CHAPTER 4: BONE, MUSCLE, AND CONNECTIVE TISSUE ADAPTATIONS

1. CHAPTER 4: BONE, MUSCLE, AND CONNECTIVE TISSUE ADAPTATIONS

2. BONE ADAPTATIONS • 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. • Axial Skeleton & Appendicular Skeleton

3. Trabecular & Cortical • 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.

4. BONE BUILDING • To stimulate bone growth, programs need to look at: • Specificity of loading • Exercise selection • Progressive overload • Variation

5. SPECIFICITY OF LOADING • The strain must be placed on the areas where bone formation is required (hip, spine, etc.). • Multijointed • Osteogenesis is specific to the area worked.

6. EXERCISE SELECTION • 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

7. PROGRESSIVE OVERLOAD • 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

8. VARIATION • 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.

9. MECHANICAL LOADS FOR STIMULUS • 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

10. CHAPTER 4 • 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)

11. Mechanical Loading from Aerobic Exercise -Interval, stair climbers and weight packs seem to generate more osteoblasts. • Mechanical Loading for Athletes • Basically the same as other programs (see pg. 64 & 65)

12. CHAPTER 4 • 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

13. As the bone grows the insertion becomes buried in the bone, thus strengthening the junction.

14. CONNECTIVE TISSUE • 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.

15. TENDONS, LIGAMENTS, FASCIA • 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.

16. CARTILAGE • The internal environment of the cartilage tissue is call the cartilage matrix. Comprised of “ground substance”. • Hyaline – More articular in nature. Composed of water, protein and carbohydrates. Collagen fibers • Fibrous – Intervertebral disks & junctions where tendons attach to bones

17. 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.