How to compare knee kinetics at different walking speeds?

Area of Science:

• Biomechanics
• Gait Analysis
• Kinetics

Background:

• Walking speed is a critical confounding factor in gait biomechanical analysis.
• Comparing gait at comfortable walking speed (CWS) can obscure true deviations due to inter-group speed differences.
• Accurate methods are needed to normalize gait data for walking speed variations.

Purpose of the Study:

• To compare methods for correcting knee kinetics (sagittal and frontal plane moments) for walking speed.
• To assess the accuracy of speed correction methods in identifying gait deviations.

Main Methods:

• Twenty-two subjects walked at CWS and four other speeds on a treadmill.
• Knee moments were calculated using inverse dynamics.
• Two speed correction methods (interpolation and principal component analysis) were evaluated using leave-one-out cross-validation.

Main Results:

• Walking speed significantly influenced knee moments (KFM and KAM) in both magnitude and shape.
• Both correction methods achieved low normalized RMSE (<5%), indicating high accuracy.
• Reconstruction methods reduced RMSE by up to 60% compared to direct CWS vs. fixed speed comparisons.

Conclusions:

• Both interpolation and PCA methods effectively correct knee kinetics for walking speed effects.
• Incorporating walking speed dependency into reference datasets is crucial for identifying true gait deviations.