Musculoskeletal Health and Fitness:
- Healthy muscles allows a person to move freely and to keep the body responsive and
Relationship among Muscle, Movement and Physical activity:
i. Muscles produce force or tension – applied or expressed in types of contraction
ii. Contractions support a variety of movements (fundamental and specialized
iii. Movements are coordinated into actions or physical activity
Muscle walking Fundamental Motor Skills (FMS) Specialized movement skills (SMS)
- FMS – 6 years of age – coordinated into specialized skills.
- Quantity (amount of muscle mass) and quality (type of muscle of cells) play large role in determining
in not only the patterns of movement but also the effectiveness of that movement.
- SMS have variety of different outcomes:
i. Functionality: it allows you to do normal daily activities
ii. Occupational: task specified – criterion preference
iii. Sport-related: any kinds of sport that have competition/performance
iv. Active lifestyle: targeted on certain parameter that are used to assess the value or the
importance of that movement on one’s health ex. CRF (cardiovascular repertory fitness) ,
strength/power, body composition, flexibility.
Classification of Musculoskeletal Disorders
a) Body structure and function: transient and reversal decrease in muscle function –
manifest itself in minutes to hours (
b) Activity limitations: injury or damage and associated pain leading to impaired – days to
years (ex. Strains, low back pain)
c) Any restriction to participation: injury leading to chronic disability, degeneration and
loss of muscle (ongoing) (ex. Osteoporosis)
Categories of Muscle
a. Skeletal muscle
iii. 600 skeletal muscles – 40-50% of total body weight
iv. Functions: locomotion and breathing, postural support, heat production during
b. Cardiac Muscle:
i. Electrically coupled cells – cells in cardiac muscle are connected through a series
of intercalated discs. This relationship between cardiac muscle cells is important in terms of function. If one gets stimulated the other cells would be stimulated
c. Smooth muscle-
i. Non-striated- tonal control
STRUCTURE OF SKELETAL MUSCLE:
- Muscle is composed of number of fascicle which are bundle of muscle fibre/cells.
- Myofibril are located within the muscle fibre/cell.
Muscle fascicle muscle cell/fibre myofibril sarcomere
There are 10,000 sarcomere in one myofibril
5000 myofibrils within a muscle cell
We have a million cells
- We have different shades or regions within the myofibril because of the density of proteins
(amount of proteins) contained within the different regions in the sarcomere.
Actin: made out of g-actin, which are globular/round individual proteins, that complex together
to form pearl like structure. Once all the g-proteins form into a double helix it is now known as
Myosin: made of number of myosin proteins. Contains the head region and the rod region. It
forms the thick filament.
The basic generation of force or productions comes from when these two proteins come
together, force production tension occurs and as result you have a moment of z-lines coming
Some of the requirements for actin and myosin to get together:
Energy – ATP; primarily focused on regulating myosin to attach/de-attach with actin Calcium – needed to prepare the thin/actin filament to be ready for myosin ,
binds to a specific proteins, troponins, that are found on the f-actin and cause a
physical movements between some of the g-actin (yellow molecules). So the site
for myosin is now available.
Alignment of proteins: protein-protein interactions.
Once Myosin is attached to ATP, a chemical energy, it has to be converted into mechanical
energy because force production/ tension production is mechanical event (not a chemical
event). To do that, you have to hydrolyze the ATP molecule into ADP+Pi.
Myosin ATPase is not an old protein anymore. It is an enzyme. ATPase refers to as myosin
protein enzymatic ability to split, breakdown, hydrolyze ATP and so doing it releases chemical
energy and transforms into to mechanical energy so that contraction can occur.
We need calcium in order for the binding to happen. Once calcium binds to actin, it can now
bind with the energized myosin, and as a result, we have mechanical energy being released
which causes the z-lines to shorten.
- Myosin ATPase doesn’t make ATP, it consumes ATP. Myosin ATPase then hydrolyzes ATP
into ADP+Pi + H + heat energy and mechanical energy.
- Within skelet