Muscle Strength: The amount of force generated by MUSCLE CONTRACTION. Muscle strength can be measured during isometric, isotonic, or isokinetic contraction, either manually or using a device such as a MUSCLE STRENGTH DYNAMOMETER.Muscle Strength Dynamometer: A device that measures MUSCLE STRENGTH during muscle contraction, such as gripping, pushing, and pulling. It is used to evaluate the health status of muscle in sports medicine or physical therapy.Muscles: Contractile tissue that produces movement in animals.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Respiratory Muscles: These include the muscles of the DIAPHRAGM and the INTERCOSTAL MUSCLES.Muscle Weakness: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251)Hand Strength: Force exerted when gripping or grasping.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Muscle Proteins: The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.Isometric Contraction: Muscular contractions characterized by increase in tension without change in length.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Muscle Fibers, Skeletal: Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.Quadriceps Muscle: The quadriceps femoris. A collective name of the four-headed skeletal muscle of the thigh, comprised of the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis.Muscle, Smooth, Vascular: The nonstriated involuntary muscle tissue of blood vessels.Resistance Training: A type of strength-building exercise program that requires the body muscle to exert a force against some form of resistance, such as weight, stretch bands, water, or immovable objects. Resistance exercise is a combination of static and dynamic contractions involving shortening and lengthening of skeletal muscles.Muscle Development: Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anchorage.Tensile Strength: The maximum stress a material subjected to a stretching load can withstand without tearing. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p2001)Muscle Fatigue: A state arrived at through prolonged and strong contraction of a muscle. Studies in athletes during prolonged submaximal exercise have shown that muscle fatigue increases in almost direct proportion to the rate of muscle glycogen depletion. Muscle fatigue in short-term maximal exercise is associated with oxygen lack and an increased level of blood and muscle lactic acid, and an accompanying increase in hydrogen-ion concentration in the exercised muscle.Knee: A region of the lower extremity immediately surrounding and including the KNEE JOINT.Torque: The rotational force about an axis that is equal to the product of a force times the distance from the axis where the force is applied.Exercise Therapy: A regimen or plan of physical activities designed and prescribed for specific therapeutic goals. Its purpose is to restore normal musculoskeletal function or to reduce pain caused by diseases or injuries.Weight Lifting: A sport in which weights are lifted competitively or as an exercise.Abdominal Muscles: Muscles forming the ABDOMINAL WALL including RECTUS ABDOMINIS, external and internal oblique muscles, transversus abdominis, and quadratus abdominis. (from Stedman, 25th ed)Physical Endurance: The time span between the beginning of physical activity by an individual and the termination because of exhaustion.Muscle Fibers, Fast-Twitch: Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.Neck Muscles: The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).Breathing Exercises: Therapeutic exercises aimed to deepen inspiration or expiration or even to alter the rate and rhythm of respiration.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Muscle Fibers, Slow-Twitch: Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.Sarcopenia: Progressive decline in muscle mass due to aging which results in decreased functional capacity of muscles.Inspiratory Capacity: The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration. It is the sum of the TIDAL VOLUME and the INSPIRATORY RESERVE VOLUME. Common abbreviation is IC.Muscle Denervation: The resection or removal of the innervation of a muscle or muscle tissue.Maximal Voluntary Ventilation: Measure of the maximum amount of air that can be breathed in and blown out over a sustained interval such as 15 or 20 seconds. Common abbreviations are MVV and MBC.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Physical Fitness: The ability to carry out daily tasks and perform physical activities in a highly functional state, often as a result of physical conditioning.Muscle, Striated: One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the CARDIAC MUSCLE and the SKELETAL MUSCLE.Neuromuscular Diseases: A general term encompassing lower MOTOR NEURON DISEASE; PERIPHERAL NERVOUS SYSTEM DISEASES; and certain MUSCULAR DISEASES. Manifestations include MUSCLE WEAKNESS; FASCICULATION; muscle ATROPHY; SPASM; MYOKYMIA; MUSCLE HYPERTONIA, myalgias, and MUSCLE HYPOTONIA.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.Range of Motion, Articular: The distance and direction to which a bone joint can be extended. Range of motion is a function of the condition of the joints, muscles, and connective tissues involved. Joint flexibility can be improved through appropriate MUSCLE STRETCHING EXERCISES.Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Exercise: Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.Thigh: The portion of the leg in humans and other animals found between the HIP and KNEE.Shear Strength: The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.Muscular Atrophy: Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation.Oculomotor Muscles: The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.Myocytes, Smooth Muscle: Non-striated, elongated, spindle-shaped cells found lining the digestive tract, uterus, and blood vessels. They are derived from specialized myoblasts (MYOBLASTS, SMOOTH MUSCLE).Muscular Diseases: Acquired, familial, and congenital disorders of SKELETAL MUSCLE and SMOOTH MUSCLE.Mitochondria, Muscle: Mitochondria of skeletal and smooth muscle. It does not include myocardial mitochondria for which MITOCHONDRIA, HEART is available.Inhalation: The act of BREATHING in.Walking: An activity in which the body advances at a slow to moderate pace by moving the feet in a coordinated fashion. This includes recreational walking, walking for fitness, and competitive race-walking.Postural Balance: A POSTURE in which an ideal body mass distribution is achieved. Postural balance provides the body carriage stability and conditions for normal functions in stationary position or in movement, such as sitting, standing, or walking.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Muscle Relaxation: That phase of a muscle twitch during which a muscle returns to a resting position.Exercise Test: Controlled physical activity which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used.Exercise Tolerance: The exercise capacity of an individual as measured by endurance (maximal exercise duration and/or maximal attained work load) during an EXERCISE TEST.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Muscle Spindles: Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.Lower Extremity: The region of the lower limb in animals, extending from the gluteal region to the FOOT, and including the BUTTOCKS; HIP; and LEG.Muscle Stretching Exercises: Exercises that stretch the muscle fibers with the aim to increase muscle-tendon FLEXIBILITY, improve RANGE OF MOTION or musculoskeletal function, and prevent injuries. There are various types of stretching techniques including active, passive (relaxed), static, dynamic (gentle), ballistic (forced), isometric, and others.Musculoskeletal Physiological Phenomena: Processes and properties of the MUSCULOSKELETAL SYSTEM.Gait: Manner or style of walking.Papillary Muscles: Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.Body Composition: The relative amounts of various components in the body, such as percentage of body fat.Diaphragm: The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.Mobility Limitation: Difficulty in walking from place to place.Respiratory Function Tests: Measurement of the various processes involved in the act of respiration: inspiration, expiration, oxygen and carbon dioxide exchange, lung volume and compliance, etc.Muscle Spasticity: A form of muscle hypertonia associated with upper MOTOR NEURON DISEASE. Resistance to passive stretch of a spastic muscle results in minimal initial resistance (a "free interval") followed by an incremental increase in muscle tone. Tone increases in proportion to the velocity of stretch. Spasticity is usually accompanied by HYPERREFLEXIA and variable degrees of MUSCLE WEAKNESS. (From Adams et al., Principles of Neurology, 6th ed, p54)Muscular Dystrophy, Duchenne: An X-linked recessive muscle disease caused by an inability to synthesize DYSTROPHIN, which is involved with maintaining the integrity of the sarcolemma. Muscle fibers undergo a process that features degeneration and regeneration. Clinical manifestations include proximal weakness in the first few years of life, pseudohypertrophy, cardiomyopathy (see MYOCARDIAL DISEASES), and an increased incidence of impaired mentation. Becker muscular dystrophy is a closely related condition featuring a later onset of disease (usually adolescence) and a slowly progressive course. (Adams et al., Principles of Neurology, 6th ed, p1415)Muscle Cells: Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.Physical Education and Training: Instructional programs in the care and development of the body, often in schools. The concept does not include prescribed exercises, which is EXERCISE THERAPY.Compressive Strength: The maximum compression a material can withstand without failure. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p427)Hip: The projecting part on each side of the body, formed by the side of the pelvis and the top portion of the femur.Masseter Muscle: A masticatory muscle whose action is closing the jaws.Ankle Joint: The joint that is formed by the inferior articular and malleolar articular surfaces of the TIBIA; the malleolar articular surface of the FIBULA; and the medial malleolar, lateral malleolar, and superior surfaces of the TALUS.Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Masticatory Muscles: Muscles arising in the zygomatic arch that close the jaw. Their nerve supply is masseteric from the mandibular division of the trigeminal nerve. (From Stedman, 25th ed)Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Myositis: Inflammation of a muscle or muscle tissue.Facial Muscles: Muscles of facial expression or mimetic muscles that include the numerous muscles supplied by the facial nerve that are attached to and move the skin of the face. (From Stedman, 25th ed)Activities of Daily Living: The performance of the basic activities of self care, such as dressing, ambulation, or eating.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Intercostal Muscles: Respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib, and contract during inspiration or respiration. (From Stedman, 25th ed)Arm: The superior part of the upper extremity between the SHOULDER and the ELBOW.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Elbow: Region of the body immediately surrounding and including the ELBOW JOINT.Electric Stimulation Therapy: Application of electric current in treatment without the generation of perceptible heat. It includes electric stimulation of nerves or muscles, passage of current into the body, or use of interrupted current of low intensity to raise the threshold of the skin to pain.Postpoliomyelitis Syndrome: A syndrome characterized by new neuromuscular symptoms that occur at least 15 years after clinical stability has been attained in patients with a prior history of symptomatic poliomyelitis. Clinical features include new muscular weakness and atrophy of the limbs, bulbar innervated musculature, and muscles of respiration, combined with excessive fatigue, joint pain, and reduced stamina. The process is marked by slow progression and periods of stabilization. (From Ann NY Acad Sci 1995 May 25;753:68-80)Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Weight-Bearing: The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot.Osteoarthritis, Knee: Noninflammatory degenerative disease of the knee joint consisting of three large categories: conditions that block normal synchronous movement, conditions that produce abnormal pathways of motion, and conditions that cause stress concentration resulting in changes to articular cartilage. (Crenshaw, Campbell's Operative Orthopaedics, 8th ed, p2019)Satellite Cells, Skeletal Muscle: Elongated, spindle-shaped, quiescent myoblasts lying in close contact with adult skeletal muscle. They are thought to play a role in muscle repair and regeneration.Vital Capacity: The volume of air that is exhaled by a maximal expiration following a maximal inspiration.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Recovery of Function: A partial or complete return to the normal or proper physiologic activity of an organ or part following disease or trauma.Myosin Heavy Chains: The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Dermatomyositis: A subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. The illness occurs with approximately equal frequency in children and adults. The skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. The disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. The childhood form of this disease tends to evolve into a systemic vasculitis. Dermatomyositis may occur in association with malignant neoplasms. (From Adams et al., Principles of Neurology, 6th ed, pp1405-6)Physical Exertion: Expenditure of energy during PHYSICAL ACTIVITY. Intensity of exertion may be measured by rate of OXYGEN CONSUMPTION; HEAT produced, or HEART RATE. Perceived exertion, a psychological measure of exertion, is included.Physical Therapy Modalities: Therapeutic modalities frequently used in PHYSICAL THERAPY SPECIALTY by PHYSICAL THERAPISTS or physiotherapists to promote, maintain, or restore the physical and physiological well-being of an individual.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Proprioception: Sensory functions that transduce stimuli received by proprioceptive receptors in joints, tendons, muscles, and the INNER EAR into neural impulses to be transmitted to the CENTRAL NERVOUS SYSTEM. Proprioception provides sense of stationary positions and movements of one's body parts, and is important in maintaining KINESTHESIA and POSTURAL BALANCE.Pectoralis Muscles: The pectoralis major and pectoralis minor muscles that make up the upper and fore part of the chest in front of the AXILLA.Hydrotherapy: External application of water for therapeutic purposes.Bone Density: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.Muscular Dystrophies: A heterogeneous group of inherited MYOPATHIES, characterized by wasting and weakness of the SKELETAL MUSCLE. They are categorized by the sites of MUSCLE WEAKNESS; AGE OF ONSET; and INHERITANCE PATTERNS.Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Shoulder: Part of the body in humans and primates where the arms connect to the trunk. The shoulder has five joints; ACROMIOCLAVICULAR joint, CORACOCLAVICULAR joint, GLENOHUMERAL joint, scapulathoracic joint, and STERNOCLAVICULAR joint.Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Accidental Falls: Falls due to slipping or tripping which may result in injury.Pelvic Floor: Soft tissue formed mainly by the pelvic diaphragm, which is composed of the two levator ani and two coccygeus muscles. The pelvic diaphragm lies just below the pelvic aperture (outlet) and separates the pelvic cavity from the PERINEUM. It extends between the PUBIC BONE anteriorly and the COCCYX posteriorly.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Mice, Inbred mdx: A strain of mice arising from a spontaneous MUTATION (mdx) in inbred C57BL mice. This mutation is X chromosome-linked and produces viable homozygous animals that lack the muscle protein DYSTROPHIN, have high serum levels of muscle ENZYMES, and possess histological lesions similar to human MUSCULAR DYSTROPHY. The histological features, linkage, and map position of mdx make these mice a worthy animal model of DUCHENNE MUSCULAR DYSTROPHY.Motor Neurons: Neurons which activate MUSCLE CELLS.Dental Bonding: An adhesion procedure for orthodontic attachments, such as plastic DENTAL CROWNS. This process usually includes the application of an adhesive material (DENTAL CEMENTS) and letting it harden in-place by light or chemical curing.Myostatin: A growth differentiation factor that is a potent inhibitor of SKELETAL MUSCLE growth. It may play a role in the regulation of MYOGENESIS and in muscle maintenance during adulthood.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Psoas Muscles: A powerful flexor of the thigh at the hip joint (psoas major) and a weak flexor of the trunk and lumbar spinal column (psoas minor). Psoas is derived from the Greek "psoa", the plural meaning "muscles of the loin". It is a common site of infection manifesting as abscess (PSOAS ABSCESS). The psoas muscles and their fibers are also used frequently in experiments in muscle physiology.Vibration: A continuing periodic change in displacement with respect to a fixed reference. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Hip Joint: The joint that is formed by the articulation of the head of FEMUR and the ACETABULUM of the PELVIS.Posture: The position or attitude of the body.Respiratory Mechanics: The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.Pain Measurement: Scales, questionnaires, tests, and other methods used to assess pain severity and duration in patients or experimental animals to aid in diagnosis, therapy, and physiological studies.Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Disability Evaluation: Determination of the degree of a physical, mental, or emotional handicap. The diagnosis is applied to legal qualification for benefits and income under disability insurance and to eligibility for Social Security and workmen's compensation benefits.Muscular Dystrophy, AnimalBack: The rear surface of an upright primate from the shoulders to the hip, or the dorsal surface of tetrapods.Myofibrils: The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .Osmolar Concentration: The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Absorptiometry, Photon: A noninvasive method for assessing BODY COMPOSITION. It is based on the differential absorption of X-RAYS (or GAMMA RAYS) by different tissues such as bone, fat and other soft tissues. The source of (X-ray or gamma-ray) photon beam is generated either from radioisotopes such as GADOLINIUM 153, IODINE 125, or Americanium 241 which emit GAMMA RAYS in the appropriate range; or from an X-ray tube which produces X-RAYS in the desired range. It is primarily used for quantitating BONE MINERAL CONTENT, especially for the diagnosis of OSTEOPOROSIS, and also in measuring BONE MINERALIZATION.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Hemiplegia: Severe or complete loss of motor function on one side of the body. This condition is usually caused by BRAIN DISEASES that are localized to the cerebral hemisphere opposite to the side of weakness. Less frequently, BRAIN STEM lesions; cervical SPINAL CORD DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; and other conditions may manifest as hemiplegia. The term hemiparesis (see PARESIS) refers to mild to moderate weakness involving one side of the body.Running: An activity in which the body is propelled by moving the legs rapidly. Running is performed at a moderate to rapid pace and should be differentiated from JOGGING, which is performed at a much slower pace.Hindlimb: Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Neuromuscular Junction: The synapse between a neuron and a muscle.Muscle Hypotonia: A diminution of the skeletal muscle tone marked by a diminished resistance to passive stretching.Dyspnea: Difficult or labored breathing.Temporal Muscle: A masticatory muscle whose action is closing the jaws; its posterior portion retracts the mandible.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Pulmonary Disease, Chronic Obstructive: A disease of chronic diffuse irreversible airflow obstruction. Subcategories of COPD include CHRONIC BRONCHITIS and PULMONARY EMPHYSEMA.Patellofemoral Pain Syndrome: A syndrome characterized by retropatellar or peripatellar PAIN resulting from physical and biochemical changes in the patellofemoral joint. The pain is most prominent when ascending or descending stairs, squatting, or sitting with flexed knees. There is a lack of consensus on the etiology and treatment. The syndrome is often confused with (or accompanied by) CHONDROMALACIA PATELLAE, the latter describing a pathological condition of the CARTILAGE and not a syndrome.Spirometry: Measurement of volume of air inhaled or exhaled by the lung.Creatine Kinase: A transferase that catalyzes formation of PHOSPHOCREATINE from ATP + CREATINE. The reaction stores ATP energy as phosphocreatine. Three cytoplasmic ISOENZYMES have been identified in human tissues: the MM type from SKELETAL MUSCLE, the MB type from myocardial tissue and the BB type from nervous tissue as well as a mitochondrial isoenzyme. Macro-creatine kinase refers to creatine kinase complexed with other serum proteins.Lung Volume Measurements: Measurement of the amount of air that the lungs may contain at various points in the respiratory cycle.Paresis: A general term referring to a mild to moderate degree of muscular weakness, occasionally used as a synonym for PARALYSIS (severe or complete loss of motor function). In the older literature, paresis often referred specifically to paretic neurosyphilis (see NEUROSYPHILIS). "General paresis" and "general paralysis" may still carry that connotation. Bilateral lower extremity paresis is referred to as PARAPARESIS.Anterior Cruciate Ligament: A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar eminence of the tibia.Fatigue: The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli.Isotonic Contraction: Muscle contraction with negligible change in the force of contraction but shortening of the distance between the origin and insertion.Frail Elderly: Older adults or aged individuals who are lacking in general strength and are unusually susceptible to disease or to other infirmity.Xiphoid Bone: Also called xiphoid process, it is the smallest and most inferior triangular protrusion of the STERNUM or breastbone that extends into the center of the ribcage.Ankle: The region of the lower limb between the FOOT and the LEG.Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Linear Models: Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.Bones of Upper Extremity: The bones of the upper and lower ARM. They include the CLAVICLE and SCAPULA.Resin Cements: Dental cements composed either of polymethyl methacrylate or dimethacrylate, produced by mixing an acrylic monomer liquid with acrylic polymers and mineral fillers. The cement is insoluble in water and is thus resistant to fluids in the mouth, but is also irritating to the dental pulp. It is used chiefly as a luting agent for fabricated and temporary restorations. (Jablonski's Dictionary of Dentistry, 1992, p159)Respiration: The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).Hypertrophy: General increase in bulk of a part or organ due to CELL ENLARGEMENT and accumulation of FLUIDS AND SECRETIONS, not due to tumor formation, nor to an increase in the number of cells (HYPERPLASIA).Immobilization: The restriction of the MOVEMENT of whole or part of the body by physical means (RESTRAINT, PHYSICAL) or chemically by ANALGESIA, or the use of TRANQUILIZING AGENTS or NEUROMUSCULAR NONDEPOLARIZING AGENTS. It includes experimental protocols used to evaluate the physiologic effects of immobility.Spinal Curvatures: Deformities of the SPINE characterized by abnormal bending or flexure in the vertebral column. They may be bending forward (KYPHOSIS), backward (LORDOSIS), or sideway (SCOLIOSIS).Organ Size: The measurement of an organ in volume, mass, or heaviness.Oxandrolone: A synthetic hormone with anabolic and androgenic properties.Dystrophin: A muscle protein localized in surface membranes which is the product of the Duchenne/Becker muscular dystrophy gene. Individuals with Duchenne muscular dystrophy usually lack dystrophin completely while those with Becker muscular dystrophy have dystrophin of an altered size. It shares features with other cytoskeletal proteins such as SPECTRIN and alpha-actinin but the precise function of dystrophin is not clear. One possible role might be to preserve the integrity and alignment of the plasma membrane to the myofibrils during muscle contraction and relaxation. MW 400 kDa.Maximal Expiratory Flow Rate: The airflow rate measured during the first liter expired after the first 200 ml have been exhausted during a FORCED VITAL CAPACITY determination. Common abbreviations are MEFR, FEF 200-1200, and FEF 0.2-1.2.Gait Disorders, Neurologic: Gait abnormalities that are a manifestation of nervous system dysfunction. These conditions may be caused by a wide variety of disorders which affect motor control, sensory feedback, and muscle strength including: CENTRAL NERVOUS SYSTEM DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or MUSCULAR DISEASES.Pharyngeal Muscles: The muscles of the PHARYNX are voluntary muscles arranged in two layers. The external circular layer consists of three constrictors (superior, middle, and inferior). The internal longitudinal layer consists of the palatopharyngeus, the salpingopharyngeus, and the stylopharyngeus. During swallowing, the outer layer constricts the pharyngeal wall and the inner layer elevates pharynx and LARYNX.Tai Ji: One of the MARTIAL ARTS and also a form of meditative exercise using methodically slow circular stretching movements and positions of body balance.Knee Injuries: Injuries to the knee or the knee joint.Lumbosacral Region: Region of the back including the LUMBAR VERTEBRAE, SACRUM, and nearby structures.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Torso: The central part of the body to which the neck and limbs are attached.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Forced Expiratory Volume: Measure of the maximum amount of air that can be expelled in a given number of seconds during a FORCED VITAL CAPACITY determination . It is usually given as FEV followed by a subscript indicating the number of seconds over which the measurement is made, although it is sometimes given as a percentage of forced vital capacity.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Ergometry: Any method of measuring the amount of work done by an organism, usually during PHYSICAL EXERTION. Ergometry also includes measures of power. Some instruments used in these determinations include the hand crank and the bicycle ergometer.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Elbow Joint: A hinge joint connecting the FOREARM to the ARM.Kinetics: The rate dynamics in chemical or physical systems.GlycogenDouble-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Pain, Referred: A type of pain that is perceived in an area away from the site where the pain arises, such as facial pain caused by lesion of the VAGUS NERVE, or throat problem generating referred pain in the ear.Elasticity: Resistance and recovery from distortion of shape.Anthropometry: The technique that deals with the measurement of the size, weight, and proportions of the human or other primate body.Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Anabolic Agents: These compounds stimulate anabolism and inhibit catabolism. They stimulate the development of muscle mass, strength, and power.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Longitudinal Studies: Studies in which variables relating to an individual or group of individuals are assessed over a period of time.Pelvic Floor Disorders: Injury, weakening, or PROLAPSE of the pelvic muscles, surrounding connective tissues or ligaments (PELVIC FLOOR).Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Single-Blind Method: A method in which either the observer(s) or the subject(s) is kept ignorant of the group to which the subjects are assigned.Pilot Projects: Small-scale tests of methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.Mice, Inbred C57BL