Plan for Week 4 n Monday, February 17 -Complete bone growth and integrity (Ch 4) -Review problems on p Introductory problems 1,2,3,8,9,10 Additional problems 1,2,3,8,10 n Wednesday, February 19 -Introduce & review unit on joint flexibility and proprioception (pp ) -Review for exam n Monday, February 24 Exam 1 Chapters 1-5

Questions on Bone Growth & Dev n Why is bone density related to body weight? n What factors contribute to increase in bone density? n When and why is there a period of lower bone density in young people? n Name 3 factors essential for an increase in bone strength. n Why is osteoporosis mostly a problem with females and the aged? n How do we prevent it? n Is there a relationship between bone health in older people (50+ years) and bone density in youth?

Position Statement of ACSM on Osteoporosis n Weight-bearing physical activity is essential for developing and maintaining a healthy skeleton n Strength exercises may also be beneficial, particularly for non-weightbearing bones n An increase in physical activity for sedentary women can prevent further inactivity-related bone loss and can even improve bone mass n Exercise is not an adequate substitute for postmenopausal hormone replacement n Ex programs for older women should include activities for improving strength, flexibility, and coordination, to lessen the likelihood of falls

Bone Growth &Structure Summary n 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 n Osteoporosis – nature & prevalence -Affects aged and mostly females. Why? -How do we prevent it? n Website on osteporosis: National Osteoporosis Foundation

Objectives n Identify factors contributing to joint stability and flexibility. n Discuss role of proprioceptors in musculotendinous stretching exercises n Discuss characteristics of effective flexibility exercises, including PNF. n Discuss common joint injuries and pathologies

Joint flexibility – Range of Motion (ROM) n Static vs dynamic n Active vs passive n 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 n 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 n 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 n Focus is on increasing length of musculotendinous units crossing the joint n 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 n Active and passive stretching n Ballistic and static stretching n Proprioceptive Neuromuscular Facilitation:

Proprioceptive Neuromuscular Facilitation (PNF) n A group of stretching procedures involving alternating contraction and relaxation of the muscles being stretched. n Done to take advantage of GTO response. n Requires partner or clinician n Contract-relax-antagonist-contract technique n Agonist-contract-relax method n Can significantly increase joint ROM over single stretching session.

Common jt injuries and pathologies n Sprains- stretching or tearing of ligaments, tendons, and connective tissues crossing a joint n Dislocations – displacement of the articulating bones at a joint n Bursitis – inflammation of bursae n Arthritis – inflammation with pain and swelling -Rheumatoid arthritis autoimmune system disorder -Osteoarthritis Joint-specific, due to wear and tear n Website on bone and joint injuries: - n Introductory problems, p 136: 3,4,5,7,8,9,10 n Additional problems, p 137: 2,6,7,10