AN INVESTIGATION OF NECK MUSCLE ACTIVITY IN ASYMPTOMATIC PARTICIPANTS WHO SHOW DIFFERENT LUMBAR SPINE MOTION PATTERNS DURING PRONE HIP EXTENSION

Objective: The objective of the current study was to investigate whether any differences exist in the activity of the cervical erector spinae and upper trapezius (TRA) muscles between asymptomatic participants who show "normal" and "abnormal" lumbar spine motion patterns during the prone hip extension (PHE) test. Methods: Twenty-six asymptomatic participants recruited from a chiropractic college participated in the study. Surface electromyography was used to record the activity of the cervical erector spinae and upper TRA muscles as each participant performed a set of 4 repetitions of PHE for each leg. An examiner observed the participant perform the movement and classified him/her as "positive" or "negative" based on the presence or absence (respectively) of 1 of 3 lumbar spine motion patterns. The mean activity levels of each muscle during the positive sets of PHE were compared with those during the negative sets. Results: The mean activity of the upper TRA ipsilateral to the side of hip extension was significantly higher in the positive group compared with the negative group (difference, 13.3%; 95% confidence interval, 0.2%-24.4%; P = .0465). No other significant between-group differences were noted. Conclusion: The results of this study indicate that the presence of abnormal lumbar spine motion patterns during the PHE test may be associated with altered cervicothoracic motor control strategies in asymptomatic individuals. Similar investigations using patients with neck pain are required to comment further on the generalizability and potential clinical importance of these findings. (J Manipulative Physiol Ther 2011;34:525-532)