1. 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

2. 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?

3. 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

4. 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

5. 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

6. 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

7. Measurement of Flexibility Direct Indirect, or composite

8. 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.

9. Muscle spindle

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

16. 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.

17. 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