Bilateral masseteric contractile activity in unilateral gum chewing: differential calculus

Area of Science:

• Biomechanics
• Muscle Physiology
• Neuromuscular Activity

Background:

• Gum chewing involves complex coordination of masticatory muscles.
• Understanding muscle fatigue during prolonged activity is crucial for oral health and performance.

Purpose of the Study:

• To quantify the electromyographic (EMG) activity and work performed by masseter muscles during unilateral gum chewing.
• To investigate the asymmetry in muscle activity between the chewing and non-chewing sides.
• To explore the relationship between chewing duration and muscle fatigue.

Main Methods:

• Surface electromyography (EMG) was used to record masseter muscle activity in 12 healthy subjects.
• Subjects performed unilateral gum chewing for varying durations (10-25 seconds).
• Mathematical functions and differential calculus were applied to analyze EMG data and calculate muscle work.

Main Results:

• Cumulative EMG activity increased linearly with chewing duration on both ipsilateral and contralateral sides.
• The ipsilateral (chewing side) masseter muscle generated significantly greater force and positive work than the contralateral side.
• Asymmetric muscle activation patterns were observed, with increasing differences over time.

Conclusions:

• Prolonged unilateral gum chewing leads to greater force and work production in the ipsilateral masseter muscle.
• Mechano-physical work is a significant factor in the development of clinical muscle fatigue during sustained unilateral chewing.
• Asymmetrical muscle loading may contribute to imbalances in masticatory muscle function.