LEC14: Neuromuscular System (Age-Related Changes in Physiology and the Effects of Exercise)

Question 1

What is sarcopenia?

Answer 1

Loss of muscle mass due to age

Question 2

Why should we pay attention to sarcopenia?

Answer 2

Individuals with clinical levels of sarcopenia (2 SD below the mean muscle mass for healthy young adults- 35 yrs) have higher rates of disability than those with greater muscle mass

Question 3

Initial patient presentation to evaluate for sarcopenia

Answer 3

Noted decline in function, strength, “health” status

Self-reported mobility-related difficulty

History of recurrent falls

Recent unintentional weight loss (>5%)

Post-hospitalization

Other chronic conditions (eg. type 2 diabetes, chronic heart failure, chronic obstructive pulmonary disease, chronic kidney disease, rheumatoid arthritis, and cancer)

Question 4

Summary of muscle strength changes in older adults across many studies

Answer 4

Healthy men and women in their seventh and eighth decades demonstrate, on average, 20-40% less strength compared to younger adults.

Strength losses are even greater for people in their ninth decade (≥ 50%).

Similar strength losses were present for proximal and distal muscles in the upper and lower extremities

Men and women experience similar relative strength losses

Question 5

What is Type I muscle fibers?

Answer 5

Slow oxidative (SO)
Slow (S)

Question 6

What is Type IIA muscle fibers?

Answer 6

Fast oxidative (FO)
Fast fatigue resistant (FR)

Question 7

What is Type IIAB muscle fibers?

Answer 7

Fast oxidative glycolytic (FOG)
Fast intermediate fatigability (FI)

Question 8

What is Type IIB muscle fibers?

Answer 8

Fast glycolytic (FG)
Fast fatigue (FF)

Question 9

Mechanisms underlying sarcopenia

Answer 9

Reduction in muscle fibre size

Reduction in number of muscle fibres

Reduction in number of motor units

Altered hormonal status

Altered diet

Question 10

What does altered hormonal control entail?

Answer 10

Effects of endocrine changes on muscle
- Age-related decreases in testosterone levels (Both have been linked to decreased muscle mass and strength losses)
- Age-related decreases in growth hormone

Question 11

What does altered diet entail?

Answer 11

• Inadequate protein intake
• Insufficient caloric intake

Question 12

What are the resistance training general recommendations for healthy older adults?

Answer 12

Sets: 1-3 sets per exercise per muscle group

Repetitions: 8-12 or 10-15

Intensity: 70-85% of 1RM

Exercise selection: 8-10 different exercises

Modality: free-weight or machine-based exercises

Frequency: 2-3 days per week, per muscle group

Power/explosive training: 40-60% of 1RM

Functional movements: exercises to mimic tasks of daily living

Question 13

Is resistance training safe for older adults?

Answer 13

A systematic review on the effects of resistance training in physically frail oldest-old (70–92 years of age and older) reported only one case of shoulder pain with resistance training out of 20 studies and 2,544 subjects

Question 14

Are the number of sets for resistance training the primary variable responsible for muscle strength increases in older adults?

Answer 14

In early phases of resistance training, the number of sets per exercise does not seem to be the primary variable responsible for muscle strength increases in older adults. Similar results have been shown in older women when comparing 1–3 sets during short-term training periods (i.e., 6–12 weeks of training) (6,486).

However, an advantage has been observed in favor of 3 sets during longer resistance training periods

Question 15

Is muscle power or muscle strength more important for the ability to perform daily activities?

Answer 15

Muscle power

Question 16

What promotes functional improvements in older adults?

Answer 16

Resistance training performed at maximal velocity during the concentric phase (i.e., explosive resistance training where muscles exert maximum force in short intervals of time) may promote greater functional improvements than resistance training performed at slower velocities in older adults

This may reflect the ability to perform ADL, which may be more dependent of the capacity to apply force quickly than the capacity to exert maximal strength

Question 17

What did meta-analysis by Steib et al. find out?

Answer 17

Explosive resistance training was more effective than traditional resistance training in improving performance of the chair rise (SMD 5 1.74), and somewhat effective for stairclimbing ability (SMD 5 1.27), whereas no differences between resistance training modes were observed in walking speed, timed up and go (TUG) test, and maximal strength.

Question 18

Explosive resistance training was (blank) than traditional resistance training in improving performance of the chair rise

Answer 18

more effective

Question 19

Explosive resistance training was (blank) than traditional resistance training in improving performance for stairclimbing ability

Answer 19

somewhat effective

Question 20

(blank) differences between resistance training modes were observed in (blank)

Answer 20

no

walking speed, timed up and go (TUG) test, and maximal strength