Module 5 Flashcards
What is immobilisation?
To reduce or eliminate motion of (the body or a part) by mechanical means or by strict bed rest.
Changes to muscle fibres during immobilisation
-When our muscles are kept in a certain position, our fibres adapt to that position that they are being kept in
-If we have an ankle joint that is being kept in plantarflexion (cast) then our calf musle is shortened and our dorsi flexors are in a lengthened position (they adapt to lose or gain sarcomeres)
-Gaining sarcomeres in the extended position, losing sarcomeres in the extended position
-The shortenedmuscle will be more stiff and have a shortened muscle length
-No tensile loading by shortening
Changes to musculo-tendinous structures without stimulus
-MT structures will adapt to the position they are in at rest
-A remodelling of the tissues, either shortening or lengthening
-Changes in muscle length cause a change in maximum force production
What is muscle atrophy? (muscle weakness and immobilisation)
- Muscular atrophy: the muscle becomes smaller, lack of stimulation when its immobilised, decrease in the cross section area of the muscle
- Reduce the capacity of the muscle to produce force because our cross sectional area is directly proportional to the amount of force we are able to produce
Cross-sectional area: rapid reduction in about a week
- Reduce the capacity of the muscle to produce force because our cross sectional area is directly proportional to the amount of force we are able to produce
Factors affecting the rate of atrophy
- Rate of atrophy is affected by various factors: type of muscle fibre (fast twitch rather than slow twitch), position of immobilisation (shortened positioned muscle will atrophy faster)
- Stretch will stimulate sarcomeres, contractions maintain cross sectional area (no contractions, no cross sectional area)
- Shortened- reduction in length, dropping off sarcomeres from that muscle fibre
When we stretch that muscle its not going to stretch as much when we apply the same amount of force, not that much angular displacement as we usually would
Relationship between full ROM and muscle force
If we don’t have full ROM there is less muscle force (less length, less force (middle point of our total available range is reduced cos we don’t have max ROM- our muscle has shortened because we have dropped off sarcomeres, joint is more stiff as well)
What causes stiff joints?
- Position of immobilisation
-Even in the absence of the muscle becoming shorter- changes in the cartilege and ligaments (fluid that lubricates joint becomes thicker and more viscous, connective tissue becomes less regularly aligned) - Adaptive shortening in the Musculo-tendinous structures
-Connective, endomysium etc - Periarticular tissues (capsule, ligaments= long term)
- Intra-articular adhesions
-Within the joint there could be ligament damage - -Scar tissue from trauma (stiffer joint in the long term)
What might change following immobilisation and how do we test that?
- Muscle length- muscle length test
- Joint stiffness- PROM test
- Muscle strength test- muscle strength test
Dynamometer- manual muscle test etc
Key points of rehab after immobilisation
- Issues: weakness, loss of extensibility, stiffness
-Strengthening muscle, lengthen muscle and mobilise/move joints (this is the rehab)
How to strengthen the muscle?
Increase muscle cross section thus increasing the capacity to generate force
-Isometric, dynamic and task-specific
Isometric muscle rehab
-No change in length of muscle
-Maximum muscle contraction against immovable resistance
-3 x 10 reps, 5 seconds hold for 5 days a week
-Pushing against a wall
-Pushing at a certain level, push to 70 percent or base it upon a pain free contraction
-How many reps until fatigue, how hard they can push for each rep to get for fatigue
-Sometimes less intensity is more effective
Concentric contractions
-Muscle shortens
-Shortening allow us to move weight up (bicep curl)
Ecentric contractions
-Will cause greater DOMS and will lead to greater gains in cross sectional area and strenth
-The lengthening of the muscle
What is rep maximum?
-Maximum load possible to lift, through range, fixed number of times
-1 RM- a single lift
-10 RM= lift possible ten times
-6-8 RM is maximum strength gain
-If working for endurance- high RM, lower weight (15-20 times)
-If working for power, 6-8 as explosively as possible, focusing on speed of movement
Stretching and muscle
-Sustained stretch with low load may improve shortened muscle (gradually lengthening that muscle)
-People with a normal muscle length however might not benefit as much
-Activation of muscle in lengthened position may enhance effect
-Stretching before or after exercise does nothing
