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 Review common joint injuries

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 Tendon receptors (stretch-sensitive golgi tendon organ, or GTO) –Stimulation inhibits contraction of host muscle and tendon Muscle receptors (stretch-sensitive muscle spindle) –Excitation facilitates contraction of host muscle -Role of proprioception in skilled movement & flexibility Goal of proprioceptive neuromuscular facilitation (PNF) stretching technique is to minimize spindle effect and maximize GTO effect.

Muscle spindle

Reciprocal inhibition

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 and muscle spindle response. n Many of the techniques require partner or clinician -Contract-relax-antagonist-contract technique -Contract-relax and hold-relax methods n Can significantly increase joint ROM over single stretching session.

Example of PNF Stretching using hamstrings n Passive stretch of hams by partner n Contract hams against partner resistance (inhibits hams via GTO excitation) -Isometricly or concentricly n Relax hams, contract quads (inhibits hams further through reciprocal inhibition via spindle excitation) -Isometricly or concentricly n Passively stretch hams n Both methods involve 4-8 reps of seconds duratin or longer

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 Self-study problems: Introductory problems, p 136: 3,,5,7,10; -Additional problems, p 137: 7 -Also, take quiz for Chapter 5 on text website