Latency to Peak Electromyographic Activation in Lower Limb Movement Patterns Described by Kabat: Timing of Selected Muscles

Abstract

Objective: To determine the activation sequence of selected muscles, in supine and standing positions, by means of the latency to peak electromyographic (EMG) activation in the movement patterns of the lower extremities described by Kabat. Methods: A comparative analytical study was conducted with an intentional sample of healthy adults between 18 and 25 years old, 20 men and 20 women with right foot dominance. Three active repetitions of the two lower limb diagonals were performed, in both supine and standing positions. The latency to peak EMG activation for eight muscles in the four movement patterns was recorded by surface electromyography. The sequence of contractions was determined by means with their 95% confidence intervals. Tests of homogeneity between positions were carried out. Results: In most patterns, a sequence of proximal to distal contractions was observed. Significant differences between supine and standing positions were only evident in nine of the 64 trajectories studied (p<0,05). Conclusions: These results partially contradict the theory of normal timing that postulates that the sequence of muscle contractions is performed from distal to proximal. Future studies should include a greater number of muscles and assess other variables such as the first contraction evidenced in the electromyographic tracing. Impact Statement: The variability found in the sequence of maximum muscle activation during the execution of lower limbs movement patterns described by Kabat, suggests that the concept of normal timing is linked to the execution of a facilitation technique through a pattern, and not to the pattern itself. This depends on the objective of the task and the individual characteristics of the subject. The need to individualize the normal timing and adapt the timing for emphasis according to each person is evident.