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Flexibility and Proprioception. Reading assignment: Read pp 125-136 of text Take quiz for Chapter 5 on text website Self-study problems : Introductory problems, p 136: 3,5,7,10; Additional problems, p 137: 7. Objectives. Identify factors contributing to joint stability and flexibility.
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Flexibility and Proprioception • Reading assignment: • Read pp 125-136 of text • Take quiz for Chapter 5 on text website • Self-study problems : • Introductory problems, p 136: 3,5,7,10; • Additional problems, p 137: 7
Objectives • Identify factors contributing to joint stability and flexibility. • Discuss role of proprioceptors in increasing flexibility (both acute and long-term) • Discuss characteristics of effective flexibility exercises, including PNF • Review common joint injuries
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
Normal ROM Values • Knee flexion 130-150 deg • Hip flexion 115-125 deg • Hip extension 25-35 deg (20% decrease in aged) • Arm flexion 160-180 • Arm extension 40-60 deg • General considerations • 10% deviation is considered normal • Small age and gender differences Source: ACSM’s Resource Manual for Guidelines for Exercise Testing and Prescription (4th ed). Pp 381-390)
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 • 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.
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 and muscle spindle response. • Many of the techniques require partner or clinician • Contract-relax-antagonist-contract technique (CRAC) • Contract-relax and hold-relax methods (CR) • Can significantly increase joint ROM over single stretching session.
Example of PNF Stretching using hamstrings (CRAC) • Passive stretch of hams by partner • Contract hams against partner resistance (inhibits hams via GTO excitation) • Isometricly or concentricly • Relax hams, contract quads (inhibits hams further through reciprocal inhibition via spindle excitation) • Isometricly or concentricly • Passively stretch hams • Both methods involve 4-8 reps of 10-15 seconds duration or longer
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