This study included 8 weeks of supplementation of black chokeberry extract with 18% standardization of the anthocyanins content (dose 2×200 mg per day) or a placebo product made from chokeberry fiber. The first research data was collected among twenty-four homogeneous female swimmers who trained intensively and attended the Sports Championship School Complex. The second research data was collected among a group of twenty-two selective and homogeneous female swimmers who attended the Sports Championship School Complex extensively.

In this study, the athletes were subjected to intensive swimming tests in breaststroke crawl (800m + 200m + 50m) with 15 minutes of active rest between test sections in the water.

Blood samples were taken from the cubital vein at three time points: before stress test (pre-exercise), one minute after the end of the test (post-exercise), and after a 3-hour recovery period (3h recovery). Measurements of morphology, 4-Hydroxynonenal (4-HNE), 8-isoprostane, cortysol, Intestinal fatty acid binding protein (I-FABP), claudin3, lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP), and levels were determined using ELISA kits (SunRed Biotechnology Company).

This study included 8 weeks of supplementation of black chokeberry extract with 18% standardization of the anthocyanins content (dose 2×200 mg per day), or a placebo product made from chokeberry fiber. The first date of research completed the group of twenty-four homogeneous female swimmers, who train swimming intensively and attend the Sports Championship School Complex. The second date of research completed the group of twenty-two selective and homogeneous female swimmers, who train swimming intensively and attend the Sports Championship School Complex.

In this study, the athletes were subjected to intensive swimming tests in breaststroke crawl (800m + 200m + 50m) with 15 minutes of active rest between test sections in the water. Blood samples were taken from the cubital vein at three time points: before stress test (pre-exercise), one minute after the end of the test (post-exercise), and after a 1-hour recovery period (3h recovery).

Measurement: All determined parameters were measured with the available equipment in the ZWKF laboratory in Gorzów Wielkopolski and using commercial assay kits. Measurements were performed by the project contractors.

1. Polyethylene tubes (2.7ml) containing dipotassium ethylenediaminetetraacetic acid (EDTA) anticoagulant were used for the following tests: (a) complete blood count (7 parameters) determined on the MYTHIC 18 hematology analyzer (Orphee Medical, Geneva, Switzerland). Red blood cell indices: RBC (Red Blood Cells), HGB (Hemoglobin), HCT (Hematocrit), MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Hemoglobin), MCHC (Mean Corpuscular Hemoglobin Concentration), RDW (Red Blood Cell Distribution Width); (b) a manual blood smear was made by placing a drop of blood on a slide and then spreading it with a uniform motion. After drying, it was colored by the May Grunwald-Giemsa method according to the procedure. After drying, the stained and fixed smear was viewed under a microscope for quantitative and qualitative assessment.
2. Polyethylene clotting activator tubes (9 ml) were centrifuged to separate the morphotic elements from the serum using a centrifuge (3000 rpm for 10 min). The serum was pipetted into several Eppendorf tubes, which were then frozen (temp. -80 °C). All biochemical parameters were determined from the extracted serum: (a) using the ELISA method by the test manufacturer's instructions. The designations include the following parameters:

4-Hydroxynonenal (4-HNE), 8-isoprostane, cortysol, Intestinal fatty acid binding protein (I-FABP), claudin3, lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP).

(3) The lactate (La) concentration was determined from the capillary blood immediately after collection using a commercially available kit (Dr. Lange, Germany).

A nutritionist thoroughly analyzed the athletes' diets before each exercise test. Using a commercially available program, the amount of energy, protein, carbohydrates, fats, and fiber was then analyzed.

The experiment was conducted in accordance with the Declaration of Helsinki. The Ethical Committee of the Medical University of Poznan approved the study protocol.

Inclusion Criteria:

• valid medical examination,
• consent of the legal guardian of the underage athlete to participate in the study,
• Training experience of a minimum of three years
• Student of a sports championship school team,
• completion of the exercise test in the swimming pool - crawl style intensive test (800 m + 200 m + 50 m) on two test deadlines

Exclusion Criteria:

• antibiotic therapy,
• supplementation, use of any drugs, or oral hormonal contraceptives
• health problems within the last month

female swimmers