Musculoskeletal Changes w/ Aging Flashcards
Week 2
How does physical stress affect tissue adaptation?
Too little stress → Decreased tolerance (atrophy, loss of function).
Adequate stress → Maintenance (no significant change in function).
Optimal stress → Increased tolerance (hypertrophy, improved function).
Excessive stress → Injury (tissue damage).
Extreme stress (too high or too low) → Death (loss of adaptation).
What are the thresholds for adaptations?
increased tolerance –> maintenance
best for us as PTs
What are the primary musculoskeletal changes with aging?
Connective tissue changes (decreased elasticity).
Joint-related changes (cartilage degeneration, reduced synovial fluid).
Strength loss (sarcopenia).
Bone loss (osteopenia/osteoporosis).
How do musculoskeletal changes lead to increased fall risk?
Loss of flexibility & joint mobility →
Postural changes (kyphosis, forward head posture) →
Increased fall risk
What are the key changes to joint structure with aging?
Reduced proliferation (slower tissue repair).
Dehydration (cartilage and synovial fluid dry out).
Reduced elasticity (less flexibility in ligaments and tendons).
Thinning in weight-bearing areas (cartilage breakdown).
Decreased resistance to tissue fatigue (joints wear down faster).
Reduced tensile strength (weaker connective tissue
When does collagen start to decline?
Age 25 with a 1% decrease each year
What are the key patterns of range of motion (ROM) loss with aging?
Cervical spine → Loss of extension & lateral flexion.
Thoracic/lumbar spine → Loss of extension.
Hip → Loss of extension.
Ankle → Loss of dorsiflexion.
What are the implications of ROM loss in aging?
Decreased postural control → More difficulty maintaining balance.
Decreased gait speed → Slower walking, reduced mobility.
Change in gait pattern → Leads to compensatory movements, increasing energy expenditure.
Increased fall risk
What is sarcopenia?
age-related loss of muscle mass, strength, and function, leading to decreased mobility, increased fall risk, and reduced independence
What is the key takeaway about muscle mass vs. function in sarcopenia?
Weakness = Decreased function
Low muscle mass ≠ Decreased function
What is a major observation with Sarcopenia?
You physically see a loss of muscle
What structural changes occur in skeletal muscle with sarcopenia?
Decline in size & number of skeletal muscle fibers.
Infiltration of fibrous & adipose tissue (fat replaces muscle).
Reduced satellite cell content (↓ muscle repair & regeneration)
How does sarcopenia impact muscle function?
Reduced skeletal muscle oxidative capacity (↓ endurance & efficiency).
Loss of the body’s protein reserve (↓ ability to recover & maintain muscle).
Decline in functional capacity & mobility, increasing fall risk.
At what rate does muscle strength decline with aging?
8% per decade until age 70.
Accelerates after 70.
What is the biggest loss in muscle function with aging?
Power loss > Strength loss.
What are the neuromuscular changes that contribute to sarcopenia?
Progressive loss of neurons (irreversible, age-related).
Loss of motor units (fewer connections to muscles).
25-50% reduction in motor units by age 60, leading to larger but less efficient motor units.
Changes at neuromuscular junction → Slower speed-to-strength ratio, reducing power.
What muscle changes occur with sarcopenia?
Progressive atrophy (muscle shrinkage).
Loss of Type II (fast-twitch) fibers, leading to reduced strength & power.
What is a key factor in the formation of sarcopenia?
chronic inflammation
high levels linked with reduced hand-grip strength + muscle mass/strength loss
What hormonal changes contribute to sarcopenia?
Loss of serum testosterone
↓ Muscle mass & strength.
↓ Bone mineral density (BMD) → Increased fracture risk.
↑ Visceral adiposity → More fat deposition, less lean muscle
How does mitochondrial dysfunction contribute to sarcopenia?
Less energy for muscle function
Poor ATP production, leading to fatigue & decreased endurance
What are the whole muscle changes associated with aging?
Decreased muscle mass (replaced by fat mass).
Decreased strength, especially in lower extremities.
Slower muscle contractile properties & rate of force development due to:
Reduced cross-bridge cycling (slower contractions).
Altered excitation-contraction coupling (weaker nerve signal transmission).
Increased compliance of tendinous attachment (less stiffness, weaker force transfer)
What muscle fiber changes occur with aging?
Type II (fast-twitch) fiber atrophy > Type I (more strength & power loss).
Fiber necrosis (cell death).
Fiber type grouping (remaining motor neurons take over, leading to larger but less efficient units).
Reduced satellite cell content in Type II fibers (↓ repair & regeneration)
Can age-related muscle changes be reversed?
Yes!
Resistance training that overloads weak/atrophied muscles can partially reverse muscle loss.
Stimulates satellite cells for muscle regeneration.
Improves contractile function & neural adaptations.
What imaging methods are used to diagnose sarcopenia?
MRI
CT
DEXA1 (gold standard)
Bioelectrical Impedance Analysis (BIA) ((Estimates muscle mass via electrical resistance))
What are the clinical cutoffs for sarcopenia classification?
Class 1 Sarcopenia → 1–2 SD below younger reference population.
Class 2 Sarcopenia → 2+ SD below younger reference population
What are the stages of sarcopenia?
Pre-sarcopenia → Muscle mass loss without functional decline.
Sarcopenia → Muscle mass loss + decreased strength OR performance.
Severe sarcopenia → Muscle mass loss + decreased strength AND physical performance.
What is the primary strength measure used to diagnose sarcopenia?
Grip Strength
What are the Grip Strength cut offs for weakness?
Men: Weak = ≤26 kg, Normal = ≥32 kg
Women: Weak = ≤16 kg, Normal = ≥20 kg
What performance tests assess sarcopenia?
TUG - Score >10.85 sec → Increased likelihood of sarcopenia
5x Sit-to-Stand Test → Assesses lower extremity power & functional strength.
What does SARC-CalF stand for?
S – Strength
A – Assistance with walking
R – Rising from a chair
C – Climbing stairs
CalF – Calf circumference (muscle mass indicator)
F - Falls
How is calf circumference measured in SARC-CalF?
Patient seated, legs relaxed, feet shoulder-width apart.
Measurement taken at thickest part of the calf.
Cutoff for low muscle mass:
Men: <34 cm
Women: <33 cm
How is SARC-CalF scored?
0-20 scale.
+10 points added if calf circumference indicates low muscle mass.
Sarcopenia risk = score of 11 or higher.
What are the T-score classifications for bone health?
Normal BMD = Within 1 SD of young adult mean (T-score ≥ -1.0)
Osteopenia (low BMD) = T-score between -1.0 and -2.5
Osteoporosis = T-score < -2.5 (More than 2.5 SD below young adult mean)
The more negative the T-score, the higher the fracture risk!
Which bones are most critically involved in osteopenia/osteoporosis?
Vertebrae, Wrist, Hip
What is Type I Osteoporosis?
Affects only women
Due to estrogen loss after menopause
What is Type II Osteoporosis?
senile
affects men and women
related to reduction in number and activity of osteoblasts
Pro-inflammatory cytokines stimulate osteoclasts –> bone demineralization
What is the difference between a T-score and a Z-score in a DEXA scan?
T-score → Compares a person’s BMD to a healthy 30-year-old of the same sex
Z-score → Compares BMD to an average person of the same age & sex
T-score is used for osteoporosis diagnosis
Z-score is used for secondary osteoporosis (e.g., from disease, medication use)
How is kyphosis measured, and what are normal vs. abnormal values?
Measured using the Cobb Angle
Normal kyphosis: 20-29°
Hyperkyphosis: >50°
What is the Wall Occiput Distance Test, and what do its results indicate?
Assesses risk for thoracic vertebral fracture & kyphosis
>2 cm = abnormal
>5 cm = predictive of kyphosis
What is the gold standard cutoff for diagnosing kyphosis using the Kyphotic Index?
Kyphotic Index ≥ 13 is the gold standard cutoff for kyphosis diagnosis
What does a reduced rib-pelvis distance indicate and what are the scores?
Can indicate a lumbar compression fracture // Suggests vertebral body collapse due to osteoporosis
Normal: ≥ 4 fingerbreadths
Abnormal (Suggestive of Fracture): ≤ 2 fingerbreadths
What is the most common etiology for vertebral compression fractures?
osteoporosis
What part of the spine is most commonly affected by vertebral compression fractures?
Thoracolumbar junction (T12-L2) → 60-75% of VCFs
L2-L5 → Accounts for 30% of cases
What part of the vertebra is compromised in a vertebral compression fracture?
Anterior column only
Considered a stable fracture
What percentage of postmenopausal women are affected by VCFs?
0.25
Most common pathophysiology of VCFs?
axial force related to flexion/extension of the spine > falls/trauma
What are management techniques for VCFs ?
Surgical - vertebroplasty, kyphoplasty
Conservative - orthoses (TLSO, LSO), Rehab
What is the FRAX?
Fracture Risk Assessment tool
screens for risk of fractures
What are the “cut offs” for the FRAX?
20% or more = risk of major fracture
3% or more = indicated for pharm treatment
Where do fragility fractures frequently occur and how?
from falling
frequently in the hip, wrist, spine
