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Related Experiment Video

Updated: Nov 30, 2025

Movement Retraining using Real-time Feedback of Performance

Movement Retraining using Real-time Feedback of Performance

Published on: January 17, 2013

The effect of increasing trunk flexion during normal walking.

Stephen J Preece¹, Wael Alghamdi¹

¹School of Health Sciences, University of Salford, Salford, Manchester, M6 6PU, UK.

|November 16, 2020

Summary

Increasing trunk flexion during walking significantly elevates knee flexor muscle activity and hamstring activation. This finding is crucial for understanding altered muscle function in conditions like knee osteoarthritis.

Keywords:

EMG Trunk flexion co-contraction hamstring knee osteoarthritis thorax

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Published on: September 14, 2017

Area of Science:

Biomechanics
Human movement analysis
Musculoskeletal modeling

Background:

The trunk's mass influences lower limb joint moments and muscle activation.
Previous research focused on frontal plane trunk inclination, leaving trunk flexion's impact unclear.

Purpose of the Study:

To investigate the effect of independently manipulating trunk flexion angle on lower limb kinematics, moments, and muscle function.

Main Methods:

Gait analysis of 20 healthy individuals under four trunk flexion conditions.
Biofeedback used to control trunk flexion (normal walking, NW-5°, NW+5°, NW+10°).
Linear mixed model analyzed joint angles, moments, and knee muscle activation.

Main Results:

Increased trunk flexion led to higher hip and ankle moments, but not knee moments.
Linear increase in knee flexor muscle activity and co-contraction with greater trunk flexion.
Significant changes in hamstring activation, with medial hamstrings showing a 100% increase in activation at 5° flexion.

Conclusions:

Knee flexor muscle activity is highly dependent on trunk flexion during walking.
Altered muscle activation patterns due to trunk flexion may contribute to increased joint loads in knee osteoarthritis.