Half Squat Mechanical Analysis Based on PBT Framework

Abstract

Muscular strength is an essential factor in sports performance and general health, especially for optimizing mechanical power, as well as for injury prevention. The present study biomechanically characterized the half squat (HS) using a systemic structural approach based on mechanical power, called Power-Based Training (PBT), through which four phases of the movement were determined (acceleration and deceleration of lowering and lifting). Five weightlifters from the Mexican national team (categories U17, U20, and U23) participated, who performed five repetitions per set of HS with progressive loads (20%, 35%, 50%, 65%, and 80% of the one repetition maximum). The behavior of the center of mass of the subject-bar system was recorded by photogrammetry, calculating position, velocity, acceleration, mechanical power, and mechanical work. The results showed a significant reduction in velocity, acceleration, and mechanical power as the load increases, as well as variations in the duration and range of displacement per phase. These findings highlight the importance of a detailed analysis to understand the neuromuscular demands of HS and to optimize its application. The PBT approach and global center of mass analysis provide a more accurate view of the mechanics of this exercise, facilitating its application in future research, as well as in performance planning and monitoring.

Keywords: exercise biomechanics; half squat; mechanical power; power-based training.

Figure 1

CoM movement description: position (m), velocity (m·s⁻¹), acceleration (m·s⁻²), and mechanical power (W/Kg) of one interval 1 (20% 1RM) subject sequence (3 repetitions). Phases (separated by dotted lines). Lines represent the mean, and the shaded areas represent the standard deviation. Repetitions were normalized over 100% of execution within 1000 frames. Left vertical axis represents position (left ticks) and velocity (right ticks). Right vertical axis represents acceleration and mechanical power.

Figure 2

CoM movement averaged time series: position (m), velocity (m·s⁻¹), acceleration (m·s⁻²), and mechanical power (W/Kg) of one subject sequence (3 repetitions) at all intervals: 1 to 5 (20% 1RM–80% 1RM). Phases appear separated by vertical dotted lines. Repetitions were normalized over 100% of execution within 1.000 frames.