Der Einfluss der erythrozytären Verformbarkeit auf die Ausdauerleistungsfähigkeit

Publication: Book/ReportDissertations

Abstract

Introduction: The major function of erythrocytes (red blood cells, RBC) is to deliver oxygen from the lungs to organs and to deliver of carbon dioxide from the organs back to the lungs. One of the main characteristics of RBC is their ability to deform themselves, which is necessary to pass smallest capillaries in the microcirculation as they often possess a smaller diameter than the RBC themselves. Hence, only highly deformable RBC can provide sufficient oxy-gen to muscles and guarantee optimal performance. Therefore, the overall objective of this thesis was to examine to what extent RBC deformability determines aerobic perfor-mance. In the separate studies it was investigated whether the aerobic capacity of the subjects influences the age structure and deformability of RBC. Further, we examined the effects of acute running modes and of a six-week running intervention on RBC age struc-ture and deformability. Moreover, we examined the effects of chronic performance orien-tated training as done by elite athletes on RBC deformability. Lastly we tried to acutely increase RBC deformability and to evaluate whether this increase in RBC deformability correlates with improved performance. Methods and results: 27 differently trained male subjects participated in study 1. After conducting a pre-experimental test with spirometric measurements, subjects were grouped into three groups in accordance to their aerobic capacity. Then all subjects conducted two different running protocols. Before and immediately after the exercise venous blood was sampled. RBC were separated by cell-age via Percoll density gradient centrifugation. The relative amount of the subfractions was calculated and RBC deformability of the entire RBC sample and of fractionated RBC was measured using ektacytometry (LORCA). The theoretical max-imal elongation index at infinite shear stress (EImax) was calculated. Results show that base-line RBC deformability is positively correlated with VO2peak and maximum running velocity of the subjects. Highly trained subjects possess 20% young RBC which was twice as much compared to untrained and normally trained subjects. In response to the acute running modes, no change in RBC deformability neither of the entire RBC population nor of the subfractions has been detected. This has been observed in all three subject groups. 31 areobically untrained male and female subjects participated in study 2 and conducted a six-week endurance intervention. Pre and post intervention, spirometric performance diagnostics with lactate measurements were performed and blood was sampled under fasting conditions. In this study, we evaluated hematological parameters as well as the nitrite concentration that was measured as a marker of RBC nitrite oxide (NO) concentra-tion using a chemiluminescence detector (CLD). In addition, RBC deformability was evalu-ated using EImax as well as the shear stress that is necessary to reach half-maximum defor-mation (SS1/2). Besides, the ratio SS1/2/ EImax (EIRatio) was calculated. Low values in SS1/2 and EIRatio represent improved RBC deformability. Results show that the intervention resulted in a higher amount of young RBC as well as more efficient middle-old RBC. The RBC NO metabolism decreased in the entire RBC population as well as in subfractions. RBC de-formability (EImax) decreased in the entire RBC population. However, SS1/2 and EIRatio de-creased showing an improvement in RBC function of the overall RBC population. The in-tervention further resulted in improved aerobic capacity (VO2peak) and a more economic lactate-metabolism. 182 male and female elite athletes were recruited in study 3. RBC deformability (EImax, SS1/2, and EIRatio) was measured using capillary blood samples. Results show that no differ-ence between male and female athletes is observed in RBC deformability. RBC deforma-bility increases during puberty up to adult age, especially in male athletes. The performed sport type affected RBC deformability. Athletes performing aerobic dominant sport types showed a higher RBC deformability compared to strength dominant sport types. 10 male subjects participated in study 4. In a single-blind, crossover, and randomized con-trol study they conducted a remote ischemic preconditioning (rIPC) manoeuvre with a subsequent ergometer testing with lactate diagnostics. Further, RBC deformability (EImax) was evaluated. With respect to the entire subject sample, results show that the rIPC ma-noeuvre had neither an effect on any performance parameter nor on RBC deformability. However, five subjects showed a higher power (>10%) at the 2 mmol/l lactate threshold when the rIPC manoeuvre preceded the exercise, compared to the control situation. In these “responders”, RBC deformability also improved. Hence, a potential connection be-tween an acute increase in RBC deformability and improved submaximal performance could be observed. Conclusions: With the above mentioned four studies we were able to demonstrate that RBC deforma-bility is positively correlated with aerobic performance, which can in part be explained by the increased turnover and the associated higher amount of young RBC. Acute running does not induce changes in RBC deformability. However, a six-week running intervention led to positive adaptations in the RBC age structure and function. This was manifested in a rejuvenation of the RBC population, an increase in efficiency in the NO metabolism and positive changes in SS1/2 and EIRatio. Though, EImax of the entire RBC population decreased probably due to the higher amount of less deformable young RBC. Chronic performance orientated aerobic training led to higher RBC deformability compared to strength domi-nant training. RBC deformability increased, especially in male athletes, during puberty up to adult age, which might be explained by an increased influx of androgens in this age period. Overall, no difference in RBC deformability was observed between male and fe-male athletes in this study. Further, we were able to present a potentially positive con-nection between an acute increase in RBC deformability, induced via a rIPC manoeuvre, and an improved submaximal performance. Yet, this phenomenon was only observed in “responders” and needs to be confirmed in a larger study population. All studies of this doctoral thesis provide a deeper insight and more detailed knowledge into the RBC func-tion in the context of physical performance. An optimal and improved RBC function that goes along with a high deformability can therefore be seen as major determinant of physi-cal performance especially in aerobic endurance situations.  
Original languageGerman
Place of PublicationKöln
PublisherDeutsche Sporthochschule Köln
Number of pages42
Publication statusPublished - 2018

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