Lower limb joint moment during walking in water

Area of Science:

• Biomechanics
• Rehabilitation Science
• Orthopedics

Background:

• Aquatic therapy is a common rehabilitation method for orthopedic disorders.
• It's believed that reduced weight-bearing in water minimizes joint stress and prevents secondary injuries.
• However, experimental data on lower-limb joint moments during water walking is scarce.

Purpose of the Study:

• To quantify and compare ankle, knee, and hip joint moments during water walking versus land walking.
• To investigate the biomechanical effects of aquatic environments on lower-limb joint loading.

Main Methods:

• Eight healthy volunteers participated in the study.
• Kinematic data and joint moments were collected using a video-motion analysis system and a waterproof force platform.
• Participants walked at a self-selected comfortable speed on both land and in water.

Main Results:

• Hip joint moments during water walking were predominantly in extension throughout stance, unlike the bidirectional (extension-flexion) moments during land walking.
• Knee joint moments showed a single, late extension peak in water, contrasting with two peaks during land walking.
• Ankle joint moments were substantially reduced in water but maintained the plantarflexion direction observed during land walking.

Conclusions:

• Walking in water alters lower-limb joint moments significantly, affecting hip, knee, and ankle mechanics.
• The study demonstrates a fundamental change in inter-joint coordination during aquatic locomotion.
• These findings challenge the simple assumption of joint moment reduction and highlight altered biomechanical strategies in water.