Biomechanical determinants of quadriceps femoris strengtcontribution to dynamic postural stability

Dynamic postural stability depends on the integration of sensory inputs, neuromuscular control, and biomechanical stability. The quadriceps femoris muscle plays a crucial role in this process, providing knee joint extension and stability. This study aims to assess the influence of the peak isokinetic torque of the quadriceps femoris on postural balance under varying sensory conditions, while also considering the participants' cognitive style. The study involved 50 participants aged 25-69 years old. Postural stability was assessed using stabilography on hard and compliant surfaces, with eyes open and closed. Analysis included calculation of frequency-domain parameters that characterize the contribution of different sensory systems to body stability, as well as measurement of center of pressure velocity. The results showed significant negative correlations between the peak torque of the quadriceps femoris muscle and the velocity of the center of pressure shift (r ≤ –0.5, p ≤ 0.05 on a hard surface; r ≤ –0.6, p ≤ 0.05 with eyes closed). On a soft surface with eyes closed, the velocity of the center of pressure shift was 19–32 mm/s in field-dependent and 16–25 mm/s in field-independent participants. Participants with a field-dependent cognitive style demonstrated a higher velocity of the center of pressure shift in all testing conditions. Conclusions: Quadriceps femoris muscle strength makes a significant contribution to dynamic postural stability, predominantly in individuals with a field-independent sensory strategy.