Transcript Neuromuscular Aspects (1)

Flexibility and Proprioception
Reading assignment:
 Read pp 125-136 of text
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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
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Joint flexibility – Range of Motion (ROM)
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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
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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
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Flexibility and injury –
- Increased potential for injury when ROM is high, low, or
imbalanced
Measurement of
Flexibility
Direct
Indirect, or
composite
Normal ROM Values
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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
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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 muscletendon 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
Active and passive stretching
 Ballistic and static stretching
 Proprioceptive Neuromuscular Facilitation:
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Proprioceptive Neuromuscular
Facilitation (PNF)
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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)
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Can significantly increase joint ROM over
single stretching session.
Example of PNF Stretching
using hamstrings (CRAC)
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Passive stretch of hams by partner
Contract hams against partner resistance (inhibits
hams via GTO excitation)
- Isometricly or concentricly
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Relax hams, contract quads (inhibits hams further
through reciprocal inhibition via spindle excitation)
- Isometricly or concentricly
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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
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- Rheumatoid arthritis
• autoimmune system disorder
- Osteoarthritis
• Joint-specific, due to wear and tear