HLTH 210 Lecture Notes - Lecture 17: Impaired Glucose Tolerance, Skeletal Muscle, Adipose Tissue
5 May 2018
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Skeletal muscle: an important determinant of human health
20-25 wks of gestation: all the muscle cells you’ll have in your life
● Key points
○ Dietary quality and time spent in physical activity are important determinants of
health
○ Dietary patterns affect skeletal muscle health, and this has important implications
for overall health
○ Incorporating regular physical activity now as opposed to when you’re older, as
exercise training can diminish many of the aging-induced alterations in skeletal
muscle
● Normal low risk <-> normal high risk <-> predisease <-> early disease <-> late disease
○ Determinants of health: environment, biology, behavior
○ Fundamental processes: inflammation, regenerative potential, immune health,
oxidative stress
○ Predisease - depression, asymptomatic precancer, impaired glucose tolerance,
early cognitive dysfunction, increased carotid IMT, depression, asymptomatic
pre-cancer
● *about 40% of premature deaths are caused by behavior patterns that could be modified
by preventative interventions
○ Diet
○ Physical activity
○ Coping with stress
○ Substance abuse/addiction
○ Sexual activity
○ Diet and physical activity contribute to an estimated 300,000 to >500,000 deaths
annually in the US
● diet/physical activity affects fat mass, adipose tissue which affects risk of disease
○ But diet/physical activity also DIRECTLY affects risk of disease, premature death
● Fat free mass - also directly affect risk of disease, premature death
○ Liver
○ Pancreas
○ bone
○ Skeletal muscle
○ ALSO AFFECTED BY DIET/PHYSICAL ACTIVITY
● Skeletal muscle mass and strength are important determinants of life span and health
span (quality of life)
○ Skeletal muscle is the largest organ in healthy adults
■ 40% of total body mass
■ Functions:
● Force generation - locomotion, posture, joint stabilization, eye
movement, mastication, manipulating the environment
● Breathing
● Metabolism
○ Skeletal muscle uses 20-30% of total resting energy expenditure
find more resources at oneclass.com
find more resources at oneclass.com
○ Responsible for ~80% of glucose uptake
■ Can result in diabetes if malfunction
○ Muscle is a reservoir for amino acids - important for protein metabolism and
glucose metabolism
● Skeletal muscle exhibits considerable plasticity
○ Muscle mass can change to a great degree
○ Maintenance of muscle mass determined by balance of synthesis (hypertrophy)
and degradation (atrophy)
○ Muscle protein turnover is highly dynamic
■ Small persistant changes in these pathways can lead to large changes in
muscle mass
● Skeletal muscle atrophy decreases functionality and increases morbidity and mortality
○ Atrophy - unintentional loss of at least 5% of muscle mass
○ Loss of muscle mass and strength is a strong risk factor for mortality
■ Healthy elderly
■ Heart and renal failure
○ Atrophy common to
■ Aging
■ Disuse - mechanical ventilation, immobilization, space flight, spine injury
■ Diabetes
■ renal/heart failure
■ Cancer
■ Rheumatoid arthritis
■ Osteoarthritis
■ COPD
■ Sepsis
○ Muscle loss leads to…
■ Decrease in metabolically active tissue, leading to decreased energy
expenditure, leading to obesity
■ Sarcopenic obesity
■ Increased insulin resistance
■ Increased circulating blood glucose (and HbA1c)
■ Modified electrolyte regulation, K+, Na+
■ Increased likelihood of osteoporosis and fractures
■ Increased functional impairment, physical disability, frailty and mortality
● Muscle mass is a predictor of health status
○ MMI= [Muscle mass (kg)]/[height (m)^2]
○ A decreased muscle mass index is an increased risk of all-cause mortality
■ Muscle mass is inversely associated with mortality risk in older adults,
independent of fat mass and CV and metabolic risk factors
■ ~20% lower risk of death in those with the highest MMI quintile vs the
lowest MMI quintile
■ Risk not predicted by BMI
○ An increased MMI
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Skeletal muscle: an important determinant of human health. 20-25 wks of gestation: all the muscle cells you"ll have in your life. Dietary quality and time spent in physical activity are important determinants of health. Dietary patterns affect skeletal muscle health, and this has important implications for overall health. Incorporating regular physical activity now as opposed to when you"re older, as exercise training can diminish many of the aging-induced alterations in skeletal muscle. Normal low risk normal high risk predisease early disease late disease. Fundamental processes: inflammation, regenerative potential, immune health, oxidative stress. Predisease - depression, asymptomatic precancer, impaired glucose tolerance, early cognitive dysfunction, increased carotid imt, depression, asymptomatic pre-cancer. *about 40% of premature deaths are caused by behavior patterns that could be modified by preventative interventions. Diet and physical activity contribute to an estimated 300,000 to >500,000 deaths annually in the us. Diet/physical activity affects fat mass, adipose tissue which affects risk of disease.
