Weeks 5-9 Flashcards
(91 cards)
What is subjective/self-reporting fatigue?
Perception
Subjective lack of physical or mental energy (or both) that is perceived by the individual to interfere with usual and desired activities
What is objective/performance fatigue?
Difficulty maintaining force output or muscular control
What can neuromuscular fatigue be due to? (2) Which is common in healthy and disease people?
- Altered neural activation (commonly with disease) OR
- Altered muscle metabolism (commonly with healthy)
What potential locations of sources of fatigue? (4)
- CNS (brain, spinal cord)
- PNS
- N-M Junction
- Muscle fibre (membrane, SR, actin-myosin)
What are peripheral factors of fatigue? (6)
- NM transmission
- Excitation contraction
- Decreased energy stores
- Increased metabolites
- Electrolyte gradients
- SNS
What are central factors of fatigue? (6)
- CNS motor drive
- Feedback from muscle
- Motivation
- Discomfort
- Sleep disorders MS
- Endocrine abnormalities
What is acute neuromuscular fatigue? What is it mostly associated with?
Local contractile failure in muscle. Mostly associated with energy production (energy supply fatigue)
What contributes to acute neuromuscular fatigue? (5)
- Lack of blood flow
- Lack of oxygen
- Nutrient fatigue or substrate depletion (creatine phosphate or glycogen depletion)
- Increased metabolites
- Altered Ca2+ signalling
What are the three types of muscle soreness?
- Acute (during activity)
- Delayed onset (24-72 hours after activity)
- Sustained (injury related)
What are characteristics of acute muscle soreness? (6)
- Occurs during physical activity
- Not usually associated with tissue damage
- Associated with lactic acid production (more in high intensity)
- May produce a burning sensation
- Recovery rapid after stopping activity
- Fastest recovery from low intensity dynamic activity
What are characteristics of DOMS? (8)
- 24-72 hours post unaccustomed physical activity
- Common when starting a new exercise program, first day of a new job or a change of job tasks
- Associated with eccentric muscle contractions (walking downhill, unloading)
- Associated with damage to muscle fibres and inflammation (mild strain injury)
- Muscles are often swollen and stiff
- Usually resolves in 2-3 days
- Provides protection for ~6 weeks
- Soreness can be severe
a) How to minimise DOMS when starting an exercise program? (2) b) In what population is this particularly important?
a)
- Use modest loads (especially eccentrically)
- Limit downhill running and increase slowly
b) The elderly
How could you minimise DOMS in the workplace for new employees?
Limit their exposure to tasks that are likely to instigate DOMS, in their first few days of work to allow for adaptation
What are characteristics of muscle soreness due to strain injury? (6)
- Muscle or associated tissue injured
- May involve fibres and/or connective tissues
- Often due to over exertion or poor mechanics
- May feel soreness immediately
- May take time to heal
- Requires rest time for recovery
What is the difference between a sprain and a strain?
Sprain - ligament or joint capsule
Strain - muscle and/or tendon
What are some causes of skeletal muscle injuries? (5)
- Damage to muscle fibres
- Damage to tendons
- Damage to myotendinous junction
- Damage to tendon attachment to bone
- Spasm (sustained contraction) due to nerve activation or irritation
What are satellite cells? When are they stimulated?
- Type of muscle stem cells that sit between the basal lamina and sarcolemma
- Stimulated and proliferate when cells are substantially damaged - when not in contact with sarcolemma
What are the steps in muscle regeneration? (5)
How long may this process take?
- Muscle fibres damaged
- Cell infiltration and inflammation
- Degenerative dismantling of damaged cell
- Proliferation of satellite cells
- Form myotubes then filled with new myofibrils
- Process may take 6 months
What muscle changes occur with disuse? What is this due to?
- Atrophy - decreased muscle fibre size (cross-sectional area)
- Weakness/loss of force
- Usually due to loss of mechanical loading rather than loss of neural activation
What are the effects of bed rest? (microgravity) (2)
- Greater atrophy in antigravity muscles
- Greater atrophy in fast twitch fibres
What are some circumstances that may induce disuse adaptations? (5)
- Sedentary behaviour
- Immobilisation of body segments
- Bed rest
- Ageing
- Denervation
What is the cause of muscle cramps?
- Triggered by nerve activity
- Not fully known
What makes muscles more susceptible to cramps and what is a strategy to overcome that?
- Water intake after dehydration makes muscles more susceptible to cramps; ? dilution of electrolytes
- Can be managed with intake of electrolytes
What factors put someone at greater risk of muscle cramps? (6)
- Fatigue
- Dehydration/electrolyte imbalance
- Reduced blood flow
- Hypothyroidism
- Pregnancy
- Genetics