Lecture 7 - 9/10/2010 Discuss the definition and...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
9/10/2010 1 Session #7 Sarcopenia Tuesday September 14, 2010 c Discuss the definition and classification of sarcopenia c Discuss the prevalence of sarcopenia c Discuss the mechanisms of sarcopenia c Provide an overview of the consequences of sarcopenia “sarco” = flesh “penia” = deficiency Sarcopenia = deficiency of flesh (muscle loss) c The gradual loss of muscle mass (quality and strength) that occurs with aging c Hypertrophy - Increase in fiber size (length and width) - Increase protein synthesis/decrease degradation c Hyperplasia - Increase in fiber number - Prenatal growth largely from hyperplasia - Some hyperplasia from birth- 4 months - in adults ?? c Birth adult, 20x increase in size; increase in diameter 20 50 μ m c Muscle/unit height is similar in boys and girls until 13 yrs c 5-18yrs: 5 x increase in males, 4x in females c 9-15yrs, female doubles muscle mass c 11-17yrs, males double muscle mass
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
9/10/2010 2 Estimation of appendicular skeletal muscle mass (ASM) using DXA as criterion using the following equation: ASM (kg) = 0.2487(Wt) + 0.0483(Ht) – 0.1584(Hip Circ) + 0.0732(grip strength) + 2.5843(sex) + 5.8828 [R² = 0.91, SEE = 1.58 kg] Relative Skeletal Muscle Mass Index (RSMI) RSMI = ASM (kg) / height (m²) Baumgartner et al, Am J Epidemiol 1998; 147:755-763 Classification RSMI Z Score Normal RSMI > -1.0 Class I sarcopenia -1.0 to -2.0 Class II sarcopenia < -2.0 Z-Score is interpreted as standard deviations above/below the RSMI mean of the young adult reference group Baumgartner et al, Am J Epidemiol 1998; 147:755-763 Baumgartner et al, Am J Epidemiol 1998; 147:755-763 %Fat s Skeletal muscle cutpoints; MRI used as criterion s Skeletal muscle mass (SMM) was estimated by BIA using the equation: SMM= [(height²/BIA resistance x 0.401) + (gender x 3.825) + (age x -0.071)] + 5.102 [R² = 0.93, SEE = 9%] c Skeletal Muscle Index (SMI) SMI = SMM (kg) / height (m²) Janssen et al, Am J Epidemiol 2004;159:413-421 c Cut-points created based on SMI Group Muscle Mass Range, kg/m² Older Men Normal Muscle 10.76 Moderate Sarcopenia 8.51-10.75 Severe Sarcopenia 8.50 Older Women Normal Muscle 6.76 Moderate Sarcopenia 5.76-6.75 Severe Sarcopenia 5.75 Table adapted from Janssen et al, JAGS 2004;52:80-85 c Classifications: 1) Muscle mass index (RSMI) of less than 2 SD below the sex specific reference for a young healthy population (Baumgartner, 2000) 2) Skeletal muscle index (SMI): uses cutpoints relative to young healthy reference population (Janssen, 2002) c Do you agree? c What about muscle strength?
Background image of page 2
9/10/2010 3 s Muscle mass decreases at a rate of 5% per decade from 40 yrs on, and is more rapid after 65 yrs 3 s Decreases in muscle tissue begins at age 50 and dramatically increases after age 60 2 Sarcopenia occurs in all individuals to some degree as a consequence of aging, but it can be accelerated by a variety of factors and chronic illness”. 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/30/2011 for the course PSIO 445 taught by Professor Staff during the Fall '08 term at Arizona.

Page1 / 11

Lecture 7 - 9/10/2010 Discuss the definition and...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online