TOPICS OF DISCUSSION• Types of Muscles• Muscle Structure and Function• Types of Muscle Contractions• The muscle/nerve interaction (motor unit)• Muscle Memory• Muscle Training Principals• Stretching• Connective Tissue (tendon/ligament) structure and function
Types of Muscles• Three types of muscle in the body• Cardiac – Involuntary – Highly resistant to fatigue – contracts and relaxes more than 100,000 x per day without tiring – Can get stronger and bigger with exercise• Smooth – Involuntary – Found in the walls of various organs and tubes in the body: blood vessels, GI tract, airways etc.• Skeletal – Voluntary – focus for yoga
Muscle Physiology• Study of muscle function• Muscles are tailored for force generation and movement• Muscle is a bundle of fibers covered by connective tissue• Muscles make up 45% of adult’s body weight.• Most abundant tissue in the body• Muscle rely on the breakdown of food to produce energy for contraction. Certain minerals are also important in the contraction of muscles
Muscle Origin and Insertion• All muscles pass over a joint. In some cases a muscle will pass over two joints• The muscle is contacted on each end to the bone by a strong connective tissue known as a tendon.• Origin – is the more proximal attachment and is the area of the greatest concentration of muscle fibers• Insertion – is the opposite or more distal end. At this end the muscle thins out.
Types of Muscle Fibers• Type I (slow twitch) these fibers are more suited for endurance type activities, have a high resistance to fatigue, dominant in postural muscles• Type II (fast twitch) these fibers are more suited for explosive activity (sprinting, jumping), rapid contraction of muscles, easily fatigued• Three subclasses under Type II are classified as intermediates
Example of different fiber typesA chicken breast represents type II muscle fibers. They are whitein appearance. A chicken flaps its wings violently for shortperiods of time throughout the day. The chicken leg representstype I muscle fibers. They are red. A chicken walks around allday which requires a level of endurance.
Muscle Innervation• Muscles are penetrated by blood vessels, which supply nutrients to the muscle cells and carry away waste products• These blood vessels are know as your capillaries• Muscles are also penetrated by nerves from the central nervous system• Motor nerves cause the muscle to contract• Sensory nerves allows the muscle to sense changes in the surrounding environment
Muscle Contraction• The motor unit is the fundamental unit of muscle contraction• The motor unit consists of the nerve cell, its axon with branches and the muscle fibers that it innervates.• The number of motor units in different muscles depends on whether fine movement or gross movement is required• Examples: the thumb – requires strength and fine motor movement so each motor unit is composed of only a few muscle fibers. The thigh which requires generating power to jump the motor unit is compoased of thousands of fibers
Types of Muscle Contraction• Concentric – the muscle shortens to generate force and overcome resistance• Eccentric – the muscle lengthens to overcome an external force on the muscle• Isometric – the muscle is activated, but instead of shortening or lengthening, it is held at a fixed length. The muscle force matches the load• Passive stretching – the muscle is lengthened in a passive state.
Muscle Roles• Mover or agonist – is the main muscle that contracts to produce movement• Prime mover – the main muscle which is responsible for causing joint movement• Assistant mover – assists the prime mover• Antagonist – opposes the agonist. Causes extension of the muscle• Stabilizer – support the agonist
Muscle Tone• Muscle movement is under voluntary control – muscle tone refers the unconscious nerves impulses coming to the muscle to keep it in a partially contracted state.• This is a positive adaptation to exercise• Even in full relaxation there is always a low level of muscle tone or firmness• Tone that is different in two antagonist muscles causes the joint to deviate from its normal position and this causes a postural defect.• Hypotonia = flaccidity• Hypertonia = spasticity
Muscle Memory• Definition – adaptation of muscles over a period of time to perform a new movement or action• When a movement – yoga pose – is repeated over time the muscles involved learn the task (termed motor learning) and can repeat it without conscious effort.• When a yoga pose is learned there is a change in brain and muscle circuitry.• Example: newborns lack muscle memory such as crawling, scooting or walking; the muscles become accustomed to these activities by active learning and later practice with trial and error
Stretching• Flexibility – is usually described as the range of motion for a specific joint. Flexibility involves the joint capsule, the surrounding muscles, and the connective tissue• To improve flexibility stretching techniques are employed.• Stretching can be passive, active (dynamic) or use of reciprocal inhibition.
What Really Stretches?• Stretching involves pulling the muscle fibers away from one another in order to increase length, but this length is limited.• A braking mechanism is necessary to avoid the muscle fibers from severing entirely.• Several braking mechanisms are in place to prevent injury when stretching. These include the ligaments, the tendons, the connective tissue surrounding the muscle, and the muscle spindles
Methods of Stretching• Passive stretching – the lengthened muscle does not contract. A position is attained which causes a tension in the muscles. The position is held for 15 seconds to longer• Dynamic stretching (active and ballistic)• Active – moving the limb through its full ROM and repeating several times.• Ballisitc – rapid bouncing at the end-range of motion – increased risk of injury• PNF – proprioceptor neuromsuclar faciliation. The muscle to stretch or its antagonist is contracted and then relaxed
Muscle Spindle• Special sensory receptors in the muscle which detect changes in the length of the muscle• Know as stretch reflex• A protective mechanism to protect muscle fibers from overstretching and becoming injured• You can overcome or trick the muscle spindle by bouncing when stretching. This is not recommended because it can lead to injury of the muscle being stretched
Muscle Tightness• Tightness is an increased tension either passive or active in the muscle.• Passive tension is a shortening of the muscle through postural adaptation or scarring• Active tension is a spasm or contraction of the muscle. The cause of spasm is not well understood. Could result from an underlying medical condition.• Tightness limits range of motion and can create muscle imbalance
STRETCHING ADAPTATION• How do we become more flexible?• The muscle adapts to repeated stretching tow ways• Increased length of the muscle which causes a reduction in tension• Increased stretch tolerance (ability to withstand more stretching force)
Muscle Cramps/Spasms• Sudden involuntary contract of a muscle or group of muscles• Painful, but does not cause long-term injury• Proposed causes• Electrolyte depletion• Dehydration• Muscle fatigue
Muscle Adaptation• Muscles adapt to the stress placed upon them• If the stress is positive the muscles will respond by changing their makeup depending upon the particular type of stress applied• Overload principle – the stress must be of sufficient magnitude and time for adaptation to occur – hypertrophy (grow larger)• Specificity – muscle adapt specifically to the nature of the stress• Reversibility – muscle will atrophy when not used• Individual differences
Core Muscle Concepts of Yoga• Increase strength – associated with general health benefits i.e. increased life expectancy, psychological benefits, prevention of illness, decreased disability• Increased flexibility – improved joint range of motion, enhanced power. Increased suppleness.• Increased stability – improved balance and neuromuscular control, injury prevention, and treatment for injuries
TENDON FUNCTION• Attach muscle to bone• Have a mechanical function: transferring muscle contraction into joint movement• Transmit forces from muscle to bone• Tendon is stiffer than muscle, but less than bone. It is 15x stronger than a ligament• It acts as a buffer to less the concentrations of stresses on the muscle with the movement of the bone.• Stores and releases energy making movement more efficient• Dissipates energy thus protecting the muscle and bone from injury
TENDON INJURIES• Because of its critical role in the mechanical movement of the body and buffering the tremendous stresses developed with muscle contraction and movement of the bone, the tendon is particularly susceptible to injury and these injuries can be highly debilitating.• Roughly 1 in 10 people will be afflicted with Achilles tendinopathy (tendon pain with damage or inflammation)
LIGAMENTS• Several ligaments are associated with each joint.• Attach bone to bone• Primary function is joint stability• Ensure that when movement occurs the bones do not separate and a full and even pressure is maintained between the two bones in contact
Illustration of a Ligament Stretching A ligament is functional when stretched and non- functional when compressed When a ligament is stretched tension develops, if the stretch is held the tension is diminished, while the length is maintained Slow stretching results in low tension.
Ligament and Tendon Adaptation• Increase size (hypertropy)• Increase strength• Increase in collagen (more protein)• Improved metabolism• Immobilization/aging results in weaker and thinner (atrophy) tissue• Less crimping• Reduced protein synthesis• Increased susceptibility to injury.
Proprioception and Kinesthetic Awareness• Proprioception – sense of joint location• Kinesthetic awareness – knowing how your body is moving through space• Improving kinesthetic awareness through yoga• Many of the yoga poses promote kinesthetic awareness• Closing the eyes during yoga asana help develop this awareness