Does an instrumented treadmill correctly measure the ground reaction forces?

Area of Science:

• Biomechanics
• Sports Engineering

Background:

• Treadmills with multi-axis force transducers measure ground reaction forces (GRF) during locomotion.
• Accuracy concerns exist regarding horizontal GRF measurement due to internal treadmill forces like friction.

Purpose of the Study:

• To validate the accuracy of force measurements on instrumented treadmills.
• To demonstrate that subject-exerted forces are correctly transmitted to transducers.

Main Methods:

• Development of a simple model for an instrumented treadmill system.
• Analysis of force transmission from the subject to the transducers.
• Evaluation of the cancellation of internal forces within the treadmill.

Main Results:

• Forces exerted by a subject on the treadmill are accurately transmitted to the underlying force transducers.
• All internal forces, including belt-tread friction and motor forces, effectively cancel each other out.
• The model confirms the validity of horizontal GRF measurements.

Conclusions:

• Instrumented treadmills can accurately measure ground reaction forces during walking and running.
• Internal forces do not impede the accurate measurement of external forces exerted by the user.
• The proposed model supports the reliability of treadmill-based biomechanical analysis.