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.

Muscle spindle

Reciprocal inhibition

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