Tihomir Kostov

Mr. Tihomir Kostov

Institute of Cardiovascular Research and Sports Medicine, Molecular and Cellular Sports Medicine, German Sport University Cologne, Cologne, North Rhine-Westphalia, Germany
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Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 November 2022 in Metabolites
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Journal Article
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DBDaniel Alexander Bizjak
Daniel Alexander Bizjak
SSSebastian Schulz
Sebastian Schulz
LJLucas John
Lucas John
JSJana Schellenberg
Jana Schellenberg
RBRoman Bizjak
Roman Bizjak
MGMarijke Grau
Marijke Grau
Moderate endurance exercise leads to an improvement in cardiovascular performance, stress resilience, and blood function. However, the influence of chronic endurance exercise over several hours or days is still largely unclear. We examined the influence of a non-stop 160.9/230 km ultramarathon on body composition, stress/cardiac response, and nutrition parameters. Blood samples were drawn before (pre) and after the race (post) and analyzed for ghrelin, insulin, irisin, glucagon, cortisol, kynurenine, neopterin, and total antioxidant capacity. Additional measurements included heart function by echocardiography, nutrition questionnaires, and body impedance analyses. Of the 28 included ultra-runners (7f/21m), 16 participants dropped out during the race. The remaining 12 finishers (2f/10m) showed depletion of antioxidative capacities and increased inflammation/stress (neopterin/cortisol), while energy metabolism (insulin/glucagon/ghrelin) remained unchanged despite a high negative energy balance. Free fat mass, protein, and mineral content decreased and echocardiography revealed a lower stroke volume, left end diastolic volume, and ejection fraction post race. Optimizing nutrition (high-density protein-rich diet) during the race may attenuate the observed catabolic and inflammatory effects induced by ultramarathon running. As a rapidly growing discipline, new strategies for health prevention and extensive monitoring are needed to optimize the athletes’ performance.

9 May 2024 in Nutrients
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Journal Article
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SVSarah Valder
Sarah Valder
Elisabeth HabersatterElisabeth Habersatter
Elisabeth Habersatter
TKTihomir Kostov
Tihomir Kostov
SQSina Quenzer
Sina Quenzer
LHLukas Herzig
Lukas Herzig
EIEduard Isenmann
Eduard Isenmann
Background: Various nutritional strategies are increasingly used in sports to reduce oxidative stress and promote recovery. Chokeberry is rich in polyphenols and can reduce oxidative stress. Consequently, chokeberry juices and mixed juices with chokeberry content are increasingly used in sports. However, the data are very limited. Therefore, this study investigates the effects of the short-term supplementation of a red fruit juice drink with chokeberry content or a placebo on muscle damage, oxidative status, and leg strength during a six-day intense endurance protocol. Methods: Eighteen recreational endurance athletes participated in a cross-over high intensity interval training (HIIT) design, receiving either juice or a placebo. Baseline and post-exercise assessments included blood samples, anthropometric data, and leg strength measurements. Results: A significant increase was measured in muscle damage following the endurance protocol in all participants (∆ CK juice: 117.12 ± 191.75 U/L, ∆ CK placebo: 164.35 ± 267.00 U/L; p = 0.001, η2 = 0.17). No group effects were detected in exercise-induced muscle damage (p = 0.371, η2 = 0.010) and oxidative status (p = 0.632, η2 = 0.000). The reduction in strength was stronger in the placebo group, but group effects are missing statistical significance (∆ e1RM juice: 1.34 ± 9.26 kg, ∆ e1RM placebo: −3.33 ± 11.49 kg; p = 0.988, η2 = 0.000). Conclusion: Although a reduction in strength can be interpreted for the placebo treatment, no statistically significant influence of chokeberry could be determined. It appears that potential effects may only occur with prolonged application and a higher content of polyphenols, but further research is needed to confirm this.

30 April 2024 in Nutrients
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Journal Article
Open access
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SVSarah Valder
Sarah Valder
RSRaphaela Staltner
Raphaela Staltner
DBDaniel Alexander Bizjak
Daniel Alexander Bizjak
TETuba Esatbeyoglu
Tuba Esatbeyoglu
DHDr. Volker Herdegen
Dr. Volker Herdegen
Patrick DielPatrick Diel
Patrick Diel
Background: Exercise and the consumption of sugars result in a dysfunction of the intestinal barrier (IB). Here, we determined the effect of sugar in a natural matrix on the intestinal barrier after moderate (A) and intensive endurance exercise (B). Method: The IB function was determined before (pre) and after running (post), and 120 and 180 min after consuming the drink by measuring serum endotoxin concentrations (lipopolysaccharides—LPS), IL-6, CD14, and i-FABP. In study A, nonspecifically trained participants (n = 24, males and females, age 26 ± 4) ran for one hour at 80% of their individual anaerobic threshold (IAT). After finishing, the runners consumed, in a crossover setup, either 500 mL of water, diluted cloudy apple juice (test drink), or an identical drink (placebo) without the fruit juice matrix (FJM). In study B, the participants (n = 30, males and females, age 50 ± 9) completed an ultra-marathon run, were divided into groups, and consumed one of the above-mentioned drinks. Results: Study A: Exercise resulted in a significant increase in serum LPS, i-FABP, and IL-6, which decreased fast after finishing. No impact of the different drinks on LPS i-FABP, or IL-6 could be observed, but there was an impact on CD14. Study B: The ultra-marathon resulted in a strong increase in serum LPS, which decreased fast after finishing in the water and test drink groups, but not in the placebo group. Conclusions: The consumed drinks did not affect the kinetics of IB regeneration after moderate exercise, but impacted CD14 serum concentrations, indicating possible beneficial effects of the FJM on the immune system. After an ultra-marathon, IB function regenerates very fast. The intake of sugar (placebo) seems to have had a negative impact on IB regeneration, which was diminished by the presence of the FJM.

21 June 2024 in npj Science of Food
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Journal Article
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RSRaphaela Staltner
Raphaela Staltner
SVSarah Valder
Sarah Valder
MWMaximilian F. Wodak
Maximilian F. Wodak
MKMagdalena Köpsel
Magdalena Köpsel
VHVolker Herdegen
Volker Herdegen
Ina BergheimIna Bergheim
Ina Bergheim
Sugar beverages are discussed as critical in the development of metabolic endotoxemia. Here, employing a cross-over design study we assessed the effect of diluted cloudy apple juice (AJ), an iso-caloric and -sweetened placebo (P), or water (W) on post-prandial endotoxemia in healthy, normal weight adults. After obtaining fasting blood, 19 healthy men and women consumed 500 mL AJ, P, or W in a randomized order and blood was taken 120 and 180 min later. Caco-2 cells were incubated with the beverages. Markers of intestinal barrier function were assessed. The intake of P but not of AJ or W was associated with a significant increase in TLR2 ligands and bacterial endotoxin in serum after 120 min and 180 min, respectively. P but not AJ significantly increased bacterial toxin permeation in Caco-2 cells. Our results suggest that the effects of sugar-sweetened beverages on markers of intestinal barrier function markedly differ from those of fruit juices.

Verified
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Elisabeth HabersatterElisabeth Habersatter
Elisabeth Habersatter
TKTihomir Kostov
Tihomir Kostov
NLNele Laing
Nele Laing
JDJürgen Drewe
Jürgen Drewe
GBGeorg Boonen
Georg Boonen
Patrick DielPatrick Diel
Patrick Diel
Cimicifuga racemosa extracts, particularly the ethanolic extract Ze 450, are widely used to alleviate menopausal symptoms, such as hot flushes and excessive sweating. While their clinical efficacy is well established, the effects of these interventions on systemic energy metabolism remain unclear. This pilot study investigated the impact of Ze 450 on body composition, metabolic markers, and voluntary physical activity in non-ovariectomized female Wistar rats. Animals (N = 36) received Ze 450 at either 30 mg/kg or 130 mg/kg body weight, with or without access to voluntary wheel running over four weeks. Neither treatment influenced body weight gain or final body weight, indicating normal growth across all groups. Post-mortem analyses included visceral fat mass, serum cholesterol, and leptin levels. Both Ze 450 and running reduced visceral fat mass, adipocyte size, and circulating leptin levels, suggesting that they share overlapping mechanisms. Serum cholesterol was significantly lowered by running but remained unaffected by Ze 450, while liver weight and alanine aminotransferase activity were unchanged, confirming hepatic safety. Collectively, Ze 450 improved key metabolic parameters related to adiposity and appetite without affecting hepatic integrity, highlighting its potential as a safe, non-hormonal metabolic modulator complementary to physical activity.

6 October 2026 in Cells
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Journal Article
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SCSIYU CHEN
SIYU CHEN
Elisabeth HabersatterElisabeth Habersatter
Elisabeth Habersatter
TKTihomir Kostov
Tihomir Kostov
JDJürgen Drewe
Jürgen Drewe
GBGeorg Boonen
Georg Boonen
Patrick DielPatrick Diel
Patrick Diel
Preservation of skeletal muscle is an important consideration when evaluating weight-loss interventions, particularly during menopause, when adverse changes in body composition occur. We investigated the effects of Cimicifuga racemosa extract Ze 450 on skeletal muscle. Differentiated C2C12 myotubes were treated with Ze 450, dexamethasone (DEX), or their combination. Non-ovariectomized female Wistar rats were assigned to one of five groups: standard diet, high-fat diet (HF), HF plus voluntary running, HF plus Ze 450 (130 mg/kg/day), or HF plus Ze 450 and voluntary running. Muscle mass and fiber cross-sectional area (CSA) were assessed in the predominantly glycolytic gastrocnemius and oxidative soleus. Markers of mitochondrial content (COX IV and CS), lipid metabolism (ATGL, HSL, FAS, and SREBP-1c), glucose transport (GLUT4), and myogenic signaling (IGF-1) were analyzed. Ze 450 had limited effects on myotube diameter under basal conditions but significantly attenuated DEX-induced myotube atrophy. In vivo, Ze 450 reduced body weight gain and fat accumulation without reducing muscle mass or fiber CSA. Ze 450 differentially affected metabolic markers in the two muscle types, decreasing markers associated with mitochondrial content in the soleus while increasing mitochondrial markers in the gastrocnemius. Taken together, these findings suggest a potential role for Ze 450 in rebalancing skeletal muscle metabolism in a muscle-type-specific manner while preserving skeletal muscle during reductions in body weight gain and adiposity.