Methodology

The COR-School project employs a rigorous methodology that combines physical, biological, and behavioral measures to provide a comprehensive view of cardiovascular health in youth. Below are the stages and procedures detailed:

Physical Tests

20-m Shuttle Run Test (20-m SRT)

• Following the standard AlphaFit protocol, developed by its original creators, to measure cardiorespiratory endurance.
• The test involves progressive speed increments to assess participants’ maximal aerobic capacity.
• Data analyzed using heart rate monitors (Polar) to provide detailed cardiovascular performance metrics.

Horizontal Jump Test

• Measures lower body explosive strength. Participants perform a maximum jump from a standing position.
• Two repetitions are recorded, with the best distance considered.

Handgrip Strength

• Measures maximal isometric strength of the forearm and hand muscles using a calibrated handheld dynamometer (Takei T.K.K. 5401).
• Participants stand upright, arms fully extended alongside the body (elbow in full extension), and squeeze the dynamometer handle with maximal effort for 3 seconds, keeping the wrist in a neutral position. Participants perform four maximal isometric squeezes—alternating hands in sequence (right, left, right, left) continuously without any rest.

Biomarker Analysis

Blood Samples

• Collected before exercise and 3 hours afterward to analyze cardiac troponins (hs-cTnT) and lipid profiles (total cholesterol and HDL).
• Samples processed in certified laboratories to ensure maximum accuracy.

Analyzed Biomarkers

• hs-cTnT: Indicator of post-exercise cardiac strain.
• Lipid Profile: To assess metabolic health and cardiovascular risk.

Validated Questionnaires

• Physical Activity: PAQ-C or PAQ-A (depending on age), validated Spanish versions, to assess daily physical activity levels.
• Sleep: Pittsburgh PQSI to determine sleep quality.
• Diet: KIDMED index to assess adherence to the Mediterranean diet.
• Perceived Physical Fitness: IFIS (International Fitness Scale), a self-reported questionnaire providing an overview of participants’ perceived physical fitness.
• Maturation: Tanner stages, using a self-reported questionnaire with descriptive drawings to determine maturational status.
• Quality of Life: KINDL, to measure health-related quality of life perceptions in children and adolescents.
• FAS: The Family Affluence Scale; a brief 6‑item survey of household assets (cars, computers, bedrooms, bathrooms, holidays, etc.) that yields a composite score classifying family affluence as low, medium or high.

Longitudinal Follow-Up

Three assessments over three years (baseline and two annual follow-ups):

• Year 1: Initial data collection.
• Years 2 and 3: Follow-up assessments to analyze changes in biomarkers, physical fitness, and health habits.

Data Collected in Each Assessment:

• Physical tests.
• Blood samples.
• Anthropometric measurements.
• Questionnaires on health habits and lifestyle.

Data Analysis

• Data analyzed using descriptive statistics and longitudinal models to explore changes in hs-cTnT and other variables over time.
• Repeated measures ANOVA and Pearson correlations used to identify patterns between biomarkers, physical fitness, and maturational factors.
• Missing data managed using “listwise deletion” or “pairwise deletion” to maximize available data usage.

Ethical and Logistical Aspects

• Participants and their families sign an informed consent form detailing procedures and participation rights.
• Data confidentiality ensured through alphanumeric codes assigned to each participant.
• Sessions conducted in suitable facilities at local sports clubs, avoiding overcrowding and ensuring a smooth experience for all involved.