Range of Motion

Speed

• Time it takes to complete linear or angular distance

• Reaction speed: electromechanical delay

• Movement speed: ability of person to move themselves or limbs at very rapid rate for relatively few repetitions

Reaction Time

• From detection of stimulus to first movement

• Elite: 130-140ms

• Average: 200-250ms

• Can be trained

What determines speed?

• Fiber type, training

• Muscle composition

• Stride length/frequency

• Physiological demands

• Neural influences

Best muscle for explosive strength?

• Muscles with long fascicles

• shorten rapidly over long length changes (quads)

• increases with heavy speed training

• Muscles with larger angle of pennation

  • high force with small ROM (calf muscles)

Neural Influences

• Minimize antagonist coactivation

• Maximize synergist contribution

Joint Flexibility

• Relative ranges of motion allowed at a joint in different directions

Range of Motion

• Degrees through which a joint can be moved

• anatomical position = 0

Static Flexibility

• ROM when segment passively moved

  • best indicator of tightness or laxity of joint

Dynamic flexibility

• ROM when segment actively moved

  • allows for normal daily movements

Factors that affect ROM

• Structure or shape of articulating bones, muscle, or fat

• Strength, arrangement, and tension of joint ligaments

• Disuse

Extensibility

• Ability of a muscle to lengthen

• Direclty related to ttissue resistance

• Measured by stiffness: change in force/ change in length of tissue

Stretching

• Muscle-tendon unit responds viscoelasticly

• Movement applied by external or internal force in order to increase muscle flexibility and joint ROM

Flexibility

• Stretching of soft tissue surrounding a joint

• Increase in muscle-tendon unit length

Muscle spindles

• Sense changes in muscle length

• Ballistic stretch

• When the muscle is close to being overstretched → neurons fire,

sending signals to contract → reduce the extension of the limb

Golgi Tendon Organs

• Sense changes in the tension generated by muscle contraction

• Tension can be generated during muscle stretch

• Stretch exceeds a critical level

Active Stretching

• Active tension development in agonist muscles

• ex. actively stretch hamstrings, quadriceps contract

Passive Stretching

• Produced by a force other than tension in the antagonist muscles

• Can achieve greater stretch

Proprioceptive Neuromuscular Facilitation (PNF)

• more effective at increasing ROM than static stretching

1. partner extends limb until muscle is stretched and tension felt

2. individual contracts stretched muscle with resistance from partner

3. Muscle is relaxed, then immediately pushed past its normal ROM