Modified vector coding analysis of trunk and lower extremity kinematics during maximum and sub-maximum back squats.

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• The back squat is a foundational resistance exercise demanding significant lower extremity and trunk engagement.
• It involves both open and closed kinetic chain elements, requiring whole-body coordination.
• Understanding joint and segment coordination is crucial for optimizing performance and preventing injury.

Purpose of the Study:

• To analyze the coordination between the thigh and shank, trunk and thigh, and hip and knee during the concentric phase of back squats.
• To compare coordination patterns across different intensities: maximum, supra-maximum (105% 1RM), and sub-maximum (80% 1RM).

Main Methods:

• Fourteen resistance-trained adults performed back squats at determined maximal loads.
• Motion capture and ground reaction force data were collected during the lifts.
• Angle-angle plots and modified vector coding were used to analyze joint coupling and moments.

Main Results:

• The concentric phase demonstrated a transition from initial knee dominance to hip dominance during ascent.
• A consistent coupling pattern of thigh rising and trunk falling was observed across all squat intensities.
• Prolonged trunk falling and thigh rising created an excessive moment arm, hindering supra-maximal lift completion.

Conclusions:

• Coordination patterns in the back squat shift from knee to hip dominance during concentric movement.
• The coupling of trunk falling with thigh rising is a key characteristic, particularly challenging at supra-maximal loads.
• This coordination dynamic may limit the ability to overcome large external loads in maximal and supra-maximal back squats.