Transcript chapter 4: bone, muscle, and connective tissue adaptations

CHAPTER 4: BONE, MUSCLE, AND
CONNECTIVE TISSUE ADAPTATIONS
BONE ADAPTATIONS
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New bone formation occurs when a
minimal essential strain is surpassed.
This MES may equate to around 1/10
the amount of force required to fracture
the bone.
The strain is of a weight bearing nature.
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Axial Skeleton & Appendicular Skeleton
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Trabecular & Cortical
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Trabecular responds more quickly than
cortical
Cortical bone has a series of canals which
run from the spongy part of the bone.
MES causes Osteoblasts to migrate to the
cortical bone for reinforcement.
BONE BUILDING
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To stimulate bone growth, programs
need to look at:
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Specificity of loading
Exercise selection
Progressive overload
Variation
SPECIFICITY OF LOADING
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The strain must be placed on the areas
where bone formation is required (hip,
spine, etc.).
Multijointed
Osteogenesis is specific to the area
worked.
EXERCISE SELECTION
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Those exercises that are multijointed
and use more muscle groups tend to be
more effective.
Isolation exercises tend not to be as
effective.
Squat vs leg extension
PROGRESSIVE OVERLOAD
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Just like any program, the strain placed
on the bones (and muscles) must
increase gradually over time to reduce
the chance of injury (stress fractures).
Ten percent rule
VARIATION
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One of the keys in overall osteogenesis
is to place the strain on the bones at
different angles. Vary the exercises
performed
Starting young also seems to be a key.
Enhance as much bone development
early in life through weightbearing
activities.
MECHANICAL LOADS FOR
STIMULUS
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Magnitude of the load (more is better)
Speed of loading (faster/powerful is
better)
Direction of forces (variations are
better)
Number of repetitions is not a
significant stimulus (more is not better).
Look at page
CHAPTER 4
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Four components of Mechanical Loading
which stimulate bone growth:
 Intensity of load
 Speed of loading
 Direction of Force
 Number of Reps (volume)
***Also known as Osteogenic Stimuli, Table
4.1)
Mechanical Loading from Aerobic Exercise
-Interval, stair climbers and weight packs
seem to generate more osteoblasts.
 Mechanical Loading for Athletes
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Basically the same as other programs (see pg.
64 & 65)
CHAPTER 4
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Mechanical Loading for Untrained or Elderly
 Physicians clearance
 Analysis of joint stability
 Recommend using “projected 1RM”
Important point regarding musculoskeletal
strength gains!
 Strength, Size or Endurance
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As the bone grows the insertion becomes
buried in the bone, thus strengthening the
junction.
CONNECTIVE TISSUE
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The degree of tissue adaptation is
proportional to the intensity of the
exercise stimulus.
Positive adaptations occur at the
tendon-bone junction, within the body
of the tendon/ligament, and in the
network of fascia around the muscle.
TENDONS, LIGAMENTS,
FASCIA
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Ligament connects bone to bone and
has its own blood supply
Tendon connects muscle to bone and
also has a blood supply
High intensity loading results in a net
growth of the involved connective
tissue.
CARTILAGE
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The internal environment of the
cartilage tissue is call the cartilage
matrix. Comprised of “ground
substance”.
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Hyaline – More articular in nature.
Composed of water, protein and
carbohydrates. Collagen fibers
Fibrous – Intervertebral disks & junctions
where tendons attach to bones
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Weight bearing forces and complete
movement through the ROM is
essential.
Moderate aerobic exercise increases
cartilage thickness. Strenuous exercise
does not seem to cause degenerative
joint disease pg. 70.