Major Benefits of Flexibility • Promotes good joint health • slows joint deterioration • improves quality of life • May prevent low-back pain and injuries • reduces frequency and severity of injuries Image source: www.globalserve.net/~mariolam/flexibility.html
Other Benefits of Flexibility • Reduces soreness and aches and pains • Improves performance in sports and other activities • Contributes to good posture • Promotes relaxation Image source: www.globalserve.net/~mariolam/flexibility.html
Types of Flexibility (I) • Dynamic flexibility (also called kinetic flexibility) is the ability to perform dynamic movements of the muscles to bring a limb through its full range of motion in the joints. Image source: http://www.intlgymnast.com/week/babcock/babcockpic.html
Types of Flexibility (II) • Static (active) flexibility is the ability to assume and maintain extended positions using only the tension of the agonists and synergists while the antagonists are being stretched. For example, lifting the leg and keeping it high without any external support (other than from your own leg muscles).
Types of Flexibility (III) • Static (passive) flexibility is the ability to assume extended positions and then maintain them using only your weight, the support of your limbs, or some other apparatus. Being able to perform the splits is an example of static-passive flexibility.
What Determines Flexibility? • Joint structure • primary determinant • Muscle elasticity and length • can be lengthened if stretched regularly • Nervous system activity • stretch receptors control the length of muscles • proprioceptive neuromuscular facilitation (PNF) technique may improve flexibility Image source: http://www.vh.org/Providers/Textbooks/ JointFluoro/Shoulder/shoulder.19.html
Muscle Tissue and Flexibility • Muscle tissue can be stretched to increase flexibility • Connective tissue is most important part of muscle tissue for flexibility • collagen (white fibers) for structure and support • elastin (yellow fibers) are elastic and flexible • titin also plays role in flexibility Image source: www.accessexcellence.com/AB/GG/collagen_ Elastin.html (cited from: essentialcellbiology.com)
Titin (Connectin) • The giant muscle protein titin, also known as connectin, is a roughly 30,000 amino acid long filament which plays a number of important roles in muscle contraction and elasticity (Labeit et al., 1997; Maruyama, 1997; Wang et al., 1993).
Titin Image source: http://www.ks.uiuc.edu/Research/smd_imd/titin/
Stretching Techniques • Static stretching • each muscle is gradually stretched and held for 10-30 seconds • Ballistic stretching • sudden stretching in a bouncing movement • NOT recommended
PNF • Proprioceptive neuromuscular facilitation (PNF) • muscle is contracted, then stretched • causes soreness, requires partner
Developing A Flexibility Program • Active and passive stretching • safest technique is active static stretching • add occasional passive assist • Intensity and duration • hold each stretch for 10-30 seconds • at least 4 repetitions of each stretch • rest for 30-60 seconds between stretches • Frequency • minimum of 2-3 days per week