Forward head posture can influence masticatory muscle activity during chewing - a preliminary study

This study analyzed the electromyography (EMG) activity of masseter and anterior temporalis muscles during chewing in 2 different posture conditions: natural head posture (NHP) and deliberate forward head posture (FHP) in healthy individuals; and to compare EMG activity between subjects based on their NHP during chewing. Fifteen subjects participated. Presence of FHP or upright head posture (UP) was assessed using a plumb line. To analyze differences between the 2 conditions, a paired t-test was used. Independent t-test was used to calculate difference between subjects with UP and FHP. A significant increase in activity was found for masseter muscle in the FHP condition. No differences were found in NHP by posture classification. A trend of increased activity was observed for masseter and temporalis muscles during chewing in deliberate FHP and in natural FHP. FHP was found to influence masticatory muscle activity during chewing.