PSG 205 a-1 PDF - Muscle Physiology

PSG 205  Figure 1  EXERCISE What roles do contractile, regulatory, and structural proteins play in muscle contraction and relaxation? How do calcium ions and ATP contribute to muscle contraction and relaxation? How does sarcomere length influence the...

PSG 205  Figure 1  EXERCISE What roles do contractile, regulatory, and structural proteins play in muscle contraction and relaxation? How do calcium ions and ATP contribute to muscle contraction and relaxation? How does sarcomere length influence the maximum tension that is possible during muscle contraction? What are the three functions of ATP in muscle contraction? Write essay on contraction and relaxation of skeletal muscle fibers Contraction and Relaxation of Skeletal Muscle Fibers Muscle Fibres and their Characteristics Muscle Fibre Types Within skeletal muscles. There are three types of fibre; - Type one (I) - Type two A (IIa) - Type two B (IIb). Each fibre types has different qualities in the way they perform and how quickly they fatigue.  Characteristics of the Muscle Fibres Characteristic Type I Type IIa Type IIb (oxidative) (oxidative glycolytic) (fast glycolytic) Structural Differences Fibre size Small Large Large No of capillaries Large Moderate Small No of mitochondria Large Moderate Small Myoglobin store High Moderate Low Glycogen stores Low High High Functional Differences Aerobic capacity High Low/moderate Low Fatigue resistance High Low/moderate Low Anaerobic capacity Low High/Moderate High Speed of contraction Slow Fast Fastest Force of contraction Low High Highest Activity Long Distance 1500KM Sprint Agonists Agonists muscles cause the movement to occur. They create the normal range of movement in a joint by contraction. Agonists are also referred to as prime movers since they are the muscles that are primarily responsible for generating the movement. Antagonists Antagonists muscles act in opposition to the movement generated by the agonists They are responsible for returning a limb to its initial position. Synergists Synergists muscles perform, or assist in performing, the same set of joint motion as the agonists. Synergists are sometimes referred to as neutralizers because they help cancel out, or neutralize, extra motion from the agonists to make sure that the force generated works within the desired plane of motion. Fixators Fixators muscles provide the necessary support to assist in holding the rest of the body in place while the movement occurs. Fixators are also sometimes called stabilizers.  Prime Movers and Synergists: The biceps brachii flex the lower arm. The brachoradialis, in the forearm, and brachialis, located deep to the biceps in the upper arm, are both synergists that aid in this motion.  Types of Muscle Contractions Muscle contractions are classified according to the movements they cause and in fitness are primarily concerned with the following types of contraction: - Isometric Contractions - Isotonic Contractions - Isokinetic Contractions Isotonic Contractions Isotonic contractions are those which cause the muscle to change length as it contracts and causes movement of a body part. There are two types of Isotonic contraction, which can be either concentric or eccentric Concentric Concentric contractions are those which cause the muscle to shorten as it contracts. An example is bending the elbow from straight to fully flexed, causing a concentric contraction of the Biceps Brachii muscle. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.  TYPES OF BONE AND THE ROLE OF LIGAMENTS, TENDONS AND CARTILAGE The bones are connected to other bones and muscle fibers via connective tissue such as tendons and ligaments. Cartilage prevents the bone ends from rubbing directly on each other. Types of Bone The human body consists of 5 types of bones; i. Long ii. Short iii. Flat iv. Irregular v. and Sesamoid bones. Table 1: Bone Classifications Bone classification Features Function(s) Examples Femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges Long Cylinder-like shape, longer than it is wide Movement, support Cube-like shape, approximately equal in length, Provide stability, support, while allowing for some width, and thickness motion Short Carpals, tarsals Points of attachment for muscles; protectors of internal organs Flat Thin and curved Sternum, ribs, scapulae, cranial bones Protect internal organs, movement, support Irregular Complex shape Vertebrae, facial bones Protect tendons from excessive forces, allow effective muscle action Small and round; embedded in Sesamoid Patellae tendons  Tendon, ligament and Cartilage A tendon or sinew is a tough band of dense fibrous connective tissue that attaches a muscle to other body parts, usually bones. It transmit the mechanical force of muscle contraction to the bones;while withstanding tension. The tendon is firmly connected to muscle fibres at one end and to components of the bone at its other end. Tendons, like ligaments, are made of collagen - which consist of bunches of collagen fibrils (the basic units of a tendon). The difference is that ligaments connect bone to bone, while tendons connect muscle to bone. Functions of Axial and Appendicular Skeleton Cont. Movement The muscular and skeletal systems work together as the musculoskeletal system, which enables body movement and stability. Muscles contract, they pull on bones of the skeleton along with them to produce movement or hold the bones in a stable position. The shape of the bones and how they fit together at the joints allows for different types of movement. For example, the leg bones come together at the knee to form a hinge joint that enables the knee to bend back and forth. Functions of Axial and Appendicular Skeleton Cont. Protection The skeleton protects the internal organs from damage by surrounding them with bone. Bone is living tissue that is hard and strong, yet slightly flexible to resist breaking. The strength of bone comes from its mineral content, which is primarily calcium and phosphorus. The flexibility is due to a substance called collagen. The combination of strength and flexibility gives the skeleton the capacity to absorb the impact of blows to the body without breaking. Functions of Axial and Appendicular Skeleton Cont. Blood Cell Production Larger bones contain bone marrow, spongy tissue inside the bones. There are two main types of marrow, red and yellow. Red marrow is responsible for the production of all of the body's red blood cells and many of its white blood cells. In adults, red marrow is found primarily in the breastbone, hips, ribs, skull, spinal bones and at the end of long bones of the arms and legs. Yellow bone marrow contains primary fat cells but can transform into red marrow if the body needs to increase blood cell production, such as if anemia develops. Functions of Axial and Appendicular Skeleton Cont. Mineral and Fat Storage On a metabolic level, bone tissue performs several critical functions. Bone tissue acts as a reservoir for a number of minerals’- calcium, and phosphorus. These minerals, incorporated into bone tissue, can be released back into the bloodstream to maintain levels needed to support physiological processes. Calcium ions, for example, are essential for muscle contractions and are involved in the transmission of nerve impulses. Yellow bone marrow contains adipose tissue, and the triglycerides stored in the adipocytes of this tissue can be released to serve as a source of energy for other tissues of the body as seen in the figure  ANALYSIS OF MOVEMENT Joints, responsible for movement and stability of the skeleton, can be classified based on structure or function. A joint (articulation or arthrosis) is a point of contact between two bones, between bone and cartilage or between bone and teeth. A joint’s structure may permit no movement, slight movement, or free movement.  In angular movements, there is an increase or decrease in the angle between articulating bones Angular movements at synovial joints—flexion, extension, hyperextension, and lateral flexion  Abduction and adduction usually occur along the frontal plane. Angular movements at synovial joints— abduction and adduction  Circumduction is the movement of the distal end of a body part in a circle Angular movements at synovial joints— circumduction.  In rotation, a bone revolves around its own longitudinal axis Rotation at synovial joints  Special movements occur only at certain synovial joints Special movements at synovial joints Summary of structural and functional classifications of joints Cont. Summary of structural and functional classifications of joints Cont. Planes of Movement  MOVEMENT ANALYSIS Movement analysis refers to the automatic analysis of sensor signals that determine the underlying motions and evaluate them with respect to a given target model. Any movement can be studied but the most commonly clinically analyzed is walking. Clinical analysis which involves obtaining a history and performing a standard physical examination of a stationary patient in an examination room is often sufficient to develop a working differential diagnosis for a particular musculoskeletal injury.  MOVEMENT ANALYSIS CONT. However, such an assessment may fail to uncover important underlying causes that stem from abnormal gait mechanics. "Gait analysis" encompasses a broad spectrum of potential assessment strategies used to evaluate normal and abnormal gait, both walking and running. Such assessments range from simple observation to a sophisticated computer analysis of biomechanics. Movement analysis is made possible by the acquisition of objective data that describes a subject’s movement and a physical examination and relevant medical history. Importance of Movement Analysis Basic scientists are interested in the control of human movement. Human movements are studied to understand and treat pathologies. The study of human athletic performance has been revolutionized by motion analysis equipment and software that make it possible to readily analyze complex three-dimensional movements. There is substantial interest in human movement from those studying ergonomics and human factors related to military applications. The kinematics of human movement has been studied by animators interested in making computer-generated characters move in realistic ways.  Analysis and Stages of Walking The analysis and stages are as follows: Heel strike, Early flatfoot, Late flatfoot, Heel rise, and Toe off. Heel Strike The heel strike phase starts the moment when the heel first touches the ground, and lasts until the whole foot is on the ground Early flatfoot The beginning of the “early flatfoot” stage is defined as the moment that the whole foot is on the ground. The end of the “early flatfoot” stage occurs when the body’s center of gravity passes over top of the foot. The main purpose of the “early flatfoot” stage is to allow the foot to serve as a shock absorber, helping to cushion the force of the body weight landing on the foot. Analysis and Stages of Walking Late flatfoot Once the body’s center of gravity has passed in front of the neutral position, a person is said to be in the late flatfoot stage. The “late flatfoot” stage of gait ends when the heel lifts off the ground. The foot needs to go from being a flexible shock absorber to being a rigid lever that can serve to propel the body forward. Phases of Gait/Walking Phases of running and arm swinging Analysis and Stages of Jumping Jumping involves three phases; - load phase - flight phase - landing phase and you will perform each of these phases hundreds of times during each jumping session. The load phase requires you to balance your body on the balls of your feet with your knees slightly flexed Phases of Jumping QUALITATIVE AND QUANTITATIVE MOVEMENT ANALYSIS Qualitative Methods of Analysis Qualitative analysis methods are also referred to as subjective methods (Marshall and Elliot, 2005), it involves a non-numerical evaluation of a skill and is most frequently performed during direct observation of movement. It is a seemingly natural characteristic of good coaches and clinicians. This is the description of quality without the use of number. This skill can be learned and improved upon through practice. Qualitative Methods of Analysis Cont. However, for one to be consistent and reliable both in observing a performer’s learning motor skills and in evaluating movement for practical, diagnostic, clinical or research purposes (viewed either in life or film), a researcher must adopt a definite observational plan. The plan might include the following steps: - view multiple times - view from multiple perspectives (planes) - focus on parts, then whole, then parts - form a visual mental image of the performance - use a checklist: either construct your own or use available ones Qualitative Methods of Analysis Cont. Most qualitative analyses are carried out through visual observation performance deficiencies may result from errors in technique, perception, or decision-making. HENCE The inclusion of a pre-observation phase, where a model of the skill to be analysed is developed and mechanical variables concerned and their relationships are described. Quantitative Methods of Analysis This method is otherwise known as objective technique in biomechanical analysis. This is the collection, measurement, and evaluation of data from the activity of interest. Quantitative analysis implies that numbers are involved Steps in quantitative analysis include the following: Pre-observation stage; and this should include: determination of performance goal and mechanical variables identification and selection of critical variables determination of acceptable range for these variables. Development of an observation plan; to include: observation desired response observed response diagnosis discrepancy (allow for individual variation) identify errors rank errors remediation communicate error correction strategies.  GAIT Gait is the action of walking (locomotion). It is a complex, whole-body movement, that requires the coordinated action of many joints and muscles of our musculoskeletal system. It mostly includes the movements of the lower limbs, upper limbs, pelvis and spine Gait also depends on the proper functioning of other body systems such as nervous, cardiovascular and respiratory system.  Phases of Gait The two main phases of gait include: - The stance phase - The swing phase Stance phase The stance phase is the period of the gait cycle when the foot is on the ground and bearing body weight More specifically, it can be described as the period between the moment that the heel of the foot touches the ground (heel strike) until the moment that the toe-off occurs. The stance phase consists of five subphases PHASES OF NORMAL GAIT CYCLE  Gait Pattern The gait pattern describes the gait characteristics of each individual. These characteristics can depend on a number of individual variables such as age, height, weight, sex, walking speed, strength, flexibility and aerobic conditioning. The gait patterns can be assessed by conducting a gait analysis.  Clinical Gait Analysis Gait disorders Gait disorders often show up as altered distance and time variables. Decreased speed and decreased stride length may indicate bilateral limb involvement, Abnormal swing-stance ratios could suggest problems in a single limb. Age, fatigue, pain, musculoskeletal injury and certain neurological disorders can all decrease step and stride lengths.  Common Pathological Gaits. Antalgic gait An antalgic (painful) gait is often seen as a result of injury to the lower extremity. The altered gait patterns include the shorter stance phase for injured limb and the shorter swing phase for un-injured limb. In addition, there is a decreased walking velocity and decreased cadence. These features are more commonly known as “limping”. Common Pathological Gaits Cont. Arthrogenic gait An arthrogenic gait is seen due to abnormal joint motion, which may or may not be accompanied by pain. For example, in the case of knee stiffness, the person may not be able to flex the knee enough to clear the toes from the ground. Common Pathological Gaits Cont. Ataxic gait The ataxic gait is typically caused by cerebellar dysfunction. It is characterized by wide step width and jerky, irregular, uncoordinated movements. The movements may appear exaggerated and the person may appear to lurch or stagger. Hemiplegic or hemiparetic gait This gait pattern is described as unilateral weakness on the affected side with weakness in flexion and dorsiflexion. This causes the person to swing the paraplegic leg outwards and in a circular motion in order to bring the leg forward. The affected upper limb is flexed, adducted, internally rotated and placed against or across the trunk as a way of improving balance. Commonly seen in stroke patients. Common Pathological Gaits Cont. Parkinsonian gait Parkinsonian gait is characterized by the flexion rigidity of the major joints (hips, shoulders, knees) and bradykinesia (short rapid steps). This type of gait can be seen in neurological conditions that affect the basal ganglia. Trendelenburg gait Trendelenburg sign is when, whilst standing on one leg, the free side of the pelvis drops towards the floor. This is caused by weakness of the gluteus medius and minimus muscle of the contralateral, stance leg. A similar pelvic drop may be seen during walking, causing excessive hip swing or wobbling, known as the Trendelenburg gait.