3) Stengthening: Muscle Atropthy Flashcards
Arrangement of Muscle
Made up of contractile and non contractile tissue
> Epimysium very dense surrounds whole muscle
> Perimysium surrounds fascicles which are bundles of muscle
> Fascia supports muscle - surrounds it
forms pathways for nerves blood vessles and lymphatics- good blood supply for continuous muscle contraction
> Endomysium surrounds individual muscle fibres- thin and inner part is called the basal lamena
Normal muscle
Variance in fibre type :between muscles, individuals and genders
Type 1
Slow oxidative
Soleus
Slow oxidative contraction- eg maintain posture
Slow & Small motor unit
Slow conduction rate
High fatigue resistance
Weak contraction
High concentration of myoglobin enable aerobic energy metabolism
Mo farah
Type 2a
Fast oxidative glycolytic
Tibialis anterior
Quick contraction
Medium motor unit
Fast conduction rate
High resistance to fatigue
Medium contraction
Low concentration of myoglobin enabling anaerobic energy metabolism
Ronaldo
Type 2b
Fast glycolytic
Lateral head rectus femoris
Very quick contraction
Large motor unit
Very fast conduction rate
Fast to fatigue
Powerful contraction
Low concentration of myoglobe in enabling anaerobic energy metabolism - creatinephosphate
Usain bolt
Motor unit
All muscle fibres that are innervated by the same motor neurone = same type
Large motor neuron phasic,fast twitch, type 2a 2b,
large motor unit 300–800 muscle fibres
Small motor neuron,tonic,slow twitch type 1
small motor unit 12–180 muscle fibres
How many muscle fibres contract from 1 innervating motor unit
Size of motor neurone
Varies between muscles and within muscles eg triceps and quads
1 motor neurone supplying fewer muscles= better control of muscles
Speed,force = eye muscle
Muscle strength
Larger motor neurone synchronised = greater the strength
Larger the muscle= greater strength
Atrophy
Decrease in muscle fibre size resulting from the lack of stimulation
ie lack of activity - obesity aswell
Why do muscles become weak
Inactivity- use it or lose it Neurological disruption Bedrest Injury – in a cast Non-weightbearing Pathology Ageing Malnutrition - proteins electrolytes
Preventing atrophy
Mechanical loading – muscles under stress- lifting weights
Increased load or resistance is paramount for protein synthesis and turnover
Hypertrophy
▪️Increase muscle mass
▪️Increased strength
▪️Increased cross-sectional area of muscle fibres
▪️Increased connective tissue
▪️Alteration of fibre type
▪️Alteration of metabolic capacity of muscle
▪️Alteration in myosin heavy chain isoforms
▪️Increased capillary density, myoglobin, enzyme activity of mitochondria and oxidative power
What must happen for hypertrophy to occur
Satilite cells need to be actively involved
Muscle stem cells
Proliferate and differentiate into myoblasts
Basal lamina and sarcolema of muscle dormant until stimulated
More nuclei leads to more protein synthesis and myofibril becoming bulkier
More mitochondria
*cytokines
Muscle strength
Ability of a muscle to produce tension and a resulting force in one maximal effort:
- Dynamic
- Static
- In relation to demands placed on it very adaptable
More info travelling via more efficient motor neurones= stronger
Hypertrophy is the physiological process
Mechanical load= actin and myosin increase which increase muscle bulk increase size and number sarcomeres
Increased rate if mitochondria= ATP
X4 weeks
Vascularisation areound muscle uses o2 more effective
Power vs Endurance
Determined by the strength of contraction and the distance moved in the specified time. Velocity of contraction. T2a T2b
Ability to contract repeatedly or sustain tension over a prolonged period of time. T1
Principles of training
Specificity Progression Overload- FIT Reversibility Tedium
Individuality,motivation,learning, diminishing returns
Diminishing returns
More injured patients are more likely to improve more in comparison to those patients who are already in good physical condition
Overload
In order to strengthen muscle it must be fatigued
*Intensity needs to be 60% of one repetition marks of maximum voluntary contraction
Some regimes= power other endurance
Fit principal
Resistance offered by free weights bodyweight theraband
Strengthening regimes
8-12 repetitions
3 times a week minimum twice a week
Start slow with low intensity
Upper limb 30-40% of 1RM
Lower limb 50-60% of 1RM
Once able to complete 12 reps increase by 5%
Progression of weight 1 –2 weeks or if elderly 2–4 weeks
Specificity
E.g Strengthening glutes for walking
Eccentric muscle contraction appears to be effective and efficient increasing muscle strength
If movement isn’t possible due to pathology isometric exercises will improve isometric strength and enhance isotonic strength and movement is allowed
Speed of isotonic contraction is can affect the strength of changes
The speed of muscle needs to contract for specific functional task is the ideal speed of the exercise
Muscle strength factors
REVIEW E LECTURE
Type of contraction Frequency of firing motor units Number of motor units activated Psychological factors Angle of pull CSA of muscle Age and fitness Length/tension relationship Neural factors Length of lever arm Strength and stiffness of connective-tissue Speed of contraction Genetics
Measuring strength
MRC
Circumferential measurement - not a good test for strength
Dynamometers- isokinetic ( cybex biotex) or handheld
Newton’s laws
Law inertia
Body will remain at rest or in a state of uniform motion unless acted upon by an external force
Weak quads reduce inertia
Law acceleration
The acceleration of the body is parallel directly proportional to the force acting on the body Is in the same direction of the force and inversely proportional to the mass of the body
Make exercise faster - Mobilising
Or slower for strengthening more demanding of motor units
Law action/inaction
To every action there is an equal and opposite reaction
Resistance is equal
Physiological process atrophy
Decrease protein synthesis rate
No stimulus body takes away protein synthesis = wastage
How do you know strengthening programme has worked
Worked/Reached fatigue
Sweating,facial expressions, compensating,unable to work through range, phasiculation (tremor)
Strengthening programme
Motivation-start easy then progress Competition Tempo Slower Through range- start mid range Power/endurance
Type of contraction- concentric is easiest
Eccentric is the hardest
