title: [Study on skeletal muscle mass of 1 836 check-up adults and its association with age in Qiqihar].
abstract: OBJECTIVE
  To analyze the correlation between skeletal muscle mass and age among check-up adults.
  
  
  METHODS
  The study objects were those who aged 18-87 years old and came to a city hospital of Qiqihar for health examination from December, 2013 to September, 2014, excepted those with coronary heart disease, infectious disease, endocrine system disease, hypertension, anemia, cancer, liver disease, kidney disease and those carrying with heart pacemaker. A total of 1 836 respondents were finally enrolled into analysis. Appendicular Skeletal Muscle (ASM) was measured by a Body Composition Analyzer, and relative skeletal muscle index (RSMI) was calculated. The relationship among ASM, RSMI and age was assessed by linear regression analysis. The difference of height, weight, BMI, waist-hip-ratio (WHR), total muscle mass and percentage of body fat between genders were tested by t-test. The difference of ASM and total skeletal muscle mass between genders and among age groups was tested by multi-factor variance analysis. The difference of the muscle decline between genders was compared by Chi-square test.
  
  
  RESULTS
  The total muscle mass in males was (52.22 ± 6.65) kg, which was significantly higher than that in females ((38.05 ± 4.39) kg) (t=28.20, P<0.001). ASM in 18-29, 30-39, 40-49, 50-59, 60-69, 70-87 years was (24.64 ± 3.23), (24.00 ± 3.12), (24.35 ± 3.03), (23.33 ± 2.97), (22.54 ± 2.91) and (21.40 ± 3.36) kg (F=16.12, P<0.001) in males, respectively, and (16.48 ± 3.14), (16.72 ± 1.93), (16.75 ± 1.93), (16.84 ± 2.28), (16.52 ± 2.35) and(14.70 ± 2.37)kg (F=4.38, P=0.001) in females, respectively. ASM in males ((23.72 ± 3.16) kg) was higher than that in females ((16.65 ± 2.25) kg) (t=55.97, P<0.001). There was a negative correlation between age and ASM in males after 50 years old, the regression equation was y=28.31-0.09x (P<0.001). While a negative correlation between age and ASM in females occurred after 60 years old, the regression equation was y=27.69-0.18x (P<0.001). The prevalence of low ASM was 16.85% (124/736) in females, which was significantly higher than that in males (8.73%, 96/1 100) (χ(2)=27.57, P<0.001).
  
  
  CONCLUSIONS
  A negative correlation was found between age and ASM in males after 50 years old and in females after 60 years old. The prevalence of low RSMI in females was significantly higher than that in males.
authors.affiliation: Department of Clinical Nutrition, Qiqihar First Hospital, Qiqihar 161005, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yongli
authors.initials: Y
authors.lastname: Song
authors.forename: Liping
authors.initials: L
authors.lastname: Meng
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Chen
authors.forename: Lirong
authors.initials: L
authors.lastname: Lin
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.forename: Yanping
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D015995:Prevalence; D055815:Young Adult