LEC14: Neuromuscular System (Age-Related Changes in Physiology and the Effects of Exercise) Flashcards
What is sarcopenia?
Loss of muscle mass due to age
Why should we pay attention to sarcopenia?
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
Initial patient presentation to evaluate for sarcopenia
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)
Summary of muscle strength changes in older adults across many studies
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
What is Type I muscle fibers?
Slow oxidative (SO)
Slow (S)
What is Type IIA muscle fibers?
Fast oxidative (FO)
Fast fatigue resistant (FR)
What is Type IIAB muscle fibers?
Fast oxidative glycolytic (FOG)
Fast intermediate fatigability (FI)
What is Type IIB muscle fibers?
Fast glycolytic (FG)
Fast fatigue (FF)
Mechanisms underlying sarcopenia
Reduction in muscle fibre size
Reduction in number of muscle fibres
Reduction in number of motor units
Altered hormonal status
Altered diet
What does altered hormonal control entail?
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
What does altered diet entail?
- Inadequate protein intake
- Insufficient caloric intake
What are the resistance training general recommendations for healthy older adults?
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
Is resistance training safe for older adults?
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
Are the number of sets for resistance training the primary variable responsible for muscle strength increases in older adults?
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
Is muscle power or muscle strength more important for the ability to perform daily activities?
Muscle power
What promotes functional improvements in older adults?
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
What did meta-analysis by Steib et al. find out?
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.
Explosive resistance training was (blank) than traditional resistance training in improving performance of the chair rise
more effective
Explosive resistance training was (blank) than traditional resistance training in improving performance for stairclimbing ability
somewhat effective
(blank) differences between resistance training modes were observed in (blank)
no
walking speed, timed up and go (TUG) test, and maximal strength
