[Outpatient expectations in dermatology consultations: A pilot study]. / Attente des patients consultant un dermatologue «de ville¼: une étude pilote.

BACKGROUND: Understanding patients' expectations with regard to medical care is critical as it guarantees an efficient therapeutic process. Our aim was to determine outpatients' expectations concerning clinical encounters in a dermatology clinic and to study how these matched the opinions of dermatologists regarding them. PATIENTS AND METHODS: Consecutive outpatients consulting in five dermatology centres in the Paris suburbs between February 2013 and March 2013 were prospectively included. For this pilot cross-sectional study, we used two standardized forms to collect data from patients and dermatologists. Patients' answers were compared to those of their dermatologist, and the degree of matching was calculated to assess the ability of dermatologists to accurately identify their patients' expectations. RESULTS: Two hundred and sixty-five patients were included, with a median age of 41 years (interquartile range: 25; 62), of whom 166 were women (65.4%). Patient's principal expectations concerned diagnosis (51.7%) and medication (40.8%), with 32.1% of patients requiring reassurance. The rates of matching between patients' and dermatologists' answers ranged from 33.3% to 65.7% according to the type of expectations. The highest rate concerned expectation with regard to medications, being only 52.6% and 58.8%, respectively for expectations regarding diagnosis and the need for reassurance. CONCLUSION: This study highlights the need for improved identification of outpatient expectations in dermatology consultations.

Familial benign chronic pemphigus and doxycycline: a review of 6 cases.

BACKGROUND: Hailey-Hailey disease (HHD) or familial benign chronic pemphigus is a rare autosomal dominant inherited skin disorder, characterized by flaccid vesicles and erosions on the intertriginous areas. Current treatments are not particularly effective. We report 6 cases dramatically improving with doxycycline. CASE REPORTS: 6 patients, aged from 33 to 77 years old, presented with a variable 4 to 40 year history of severe treatment-resistant HHD. All 6 patients were then treated successfully with doxycycline 100 mg per day for at least 3 months. DISCUSSION: An improvement was observed in all 6 patients from 1 week to 3 months after the beginning of treatment. Relapses were observed after various periods. Maintenance half-dose therapy seemed to be beneficial in patients experiencing recurrence. Only one patient developed gastro-intestinal intolerance. No other side effects were reported. Currently, 2 patients have improved and present a decreased number of exacerbations, 2 others are in complete remission after more than 5 years of follow-up. Treatment efficiency is difficult to evaluate in HHD as it is a rare condition. No controlled studies have been published. Local treatments may improve inflammation but do not treat the underlying cause, targeted systemic therapies exist but there is little evidence supporting their use, physical treatments are cumbersome. Besides their antibiotic potential, tetracycline antibiotics also have anti-inflammatory properties and anticollagenase activity via inhibition of matrix metalloproteinases. CONCLUSIONS: Doxycycline appears to be an interesting therapeutic option in Hailey-Hailey disease.

Large changes in Pluto's atmosphere as revealed by recent stellar occultations.

Pluto's tenuous nitrogen atmosphere was first detected by the imprint left on the light curve of a star that was occulted by the planet in 1985 (ref. 1), and studied more extensively during a second occultation event in 1988 (refs 2-6). These events are, however, quite rare and Pluto's atmosphere remains poorly understood, as in particular the planet has not yet been visited by a spacecraft. Here we report data from the first occultations by Pluto since 1988. We find that, during the intervening 14 years, there seems to have been a doubling of the atmospheric pressure, a probable seasonal effect on Pluto.

Training-induced improvement in lipid oxidation in type 2 diabetes mellitus is related to alterations in muscle mitochondrial activity. Effect of endurance training in type 2 diabetes.

AIM: We investigated whether or not, in type 2 diabetic (T2D) patients, an individualized training effect on whole-body lipid oxidation would be associated with changes in muscle oxidative capacity. METHODS: Eleven T2D patients participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during graded exercise. Blood samples for measuring blood glucose and free fatty acids during exercise, and muscle oxidative capacity measured from skeletal muscle biopsy (mitochondrial respiration and citrate synthase activity), were investigated in the patients before and after a 10-week individualized training program targeted at LIPOXmax, corresponding to the power at which the highest rate of lipids is oxidized (lipid oxidation at LIPOXmax). RESULTS: Training induced both a shift to a higher-power intensity of LIPOXmax (+9.1+/-4.2W; P<0.05) and an improvement of lipid oxidation at LIPOXmax (+51.27+/-17.93 mg min(-1); P<0.05). The improvement in lipid oxidation was correlated with training-induced improvement in mitochondrial respiration (r=0.78; P<0.01) and citrate synthase activity (r=0.63; P<0.05). CONCLUSION: This study shows that a moderate training protocol targeted at the LIPOXmax in T2D patients improves their ability to oxidize lipids during exercise, and that this improvement is associated with enhanced muscle oxidative capacity.

[Presenting skin disorders in black Afro-Caribbean patients: a multicentre study conducted in the Paris region]. / Motifs de consultation en dermatologie des sujets de peau noire d'origine africaine et antillaise: enquête multicentrique en région parisienne.

BACKGROUND: There have been few studies in France concerning the specific features of dermatological practice regarding dark skin (Fitzpatrick's phototype V and VI) or the special requirements of black African and Afro-Caribbean patients. AIM: To determine the principal reasons for dermatological consultation among black patients of African or Afro-Caribbean descent in the Paris region. METHODS: This was a prospective clinical study conducted between 15 February and 15 May 2004. The diagnoses of cutaneous conditions leading to dermatological consultation for all black patients of phototype V to VI were recorded by 10 dermatologists practicing in 14 centres within the Paris region. LIMITS: The method used did not allow any conclusions to be drawn regarding the incidence of the presenting conditions among the global population nor did it allow comparison between populations of different phototypes. The absence of any preset list of diagnoses or of precise inclusion criteria regarding evaluation of skin colour left individual investigators with a broad margin of interpretation. RESULTS: In 836 adults and 228 children (half of whom were from Africa and half from the West Indies), diagnoses were as follows: acne in 29.2% of adults and 13.2% in children, and eczema in 6.8% of adults and 27.2% of children. Among dermatoses more specific to black subjects, scalp conditions were frequently seen in both adults (alopecia 7% of diagnoses) and children (tinea capitis 9.6% and alopecia 3.6% of diagnoses). In at least 25% of cases, consultation was associated with dyschromia. Clinical signs suggesting the use of skin lightening products were seen in 95 patients. CONCLUSION: In France, as in other industrialized countries, black patients consult dermatologists essentially for common benign dermatoses also seen amongst white people. Nevertheless, it is important to emphasise the presence of skin problems specific to black patients such as dyschromia and pigmentary disorders, hair and scalp dermatoses, and side effects associated with the use of skin lightening products.

[Late diagnosis of a McArdle disease's case (type V glycogenosis)]. / Diagnostic tardif d'une maladie de McArdle (glycogénose de type V).

McArdle's disease is a metabolic myopathy characterized by a myophosphorylase deficiency resulting in an inability to degrade glycogen stores. We report the case of a 48 years old patient who complained since adolescence of rest and exercise myalgias and presented a chronic increased plasma creatine kinase activity. First, a maximal exercise test was performed. This test demonstrated a quasi lack of rise of respiratory exchange ratio and of blood lactate, possibly due to a glycogenolytic/glycolytic pathway deficiency. Second, a biopsy of vastus lateralis muscle was performed using Bergström needle. As expected, the analysis of mitochondrial function was normal. The in vitro screening test of the glycogenolysis/glycolysis pathway showed a lack of lactate production in presence of glycogen substrate. The study of muscular metabolism of glycogen revealed a glycogen accumulation and a decrease of active and total phosphorylase activities. These data allowed us to diagnose a type V glycogenosis, or McArdle's disease. The patient appeared heterozygous for the most frequent mutation (p.R50X).

Substrate oxidation during exercise: type 2 diabetes is associated with a decrease in lipid oxidation and an earlier shift towards carbohydrate utilization.

OBJECTIVES: Exercise is a recommended treatment for type 2 diabetes but the actual pattern of metabolic adaptation to exercise in this disease is poorly known and not taken in account in the protocols used. Metabolic defects involved in the pathways of substrate oxidation were described in type 2 diabetes. We hypothesized that type 2 diabetes, regardless of age, gender, training status and weight, could influence by its own the balance of substrates at exercise. METHODS: 30 sedentary type 2 diabetic subjects and 38 sedentary matched control subjects were recruited. We used exercise calorimetry to determine lipid and carbohydrate oxidation rates. We calculated two parameters quantifying the balance of substrates induced by increasing exercise intensity: the maximal lipid oxidation point (PLipoxMax) and the Crossover point (COP), intensity from which the part of carbohydrate utilization providing energy becomes predominant on lipid oxidation. RESULTS: Lipid oxidation was lower in the diabetic group, independent of exercise intensity. PLipoxMax and COP were lower in the diabetic group [PLipoxMax=25.3+/-1.4% vs. 36.6+/-1.7% %Wmax (P<0.0001)] - COP =24.2+/-2.2% vs. 38.8+/-1.9% %Wmax (P<0.0001). CONCLUSIONS: Type 2 diabetes is associated with a decrease in lipid oxidation at exercise and a shift towards a predominance of carbohydrate oxidation for exercise intensities lower than in control subjects. Taking into account these alterations could provide a basis for personalizing training intensity.

Insulin resistance and associated metabolic abnormalities in muscle: effects of exercise.

Skeletal muscle is a major site of insulin resistance. In addition to glucose transport, oxidative disposal and storage defects, insulin resistant muscle exhibit many other metabolic abnormalities. After a brief review of insulin resistance determinants, we will focus on muscular abnormalities in obesity and type 2 diabetes. Glucose and lipid metabolism defects will be analysed and their interactions discussed. Exercise can improve many of these muscular abnormalities and the mechanisms underlying exercise-induced benefits have been clarified during the past decades. Therefore, exercise training has proved to be useful in the management of insulin resistant states, i.e. mainly obesity, especially in its truncal distribution, and type 2 diabetes. However, exercise prescription remains poorly codified, and results on glycaemic control are sometimes conflicting. In the last part of this review, we will emphasize the pathophysiological basis for an individualized exercise prescription in insulin resistant subjects.

Metachromatic leukodystrophy. Ultrastructural and enzymatic study of a case of variant O form.

A variant of metachromatic leukodystrophy (MLD), Austin disease, is characterized by a multiple isozyme deficiency of arylsulfatase. A 3 1/2-year-old girl with progressive mental and physical deterioration had decreased activities of arylsulfatases A and B in the leukocytes, shown by acylamide gel electrophoresis. Under the electron microscope, biopsy specimens of the brain and the peripheral nerve showed lamellar structures with socalled zebra bodies in the cytoplasmic processes of glial cells, granulo-membranous inclusions with fingerprint configurations in neurons, and myelinlike material in Schwann cells. Results from our study suggest an intricate nature of this dysmetabolic disorder, which shows ultrastructural changes usually seen in classic MLD, a deficiency of arylsulfatase A only, concomitant with those seen in mucopolysaccharidoses such as Hurler and Sanfilippo syndromes.

Relationships between fibrinogen and insulin resistance.

A relationship between plasma fibrinogen levels and insulinemia, as well as the different parameters of the insulin resistance syndrome has been described. The aim of the present paper was to investigate whether plasma fibrinogen concentrations were linked to plasma insulin levels or to the degree of insulin resistance. For this purpose, 62 nondiabetic, nonhypertensive patients, 30 men and 32 women, with body mass indexes (BMIs) and ages ranging from 18.6 to 50.2 kg/m(2) and from 19 to 60 years, respectively, were studied. Insulin sensitivity was quantified by the minimal model procedure over a 180-min intravenous glucose tolerance test with iterative sampling. Plasma insulin was determined by radioimmunoassay without cross-reactivity to human proinsulin, and fibrinogen by the method of Clauss. Insulin sensitivity ranged from 0.009 to 23.2 min(-1)/(microU/ml)x10(-4), covering the whole range of insulin sensitivities. Fibrinogen ranged from 1.70 to 5.07 g/l. There was a significant negative correlation between fibrinogen and insulin sensitivity (r=-0.76,P<0.0001) and a positive correlation between fibrinogen and basal insulin (r=0.56,P<0.0001). After adjustment for BMI, body fat mass and waist-to-hip ratio, these two relationships remained significant. In addition, a multiple regression analysis was performed to assess the independent effect of the following related variables: fibrinogen, insulin sensitivity, insulinemia and BMI. Only insulin sensitivity appeared to account for the ability to predict fibrinogen values. Thus, we hypothesized it was likely that the state of insulin resistance rather than hyperinsulinemia per se was related to hyperfibrinogenemia. We proposed an interpretation of these data in connection with some factors like free fatty acids or tumor necrosis factor-alpha, which have been implicated in the pathogenesis of insulin resistance. Nevertheless, prospective and intervention studies are needed to assess whether there is a simple association or a causal relationship between insulin resistance and hyperfibrinogenemia.

Streptozotocin-induced diabetes decreases rat sarcolemmal lactate transport.

Impaired lactate metabolism is a metabolic disorder, which is not fully understood in the diabetic state including streptozotocin (STZ)-induced diabetes. We investigated whether STZ-induced diabetes results in altered lactate exchanges using the rat muscle sarcolemmal vesicles (SV) model. Fifteen days after diabetes onset (1 STZ-injection, 65 mg/kg, intraperitoneal [IP]), rats had higher blood and muscle lactate concentrations compared with normal rats (1.50 +/- 0.09 v 1.95 +/- 0.21 mmol/L (not significant [NS]) and 21.02 +/- 1.26 v 25.53 +/- 0.98 mmol/kg wet weight (ww); P < .05). The initial rate of lactate uptake was measured at various external lactate concentrations using SV of both group in zero-trans conditions. STZ-induced diabetes decreased the initial rate of total lactate influx at external lactate concentrations from 1 to 100 mmol/L (P < .05). This decrease in lactate transport was found in addition to an increased free radical production, as indicated by a significant increase in malonedialdehyde (MDA) concentration (64.3 +/- 8.7 v 100.3 +/- 13.5 nmol. g(-1) ww, P < .05), coupled with a higher glutathione peroxidase (Gpx) activity (48.03 +/- 3.13 v 84.7 +/- 15.01 micromol. min(-1). mg(-1) protein, P < .05) in red gastrocnemius. We concluded that STZ-induced diabetes decreases total lactate transport activity in rat SV and is associated with increased muscular oxidative stress.

Relationships between maximal muscle oxidative capacity and blood lactate removal after supramaximal exercise and fatigue indexes in humans.

The present study investigated whether blood lactate removal after supramaximal exercise and fatigue indexes measured during continuous and intermittent supramaximal exercises are related to the maximal muscle oxidative capacity in humans with different training status. Lactate recovery curves were obtained after a 1-min all-out exercise. A biexponential time function was then used to determine the velocity constant of the slow phase (gamma(2)), which denoted the blood lactate removal ability. Fatigue indexes were calculated during all-out (FI(AO)) and repeated 10-s cycling sprints (FI(Sprint)). Biopsies were taken from the vastus lateralis muscle, and maximal ADP-stimulated mitochondrial respiration (V(max)) was evaluated in an oxygraph cell on saponin-permeabilized muscle fibers with pyruvate + malate and glutamate + malate as substrates. Significant relationships were found between gamma(2) and pyruvate + malate V(max) (r = 0.60, P < 0.05), gamma(2) and glutamate + malate V(max) (r = 0.66, P < 0.01), and gamma(2) and citrate synthase activity (r = 0.76, P < 0.01). In addition, gamma(2), glutamate + malate V(max), and pyruvate + malate V(max) were related to FI(AO) (gamma(2) - FI(AO): r = 0.85; P < 0.01; glutamate + malate V(max) - FI(AO): r = 0.70, P < 0.01; and pyruvate + malate V(max) - FI(AO): r = 0.63, P < 0.01) and FI(Sprint) (gamma(2) - FI(Sprint): r = 0.74, P < 0.01; glutamate + malate V(max) - FI(Sprint): r = 0.64, P < 0.01; and pyruvate + malate V(max) - FI(Sprint): r = 0.46, P < 0.01). In conclusion, these results suggested that the maximal muscle oxidative capacity was related to blood lactate removal ability after a 1-min all-out test. Moreover, maximal muscle oxidative capacity and blood lactate removal ability were associated with the delay in the fatigue observed during continuous and intermittent supramaximal exercises in well-trained subjects.

[Interrelation of visceral fat and muscle mass in non insulin-dependent diabetes (type II): practical implications]. / Interrelation de la masse grasse viscérale et du muscle dans le diabète non insulino-dépendant (type II): implications pratiques.

Insulin resistance, which is found in 85-95% of non-insulin-dependent diabetes mellitus (NIDDM) patients, results from three factors: genetic background (which has been widely investigated), nutritional status (mostly obesity and fat distribution) and exercise. Upper body obesity, which can be found in 85% of these subjects, can increase muscular insulin resistance through several mechanisms, the best known being a free fatty acid-induced decrease in intracellular free CoA/acylCoA that inhibits the stimulatory effect of insulin on glycolysis, glucose transport across cell membrane, and glycogen storage. However, muscle insulin resistance in NIDDM exists before adiposity and is likely to induce it. Actually, muscles of subjects at risk for NIDDM exhibit a very early defect in both glycogen storage ability and free fatty acid oxidation capacity that can impair fuel utilization and increase fat storage. Regular exercise induces muscular metabolic changes which can compensate for those diabetogenic defects and thus prove useful in the management of NIDDM. Moreover, exercise has been shown to prevent subjects at risk for NIDDM from developing overt diabetes.

Balance of substrate oxidation during submaximal exercise in lean and obese people.

OBJECTIVES: To compare fat and carbohydrate oxidation at different exercise intensities between overweight and normal-weight subjects, in order to analyze the influence of muscular metabolic abnormalities in obese people on substrate utilization during exercise. MATERIAL AND METHODS: 32 healthy sedentary overweight subjects (Body Mass Index (BMI): 30.8 +/- 0.8 kg/m(2); body fat: 37.4 +/- 1.1%; mean +/- SEM) and 26 controls (BMI: 23 +/- 0.4 kg/m(2); body fat: 22.7 +/- 1.1%) matched for age and sex were examined. The test consisted in four six-min. submaximal steady-state workloads with calculation of substrate oxidation rates and derived quantitative parameters, i.e., crossover point (defined as the power at which carbohydrate-derived energy becomes predominant) and maximal fat oxidation rate point. In addition, the accuracy of the test was analyzed and was found to be satisfactory. RESULTS: While exercise intensities were similar in both group, fat oxidation rates were significantly lower in overweight group (p<0.05). The crossover and the maximal fat oxidation rate points were significantly lower in overweight subjects than in controls: 33.3 +/- 2 vs 50.1 +/- 3.4% and 30.5 +/- 2.3 vs 44.6 +/- 3.3% of maximal aerobic power, respectively (p<0.001). CONCLUSION: Sedentary overweight subjects, compared to controls at the same exercise intensities, exhibited an alteration of the balance of substrate oxidation, reflected by lower rates of fat oxidation and a shift of quantitative parameters to lower intensities. The test appeared to be reliable and could be of interest to advise an individualized exercise prescription in obese people.

Glucocorticoid receptor concentrations in human lung at different growth stages.

We measured glucocorticoid receptor concentrations in human lung at different stages of alveolar growth. Lung tissue was obtained from 9 surgically aborted or stillborn fetuses of 15 to 28 weeks gestational age, and from 6 infants and children, aged 2 months to 9 years, after lobar resection or at autopsy. Samples were taken from macroscopically healthy areas. Lung histology was performed in all cases. The receptor assay was done by establishing saturation curves for labeled dexamethasone in the absence or presence of a hundredfold excess of unlabeled dexamethasone. Total binding capacity and the dissociation constant were calculated from the saturation curves by the method of Scatchard. The receptor concentration in the fetuses was high (182 +/- 88 fmol/mg prot.), irrespective of gestational age. The lowest concentration (35 fmol/mg prot.) was found in a fetus with pulmonary hypoplasia. In the infants and children the mean receptor concentration was significantly lower (14.6 +/- 9.9 fmol/mg prot.); these included a case of sudden death in which the parenchymal structure was normal.

Cerebrospinal fluid cytomorphology in neonates.

A prospective cytologic study of cerebrospinal fluids from 57 full-term neonates confirmed the previously reported cellular polymorphism. The cells were classified as (1) exogenous cells, (2) blood and bone-marrow cells, (3) histiomonocytes, (4) cell aggregates and (5) "free" cells. Histiomonocytes were a constant feature in these fluids and were the cause of neonatal pleiocytosis. Various degrees of activation could be recognized. The so-called inactive forms were closely related to brain damage. Identification of erythrophages and siderophages had diagnostic significance. The presence of fat in macrophages (lipophages) suggested a serious developmental disorder. The free cells were incompletely identified, as were the cell aggregates, which probably originate in the meningeal lining. Both require further study.

Relationships among body composition, hemorheology and exercise performance in rugbymen.

We investigated relationships among body composition, blood rheology, and exercise performance in 14 rugbymen (19-31 yr, weight 65.8-109.2 kg, height 1.7-1.96 m, body mass index 21.7-33.1 kg/m2) who underwent a standardized submaximal exercise session on cycloergometer corresponding to 225 kJ over 30 min. The rheologic response to exercise was measured with the MT90 viscometer and the Myrenne aggregometer. Dehydration, evaluated by precision weighing, resulted in a loss of 360 to 973 g water, i.e., 1.69 to 4.32 g/kJ. This loss of water is not correlated to plasma volume contraction as assessed by the equation of Greenleaf. Hemorheologic changes are observed, but they are correlated neither to water loss, nor to plasma volume contraction. A 36% increase in blood viscosity (p < 0.01) is mainly explained by a red blood cell rigidification (p < 0.02), although hematocrit and plasma viscosity also increase (p < 0.01). Isometric adductor strength (specific ergometer) is correlated to erythrocyte flexibility (r = 0.680, p < 0.01). Red cell aggregability (Myrenne aggregometer) is correlated to fat mass measured by bioelectrical impedance (r = 0.634, p < 0.02). Aerobic working capacity index W170 is negatively correlated to the increase in plasma viscosity during exercise (r = -0.546, p < 0.05), suggesting that this event is less important in stronger individuals. This study shows that fat mass, even within a physiological range, is a determinant of erythrocyte aggregability, suggesting that training-induced alterations in body composition play a role in the specific hemorheologic profile of athletes. In addition, both erythrocyte flexibility and the magnitude of fluid shifts during exercise appear to be related to fitness in these sportsmen.

Negative correlation between plasma fibrinogen and insulin sensitivity measured with the minimal model technique.

We aimed at investigating relationship between plasma fibrinogen and insulin sensitivity, which are two major determinants of metabolic Syndrome X (insulin resistance syndrome). We designed a prospective study of 27 non-diabetic, non-hypertensive subjects, presenting a wide range of body mass index BMI (10 men, 17 women; mean age+/-SEM: 35.9+/-2.2 years; BMI ranging from 21.1-45.2 kg/m2). Insulin sensitivity was assessed with the minimal model procedure, over a 180 min intravenous glucose tolerance test with iterative sampling. Fibrinogen levels were determined by the method of Clauss. The insulin sensitivity index SI (i.e., the slope of the dose-response relationship between insulin increased above baseline and glucose disposal) ranged from 0.0009 to 16 x 10(-4) min(-1)/(microU/ml), with a mean value of 4.76+/-0.73 x 10(-4). Mean values of plasma fibrinogen were 3.33+/-0.13 g/l, ranging from 2.21 to 5.07 g/l. There were highly significant negative correlations between SI and the level of plasma fibrinogen (r = -0.61, p = 0.0007) and between the basal effect of insulin BIE and plasma fibrinogen (r = -0.521, p = 0.005). Basal insulin was positively correlated to fibrinogen (r = 0.386, p = 0.046). When we analysed the data using partial correlation analysis, the negative relation between SI and fibrinogen was maintained independently from BMI (r = -0.45, p < 0.05). These data establish a strong negative association between insulin sensitivity and fibrinogen, involved in the increased cardiovascular risk of metabolic Syndrome X.

The triphasic effects of exercise on blood rheology: which relevance to physiology and pathophysiology?

The life-extending effects of regular exercise are related to a decrease in both coronary and peripheral vascular morbidity, associated with some improvements in cardiovascular risk factors. A possible link between the beneficial metabolic and hemodynamic effects of exercise could be blood rheology, which is markedly affected by exercise. We propose here a description of the hemorheological effects of exercise as a triphasic phenomenon. Short-term effects of exercise are an increase in blood viscosity resulting from both fluid shifts and alterations of erythrocyte rheologic properties (rigidity and aggregability). Increased blood lactate, stress, and acute phase play a role in this process. Middle-term effects of regular exercise are a reversal of these acute effects with an increase in blood fluidity, explained by plasma volume expansion (autohemodilution) that lowers both plasma viscosity and hematocrit. Long-term effects further improve blood fluidity, parallel with the classical training-induced hormonal and metabolic alterations. While body composition, blood lipid pattern, and fibrinogen improve (thus decreasing plasma viscosity), erythrocyte metabolic and rheologic properties are modified, with a reduction in aggregability and rigidity. On the whole, these improvements reflect a reversal of the so-called "insulin-resistance syndrome" induced by a sedentary lifestyle. Since impaired blood rheology has been demonstrated to be at risk for vascular diseases, the hemorheologic effects of exercise can be hypothesized to be a mechanism (or at least a marker) of risk reversal. This latter point requires further investigation. The physiological meaning of the triphasic pattern of exercise-induced alterations of blood rheology is uncompletely understood, but increased blood fluidity may improve several steps of oxygen transfer to muscle, as clearly demonstrated in hypoxic conditions. Increasing evidence emerges from the literature, that blood fluidity is a physiological determinant of fitness.