The Effect of a Training Programme in the Variation of Fitness Parameters, Physiological, Hematological and Biochemical Indicators of Soccer Players During the Preseason Period

The goal of this study is to investigate the effects of varying friendly match-play exposure during the late pre-season on physiological, biochemical, and performance adaptations in soccer players. It is hypothesized that (i) significant changes will occur across the pre-season in both the extended- and limited-play groups when analysed independently; (ii) distinct group-specific adaptations will emerge by the end of the preparatory period; and (iii) match-play exposure, when analysed across all participants, will be significantly correlated with physiological and performance outcomes at pre-season completion. Players from a randomly selected team will be assessed at three time points: pre-season start, mid-pre-season (MPS), and pre-competition phase (PC). Assessments will include anthropometry, physical performance, and markers of muscle damage, inflammation, hormonal status, and haematology. Based on the total match-play time of 8 friendly games during the late pre-season, players will be retrospectively categorised into extended-play (EP) and limited-play (LP) cohorts.time of 8 friendly games during the late pre-season, players will be retrospectively categorised into extended-play (EP) and limited-play (LP) cohorts.

Study Overview

• Status: Enrolling by invitation
• Conditions: Inflammation; Athletic Performance; Muscle Damage; Physical Fitness; Soccer; Exercise Test; Exercise Physiology; Exercise-induced Inflammation; Pre-season Training
• Intervention / Treatment: Other: Friendly Match-Play Exposure: extended vs. limited

• Study Type: Observational
• Enrollment (Estimated): 24

Contacts and Locations

Study Locations

• Greece
  • Daphni
    • Athens, Daphni, Greece, 17237
      • School of Physical Education and Sports Science, National and Kapodistrian University of Athens

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

All participants are highly active soccer players (i.e., >1000 MET-min·week-¹) and compete at national-level standards.

Description

Inclusion Criteria:

• Male participants
• Aged 18 years or older
• Non-smokers
• Injury-free for the past 6 months
• Medication-free for the past 6 months
• Abstinent from alcohol
• Living at an altitude below 1500 meters
• Committed exclusively to soccer (no participation in other sports)

Exclusion Criteria:

• History of serious injuries (e.g., fractures, ligament tears) within the past 6 months
• Chronic medical conditions such as cardiovascular disease, diabetes, or respiratory disorders
• Current use of performance-enhancing drugs or supplements
• Participation in non-soccer-related sports or activities during the study period

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Extended-Play; Participants with higher cumulative friendly match-play exposure during the late pre-season phase.	Other: Friendly Match-Play Exposure: extended vs. limited; This research explores the multidimensional physiological and biochemical responses to differing volumes of friendly match-play (i.e., extended vs. limited) during the late pre-season phase in soccer players.
Limited-Play; Participants with lower cumulative friendly match-play exposure during the late pre-season phase.	Other: Friendly Match-Play Exposure: extended vs. limited; This research explores the multidimensional physiological and biochemical responses to differing volumes of friendly match-play (i.e., extended vs. limited) during the late pre-season phase in soccer players.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body Mass	Description: Body mass measured at standard anatomical sites using a calibrated scale to track longitudinal changes over the pre-season. Unit of Measure: kg	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Body Fat	Description: Body fat percentage measured using skinfold calipers at standard sites to monitor longitudinal changes. Unit of Measure: %	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Rate of Perceived Exertion (RPE)	Description: Participants rate exertion during standardized training sessions using the Borg Scale (6 = no exertion, 20 = maximal exertion). Unit of Measure: Borg 6-20 scale	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Glucose	Description: Fasting blood glucose measured to track metabolic changes over pre-season. Unit of Measure: mg/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Cholesterol	Description: Total serum cholesterol measured to assess lipid profile adaptations. Unit of Measure: mg/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Triglycerides	Description: Serum triglycerides measured to monitor metabolic response to training. Unit of Measure: mg/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
SGOT (AST)	Description: Serum glutamic-oxaloacetic transaminase measured to assess liver/muscle stress. Unit of Measure: U/L	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
SGPT (ALT)	Description: Serum glutamic-pyruvic transaminase measured to monitor liver/muscle stress. Unit of Measure: U/L	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Creatine Phosphokinase (CPK)	Description: CPK measured to detect skeletal muscle damage. Unit of Measure: U/L	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Myoglobin	Description: Myoglobin measured as a marker of muscle damage. Unit of Measure: ng/mL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Iron	Description: Serum iron measured to assess iron status. Unit of Measure: µg/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Ferritin	Description: Serum ferritin measured to monitor iron storage. Unit of Measure: ng/mL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
C-Reactive Protein (CRP)	Description: CRP measured as a marker of systemic inflammation. Unit of Measure: mg/L	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
High-sensitivity CRP (hs-CRP)	Description: hs-CRP measured to detect low-grade inflammation. Unit of Measure: mg/L	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Interleukin-6 (IL-6)	Description: IL-6 measured from serum to assess inflammatory response. Unit of Measure: pg/mL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Tumor Necrosis Factor-alpha (TNF-α)	Description: TNF-α measured as a marker of systemic inflammation. Unit of Measure: pg/mL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Testosterone	Description: Serum testosterone measured to assess hormonal adaptations. Unit of Measure: ng/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Cortisol	Description: Serum cortisol measured to monitor stress response. Unit of Measure: µg/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Testosterone-Cortisol Ratio	Description: Calculated ratio to estimate anabolic-catabolic balance. Unit of Measure: Ratio	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Red Blood Cells (RBC)	Description: RBC count measured from blood to assess oxygen transport capacity. Unit of Measure: million cells/µL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Hemoglobin	Description: Hemoglobin measured to evaluate oxygen-carrying capacity. Unit of Measure: g/dL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Hematocrit	Description: Hematocrit measured as percentage of RBC in blood. Unit of Measure: %	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
White Blood Cells (WBC)	Description: WBC count measured to monitor immune function. Unit of Measure: cells/µL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Platelets	Description: Platelet count measured to assess hematological health. Unit of Measure: cells/µL	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Countermovement Jump Height	Description: Jump height measured (cm) to assess lower-limb explosive power. Unit of Measure: cm	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Knee Extensor Power, Dominant Leg	Description: Measured using isokinetic dynamometer. Unit of Measure: Watts	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Knee Extensor Power, Non-Dominant Leg	Description: Measured using isokinetic dynamometer. Unit of Measure: Watts	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Knee Flexor Power, Dominant Leg	Description: Measured using isokinetic dynamometer. Unit of Measure: Watts	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
Knee Flexor Power, Non-Dominant Leg	Description: Measured using isokinetic dynamometer. Unit of Measure: Watts	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
10-m Sprint Time	Description: Sprint time measured using photocell gates; lower times indicate better performance. Unit of Measure: seconds	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).
T-Test Agility	Description: Participants perform T-test agility course; lower times indicate better agility. Unit of Measure: seconds	Each measure assessed at Baseline (pre-season start), 4 weeks (mid-pre-season), and 8 weeks (pre-competition phase).

Collaborators and Investigators

• Sponsor: Emmanouil D. Zacharakis

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2025
• Primary Completion (Estimated): September 15, 2025
• Study Completion (Estimated): September 15, 2025

Study Registration Dates

• First Submitted: July 1, 2025
• First Submitted That Met QC Criteria: September 5, 2025
• First Posted (Estimated): September 12, 2025

Study Record Updates

• Last Update Posted (Estimated): September 19, 2025
• Last Update Submitted That Met QC Criteria: September 13, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Effect; Football; Biochemical markers; Training intensity; Physiological stress; Pre-season training; Match-play exposure; Physiological adaptation; Recovery strategies; Aerobic-anaerobic; Athletic; Performance adaptation
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Inflammation
• Other Study ID Numbers: ERC-002/2023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No