Physics

Sports biomechanics

Movement (music)

Motion capture

Inertial measurement unit

Accelerometer

Intensity (physics)

Match moving

Motion (physics)

Operating system

Optics

Inertial frame of reference

Political science

Units of measurement

Artificial intelligence

Acoustics

Motion analysis

Football

Computer science

Quantum mechanics

Kinematics

Simulation

Medicine

Classical mechanics

Physical medicine and rehabilitation

Sensors

Inertial sensor-based measurements of lower body kinematics in football players may improve physical load estimates during training sessions and matches. However, the validity of inertial-based motion analysis systems is specific to both the type of movement and the intensity at which movements are executed. Importantly, such a system should be relatively simple, so it can easily be used in daily practice. This paper introduces an easy-to-use inertial-based motion analysis system and evaluates its validity using an optoelectronic motion analysis system as a gold standard. The system was validated in 11 football players for six different football specific movements that were executed at low, medium, and maximal intensity. Across all movements and intensities, the root mean square differences (means ± SD) for knee and hip flexion/extension angles were 5.3° ± 3.4° and 8.0° ± 3.5°, respectively, illustrating good validity with the gold standard. In addition, mean absolute flexion/extension angular velocities significantly differed between the three movement intensities. These results show the potential to use the inertial based motion analysis system in football practice to obtain lower body kinematics and to quantify movement intensity, which both may improve currently used physical load estimates of the players.

Inertial Sensor-Based Motion Tracking in Football with Movement Intensity Quantification