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The current study analyzes the suitability and reliability of selected neurophysiological and vegetative nervous system markers as biomarkers for exercise and recovery in endurance sport. Sixty-two healthy men and women, endurance trained and moderately trained, performed two identical acute endurance tests (running trial 1 and running trial 2) followed by a washout period of four weeks. Exercise protocol consisted of an acute running trial lasting 60 minutes. An intensity corresponding to 95% of the heart rate at individual anaerobic threshold for 40 minutes was followed by 20 minutes at 110%. At pre-exercise, post-exercise, three hours post-exercise and 24 hours post-exercise, experimental diagnostics on Brain-derived neurotrophic factor (BDNF), heart rate variability (HRV), Stroop Color and Word Test (SCWT), and Short-Form McGill Pain Questionnaire (SF-MPQ) were performed. Significant changes over time were found for all parameters ( p < .05). Furthermore, there was an approached statistical significance in the interaction between gender and training status in BDNF regulation (F (3) = 2.43; p = 0.06), while gender differences were found only for LF/HF-ratio (3hPoEx, F (3) = 3.40; p = 0.002). Regarding the reliability, poor ICC-values (< 0.5) were found for BDNF, Stroop sensitivity and pNN50, while all other parameters showed moderate ICC-values (0.5-0.75). Plasma-BDNF, SCWT performance, pain perception and all HRV parameters are suitable exercise-sensitive markers after an acute endurance exercise. Moreover, pain perception, SCWT reaction time and all HRV parameters show a moderate reliability, others rather poor. In summary, a selected neurophysiological and vegetative marker panel can be used to determine exercise load and recovery in endurance sports, but its repeatability is limited due to its vaguely reliability., (© Journal of Sports Science and Medicine.)

There is currently insufficient evidence about the reliable quantification of exercise load and athlete's recovery management for monitoring training processes. Therefore, this test-retest study investigated the reliability of various subjective, muscle force, and blood-based parameters in order to evaluate their suitability for monitoring exercise and recovery cycles. 62 subjects completed two identical 60-min continuous endurance exercise bouts intermitted by a four-week recovery period. Before, immediately after, three, and 24 h after each exercise bout, analysis of parameters were performed. Significant changes over time were found for rating of perceived exertion (RPE), multidimensional mood state questionnaire (MDMQ), maximum voluntary contraction parameters (MVCs), and blood-based biomarkers (p < 0.05). Excellent reliability was calculated for MVCs, mean corpuscular volume and 5-bound distance (ICC > 0.90). A good reliability was found for thiobarbituric acid reactive substances (TBARS) (ICC = 0.79) and haematological markers (ICC = 0.75-0.86). For RPE, MDMQ, interleukin (IL-) 1RA, IL-6, IL-8, IL-15, cortisol, lactate dehydrogenase (LDH), creatine kinase (CK) only moderate reliability was found (ICC < 0.75). Significant associations for IL1-RA and CK to MVC were found. The excellent to moderate reliability of TBARS, LDH, IL-1RA, six measured haematological markers, MVCs and MDMQ implicate their suitability as physiological exercise response and recovery markers for monitoring athletes' load management.

Objective: To investigate the acute effects of high-intensity exercise on blood hepcidin levels and other iron metabolic and hematological parameters in highly trained athletes of dragon boating as a sport performed in a sitting position., Methods: We conducted an exercise intervention study with a pre- and posttest blood measurement to determine the effects of high-intensity training on hematological and iron metabolic parameters in both male (n = 19) and female (n = 12) elite athletes of the German national dragon boating team. The study took place during the final training camp before the European championships. Blood samples were collected at baseline and 3 h after 3 consecutive high-intensity training bouts at the same day, each one lasting 1 h in duration., Results: After exercise, leukocytes, CPK, CKMB, and hepcidin levels increased significantly both in men and women. In contrast, iron concentrations decreased significantly. No gender-related differences were found. Compared with baseline, the postexercise concentrations of serum iron decreased significantly both in men [99.3 ± 46.3 to 61.2 ± 20.9 µg/dL (p < 0.001)] and in women [116.3 ± 34 to 67.1 ± 21.8 µg/dL (p < 0.001)] without a gender difference (p = 0.28). Hepcidin levels increased significantly both in men [9.1 ± 6.5 to 12.2 ± 5.8 ng/mL (p < 0.001)] and in women [8.0 ± 4.6 to 11.7 ± 5.7 ng/mL (p < 0.001)] without a significant gender difference in hepcidin changes (p = 0.34)., Conclusions: In conclusion, three consecutive high-intensity training bouts lead to elevated hepcidin levels and decreased iron levels in elite athletes of dragon boating. The increase in hepcidin levels may contribute to the risk of anemia in these athletes.

Introduction: High-intensity interval training (HIT) exercise has gained much interest in both performance and recreational sports. This study aims to compare the effect of HIT versus continuous (CONT) exercise with regard to changes of circulating T cells and progenitor cells., Methods: Subjects (n = 23) completed an HIT test and an isocaloric CONT test. Blood samples were collected before, immediately after, and 3 and 24 h postexercise for the assessment of low differentiated (CD3CD28CD57), highly differentiated T cells (CD3CD28CD57), regulatory T cells (Tregs) (CD4CD25CD127), hematopoietic progenitor cells (CD45CD34), and endothelial progenitor cells (CD45CD34KDR) by flow cytometry. The detection of apoptosis was performed by using labeling with annexin V. To analyze potential mechanisms affecting T cells, several hormones and metabolites were analyzed., Results: Both exercise tests induced an increase of catecholamines, cortisol, and thiobarbituric acid-reactive substances (P < 0.05). CONT induced a higher increase of apoptosis in low differentiated T cells compared with the HIT (CONT: 3.66% ± 0.21% to 6.48% ± 0.29%, P < 0.05; HIT: 3.43% ± 0.31% to 4.71% ± 0.33%), whereas HIT was followed by a higher rate of apoptotic highly differentiated T cells (CONT: 21.45% ± 1.23% to 25.32% ± 1.67%; HIT: 22.45% ± 1.37% to 27.12% ± 1.76%, P < 0.05). Regarding Tregs, HIT induced a mobilization, whereas CONT induced apoptosis in these cells (P < 0.05). The mobilization of progenitor cells did not differ between the exercise protocols., Conclusion: These results suggest that HIT deletes mainly highly differentiated T cells known to affect immunity to control latent infections. By contrast, CONT deletes mainly low differentiated T cells and Tregs, which might affect defense against new infectious agents.