Indoleamine 2,3-dioxygenase and regulatory t cells in intestinal mucosa in children with inflammatory bowel disease.

Impaired immune regulation has been suggested as an underlying mechanism of inflammatory bowel disease. Indoleamine 2,3-dioxygenase (IDO) and regulatory T cells expressing FOXP3 are crucial elements of immune regulation. Conversion of FOXP3- lymphocytes to Tregs is one of the functions of IDO. The aim of this study was to evaluate the number of cells expressing FOXP3 and IDO in the lamina propria of intestinal mucosa and to evaluate correlations between these parameters and disease activity. Sixty-six children newly diagnosed with inflammatory bowel disease (41 patients with ulcerative colitis and 25 patients with Crohn’s disease) were included in the study. Clinical activity of the disease was assessed by the Pediatric Ulcerative Colitis Activity Index and the Pediatric Crohn’s Disease Activity Index. Histopathological activity was scored according to the system described by Geboes. The infiltration of FOXP3+ and IDO+ cells was evaluated by immunohistochemistry. Sixteen patients with a diagnosis of irritable bowel syndrome (IBS) served as a control group. Lamina propria demonstrated a significantly higher infiltration of FOXP3+ and IDO+ cells in inflammatory bowel disease compared to the control group (p=0.001, p=0.004, respectively). The number of IDO+ and FOXP3+ cells correlated with clinical and histopathologic activity of Crohn’s disease. A positive correlation between the number of IDO+ and FOXP3+ cells was found in both types of inflammatory disease but not in patients with IBS. We conclude that indoleamine dioxygenase and FOXP3+ cells are upregulated in the intestinal mucosa of children with inflammatory bowel disease. IDO mediated conversion of FOXP3 -T cells to Tregs predominantly occurs in inflammation.

Cardiovascular and hormonal responses to static handgrip in young and older healthy men.

The purpose of this study was to investigate the effect of age on cardiovascular changes and plasma concentrations of adrenomedullin (ADM), catecholamines, endothelin-1 (ET-1) and plasma renin activity (PRA) in healthy men. A total of 15 young (21 ± 0.3 years) and 15 older (64 ± 0.7 years) healthy men performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand without any break between the bouts. During exercise heart rate (HR), blood pressure (BP), stroke volume (SV) and pre-ejection period (PEP) and left ventricle ejection time (LVET) were measured. Blood samples were taken before exercise, at the end of both exercise bouts and in the fifth minute of the recovery period. The handgrip-induced increases in HR and cardiac output were significantly smaller in older than in young men (p < 0.01). SV decreased only in older men (p < 0.001). There were no differences between groups in BP increases. The baseline plasma ADM and catecholamines were higher in older man compared to young subjects. Handgrip caused increases in plasma ADM, ET-1 and PRA only in older men (p < 0.05). The increases in plasma ADM correlated positively with those of noradrenaline (NA), PRA, ET-1 and LVET and negatively with changes in total peripheral resistance (TPR), SV, PEP and PEP/LVET ratio. The increases in plasma ET-1 correlated positively with those of NA, PRA, TPR, mean BP and SV. These results revealed that ADM, ET-1 and angiotensin II can contribute to maintain vascular tone during static exercise in older but not in younger men.

Theoretical investigation of unsteady MHD flow within non-stationary porous plates.

Porous-permeable structures with magnetohydrodynamics (MHD) flow have a lot of applications in various disciplines of engineering. Transport of ferro-fluid in magnetic field has attained more focus in recent years. In this work, an analysis is accomplished to investigate the MHD transport of in-compressible viscid ferro-fluid (electrically conductive) amid two movable porous-permeable plates (PPP). Here asymptotic method is then selected to solve the model. In this study, the effects of diverse considerable parameters and constraints like surface permeability, Reynold's factor, and Hartmann's factor are elaborated in details.

Brain Cancer Prediction Based on Novel Interpretable Ensemble Gene Selection Algorithm and Classifier.

The growth of abnormal cells in the brain causes human brain tumors. Identifying the type of tumor is crucial for the prognosis and treatment of the patient. Data from cancer microarrays typically include fewer samples with many gene expression levels as features, reflecting the curse of dimensionality and making classifying data from microarrays challenging. In most of the examined studies, cancer classification (Malignant and benign) accuracy was examined without disclosing biological information related to the classification process. A new approach was proposed to bridge the gap between cancer classification and the interpretation of the biological studies of the genes implicated in cancer. This study aims to develop a new hybrid model for cancer classification (by using feature selection mRMRe as a key step to improve the performance of classification methods and a distributed hyperparameter optimization for gradient boosting ensemble methods). To evaluate the proposed method, NB, RF, and SVM classifiers have been chosen. In terms of the AUC, sensitivity, and specificity, the optimized CatBoost classifier performed better than the optimized XGBoost in cross-validation 5, 6, 8, and 10. With an accuracy of 0.91±0.12, the optimized CatBoost classifier is more accurate than the CatBoost classifier without optimization, which is 0.81± 0.24. By using hybrid algorithms, SVM, RF, and NB automatically become more accurate. Furthermore, in terms of accuracy, SVM and RF (0.97±0.08) achieve equivalent and higher classification accuracy than NB (0.91±0.12). The findings of relevant biomedical studies confirm the findings of the selected genes.

Effect of prolonged dynamic exercise on plasma adrenomedullin concentration in healthy young men.

The aim of the study was to find out whether prolonged exercise influences plasma adrenomedullin (ADM) concentration and whether it is related to the hormonal, metabolic and cardiovascular changes. Eighteen healthy subjects (age 25+/-1 yrs) were submitted to cycle exercise for 90 min at 70% of maximal oxygen uptake. Heart rate (HR) and blood pressure (BP) were measured continously. Before, at 30(th) min, and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], atrial natriuretic peptide [ANP], plasma renin activity PRA, interleukin-6 [IL-6] and lactate [LA] determination. Significant increases in plasma ADM and IL-6 were found at 90(th) min whereas other hormones were elevated already at 30(th) min of exercise. Positive correlations were ascertained between [ADM] and [NA] (r=0.47), [ANP] (r=0.35) or [IL-6] (r=0.35) and between exercise-induced increases in [ADM] and [NA] (r=0.38). PRA correlated positively with [NA] and [ANP]. Negative correlation was found between plasma [ADM] and diastolic BP. The present data suggest that increase in sympathetic nervous activity and cytokine induction during prolonged exercise may be involved in plasma ADM release and that increase in ADM and ANP secretion may be a compensatory mechanism against further elevation of blood pressure.

Effect of 6-week endurance training on hemodynamic and neurohormonal responses to lower body negative pressure (LBNP) in healthy young men.

Endurance training is considered as a factor impairing orthostatic tolerance although an improvement and lack of effect have been also reported. The mechanisms of the changes and their relation to initial tolerance of orthostasis are not clear. In the present study, effect of moderate running training on hemodynamic and neurohormonal changes during LBNP, a laboratory test simulating orthostasis, was investigated in subjects with high (HT) and low (LT) tolerance of LBNP. Twenty four male, healthy subjects were submitted to graded LBNP (-15, -30 and -50 mmHg) before and after training. During each test heart rate (HR), stroke volume (SV) and blood pressure, plasma catecholamines, ACTH, adrenomedullin, atrial natriuretic peptide, and renin activity were determined. Basing on initial test, 13 subjects who withstood LBNP at -50 mmHg for 10 min were allocated into HT group and 11 subjects who earlier showed presyncopal symptoms to LT group. Training improved LBNP tolerance in six LT subjects. This was associated with attenuated rate of HR increase and SV decline (before training, at -30 mmHg deltaHR was 21 +/- 4 beats/min and deltaSV - -36+/- 8 ml while after training the respective values were 8 +/- 4 beats/min and -11+/- 6 ml). No differences in hemodynamic response were found in HT subjects and those from LT group whose LBNP tolerance was unchanged. In neither group training affected neurohormonal changes except inhibition of plasma ACTH rise in subjects with improvement of LBNP tolerance. It is concluded that some subjects with low orthostatic tolerance may benefit from moderate training due to improvement of cardiac function regulation.

Effect of adrenergic blockade on plasma adrenomedullin concentration during static handgrip in patients with heart failure.

Our previous study showed that static handgrip caused increases in the plasma adrenomedullin (ADM) both in patients with heart failure (HF) and healthy subjects. The present study was designed to determine the role of the sympathetic nervous system in mediating plasma ADM changes during handgrip in patients with HF. Twelve male HF patients (II class NYHA) treated with carvedilol, a non-selective adrenergic blocker (TC) and 12 patients untreated with carvedilol (UC) performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand. At the end of both exercise bouts and in 5 min of the recovery period, plasma ADM and catecholamines were determined. In addition, heart rate, blood pressure and stroke volume (SV) were measured. The baseline plasma ADM, noradrenaline (NA) and adrenaline (A) levels were similar in the two groups of patients, while SV was higher (P<0.05) in TC than in UC. During exercise plasma ADM concentrations were lower (P<0.05) in TC than in UC, but the handgrip-induced increases in plasma ADM did not differ between the groups. Plasma ADM correlated with NA concentrations (r = 0.764) and with SV (r = -0.435) and increases in plasma ADM expressed as percentage of baseline values correlated with those of plasma NA (r = 0.499), diastolic BP (r = 0.550) and total peripheral resistance (r = 0.435). The study suggests that the sympathetic nervous system may be involved in the stimulation of ADM secretion during static exercise either directly or by changes in the haemodynamic response.

Early effects of short-term endurance training on hormonal responses to graded exercise.

Twelve male, sedentary volunteers (22.0 +/-) were submitted to three weeks of a bicycle ergometer training, consisting of 45 min exercise (at 70% VO2max), 4 times in the first week and 3 times in the next 2 weeks. They performed four incremental exercise tests with the power output increased by 50 W every 3 min until volitional exhaustion: two before training (C1 and C2), and after one (T1) and three (T3) weeks of training. Before and after each load the plasma noradrenaline (NA), adrenaline (A) and blood lactate (LA) concentrations were determined in venous blood samples as well as plasma growth hormone (HGH) and cortisol concentrations before and at the end of exercise. A decrease in NA concentration was found already after 1 week of training at power output of 100 W (p<0.01) and 200 W (p<0.05). Similar decline was maintained after 3 weeks of training. No significant training-induced differences in plasma A concentration were found, however, the thresholds for both catecholamines were significantly shifted towards higher values after 3 weeks of training. One week of training caused a decrease in the pre-exercise (p<0.01), as well as post-exercise (p<0.05) plasma cortisol and HGH concentrations. It was concluded that endurance training induced a decrease in HGH, cortisol and NA concentration already after one week of training. A decline of pre-exercise plasma HGH and cortisol levels with time of experiment may, in part, indicate familiarization to exercise protocol.

Hemodynamic and neuroendocrine predictors of lower body negative pressure (LBNP) intolerance in healthy young men.

Exposure to LBNP results in body fluid shift to lower extremities similarly as under influence of orthostatic stress. In susceptible persons it leads to syncope. For better understanding why certain individuals are more susceptible to orthostatic challenges it seemed necessary to collect more data on hemodynamic and neuroendocrine adjustments occurring before onset of presyncopal symptoms Accordingly, in this study heart rate (HR), blood pressure (BP), stroke volume (SV), cardiac output (CO), hematocrit, plasma catecholamines, adrenomedullin, ACTH and plasma renin activity (PRA) were measured in 24 healthy men during graded LBNP (-15, -30 and -50 mmHg). Thirteen subjects completed the test (HT group) whereas 11 had presyncope signs or symptoms at -30 mmHg or at the beginning of -50 mmHg (LT group). Comparison of these groups showed that LT subjects had lower baseline total peripheral resistance and higher plasma adrenomedullin. During LBNP plasma catecholamine and PRA increases were even greater in LT than in HT group while plasma adrenomedullin elevations were similar in both groups. Plasma ACTH increased only in LT group following presyncope symptoms. Low tolerant group showed more rapid decline of SV and CO than HT subjects from the beginning of LBNP. It is suggested that measurements of SV at the level of LBNP which did not evoke any adverse symptoms may be of predictive value for lower orthostatic tolerance.

Exercise training and 3-day head down bed rest deconditioning: exercise thermoregulation.

UNLABELLED: Bed rest (BR) deconditioning causes excessive increase of exercise core body tempera-ture, while aerobic training improves exercise thermoregulation. The study was designed to determine whether 3 days of 6 degrees head-down bed rest (HDBR) affects body temperature and sweating dynamics during exercise and, if so, whether endurance training before HDBR modifies these responses. Twelve healthy men (20.7+/-0.9 yrs, VO2max: 46+/-4 ml x kg(-1) x min(-1) ) underwent HDBR twice: before and after 6 weeks of endurance training. Before and after HDBR, the subjects performed 45 min sitting cycle exercise at the same workload equal to 60% of VO2max determined before training. During exercise the VO2, HR, tympanic (Ttymp) and skin (Tsk) temperatures were recorded; sweating dynamics was assayed from a ventilated capsule on chest. Training increased VO2max by 12.1% (p<0.001). Resting Ttymp increased only after first HDBR (by 0.22 +/- 0.08 degrees C, p<0.05), while exercise equilibrium levels of Ttymp were increased (p<0.05) by 0.21 +/- 0.07 and 0.26 +/- 0.08 degrees C after first and second HDBR, respectively. Exercise mean Tsk tended to be lower after both HDBR periods. Total sweat loss and time-course of sweating responses were similar in all exercise tests. The sweating threshold related to Ttymp was elevated (p<0.05) only after first HDBR. IN CONCLUSION: six-week training regimen prevents HDBR-induced elevation of core temperature (Ttymp) at rest but not during ex-ercise. The post-HDBR increases of Ttymp without changes in sweating rate and the tendency for lower Tsk suggest an early (<3d) influence of BR on skin blood flow.

Can preschool-aged children swallow several minitablets at a time? Results from a clinical pilot study.

Minitablets are a novel, multi-compartment solid drug formulation, particularly intended for children between 1 and 6 years of age. Available literature shows that even infants are capable of swallowing a single minitablet. In this study, we have explored the level of acceptance of minitablets administered in units of 5 or 10. A group of thirty two 2-year-old children (2-years) and twenty eight 3-year-old children (3-years) have been enrolled in the study. Each child was asked to swallow placebo minitablets (2mm or 3mm) suspended in a fruity jelly on a spoon. The swallowing of minitablets (with or without chewing) was registered for 75% of 2-year-olds and for 93% of 3-year-olds. Moreover, most of the children (57% of all participants) were fully capable of swallowing all units without chewing (2-years: 50%; 3-years: 64%). However, no statistically significant differences in the swallowing ability were observed in gender and age groups. None of the children choked. Neither the number, nor the diameter of the administered minitablets have significantly influenced the ability to swallow units. The results show that minitablets administered in several units mixed with jelly food are safe and could be accepted by a pediatric population.

Electrical stimulation partly reverses the muscle insulin resistance caused by tenotomy.

It was shown that 15-min electrical stimulation of the rat sciatic nerve greatly increases the in vitro measured sensitivity of lactate formation, glucose transport, and glycogen synthesis to insulin, impaired by previous tenotomy. The insulin sensitivity of all these processes was, however, still below that found in the stimulated intact soleus muscle. Extending the stimulation up to 30 min did not cause any further changes in insulin sensitivity either in tenotomized or in intact muscles.

Influence of caffeine, cold and exercise on multiple choice reaction time.

RATIONALE: The effects of caffeine on psychomotor performance have been evaluated under resting conditions and in a thermoneutral environment. Our hypothesis was that these effects could be modified by factors enhancing the level of alertness, such as exercise and cold exposure. OBJECTIVE: The purpose of this study was to follow up changes in the multiple choice reaction time (RT) during exercise at room and low ambient temperatures after caffeine or placebo administered in a double blind manner. METHODS: Nine soccer players performed multistage, incremental exercise until volitional exhaustion on a bicycle ergometer at 22 degrees C or 4 degrees C, 1 h after ingestion of coffee with caffeine (CAF) or without it (PL). Immediately before exercise and at the end of each workload, RT and blood lactate (LA) were measured. Oxygen uptake (VO2) and heart rate (HR) were recorded continuously. Blood LA threshold and the workload associated with the shortest RT were determined. RESULTS: During exercise at 22 degrees C, RT was significantly shorter in CAF than in the PL test, while at 4 degrees C there were no differences in RT between CAF and PL trials. Cold exposure did not affect RT either at rest or during exercise. Neither caffeine nor cold exposure influenced the maximal VO2, the maximal HR and LA threshold. CONCLUSION: In the thermoneutral environment, caffeine ingestion improved psychomotor performance during exercise, whilst at low ambient temperature this effect was blunted. These findings suggest that the stimulating action of caffeine depends on the level and source of arousal.

Exercise hyperthermia as a factor limiting physical performance: temperature effect on muscle metabolism.

The muscle contents of high-energy phosphates and their derivatives [ATP, ADP, AMP, creatine phosphate (CrP), and creatine], glycogen, some glycolytic intermediates, pyruvate, and lactate were compared in 11 dogs performing prolonged heavy exercise until exhaustion (at ambient temperature 20.0 +/- 1.0 degrees C) without and with trunk cooling using ice packs. Without cooling, dogs were able to run for 57 +/- 8 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 +/- 0.2 and 43.0 +/- 0.2 degrees C, respectively. Compared with noncooling, duration of exercise with cooling was longer by approximately 45% while Tre and Tm at the time corresponding to the end of exercise without cooling were lower by 1.1 +/- 0.2 and 1.2 +/- 0.2 degrees C, respectively. The muscle contents of high-energy phosphates (ATP + CrP) decreased less, the rate of glycogen depletion was lower, and the increases in the contents of AMP, pyruvate, and lactate as well as in the muscle-to-blood lactate ratio were smaller. The muscle content of lactate was positively correlated with Tm. The data indicate that with higher body temperature equilibrium between high-energy phosphate breakdown and resynthesis was shifted to the lower values of ATP and CrP and glycolysis was accelerated. The results suggest that hyperthermia developing during prolonged muscular work exerts an adverse effect on muscle metabolism that may be relevant to limitation of endurance.

Hypothalamic, rectal, and muscle temperatures in exercising dogs: effect of cooling.

To investigate mechanisms that may be involved in the prolongation of exercise performance with body cooling hypothalamic (Thy), rectal (Tre), and exercising muscle (Tm) temperatures, as well as the heart rate, respiratory rate, blood lactic acid concentration ( [LA] ), and plasma osmolality (Osm) were measured in five dogs during exhaustive treadmill exercise at an ambient temperature (Ta) of 22 +/- 1 degree C without cooling (control) and with external cooling by use of ice packs. In both series of experiments, dehydration of animals was prevented. Compared with exercise with noncooling, exercise with cooling resulted in 1) increased exercise duration from 90 +/- 14 to 145 +/- 15 min (62%, P less than 0.05); 2) attenuated increases in Thy, Tre, and Tm; 3) decreased respiratory and heart rates; and 4) lowered LA. Significant negative correlations were found between both Tm and delta Tm attained at 60 min of the run and time of exercise until exhaustion (r = -0.72 and -0.74, respectively; P less than 0.02). This work failed to differentiate clearly changes or equilibrium levels of brain, core, or muscle temperature as separate factors affecting work tolerance. However, the inverse relationship between Tm reached at 60 min of the run (in both experiments) and the total duration of exercise indicates that sustained muscle hyperthermia may largely contribute to limitation of working ability.

Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men.

To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

Plasma adrenomedullin response to maximal exercise in healthy subjects.

The aim of the study was to find out whether maximal exercise performed by healthy young men influences plasma adrenomedullin concentration (ADM) and is the peptide level related to the cardiovascular, metabolic and hormonal changes induced by exercise. Ten subjects (age 24+/-1.0 yr) participated in the study. They performed graded bicycle ergometer exercise until exhaustion. Heart rate (HR) and blood pressure (BP) were measured throughout the test. Before and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], growth hormone [hGH], cortisol and lactate [LA] determination. Plasma [ADM] decreased during exercise from 1.71+/-0.09 to 1.53+/-0.10 pmol x l(-1) (p<0.01). This was accompanied by increases in plasma catecholamines and [hGH], while plasma cortisol level did not change. Positive correlation was found between the exercise-induced decreases in plasma ADM and diastolic BP. Blood [LA], systolic and mean BP at the end of exercise correlated negatively with plasma [ADM]. No significant interrelationships were found between plasma ADM, catecholamines or the other hormones measured. The present data suggests, that maximal exercise inhibits ADM secretion in young healthy men. Metabolic acidosis and a decrease in peripheral resistance might be involved in this effect.

The influence of endurance training on the transient haemodynamic response to orthostatic manoeuvre.

Several investigations demonstrated that aerobic fitness is associated with a tendency towards orthostatic hypotension whereas other reports did not show any differences in cardiovascular adjustment to orthostatic challenges between endurance trained and sedentary subjects. In the present work, the time course of changes in heart rate (HR), systolic time intervals (STI), stroke volume (SV), cardiac output (CO) and blood pressure was studied during 8 minutes following standing up from supine position in 7 healthy volunteers before and after 10 weeks of endurance training on bicycle ergometer. Impedance cardiography was used for measurement of cardiac postural responses. The training program applied in this study increased the subjects' aerobic capacity (VO2max) by approx. 18%. After training, the steady-state supine HR and contribution of the pre-ejection period and ejection time to the total R-R interval in ECG were lowered while SV was significantly increased. No significant training-induced changes were found in magnitude and time-courses of HR, STI, SV and CO changes following standing up. Diastolic blood pressure during standing was greater after than before training. It is concluded that the short-time endurance training does not affect adversely cardiovascular orthostatic response and may even improve orthostatic tolerance due to the augmentation of diastolic blood pressure response.

Effect of low-carbohydrate-ketogenic diet on metabolic and hormonal responses to graded exercise in men.

Maximal oxygen uptake (VO2 max) and lactate threshold (LT) were measured during graded, incremental exercise in 8 healthy, untrained volunteers (aged 22 +/- 0.9 yrs) following 3 days on a control, mixed diet, or a ketogenic (50% fat, 45% protein and 5% carbohydrates) diet of equal energy content. Before and after exercise tests acid base balance, plasma beta-hydroxybutyrate (beta-HB), free fatty acid (FFA), and some hormone concentrations were determined. In comparison with the normal diet, the ketogenic diet resulted in: an increased VO2 max, decreased respiratory exchange ratio an a shift of LT towards higher exercise loads. Blood LA concentrations were lower before, during and after exercise. Post exercise blood pH, as well as pre-and post exercise base excess and bicarbonates were reduced. Resting beta-HB concentration was elevated to approx. 2.0 mM, and FFA to approx. 1.0 mM. During a 1 h recovery period beta-HB decreased to 0.85 mM (p < 0.01) after the ketogenic diet, while plasma FFA did not change after exercise under either conditions. Both the pre-and post-exercise levels of adrenaline, noradrenaline, and cortisol were enhanced, whilst plasma insulin concentration was decreased on the ketogenic diet. It is concluded that the short-term ketogenic diet does not impair aerobic exercise capacity, as indicated by elevated VO2 max and LT. This may be due to increased utilization of beta-HB and FFA when carbohydrate stores are diminished. Stimulation of the sympatho-adrenal system, and cortisol secretion with reduced plasma insulin concentration seem to be of importance for preservation of working capacity.