Key load indicators and load variability in professional soccer players: a full season study

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Professional soccer involves numerous load variables, making comprehensive analysis challenging for coaches.
• Understanding load variability within a microcycle is crucial for optimizing training and preventing fatigue.

Purpose of the Study:

• To identify key load indicators in professional soccer using Principal Component Analysis (PCA).
• To analyze the load variability across training and match days within a microcycle, considering identified key indicators.

Main Methods:

• Collected data from 111 load variables using tracking systems for training and match days (MD).
• Applied PCA to identify principal components explaining total variance in load indicators.
• Analyzed load variability across different days of the microcycle (-5MD to +1MD).

Main Results:

• Seven key variables, including Metabolic power and total steps, explained 80.3% of the total variance in the first two PCA components.
• The day before a match (-1MD) showed the lowest load variability.
• +1MD exhibited significantly higher load variability compared to -5MD and -4MD.

Conclusions:

• PCA effectively reduces the high dimensionality of load data in team sports, aiding strength and conditioning coaches.
• Analyzing microcycle load variability provides insights into training load management and recovery strategies.