an 8% carbohydrate or placebo solution. The beverages were administered 25 min before (4.5 ml kg-1) and at the end (4.5 ml kg-1) of the ride. With carbohydrate feeding, plasma glucose tended (P = 0.21) to rise before the time trial. Compared with rest, the plasma glucose concentration decreased significantly (P < 0.05) at the end of both rides, with no statistically significant difference being observed between treatments. Thereafter, plasma glucose increased significantly (P < 0.05) at 15 and 30 min into recovery and was significantly higher at 30 min during the carbohydrate trial compared with the placebo trial. No significant changes in plasma free fatty acids were observed during the ride. However, a significant increase (P < 0.05) in free fatty acids was found at 15 and 30 min into recovery, with no difference between trials. Mean power output was significantly (P < 0.05) greater during the carbohydrate compared with the placebo trial (mean +/- S.E.: 277 +/- 3 and 269 +/- 3 W, respectively). The greater distance covered in the carbohydrate compared with the placebo trial (41.5 +/- 1.06 and 41.0 +/- 1.06 km, respectively; P < 0.05) was equivalent to a 44 s improvement. We conclude that pre-exercise carbohydrate ingestion significantly increases endurance performance in trained cyclists during a 1 h simulated time trial. Although the mechanism for this enhancement in performance with carbohydrate ingestion cannot be surmised from the present results, it could be related to a higher rate of carbohydrate oxidation, or to favourable effects of carbohydrate ingestion on the central component of fatigue.

Adult↗

PubMed1996

Effects of high and low intensity aerobic conditioning programs on blood fibrinolysis and lipid profile.

The purpose of this study was to determine the effect of high and low intensity exercise conditioning programs on components pertinent to blood fibrinolysis and selected lipid profile variables in sedentary, but healthy individuals. Eighteen normal subjects were divided into two equal groups: high intensity, and low intensity exercise groups. Each subject in the high and low intensity groups exercised on a bicycle ergometer for 20 min, three times a week for 12 weeks at an intensity corresponding to 80% and 30% VO2 max, respectively. One week before and 1 week after the conditioning programs data were collected for body weight, percentage body fat, VO2 max and 12 h fasting blood levels of total tissue-type plasminogen activator (t-PA), tissue-type plasminogen activator activity (t-PAa), total plasminogen activator inhibitor (PAI-1), plasminogen activator inhibitor activity (PAI-1a), cholesterol (CHOL), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C). Post-conditioning, maximum oxygen consumption increased significantly (P < 0.05) only in the high intensity exercise group while body weight and percentage body fat did not change (P > 0.05) in either of the groups. Physical conditioning induced no statistically significant (P > 0.05) changes in the resting baseline of CHOL, TG or HDL-C. The resting baseline values of t-PA, t-PAa, PAI-1 and PAI-1a before conditioning did not vary significantly (P > 0.05) between two groups. Similarly, after training no significant change in t-PA, t-PAa or PAI-1. However, PAI-1a decreased significantly (P < 0.05) in the high intensity group, but not in the low intensity (P > 0.05). It is concluded that high, but not low, intensity physical conditioning significantly enhances the cardiorespiratory fitness and reduces the resting level of plasminogen activator inhibitor activity which may be linked with the favourable effects of exercise conditioning.

Adult↗

PubMed1996

Fibrinogen levels and exercise. Is there a relationship?

Haemostatic disturbances associated with elevated plasma fibrinogen levels have been implicated in coronary heart disease. Changes involving plasma fibrinogen levels have been reported after acute exercise. However, the results reported have sometimes been controversial, due to differences in the populations studied, exercise protocols and testing procedures, and the analytical methods employed for the assessment of plasma fibrinogen levels. The influence of physical training on plasma fibrinogen levels is more controversial and less well known. Cross-sectional studies suggest that regular exercise reduces plasma fibrinogen concentration. However, the influence of training programmes on plasma fibrinogen levels is less well studied and the available data are still poor with conflicting results being reported. This lack of evidence warrants further investigations in order to clarify the exact effects of acute exercise and physical training on plasma fibrinogen levels in normal healthy individuals and patients.

Cross-Sectional Studies↗

PubMed1996

Effects of exercise on blood coagulation, fibrinolysis and platelet aggregation.

Disturbances of the haemostatic balance may result in thrombosis or bleeding tendency. There have been abundant reports on the effects of exercise on blood haemostasis, but the results reported have been conflicting and difficult to interpret. This review outlines and critically evaluates the relevant literature on the effects of short term exercise and physical training on the 3 systems of blood haemostasis i.e. blood coagulation, fibrinolysis and platelet aggregation. Short term exercise is usually associated with a significant shortening of activated partial thromboplastin time (APTT) and a marked increase in factor VIII (FVIII). The rise in FVIII is directly related to exercise intensity and the individuals' training status. Exercise also induces a significant increase in blood fibrinolysis which is dependent on exercise intensity, duration and training condition. The rise in blood fibrinolysis is mainly due to an increase in tissue-type plasminogen activator (t-PA) and a decrease in its main inhibitor plasminogen activator inhibitor (PAI-1) which are released from the endothelial cells of the vessel wall. Platelet count increases in exercise and this is probably due to a fresh release of platelets from the spleen, bone marrow and lungs. Studies on the effects of exercise on platelet aggregation and markers of platelet activation have produced conflicting results, and the exact effects of exercise remain as yet undetermined. It is suggested that short term exercise activates blood coagulation and enhances blood fibrinolysis and the delicate balance between clot formation and clot dissolution is maintained in normal populations. No valid conclusion could be reached regarding the actual effects of physical training on blood coagulation, fibrinolysis and platelet aggregation. This is undoubtedly due to variations in training programmes employed, populations studied, and the analytical methods used.

Blood Coagulation↗

PubMed1995

Effects of carbohydrate feeding before and during prolonged exercise on subsequent maximal exercise performance capacity.

The study examined the effect of carbohydrate ingestion on exercise performance capacity. Nine male cyclists performed two separate trials at 70% VO2max for 60 min followed by a maximal ride for 10 min. During trials subjects were fed either an 8% glucose solution (CHO) or a placebo solution (PL), which were administered at rest and during and immediately after submaximal exercise. Statistical analyses indicated that glucose levels at rest increased significantly 15 min after the ingestion of CHO compared to PL. At 30 and 60 min during submaximal exercise, plasma glucose levels decreased significantly in the CHO but not in the PL trial. Following the performance ride, glucose levels increased significantly only during the CHO test trial. Free fatty acids did not change significantly during testing trials. The maximal performance ride results showed that in the CHO trial, a significantly greater external work load was accomplished compared to the PL trial. It is concluded that CHO ingestion improves maximal exercise performance after prolonged exercise.

Adult↗

PubMed1995

A physical conditioning program does not alter fibrinogen concentration in young healthy subjects.

Twenty five subjects were divided into experimental (N = 13, 7 male and 6 female, age 32.1 +/- 6.4 yr) and control groups (N = 12, 6 male and 6 female, age 33.4 +/- 5.4 yr) in order to examine the effect of a conditioning program on fibrinogen concentration. Before and after conditioning, VO2max was determined in all subjects. The experimental group (E) exercised for 30 min, 3 d.wk-1 for 12 wk at 70% (initial 6 wk) and 80% (latter 6 wk) of maximum heart rate. The control group (C) maintained normal activity pattern. After conditioning, subjects in E, but not in C, increased (P < 0.001) their VO2max. Resting fibrinogen concentrations (RFC) before conditioning were similar between the two groups, and demonstrated no change in the C group (242.9 +/- 40.3 mg.dl-1 vs 247.4 +/- 38.7 mg.dl-1, P > 0.05) after conditioning. Although RFC showed a 6% decrease in the E group post conditioning (249.1 +/- 21.5 mg.dl-1 vs 236.4 +/- 34.6 mg.dl-1), this decrease was not significant (P > 0.05). A significant increase (P < 0.05) in fibrinogen concentrations were observed after maximal exercise in both groups pre and post conditioning; however, this increase disappeared (P > 0.05) when data were corrected for hemoconcentration. These results suggest that after conditioning the 6% decrease in RFC was not statistically significant, but the possibility of Type II error is high.

Adult↗

PubMed1993

The influence of blood sampling site on lactate concentration during submaximal exercise at 4 mmol.l-1 lactate level.

This study examined lactate concentration during incremental and submaximal treadmill exercise at work rates corresponding to 4 mmol.l-1 lactate concentration, determined by fingertip (OBLA1) and venous blood (OBLA2). Initially, eight subjects performed a 4-min incremental exercise test until exhaustion. On two other occasions, seven of the subjects undertook submaximal exercise tests (30 min) at work rates corresponding to OBLA1 and OBLA2. Blood was simultaneously obtained from both sites at rest and at the end of each exercise stage during the incremental exercise, and at 5, 10, 20 and 30 min during the submaximal exercise and 5 min into recovery. Fingertip blood lactate concentrations were significantly higher (P < 0.05) than venous blood at rest, throughout the incremental exercise, consistently during exercise at OBLA1 and OBLA2, and into recovery. Data also revealed an exercise intensity-dependent lactate difference between the two sampling sites during both exercise protocols. Exercise at OBLA1 did not result in a progressive increase in lactate level nor exhaustion, and the lactate value at the end of 30 min corresponded to the predetermined value. However, exercise at OBLA2 resulted in a significantly higher (P < 0.05) lactate level than OBLA1, the lactate concentration at the end of 30 min was substantially higher than the predetermined value (P < 0.05) and exhaustion was evident. It is concluded that the lactate concentration value during incremental and submaximal exercise (at 4 mmol.l-1 OBLA) is dependent on the blood sampling site. This finding should be considered in studies concerned with the determination of OBLA.

Adult↗

PubMed1993

Effect of acute heat exposure on triglyceride transfer to the preovulatory follicles of the laying fowl (Gallus domesticus).

1. The effect of acute heat exposure on triglyceride (TG) transfer to preovulatory follicles was studied in the laying fowl. 2. Heat exposure of laying fowl resulted in a 1.1 degree C rise in body temperature, a 10-fold increase in respiration frequency and mild hypocapnia and hypoxaemia. 3. Plasma and follicular tissue TG concentrations were not significantly affected by heat exposure, but plasma TG specific radioactivity decreased significantly and was negatively correlated with body temperature. 4. The transfer rate of TG to the preovulatory follicles was not affected significantly by hyperthermia. 5. We conclude that nutrient supply to the developing follicles is not compromised in acutely heat-exposed laying fowl.

Animals↗

PubMed1993

Blood flow distribution during graded treadmill exercise in domestic cockerels.

1. White Leghorn cockerels were exercised continuously for 45 minutes on a treadmill at work loads equivalent to 2.1 and 2.7 times pre-exercise metabolic rates, the latter being close to the performance limits of the experimental birds. 2. Relative blood flow to the abdominal viscera and selected leg muscles was estimated using 113Sn-, 153Gd- and 46Sc-labelled microspheres, injected into the root of the aorta. 3. There was no significant shift of blood flow away from the viscera towards the leg muscles at either work load. However, relative colonic and duodenal blood flow fell significantly at both work loads and relative pancreatic blood flow doubled at the higher work load. 4. It is concluded that, as previously reported in female domestic fowl performing physical exercise close to their performance limits, male fowl are largely refractory to shifts in blood flow away from the viscera to the working muscles. Nevertheless, there is evidence of blood flow shifts between visceral organs, probably related to the intermediary metabolism of fuel substrates.

Animals↗

PubMed1993

Fingertip and venous blood lactate concentration in response to graded treadmill exercise.

Fingertip and venous blood lactate concentrations were determined pre-exercise and after 4-min bouts of treadmill running at 2.69, 3.13, 3.58 and 4.03 m s-1 in 14 normal healthy volunteers. A 1-min rest period intervened each exercise period, and was used for the simultaneous sampling of fingertip and venous blood. Compared to pre-exercise, fingertip and venous blood lactate (BLa) concentrations increased significantly (P < 0.05) in a progressive pattern with increasing exercise intensity. Fingertip BLa concentrations were significantly higher (P < 0.05) than venous blood prior to exercise and in response to all four running speeds. Treadmill speed, heart rate and oxygen consumption were significantly lower (P < 0.05) at a BLa concentration of 4 mM when estimated from fingertip blood as compared with venous blood. These results indicate that differences between fingertip and venous blood exist during treadmill exercise and should be considered when lactate determination is employed as a criterion to evaluate and predict performance and when used as a training guide to standardize exercise intensity.

Adult↗

PubMed1993

Fibrinolytic and hemostatic parameter response after resistance exercise.

These experiments were designed to study the effect of resistance exercise on parameters pertinent to the hemostatic and fibrinolytic systems. Seven normal healthy subjects (6 male, 1 female, 25 +/- 3 yr mean SD) were studied under three conditions: control (C) [no exercise], high volume resistance exercise (HVRE), and low volume resistance exercise (LVRE), which were randomized for each subject, with 7 d separating tests. Both HVRE and LVRE trials encompassed the performance of five sets of nine exercises. After establishing one repetition maximum (1 RM), the HVRE involved the performance of moderate resistance, higher repetition, and shorter resting periods, whereas LVRE involved the use of high resistance, lower repetition, and longer resting intervals. Heart rate (HR) was monitored at rest and continuously during trials and venous blood was removed with minimum stasis, before and immediately after HVRE, LVRE, and before and after 38 min of supine rest (C). The blood was enzymatically analyzed for lactic acid (LA) and assayed using chromogenic substrates for the determination of tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI), and Factor VIII (FVIII) activities. Global fibrinolysis (GF) was also screened in the fibrin plate and hematocrit ratios were employed to calculate percent plasma volume changes. Values were corrected for changes in plasma volume then data were analyzed using repeated measures ANOVA. There were no significant (P > 0.05) changes in the parameters measured in the resting condition over the three testing occasions and no significant differences (P > 0.05) were observed during the control experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Extrinsic plasminogen activator response to exercise after a single dose of propranolol.

The level of plasminogen activators was measured in 12 volunteers at rest and after maximum exercise. Two formulations of a beta-blocker "propranolol," or placebo, were given (oral dose, 10 mg) 2 h before exercise commenced. At weekly intervals over 21 d, randomized double-blind, cross-over trials were conducted. Two hours after drug/placebo administration, subjects exercised to maximal capacity using an incremental exercise protocol on a bicycle ergometer. Before and 2 h after drug/placebo administration and immediately after maximum exercise, heart rate, blood pressure, and oxygen consumption were measured, venous blood was removed, and plasma separated for the measurement of plasminogen activators using the fibrin plate method. Duplicate portions of plasma were taken: portion 1 for determination of total plasminogen activators activity, by the addition of dextran sulphate and flufenamic acid; portion 2 to assay extrinsic plasminogen activator, intrinsic plasminogen activator being blocked by the addition of C1-inactivator. Resting and postmaximum exercise heart rates showed significant decreases (P less than 0.05), with a nonsignificant difference in the resting level of extrinsic and intrinsic activators when the subjects were premedicated with either of the two formulations. Total and extrinsic activities, but not intrinsic activity, were significantly increased (P less than 0.05) to maximum exercise when subjects were given placebo. However, premedication with the drug formulations 1 and 2 significantly decreased (P less than 0.05) the normal total and extrinsic activities response to maximum exercise, with no effect on the intrinsic activity. It is suggested that the resting level of activators activity may not be affected by premedication with propranolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1990

Effects of treadmill exercise on the distribution of blood flow between the hindlimb muscles and abdominal viscera of the laying fowl.

1. Blood flow distribution between the abdominal viscera and the leg muscles of regularly-laying Rhode Island Red hens was measured at rest and immediately following treadmill exercise, using the radioactive microsphere technique. 2. Exercise brought about a 150% increase in metabolic rate and this was maintained continuously for 90 min. 3. Although there was a small shift in blood flow distribution towards the hindlimb muscles at the expense of the kidneys and reproductive organs, this was not statistically significant. 4. There was a significant reduction in blood flow to the preovulatory follicles of the ovary during exercise, relative to the rest of the abdominal viscera. 5. It is concluded that exercise of this intensity is insufficient to bring about gross changes in blood flow distribution between the abdominal viscera and the hindlimb muscles. The implications of this finding are discussed in relation to the nutrient and blood flow requirements of the reproductive organs.

Animals↗

PubMed1990

Vasopressin and plasma volume response to submaximal and maximal exercise in man.

Plasma arginine vasopressin (PAVP), plasma volume loss (PVL) and blood lactic acid (LA) responses to submaximal exercise were examined in 16 normal, healthy individuals. Subjects volunteered to participate in three experiments conducted at the same time of day (9 am) with 7 days intervening between tests. Venous blood was removed before and immediately after 15 min exercise at 40% and 70% VO2max, and before and after 100% VO2max which lasted for 14.3 +/- 1.4 mins (mean +/- SD). The resting mean values of PAVP were similar on the three testing occasions (p greater than 0.05). PAVP rose significantly (p less than 0.05) to all exercise treatments and exhibited an exercise-intensity related response. Similarly, PVL (calculated from changes in haematocrit) and LA responses to exercise were increased with increasing workload. No direct relationship was found between PAVP changes and PVL or LA responses to submaximal exercise (p greater than 0.05). These results suggest that (a) PAVP levels increase to exercise with a response related to exercise intensity; (b) the stimuli generated directly or indirectly to exercise may be one of many factors causing an increase in PAVP.

Adult↗

PubMed1990

Exercise intensity-related responses of fibrinolytic activity and vasopressin in man.

The physiological mechanism of exercise-induced hyperfibrinolysis is not fully understood. It has been reported that exercise increases plasma arginine vasopressin (PAVP) and that PAVP infusion enhances blood fibrinolytic activity (FA). To characterize the fibrinolytic role of PAVP during exercise, PAVP and FA were examined before and after submaximal and maximal exercise in 16 normal, healthy volunteers. After completion of a 100% VO2max exercise test on a bicycle ergometer, which elicited exhaustion in 14.3 +/- 1.4 min (MSD), subjects were randomly assigned to exercise trials at 40% and 70% VO2max for 15 min, each of the three tests being separated by 7 d. Prior to and immediately after the completion of the respective exercise treatment, heart rate, VO2 uptake, and respiratory quotient were measured and venous blood was removed and analyzed for PAVP using radioimmunoassay. The fibrin plate method (FP) and euglobulin lysis time (ELT) technique were employed to assess FA. The intrinsic and extrinsic plasminogen activators' response to all exercise treatments was also examined in pooled plasma prepared from the same subjects. Differentiation between the intrinsic and extrinsic activators' activity was ascertained in the FP by blocking the former with the addition of C1-inactivator. Lactic acid was measured using a standard spectrophotometric method. Compared to rest, FA was significantly increased (P less than 0.05) in all exercise tests when assessed using ELT, with a response related to exercise intensity. However, the 40% VO2max exercise trial caused a nonsignificant increase (P greater than 0.05) in FA using the FP method, with a significant increase (P less than 0.05) being observed in 70% and 100% VO2max exercise tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Effects of moderate intensity treadmill exercise on triglyceride production in the laying fowl.

1. Sustained aerobic exercise in domestic fowl has previously been shown to enhance lipid utilization by the skeletal muscles. The present study examined the possibility that such increased lipid oxidation in the laying female might lower the production of plasma triglycerides destined for transfer to the developing oocytes. 2. Following an intravenous injection of 25 muCi of 14C-labelled glycerol trioleate, the experimental birds performed 90 min of treadmill exercise at a work intensity approximately equivalent to 2.5 times the resting metabolic rate. 3. There was no evidence of either glycogen or triglyceride depletion in either the leg muscles or the viscera of the exercised birds. The specific activity of triglyceride TG-SRA found in the tissues was also the same in control and experimental birds. The time-course of the changes in plasma TG-SRA throughout the experimental period gave no indication that TG production had been affected by exercise. 4. It is concluded that the increased energy substrate demand arising from moderate-intensity, aerobic exercise is almost fully met by the liberation of fatty acids from adipose tissue TG stores, and has minimal impact on the hepatic manufacture of egg lipids.

Animals↗