Plan for Week 4 Monday, February 17

- Complete bone growth and integrity (Ch 4)- Review problems on p. 105-106

• Introductory problems 1,2,3,8,9,10• Additional problems 1,2,3,8,10

Wednesday, February 19- Introduce & review unit on joint flexibility and proprioception (pp

123-137)- Review for exam

Monday, February 24• Exam 1 Chapters 1-5

Questions on Bone Growth & Dev

Why is bone density related to body weight? What factors contribute to increase in bone density? When and why is there a period of lower bone density in

young people? Name 3 factors essential for an increase in bone strength. Why is osteoporosis mostly a problem with females and

the aged? How do we prevent it? Is there a relationship between bone health in older

people (50+ years) and bone density in youth?

Position Statement of ACSM on Osteoporosis http://www.acsm.org/

Weight-bearing physical activity is essential for developing and maintaining a healthy skeleton

Strength exercises may also be beneficial, particularly for non-weightbearing bones

An increase in physical activity for sedentary women can prevent further inactivity-related bone loss and can even improve bone mass

Exercise is not an adequate substitute for postmenopausal hormone replacement

Ex programs for older women should include activities for improving strength, flexibility, and coordination, to lessen the likelihood of falls

Bone Growth &Structure Summary Quality of mechanical properties depends on

- age (bmc peaks in 20’s, declines 2 % per decade after 30)- nutritional status - what nutrients are important?- type of bone - trabecular or cortical- hormonal status -which hormones?- duration and magnitude of stress

Osteoporosis – nature & prevalence- Affects aged and mostly females. Why?- How do we prevent it?

Website on osteporosis: http://www.nof.org National Osteoporosis Foundation

Objectives

Identify factors contributing to joint stability and flexibility.

Discuss role of proprioceptors in musculotendinous stretching exercises

Discuss characteristics of effective flexibility exercises, including PNF.

Discuss common joint injuries and pathologies

Joint flexibility – Range of Motion (ROM) Static vs dynamic Active vs passive Measuring joint range of motion

- Direct measurement – • Goniometer (Fig 5.9, p 127)• Leighton flexometer (Fig 5.10, p 127)

- Indirect & composite – e.g., sit and reach Factors influencing joint flexibility

- Shape of articulating bone surfaces (ex.: forearm extension)- Intervening muscle and fat (ex. : forearm flexion)- Length of ligaments and musculotendinous units crossing joint

Flexibility and injury – - Increased potential for injury when ROM is high, low, or imbalanced

Measurement of Flexibility

Direct

Indirect, or composite

Techniques for increasing joint flexibility Focus is on increasing length of musculotendinous units crossing the

joint Neuromuscular response to stretch

- The sensory unit• Consists of receptors, sensory neuron• Role is to provide feedback to provide body position and muscle-tendon condition sense &

to enable motor control

- Proprioceptors • cutaneous receptors (pressure-sensitive)• Joint receptors

– pressure-sensitive Pacinian corpuscles – Position and velocity-sensitive Ruffini endings

• Tendon receptors (stretch-sensitive golgi tendon organ, or GTO) • Muscle receptors (stretch-sensitive muscle spindle)

- Role of proprioception in skilled movement & flexibility Goal of stretching is to minimize spindle effect and maximize GTO effect.

Muscle spindle

Increasing flexibility Active and passive stretching Ballistic and static stretching Proprioceptive Neuromuscular Facilitation:

Proprioceptive Neuromuscular Facilitation (PNF)

A group of stretching procedures involving alternating contraction and relaxation of the muscles being stretched.

Done to take advantage of GTO response. Requires partner or clinician Contract-relax-antagonist-contract technique Agonist-contract-relax method Can significantly increase joint ROM over

single stretching session.

Common jt injuries and pathologies Sprains- stretching or tearing of ligaments, tendons, and

connective tissues crossing a joint Dislocations – displacement of the articulating bones at a

joint Bursitis – inflammation of bursae Arthritis – inflammation with pain and swelling

- Rheumatoid arthritis• autoimmune system disorder

- Osteoarthritis• Joint-specific, due to wear and tear

Website on bone and joint injuries: - http://www.arthroscopy.com/

Introductory problems, p 136: 3,4,5,7,8,9,10 Additional problems, p 137: 2,6,7,10