LECTURE 3: stretching Flashcards
what are the ROM limiting factors
Active structures Passive structure Viscosity CNS Discomfort
active structures
muscle fascicles (structural proteins such as myosin, actin, titin, and others)
passive structures
tendons, aponeuroses, joint capsules, and ligaments.
viscosity
50% to 78% fluid (water), dependent on age, sex, hydration, and other factors.
CNS
a highly activated central nervous system could increase muscle tonus.
Discomfort
pushing a joint to its maximum ROM can be uncomfortable or painful
biarticular
easily stretched e.g. hamstrings, gastrocnemius, rectus femoris
monoarticular
anatomically impossible e.g. tibialis anterior, masseter, temporalis, brachialis
acute effects
Thixotropic effects (muscle, tendons and fascia)
Tonic muscle reflexes
Static stretching = Disfacilitation of motor neuron from suppression of monosynaptic spinal reflex. Stress relaxation. Effect is global
Dynamic stretching = excitation of myotatic reflex (muscle spindles)
chronic effects
Increased stretch tolerance
- Inhibition of E reflexes (cutaneous pain receptors)
Morphological Mechanisms
stretching reduces risk of injury depending on
who, what, when + where
injury for non athletes: poor flexibility has been associated with
Difficulty when performing your daily activities
Joint stiffness, muscle tightness, lower back pain and other postural, and health related problems.
Greater arterial stiffening. Arterial stiffening is called arteriosclerosis and it influences how hard your heart has to work to pump blood through your body. Myocardial infarction (heart attack) and stroke are both a direct consequence of atherosclerosis.
static stretching has a negative impact on performance
Strength Power Speed Agility Balance Mean deficit 1% (<30s) to ~5% (60-120s)
Stretching will (Acutely and Chronically) increase ROM in muscles that we can anatomically stretch by
Warming up fluids, inhibiting tonic muscle reflexes, increasing stretch tolerance.
Stretching may plausibly reduce risk of injury in hamstring muscles in sprinting/field athletes.
No evidence of reduced injury risk in recreationally active people.
Static stretching will not improve performance when done prior to event (i.e., in warm-up)
Particularly in power/speed based sports.
why stretch
increases ROM
who should stretch
Want to improve flexibility – general health
Athletes who require large ROM (e.g., gymnasts, Ice hockey goalies, dancer)
Potentially beneficial to field athletes as protection for hamstring (more evidence required)
when should one stretch
Not before competition, unless other dynamic tasks are done to mitigate effects.
As part of normal training or as periodised as part of pre-season preparation.
proposed mechanism link between stretching and ROM
The acute increase in range of motion (ROM) was thought to reduce resistance to movement, and to provide greater limb excursions which would be important for work output (work = force × linear or angular distance), running stride length, activities that need substantial flexibility (e.g. gymnastics, dance, figure skating, and others), and other movements.
