Experimental muscle pain during a forward lunge--the effects on knee joint dynamics and electromyographic activity.

Abstract

The purpose of this study was to investigate whether the knee joint dynamics during a forward lunge could be modulated by experimentally induced vastus medialis pain in healthy subjects. Randomised cross-over study. Biomechanical movement laboratory. 20 healthy subjects were included. One subject was excluded during data collection. The subjects performed forward lunges before, during and 20 minutes after induction of experimental quadriceps muscle pain. Muscle pain was induced using hypertonic saline (5.8%) injected intramuscularly. Isotonic saline (0.9%) was used as control. Three-dimensional movement analyses were performed and inverse dynamics were used to calculate joint kinematics and kinetics for ankle, knee and hip joints. Electromyographic (EMG) signals of the hamstrings and quadriceps muscles were recorded. During and after pain, significant decreases in knee joint dynamics and EMG recordings were observed. The study shows that local pain in the quadriceps is capable of modulating movements with high knee joint dynamics. The results may have implications in the management of muscle pain and prevention of injuries during activities involving the knee joint.