title: Muscle hardness characteristics of the masseter muscle after repetitive muscle activation: comparison to the biceps brachii muscle.
abstract: The purpose of this study was to compare hardness characteristics of the masseter muscle to those of the biceps brachii muscle during repetitive muscle movements. Seventeen asymptomatic female subjects participated in this study. Each subject, on separate days, undertook a 5-minute unilateral chewing gum task on the right side and a 5-minute flexion-extension exercise on the right hand with a 2kg dumbbell. Using a handheld hardness meter, muscle hardness was measured in the right masseter and in the biceps brachii muscle at eight time points (before the task, immediately after the task, and at 1, 3, 5, 10, 30, and 60 minutes after the task), and the data obtained before and after the task on each muscle were compared. Comparisons of the normalized data were also performed between the two muscles at each time point. As a result, a significant increase in muscle hardness was seen at 1 minute after the task in the biceps brachii muscle (p=0.0093). In contrast, the masseter muscle showed a tendency to lower hardness, with the lowest point of hardness occurring at 10 minutes after the task (p = 0.0160). Between the two muscles, there was a difference in the normalized data immediately after the task, and at 1, 5, and 10 minutes after the task (0.01 <p<0.05). In conclusion, it was found that muscle hardness characteristics of the masseter muscle completely differed from those of the biceps brachii muscle after repetitive muscle activation.
authors.affiliation: Dept. of Oral and Maxillofacial Surgery, Miyazaki Medical College, 5200 Kihara, Kiyotake-cho, Miyazaki 889-1692, Japan. kojikash@post.miyazaki-med.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Kashima
authors.forename: Shuichi
authors.initials: S
authors.lastname: Higashinaka
authors.forename: Naoshi
authors.initials: N
authors.lastname: Watanabe
authors.forename: Sho
authors.initials: S
authors.lastname: Maeda
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Shiba
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm / Q000502:physiology*; D002638:Chewing Gum; D005260:Female; D005500:Follow-Up Studies; D006244:Hardness; D006801:Humans; D008406:Masseter Muscle / Q000502:physiology*; D016555:Matched-Pair Analysis; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010146:Pain / Q000503:physiopathology; D010147:Pain Measurement; D018709:Statistics, Nonparametric; D014891:Weight Lifting
chemical_list: D002638:Chewing Gum