Stretching and Flexibility Quiz 1

What are the benefits of stretching?

Aids in injury prevention, minimiz muscle soreness, improves efficiency in all physical activity, improve quality of life and functional independence, pain relief, improved mobility for those with chronic conditions (like arthritis), prevent and relieve muscle cramps.

Extension

An incease in the angle of a joint

How does stretching work?

Applying force, either actively or passively, to decrease tissue stiffness -> elongate the musculotendinous unit and increase the available range of motion

Sarcomeres

Basic functional conntractile units of a muscle/ contractile units within myofibrils, the smallest contractile unit of a muscle

How are neuron and muscle cells activated?

By changing their electrical charges

Proprioceptors

Specialized sensors that provide information about joint angle, muscle length, and muscle tension.

What kind of stretching do athletes usually use?

Static and dynamic

Most common stretching used to improve flexibility

Static stretching

Proprioceptive Neuromuscular Facilitation (PNF) stretching.

Stretch muscle statically, contract and stretch muscle statically beyond initial static stretch -Passive stretching combined w/ isometric muscle contraction either throughout the joint's range of motion or at the end of the range of motion. -Best done w/ help of another person -Induces greatest range of motion, maintains increased range of motion, increases muscle stregth, especially when done after daily exercise. -When performed before exercise. PNF decreases maximal effort performance.

Passive stretches

Stretches performed with assistance from another person.

active stretches

Stretches performed without assistance from another person.

Passive structural stiffness

The degree of compliance (or resistance to a stretch) found in muscle fascicles, tendons, ligaments, aponeuroses, and joint capsules

A sarcomere is defined as_____

The segment between two neighboring Z-lines.

How do neurotransmitters work?

They work by enabling positive sodium ions to enter the cells and make the resting membrane potential more positive. Once the resting membrane potential reaches a threshold potential (generally -62 millivolts), the cell becomes excited, or active. Activated neurons release other neurotransmitters to activate other nerves, causing activated muscle cells to contract.

Three basic parts of a sarcomere

Thick filaments, thin filaments, and Z-lines.

inherent flexibility

Those who are inherently more flexible are less prone to exercise-related injuries. Is increased with heavy stretching 3-4 days a week.

What are the causes of nighttime leg cramps?

Too much exercise; muscle overuse; standing on a hard surface for a long time; flat feet; sitting for a long time; an awkward leg position during sleep; insufficient potassium, calcium, or other minerals; dehydration; certain medicines such as antipsychotics, birth control pills, diuretics, statins, and steroids; and diabetes or thyroid disease.

When is the best time to stretch?

You should do the majority of your stretching at the end of a workout.

ballistic stretching

a series of quick but gentle bouncing or bobbing motions designed to stretch your muscles. -Can activate the stretch reflex so many believe has a greater potential to cause muscle or tendon damage (especially in the tightest muscles) -Not recommended for novices or those w/ thight muscles -Should only be used by knowledgeable athletes preparing for strenuous activity

static stretching

a technique in which a muscle is slowly and gently stretched and then held in the stretched position (usually hold 15-60 seconds) -Most commonly used -Is easiest for most people -Can decrease the ability of the nerves to activate muscle properly. -Allows muscles, fascia, ligaments, and tendons to gradually lengthen -Loss of muscle tension and decreased excitability can lead to reduced muscle performance.

Slow stretches

allow the muscle spindles to relax and adapt to the new longer length.

Thin filaments

are attached to both sides of a Z-line and extend out from the Z-line for less than one-half of the total length of the sarcomere

Four basic types of stretching

ballistic, proprioceptive neuromuscular facilitation (PNF), static, and dynamic

Fast length changes

can trigger a stretch, or myotatic, reflex that attempts to resist the change in muscle length by causing the stretched muscle to contract

motor unit

consists of one motor (muscle) neuron and all the muscle cells to which it connects, as few as 4 to more than 200. Subdivided into individual muscle cells.

Nerver cells (neurons) and muscle cells are ______

electrically charge.

The membrane potential can be altered to cause either____

facilitation or inhibition.

Stretch routines not only improve flexibility but also_____

increase strength and strength endurance, and improve balance.

The initial length of a sarcomere____

is an important factor in muscle function.

The ammount of force produced by each sarcomere is influenced by____

length in a pattern similar in shape to an upside-down letter U.

A more flexible muscle is

less likely to cramp (stretching helps immediately reduce the cramp)

supine

lying face up

When stretching exercises are incorporated in a daily or alternate day program____

many problems that accompany the natural aging prcess can be alleviated.

Each end of a single thick filament is____

surrounded by six thin filaments in a helical array.

The muscle relaxes and quits working when____

the calcium ions are restored within the SR.

In isometric work____

the filaments do not move

All forms of work are initiated by____

the release of calcium ions from the SR, which occurs only when the muscle cell's resting membrane potential exceeds the threshold potential.

Force is reduced when____

the sarcomere length is either long or short.

In eccentric work____

the thick filaments try to prevent the thin filaments from sliding apart

In concentric work____

the thin filaments slide toward each other

When the sarcomere shortens, ____

the thin filaments start to overlap each other. This overlap also reduces the number of positive force-producing connections.

Muscle fiber

A bundle of rodlike structures called myofibrils that are surrounded by a network of tubes called the sarcoplasmic reticulum (SR)

Flexion

A decrease in the angle of a joint

Protraction

A movement of a body part in an anterior (forward) direction

Acute stretching

AKA short-term stretching. When acute stretches cause a noteable increase in a joint's range of motion, the person can experience either inhibition of motor nerves, overlengthening of the muscle sarcomeres, or increased length and compliance of the muscle's tendons. Manifested in a decrease in maximal strength, power, and endurance. Can help an extremely tight person reduce the risk of muscle strains, but most people gain minimal injury-prevention benefits from acute stretching.

Antagonist

Acts in opposition to the desired movement

During muscle work (concetric, eccentric, or isometric), the thick filaments ____

Control the amount and direction that the thin filaments slide over the thick filaments.

Used as a warm-up or prep for competition

Dynamic stretching

Tonic reflex activity

Etonic refforts of the nervous system to maintain muscle tone make up tonic reflex activity. -Has either peripheral origins (muscle spindles and Golgi tendon organs), central origins (pre- and postsynaptic inhibition), or a combination of the two.

_____ increases the likelihood that any succeeding neurotransmitter releases will cause the potential to exceed the threshold (this enhances the chances of the neuron's firing and activating the target).

Facilitation

How can those who live a sedentary life benefit from flexibility?

Flexibility helps prevent joints from stiffening by maintainign the elasticity of the muscles and providinf a wider range of motion in the joints.

What is just as important for optimal health and activity as regular exercise?

Flexible joints and regular stretching.

Deviation

Flexing the wrist towards one side or the other

Benefits of a stretching program

Greater ability to exert maximum force through a wider range of motion, prevention of some lower back problems, improved appearance and self-image, improved body alignment and posture, better warm-up and cool down in exercise sessions, improved maintenance of blood glucose

What are the benefits of flexibilty?

It can improve quality of life and functional independence.

Prone

Lying face down

Agonist

Major (prime) mover muscle, works for the desireed movement

Myofibrils

Microscopic protein filaments that make up muscle cells. Formed by a series of repeating structures called sarcomeres.

Resting electrical charge/ resting membrane potential

Negative and generally around -70 millivolts

Muscles are complex organs composed of:

Nerves, blood vessels, tendons, fascia, and muscle cells.

How do neurons communicate?

Neurotransmitters cross the synapse and bind with receptors on the postsynaptic dendrite.

Facilitation

Occurs when the resting membrane potential is raised slightly above normal but below the threshold potential.

inhibition

Occurs when the resting membrane potnetial is lowederd below the normal potential, thereby decreasing the likelihood of reaching the threshold (usually this prevent the neuron froma activating its target).

Golgi tendon organs (GTOs)

Other type of proprioreceptor. Lie in series with the muscle cells, provide info about changes in muscle tension and indirectly can influence muscle length.

Chronic stretching

stretching done multiple times a week. Regular heavy stretching for 10-15 min 3-4 days a week results in a development of increased strength, power, strength endurance, and improved flexibility and mobility (maybe because of increased number of sarcomeres in series).

To perform work, the muscle is subdivided into_____

motor units

Retraction

movement of a body part in a posterior (backward) direction

A single muscle cell is referred to as a _____.

muscle fiber

As the sarcomere lengthens, ____

only the tips of the thick and thin filaments can contact each other (this reduces the number of force-producing connections between the two filaments).

Two general sources of resistance to a stretch

passive structural stiffness and tonic reflex activity

Muscle contraction

produces tension in the tendon and GTOs, and can induce reciprocal inhibition/ the relaxation of the opposing muscle.

Sarcomere length is controlled by

proprioceptors, or specialized structures incorporated within the muscle organs (especially within the muscles of the limbs).

dynamic stretching

stretching done in continuous, slow, and controlled manner -Often seen as swinging, jumping, or other exaggerated movements in which limb is moved past regular limits of the range of motion. -Held for less than 3 seconds -Enables musce to amek faster powerful contractions -Incrtease muscle temperature and proprioceptive activation -Improves athletic performance