Regular ArticleExercise intensity: Platelet function and platelet–leukocyte conjugate formation in untrained subjects
Introduction
It has been confirmed in different studies that physical exercise influences platelet function and platelet leukocyte interaction as well as blood coagulation and fibrinolysis [1], [2], [3], [4]. Studies have pointed to an association between exercise and a risk of cardiovascular events [5], [6], often however without a clear differentiation of the types of exercise done. Because duration as well as intensity are the main factors which define a type of exercise, more precise descriptions of the particular exercise intervention is mandatory. Although only few studies have investigated platelet function after different types of exercise, in particular, the investigations of Wang et al. have demonstrate the diverse effects of different exercise intensities on platelet function [7], [8], [9]. These studies have shown that strenuous exercise enhances platelet activity while moderate exercise suppresses platelet function. However, these specific effects of moderate exercise have not yet been confirmed in other studies [3], [10], [11], [12], [13], [14]. Different factors complicate a convenient comparison of the available results. For example, various methods are used to control the exercise program. In addition, different methods are used to measure platelet function with a wide range of multiple laboratory analyses from use of in vivo markers such as β-thromboglobulin and platelet factor 4, to aggregation and adhesion tests, to various other techniques such as the flow cytometry. The reason is, that clear and accepted standards for the evaluation of platelet function, to enable convenient comparability of the different methods are still lacking. Therefore the results of these different laboratory methods are not always in line, making the interpretation more complex.
The aim of the present study was to investigate platelet function and platelets leukocyte interaction as well as changes in microparticles and aggregates after standardised exercises at 80 and 100% of the individual anaerobic threshold (IAT) for 60 min which corresponds approximately in our case with 57 and 69% of the peak oxygen consumption (peak VO2) in mean. These exercise intensities correlate to a strenuous (100%) and a moderate exercise (80%); moderate exercise is recommended for prevention or rehabilitation training. This part of the study, focussing on platelet function, should help to clarify the following: (a) does moderate exercise increase platelet function or not, (b) platelet leukocyte interaction and (c) the number of microparticles or aggregates in comparison with strenuous exercise in healthy untrained participants. For the investigation of these questions a standardised flow cytometric technique was used to analyse platelet function on their direct surface in whole blood avoiding any artificial effects during the preparation of the platelets as much as possible.
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Subjects
Twenty-five healthy untrained non-smoking males were included in the study. Two participants did not take part in the second test and three discontinued the second test before 45 min. Three subjects ended their second trial between 45 and 60 min whereas the other participants finished both exercises precisely after 60 min and these 20 were included to the study group which was further investigated. The main characteristics, anthropometric and performance data of the 20 subjects are shown in
Exercise performance, heart rates, metabolic and control data
Performance, heart rate and metabolic data are shown in Table 1. These data underline the diverse effects of the different exercise intensities on the cardiac and metabolic system. The exercise intensities of 80 and 100% of the individual anaerobic threshold corresponded to 57 and 69% of the peak VO2 of this intervention group on average, which can be defined as a moderate, and strenuous, exercise. The norepinephrine concentration was intensity dependent increased after exercise whereas the
Discussion
Physical exercise can increase the risk of cardiovascular events as described in several publications, yet on the other hand is also recommended to prevent such events [5], [6]. Numerous authors have suggested the importance of the exercise intensity in this respect. However which intensity level may be borderline dangerous and which intensity is most optimal for prevention and rehabilitation training remains to be clarified. There are currently only few studies on this topic including
Conclusion
It can be summarized from our study, that a) moderate exercise enhances platelet activity and reactivity, b) yet moderate exercise intensity results in a significantly lower increase in conjugate formation compared to strenuous exercise, and that c) aggregates are enhanced after both exercises after TRAP stimulation.
Based on these results, it is recommended that the IAT should be improved in order for everyone to be in the position to carry out daily activities and also to exercise well below
Acknowledgements
The authors thank Mrs. B. Tauch, Mrs. S. Hörnlein and Mr. M. Soßdorf for their excellent assistance, and the management of POM (Planet of motion) for the support of the study.
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