title: Changes in muscle thickness of gastrocnemius and soleus associated with age and sex.
abstract: OBJECTIVE
  Gastrocnemius and soleus in the triceps surae have functional and histological differences.We therefore investigated age-related changes in muscle thickness of these two muscles, as well as the difference in these changes between men and women.
  
  
  METHODS
  Participants comprised 847 healthy adults aged 20 to 79 years. A B-mode ultrasound scanner, with participants sitting on a chair, was used to measure muscle thickness from the midpoint of the gastrocnemius medialis muscle at the level of maximum girth (target point). The ratio of muscle thickness to height was calculated. The inter-rater and intra-rater reliability of measuring muscle thickness with the ultrasound scanner and the validity of the target point were demonstrated before the examination.
  
  
  RESULTS
  Gastrocnemius was significantly thinner in women aged 60 or older and in men aged 50 or older, compared with their counterparts in their 20s. For soleus, no significant differences in thickness were found among the age groups in either sex. Decline in muscle thickness from age 40-79 was greater for gastrocnemius than for soleus.
  
  
  CONCLUSIONS
  These results confirm that gastrocnemius starts to deteriorate earlier and atrophies at a faster pace than soleus. A significant sex difference was found only in the onset age of gastrocnemius deterioration, which was earlier in men than in women.
authors.affiliation: Department of Human Movement and Health, Graduate School of Medical Science, Kanazawa University, Kanazawa 920-8640, Japan. fujikatu@med.m.kanazawa-u.ac.jp
authors.forename: Katsuo
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Asai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Toyama
authors.forename: Kenji
authors.initials: K
authors.lastname: Kunita
authors.forename: Chie
authors.initials: C
authors.lastname: Yaguchi
authors.forename: Naoe
authors.initials: N
authors.lastname: Kiyota
authors.forename: Hidehito
authors.initials: H
authors.lastname: Tomita
authors.forename: Jesse V
authors.initials: JV
authors.lastname: Jacobs
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001827:Body Height; D001835:Body Weight; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000166:cytology / Q000254:growth & development*; D009929:Organ Size; D012727:Sex Characteristics; D055815:Young Adult