Effect of 6-Min Mastication Test on Masticatory Function in Young Versus Older Adults: A Comparative SEMG Study

Introduction: Aging impacts masticatory and swallowing functions due to muscle atrophy, neural degeneration, and reduced endurance. This study evaluated age-related differences in masticatory muscle function using the 6-min mastication test (6MMT) with surface electromyography (SEMG). Methodology: The study included two groups: healthy young adults (18-35 years) and healthy older adults (60 years and above). Muscle activity of the masseter and submental muscles was recorded using electrodes during mastication. Participants were instructed to chew bubble gum in synchronization with a metronome set at 80 bpm, with verbal reinforcement provided every minute. Results: Results revealed significant age-related differences in the masseter muscle for all parameters and in the submental muscle for peak values. Older adults demonstrated reduced masticatory muscle performance, attributed to sarcopenia, neural degeneration, and increased noncontractile tissue. Within-group analysis showed progressive changes in submental muscle mean average and power values over the 6-min task, reflecting fatigue, while no significant differences were observed in masseter muscle parameters in healthy young adults, possibly due to a warm-up effect or compensatory motor unit recruitment. Conclusion: The study demonstrated that masseter muscle activity significantly declines with age, with large effect sizes observed for all the parameters. Additionally, fatigue-related reductions in submental muscle parameters were observed across both age groups. These findings suggest that age-related and task-induced fatigue differentially affect masticatory muscles, highlighting the need for tailored interventions to support oral function in older adults.