Post on 16-Dec-2015
transcript
Objectives
Describe the anatomy of bone, muscle, tendon and ligaments
Discuss the response of the tissues above to training
Design a program to stimulate growth of the above tissues
Bone ModelingWolff’s Law- bone responds by
adapting to applied stress– Osteoblasts (formation of bone)
– Osteoclasts (removal of bone)
– Collagen matrix
– Periosteum (outer covering)
– Trabecular bone (spongy)
– Cortical bone (solid)
SkeletonAxial skeleton- skull, spinal
columnAppendicular skeleton-
upper extremity, shoulder girdle, lower extremity, pelvic girdle
Bone HypertrophyMinimal essential strain- the
threshold stimulus for the formation of new bone
Activities must be weight-bearing to stimulate increases in bone density
Bone Atrophy Bone atrophy occurs with
– Bed rest– Prolonged inactivity– Space travel– Osteoporosis
• Menopause related• Age related• Female athletic triad (disordered eating,
amenorrhea and osteoporosis. A female athlete can have one, two, or all three parts of the triad.
Designing training programs to elicit osteogenic stimuliSpecificity of loading- perform
exercises that stress the part of the skeleton where increases in bone density are desired– Axial loading
Exercise selection- force vectors through the spine and hip, multiple muscles, multi-joint, use greater absolute loads
Designing training programs to elicit osteogenic stimuli
Progressive overload- gradually increase the training loads
Training variation- vary the selection of exercises to vary the distribution of forces
Mechanical Loading of the Musculoskeletal SystemMagnitude of the load
(intensity)Rate (speed) of loadingDirection of the forcesVolume of loading (sets x
repetitions)
Activity and Bone Density Resistance exercise- few studies
have looked at bone mineral density with resistance training, results are variable, no studies focus on the rate and magnitude of loading
Aerobic exercise- high intensity repetitive activities such as rowing, stair climbing, and running have been moderately successful in demonstrating bone mineral density increases
Resistance Exercise Rx for Stimulating Bone Density Volume 3-6 sets, up to 10 repetitions Load- 1RM to 10RM range Rest- 1-4 minutes Variation- periodized Exercise selection- structural
exercises: squats, cleans, deadlifts, bench presses, shoulder presses
Training for Muscle StrengthHigh resistance, near
maximal muscle actions, few number of repetitions, complete recovery between sets, stimulate FT muscle fibers
Connective Tissue AdaptationType I collagen is a protein that
is the major collagen fiber in bone, tendons, and ligaments
Fibroblasts, cells that synthesize new materials, synthesize procollagen
Procollagen consists of three strands of protein in a triple helix
Microfibril- parallel arrangement of collagen filaments
Collagen “cross links” (covalent cross linking) to increase tensile strength
Collagen is in the extracellular space- outside the cell membrane
Ligaments, Tendons, and FasciaLigaments- connect bone to boneTendons- connect muscle to boneFascia- fibrous covering of skeletal
muscleEndomycium, perimysium,
epimysium
Cartilage Provide a smooth articulating surface
between two bones in a joint Act as a shock absorber Aid in attaching muscles to bone Limits translation
Cartilage Chondrocytes- cells that produce
cartilage Hyaline cartilage (articular cartilage)
covers the ends of long bones Ground substance- gel-like
carbohydrate material in the type II collagen of cartilage
Fibrous cartilage- tough fibrous bundles of type I and type I collagen, intervertebral disks, menisci
Tendons and Ligaments In aerobic exercise, collagen
metabolism increases to repair collagen damaged during exercise
In high intensity exercise, there is a net growth of connective tissue (ligaments and tendons) causing an increase in cross-sectional area and strength
Ligament/bone attachment is the weakest link in that system
Changes in Tendon Increase in collagen fibril diameter A greater number of covalent cross-
links within a fibril of increased diameter
An increase in the number of collagen fibrils
An increase in the packing density of collagen fibrils
Enhanced ability to withstand greater tensile forces
Effects of Physical Activity on Cartilage Cartilage gets its nutrient
supply from synovial fluid Joint movement (exercise)
increases the nutrient supply to cartilage
Immobilization of a joint causes death of chondrocytes and resorption of cartilage matrix
Moderate aerobic exercise increases cartilage thickness
Severe aerobic exercise or anaerobic exercise does not appear to cause degenerative joint disease