This observational study aims to evaluate multilevel physiological, molecular, metabolic, intestinal, immunological, and psychophysiological responses to rowing-specific exercise in elite rowers. The study is designed to investigate how maximal and prolonged rowing ergometer exercise influences integrated adaptive mechanisms related to mitochondrial function, metabolic regulation, intestinal permeability, immune activation, DNA damage response, and psychological status.

Thirty members of the Polish Youth National Rowing Team, aged 19-24 years, will participate in the study during two different training periods. During the competitive phase, participants will perform a 2000-m maximal rowing ergometer test, whereas during the preparatory phase they will complete a 6000-m rowing ergometer test. Blood samples and physiological measurements will be collected before exercise, immediately after exercise, and after 1 hour of recovery.

The study will assess gene expression, circulating biomarkers, flow cytometry parameters, blood morphology, lactate concentration, continuous glucose monitoring data, wearable metabolic sensor measurements, nutritional status, and psychological responses. The primary objective is to identify integrated biomarkers reflecting exercise load, recovery dynamics, and adaptive capacity in highly trained athletes. The study also aims to improve understanding of the interaction between metabolic, mitochondrial, intestinal, immunological, and psychophysiological responses to intensive exercise in rowing.

This study is designed to investigate integrated physiological, molecular, metabolic, intestinal, immunological, and psychophysiological responses to rowing-specific exercise in elite athletes. The study focuses on identifying biomarkers associated with exercise load, early recovery, and adaptive capacity in competitive rowers exposed to maximal and prolonged ergometer exercise.

Modern exercise physiology indicates that the response to intensive physical effort involves coordinated interactions between metabolic, mitochondrial, immune, neuroendocrine, and intestinal regulatory systems. High-intensity rowing exercise induces substantial metabolic stress, activation of mitochondrial signaling pathways, inflammatory and stress-related responses, and transient disturbances in intestinal barrier integrity. In addition, psychological factors, including mood state and pre-competition anxiety, may modulate physiological responses to exercise and recovery processes. However, previous studies have typically evaluated isolated physiological or biochemical markers without integrating molecular, cellular, and psychophysiological responses within a rowing-specific exercise model.

The study will include 30 competitive rowers, members of the Polish Youth National Rowing Team, aged 19 to 24 years, of both sexes. Assessments will be performed during two distinct phases of the annual training cycle. During the competitive phase (May-June 2026), participants will complete a 2000-m maximal rowing ergometer test. During the preparatory phase (November 2026), participants will perform a 6000-m rowing ergometer test. Both exercise protocols are routinely used within elite rowing training and performance monitoring.

Blood samples and physiological measurements will be collected at three time points during each testing session: before exercise (baseline), immediately after exercise, and after 1 hour of recovery. Venous blood samples will be used for hematological, biochemical, molecular, and flow cytometric analyses. Capillary blood samples will be collected for lactate assessment.

The study includes several integrated research modules:

The metabolic and adaptive response module will evaluate exercise-induced mitochondrial and metabolic signaling through analysis of gene expression related to mitochondrial biogenesis and energy regulation, including PPARGC1A, TFAM, PRKAA1, and SOD2. Circulating biomarkers associated with metabolic stress and adaptive signaling, including GDF15, apelin, irisin, myonectin, HSP70, and BDNF, will also be assessed. Psychological questionnaires evaluating mood state, perceived recovery, and competitive anxiety will be administered to characterize psychophysiological status.

The muscle-liver axis module will assess hormonal and metabolic regulation associated with glucose homeostasis and exercise adaptation. Measurements will include insulin, glucagon, FGF21, fetuin-A, IL-6, and myoglobin concentrations, together with expression of genes related to IL-6 signaling, gluconeogenesis, and glucose transport, including STAT3, SOCS3, PCK1, and SLC2A4 (GLUT4). Continuous glucose monitoring (CGM) and wearable metabolic monitoring systems will be used to evaluate glucose dynamics, lactate responses, hydration status, heart rate, and sodium loss during exercise and recovery.

The intestinal permeability and exercise-induced endotoxemia module will investigate exercise-associated disruption of intestinal barrier integrity and activation of innate immune responses. The study will assess circulating markers of endotoxemia and immune activation, including lipopolysaccharide (LPS), lipopolysaccharide-binding protein (LBP), soluble CD14, soluble TLR2, and soluble TLR4. Flow cytometry will be used to characterize monocyte phenotypes and receptor expression (CD45, CD14, CD16, TLR2, TLR4), while RT-qPCR analyses will evaluate expression of TLR2 and TLR4 genes.

The DNA damage response module will evaluate transient exercise-induced DNA damage and activation of cellular repair mechanisms. Biomarkers of oxidative DNA damage and DNA repair signaling, including 8-OHdG/8-oxo-dG, nucleosomes, HMGB1, AP sites, APE1/APEX1, and poly(ADP-ribose), will be analyzed together with expression of genes involved in DNA damage response and repair pathways, including CDKN1A, GADD45A, APEX1, and PARP1.

Body composition analysis will be performed using the TANITA MC-780MA analyzer. Nutritional intake will be evaluated using dietary assessment questionnaires and food records to support interpretation of metabolic and physiological responses.

All laboratory analyses will be performed according to standardized laboratory procedures and quality-control protocols. Blood morphology analyses will be conducted immediately after collection, while serum and plasma samples will be processed, centrifuged, and stored at -80°C until analysis. Molecular and flow cytometry analyses will be performed in specialized laboratory facilities using validated methods and equipment.

The study is observational in nature and does not involve therapeutic intervention, pharmacological treatment, or experimental supplementation. All exercise procedures represent standard performance tests routinely used in elite rowing training. The project aims to improve understanding of integrated exercise physiology in high-performance athletes and to support development of personalized monitoring strategies for training optimization, recovery management, and early detection of excessive physiological strain.

Inclusion Criteria:

• Male and female members of the Polish Youth National Rowing Team.
• Age between 19 and 24 years.
• Regular participation in structured rowing training.
• Medical clearance for participation in maximal exercise testing.
• Ability and willingness to provide written informed consent.

Exclusion Criteria:

• Lack of consent for blood sampling or study participation.
• Current injury or health condition contraindicating maximal exercise.
• Acute infection, fever, or inflammatory condition at the time of testing.
• Use of anti-inflammatory medications.
• Use of performance-enhancing substances.
• Use of dietary supplements within 3 months before study participation.
• Any medical contraindications identified by the study physician.

The study population will consist of male and female competitive rowers aged 19-24 years who are members of the Polish Youth National Rowing Team. Participants will be recruited from athletes engaged in regular high-performance rowing training and who participate in standardized rowing ergometer testing as part of routine performance monitoring across different phases of the training season. All participants will be medically cleared for maximal exercise testing and will represent elite-level endurance athletes.

Individual participant data sharing has not yet been determined. Future sharing of de-identified data will depend on institutional policies, ethical considerations, participant consent, and planned secondary analyses.