Time course of hemorheological alterations after heavy anaerobic exercise in untrained human subjects

Mild haemorheological changes induced by a moderate endurance exercise in patients with sickle cell anaemia

The levels and duration of physical activity that can be considered as completely safe in patients with sickle cell anaemia (SCA) is unknown. The present study compared the haemorheological and haematological profile, cell density distribution and basic biochemistry between a group of 17 patients with SCA and 21 healthy subjects before and after a 20 min duration submaximal cycling exercise at the same absolute workload. Blood was sampled at rest and 3 min after the end of exercise for measurement of biological parameters. Exercise did not affect the haematocrit and blood viscosity in the two groups. Plasma viscosity was not different between the two groups at rest and similarly increased with exercise. The proportion of intermediary dense cells (with density between 1·11 and 1·12 g/ml) decreased with exercise in the SCA group resulting in an increase in the proportion of red blood cells with a density >1·12 g/ml. No change was observed in the control group. The present study suggests that mild-moderate exercise is not very harmful for SCA patients. The haemorheological and haematological changes were very mild, except for the formation of dense cells but no clinically significant signs of medical complication were present in any of the patients.

Increased hematocrit after applications of conducted energy weapons (including TASER(®) devices) to Sus scrofa

Conducted energy weapons (CEWs) are used by law enforcement personnel to incapacitate individuals quickly and effectively, without intending to cause lethality. CEWs have been deployed for relatively long or repeated exposures in some cases. In laboratory animal models, central venous hematocrit has increased significantly after CEW exposure. Even limited applications (e.g., three 5-sec applications) resulted in statistically significant increases in hematocrit. Preexposure hematocrit was significantly higher in nonsurvivors versus survivors after more extreme CEW applications. The purpose of this technical note is to address specific questions that may be generated when examining these results. Comparisons among results of CEW applications, other electrical muscle stimulation, and exercise/voluntary muscle contraction are included. The anesthetized swine appears to be an acceptable animal model for studying changes in hematocrit and associated red blood cell changes. Potential detrimental effects of increased hematocrit, and considerations during law enforcement use, are discussed.

Does repeated and heavy exercise impair blood rheology in carriers of sickle cell trait?

OBJECTIVE

To determine if the time courses of hemorheologic parameters are different between carriers of sickle cell trait (SCT) and subjects with normal hemoglobin in response to exercise.

DESIGN

Observational and comparative study.

SETTING

Testing was conducted in a laboratory of exercise physiology.

PARTICIPANTS

Nine carriers of sickle cell trait (SCT group) and 7 subjects with normal hemoglobin (CONT group) performed an exercise protocol of the repetition of 3 successive maximal ramp exercise tests.

INTERVENTIONS

Blood was sampled at rest (TR), at the end of each of the 3 tests (T1, T2, T3), and during the immediate (T2h) and late (T24h, T48h) recovery periods.

MAIN OUTCOME MEASUREMENTS

Blood and plasma viscosity (etab and etap, respectively), hematocrit (Hct), and red blood cell (RBC) rigidity (Tk and k indexes) were determined.

RESULTS

In both groups, etab significantly increased in response to exercise but the SCT group had significantly higher etab at T3 and T2h. etab then returned to baseline value at T2h in the CONT group and at T24h in the SCT group. Tk and k were not changed by exercise but significantly increased above baseline value in both groups at T24h and T48h. The increase in Tk and k during late recovery was higher in the SCT group than in the CONT group, indicating that SCT carriers had significantly higher RBC rigidity than the CONT group at that time.

CONCLUSIONS

The hemorheologic changes induced by exercise in the SCT carriers could trigger microcirculatory disorders during the recovery.

Effects of short supramaximal exercise on hemorheology in sickle cell trait carriers

This study compared the hemorheological profile at rest and in response to a short supramaximal exercise test between sickle cell trait (SCT) carriers and a control group. Eight SCT carriers and eight control subjects performed a ramp exercise test on a cycle ergometer conducted to maximal oxygen uptake (VO2max). One week later, they performed a supramaximal exercise test consisting of pedaling for 1 min at 110% VO2max. Blood viscosity (eta(b)), plasma viscosity (eta(p)), hematocrit (Hct) and red blood cell (RBC) rigidity were assessed at rest, at the end of exercise and at the 15th, 30th and 60th min of recovery. Exercise increased eta(b), eta(p) and Hct above resting values in both groups and these parameters remained higher until the 15th or 30th min of recovery as compared to resting values. RBC rigidity was unchanged from baseline values in both groups during exercise and recovery. No difference was observed between the two groups for eta(p) and Hct but eta(b) and RBC rigidity were higher in the SCT carriers at every time point compared with the control group. The higher RBC rigidity and eta(b) found in SCT carriers at rest and in response to a brief supramaximal exercise might constitute a risk factor for microcirculatory complications. Indeed, a short supramaximal exercise test may not be completely inoffensive for SCT carriers.

Hemorheology, Sickle Cell Trait, and α-Thalassemia in Athletes: Effects of Exercise

PURPOSE

This study investigated hemorheological parameters in response to exercise in sickle cell trait (SCT) athletes with or without alpha-thalassemia

METHODS

Six athletes with SCT (HbAS), 7 athletes with SCT and alpha-thalassemia (HbASAT), and 10 control athletes (HbAA) performed a progressive and maximal exercise test on cycloergometer. Blood viscosity (etab), plasma viscosity (etap), etab at corrected hematocrit (etab45), hematocrit (Hct), and red blood cell (RBC) rigidity were assessed at rest, at maximal exercise and 24 h after exercise

RESULTS

etab and etap were not different between the three groups at any time. Exercise induced changes in etab in HbAA and HbASAT groups but not in HbAS group. etab45 was higher in HbAS group compared with the other groups (P < 0.05), at rest and 24 h after exercise and increased only in HbAA group in response to exercise. HbAS group had lower Hct than HbAA group at any time. Hct and etap increased after exercise and declined under baseline values 24 h after exercise in all groups. RBC rigidity was higher in HbAS group compared with HbAA and HbASAT groups at any time, and was lower and higher at maximal exercise and 24 h after exercise, respectively, in all groups compared with resting values

CONCLUSIONS

These results demonstrate that HbAS group is prone to higher RBC rigidity, which might lead to hemorheological alterations that are thought to participate to microcirculation disorders. However, these alterations are limited by the coexistence of alpha-thalassemia. Moreover, hemorheological parameters were not further impaired in SCT athletes with or without alpha-thalassemia in response to exercise. Training status might be protective from physiological stresses usually leading to sickling process in SCT carriers.

Exercise-induced oxidative stress leads hemolysis in sedentary but not trained humans

Intravascular hemolysis is one of the most emphasized mechanisms for destruction of erythrocytes during and after physical activity. Exercise-induced oxidative stress has been proposed among the different factors for explaining exercise-induced hemolysis. The validity of oxidative stress following exhaustive cycling exercise on erythrocyte damage was investigated in sedentary and trained subjects before and after antioxidant vitamin treatment (A, C, and E) for 2 mo. Exercise induced a significant increase in thiobarbituric acid-reactive substance and protein carbonyl content levels in sedentary subjects and resulted in an increase of osmotic fragility and decrease in deformability of erythrocytes, accompanied by signs for intravascular hemolysis (increase in plasma hemoglobin concentration and decrease in haptoglobulin levels). Administration of antioxidant vitamins for 2 mo prevented exercise-induced oxidative stress (thiobarbituric acid-reactive substance, protein carbonyl content) and deleterious effects of exhaustive exercise on erythrocytes in sedentary subjects. Trained subjects' erythrocyte responses to exercise were different from those of sedentary subjects before antioxidant vitamin treatment. Osmotic fragility and deformability of erythrocytes, plasma hemoglobin concentration, and haptoglobulin levels were not changed after exercise, although the increased oxidative stress was observed in trained subjects. After antioxidant vitamin treatment, functional and structural parameters of erythrocytes were not altered in the trained group, but exercise-induced oxidative stress was prevented. Increased percentage of young erythrocyte populations was determined in trained subjects by density separation of erythrocytes. These findings suggest that the exercise-induced oxidative stress may contribute to exercise-induced hemolysis in sedentary humans.

Effect of antioxidant vitamin treatment on the time course of hematological and hemorheological alterations after an exhausting exercise episode in human subjects

This study examined the effects of a 2-mo antioxidant vitamin treatment on acute hematological and hemorheological alterations induced by exhausting exercise; both sedentary and trained individuals were employed. Eighteen young male, human subjects (9 sedentary, 9 trained by regular exercise) participated in the study and performed an initial maximal aerobic cycle ergometer exercise with frequent blood sampling over a 24-h period and analysis of hematological and hemorheological parameters. All subjects were treated with an antioxidant vitamin A, C, and E regimen, supplemented orally for 2 mo, and then subjected to a second exercise test and blood sampling at the end of this period. In the sedentary group during the first testing period (before vitamin treatment), white blood cell counts and granulocyte percentages were increased at 2 h after the exercise test and remained elevated for 4-12 h. Red blood cell (RBC) deformability and aggregation were also altered by exercise in the sedentary group before vitamin treatment. However, none of these parameters in the sedentary group were altered by exercise after the 2-mo period of antioxidant vitamin treatment. With the exception of a transient rise in granulocyte percentage, these parameters were also not affected in the trained subjects before the vitamin treatment. Significant increases of RBC lipid peroxidation observed 12 h after the exercise test in both sedentary and trained subjects were also totally prevented by vitamin treatment. Our results indicate that antioxidant vitamin treatment is effective in preventing the inflammation-like response and coincident adverse hemorheological changes after an episode of exhausting exercise, and suggest that such changes may be related to exercise-induced death events.