Relationships Between Training Load Indicators and Training Outcomes in Professional Soccer

Area of Science:

• Sports Science
• Exercise Physiology
• Performance Analysis

Background:

• Training load monitoring in professional soccer aims to optimize workload, enhance physical fitness, and prevent injuries or illnesses.
• Current practices utilize diverse training load indicators, but their direct correlation with specific training outcomes remains unclear.

Purpose of the Study:

• To systematically review the existing knowledge on the relationship between training load indicators and training outcomes in professional soccer.
• Key outcomes examined include physical fitness, injury incidence, and illness occurrence.

Main Methods:

• A systematic literature search was performed across four major electronic databases.
• Training load was defined as accumulated stress from training sessions or matches, measured by external (e.g., distance) or internal load (e.g., heart rate).

Main Results:

• High-intensity training (over 90% maximal HR) during pre-season correlated with improved aerobic fitness.
• Exposure time (training, match, or combined) showed varied relationships with fitness changes throughout a season.
• High-intensity training may increase injury risk, while detailed external load indicators are under-researched.

Conclusions:

• Heart rate indicators demonstrate a link to positive fitness changes in pre-season training.
• While some load indicators show potential, robust evidence linking modern, detailed indicators to outcomes like injury and illness is limited.
• Future research should focus on continuous monitoring and individual characteristics to clarify training load-outcome relationships.