The Effect of Age on Electromyographic (EMG) Activity Patterns of the Masseter and Temporalis Muscles During Chewing of Foods with Different Hardness Levels

Aging is accompanied by changes in the neuromuscular system that may affect the function of masticatory muscles, including the masseter and temporalis, during the chewing process. Objective: This study aimed to investigate the effect of age on the electromyographic (EMG) activity patterns of the masseter and temporalis muscles during the mastication of foods with different hardness levels. Methods: In this cross-sectional study, 40 healthy participants were divided into four age groups: children (8–12 years), young adults (20–30 years), middle-aged adults (40–55 years), and elderly adults (65 years and above). Bilateral surface EMG (sEMG) activity of the masseter and temporalis muscles was recorded during chewing of three types of food with varying hardness: banana, toast bread, and raw carrot. Data were analyzed based on root mean square (RMS) amplitude, duration of muscle activity, and mean frequency of the EMG signals. Results: The findings showed a significant decrease in the amplitude and duration of muscle activity with increasing age (p < 0.05). Meanwhile, increasing food hardness significantly elevated muscle activity across all groups (p < 0.01), although the muscular response in the elderly group was notably lower compared to other groups. Conclusion: These results highlight the combined influence of age and food hardness on masticatory muscle activity. The decline in muscle function in elderly individuals may be attributed to muscular atrophy, reduced neuromuscular control, and diminished functional adaptation. Such findings could inform the design of appropriate dietary plans and rehabilitative interventions for the elderly population.