Stretching versus ROM

Range of Motion (ROM)

  • Range of motion describes specific (joint) or gross (limb and trunk) movement.
  • ROM can load and stress soft tissues
  • ROM may be selected as a therapeutic exercise in order to:
    • decrease pain
    • prevent contracture
    • promote circulation
    • maintain and promote elasticity
  • Early healing ROM follows a predictable sequence: PROM, then AAROM, then AROM
  • The type for ROM exercise (PROM, AAROM, AROM) is largely based on tissue healing stages and any subsequent post-operative precautions

Stretching

  • Stretching includes applying a force over time in the end range of the tissue to create lasting changes in soft tissue length
  • Stretching is most effective when the soft tissues are heated to promote extensibility
  • Stretching may be selected as a therapeutic exercise in order to:
    • increase ROM
    • reduce posture impairment
    • decrease pain
    • increased strength
    • reduce functional mobility impairment

 

  • Techniques can be passive (i.e., static stretch) or active (i.e., hold-relax, contract-relax)
  • General descriptions include static, cyclic, ballistic, and PNF stretch
  • Stretch durations between 15 seconds and 2 minutes can produce changes in muscle length
  • A minimum of frequency of 2 x week over 6 weeks is needed to produce lasting changes in muscle length

Stretching is not the same as applying PROM nor progressing to AAROM and AROM

  • Muscle is comprised of contractile and noncontractile elements (i.e., soft tissue)
  • Stretching - elongation of soft tissue
    • Stress-Strain curve illustrates how the effect of a sustained load on soft tissue over time results in a lasting change in the length of the connective tissue
    • Stress = load or force causing the strain; strain = elongation of the tissue as a % of its original length
    • Creep describes how soft tissue will become increasingly stretched over time when the load on the soft tissue is constant
    • Relaxation describes how the soft tissue length decreases when the load is removed.
    • Yield point - when the soft tissue will no longer return to it's original resting length
  • Viscoelasticity of soft tissue is represented by the strength-strain curve; repetitive stretching allows for the soft tissue to experience greater strain (length) under the same stress (load)
    • movement in the elastic range will result in no change to muscle length - the tissue "bounces" back
    • stretching occurs in the plastic range and will result in soft tissue lengthening by "breaking" collagen fibers; energy from breaking collagen is released as heat
    • longer strain durations are indicated for older patients due to changes (e.g., decreased) plasticity of soft tissue
    • overstretching can result in tissue failure, tearing, strain and/or rupture (failure point)
    • Stress Strain Curve
    • http://www.pt.ntu.edu.tw/hmchai/bm02/bm02method/ForceMeasure.files/StressStrain.jpg

 

Static stretch is the safest form of stretching. A constant load applied over time will allow the soft tissue to safely yield, target collagen fibers which restrict motion, yet protect from strain and/or tear.

PNF stretching is the most effective method to increase muscle length over time.