Can segmental model reductions quantify whole-body balance accurately during dynamic activities?

Area of Science:

• Biomechanics
• Kinesiology
• Sports Science

Background:

• Accurate tracking of the whole-body centre of mass (CoM) and extrapolated centre of mass (XCoM) is vital for analyzing dynamic tasks and whole-body balance.
• However, full-body motion capture systems required for precise tracking involve significant measurement effort.

Purpose of the Study:

• To evaluate the adequacy of reduced kinematic models in representing CoM and XCoM during dynamic sporting activities.
• To determine if simplified models can provide acceptable accuracy for whole-body balance investigations.

Main Methods:

• Seventeen healthy participants performed dynamic tasks: jumping, kicking, and overarm throwing.
• Marker-based kinematic data were captured using an optoelectronic system.
• CoM and XCoM from reduced models were compared to a full-body model (gold standard) using Bland-Altman analysis.

Main Results:

• Models incorporating lower limbs, trunk, and upper limbs showed strong agreement with the gold standard for CoM and XCoM.
• Reduced models (lower limbs and trunk only) demonstrated slightly lower agreement.
• Models using only lower limbs showed the least agreement, especially for XCoM during kicking.

Conclusions:

• Certain reduced kinematic models can provide acceptable CoM and XCoM representations for whole-body balance studies.
• These findings justify using specific model reductions to decrease measurement effort without compromising accuracy in dynamic sporting tasks.