Question:

How do you show more definition if your body is muscular but you have a little more fat then muscle?

Answer:

Being toned or being defined means, when you have muscle, and when you have a low enough body fat percentage so that this muscle can be seen. So, the less fat you have covering your muscles, the more "tone" and "definition" you will appear to have.

More Info:

Sarcopenia (from the Greek meaning "poverty of flesh") is the degenerative loss of skeletal muscle mass (0.5-1% loss per year after the age of 25), quality, and strength associated with aging. Sarcopenia is a component of the frailty syndrome. As of 2009[update] there is no generally accepted definition of sarcopenia in the medical literature. The European Working Group on Sarcopenia in Older People (EWGSOP) has developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia. For the diagnosis of sarcopenia, the working group has proposed using the presence of both low muscle mass and low muscle function (strength or performance). Sarcopenia is characterized first by a muscle atrophy (a decrease in the size of the muscle), along with a reduction in muscle tissue "quality," caused by such factors as replacement of muscle fibres with fat, an increase in fibrosis, changes in muscle metabolism, oxidative stress, and degeneration of the neuromuscular junction. Combined, these changes lead to progressive loss of muscle function and frailty. Lack of exercise is currently thought to be a significant risk factor for sarcopenia. Not only muscle but the entire musculoskeletal system of muscle, neuromuscular responsiveness, endocrine function, vasocapillary access, tendon, joint, ligament, and bone, depends on regular and lifelong exercise to maintain integrity. Exercise and increases in activity have been shown to be beneficial in settings of sarcopenia, even in the very old. However, even highly trained athletes experience the effects of sarcopenia. Even Master class athletes who continue to train and compete throughout their adult life, exhibit a progressive loss of muscle mass and strength, and records in speed and strength events decline progressively after age 30. Simple circumference measurement does not provide enough data to determine whether or not an individual is suffering from severe sarcopenia. Sarcopenia is also marked by a decrease in the circumference of distinct types of muscle fibers. Skeletal muscle has different fiber-types, which are characterized by expression of distinct myosin variants. During sarcopenia, there is a decrease in "type 2" fiber circumference (Type II), with little to no decrease in "type I" fiber circumference (Type I), and deinervated type 2 fibers are often converted to type 1 fibers by reinnervation by slow type 1 fiber motor nerves. Satellite cells are small mononuclear cells that abut the muscle fiber. Satellite cells are normally activated upon injury or exercise. These cells then differentiate and fuse into the muscle fiber, helping to maintain its function. One theory is that sarcopenia is in part caused by a failure in satellite cell activation. Therefore, the ability to repair damaged muscles or respond to nutritional signals is impaired. Extreme muscle loss is often a result of both diminishing anabolic signals, such as growth hormone and testosterone, and promotion of catabolic signals, such as pro-inflammatory cytokines. Due to the lessened physical activity and increased longevity of industrialized populations, sarcopenia is emerging as a major health concern. Sarcopenia may progress to the extent that an older person may lose his or her ability to live independently. Furthermore, sarcopenia is an important independent predictor of disability in population-based studies, linked to poor balance, gait speed, falls, and fractures. Sarcopenia can be thought of as a muscular analog of osteoporosis, which is loss of bone, also caused by inactivity and counteracted by exercise. The combination of osteoporosis and sarcopenia results in the significant frailty often seen in the elderly population. Strength losses with ageing for men and women are relatively similar. They are greater for lower than upper extremity muscles. Maximum attainable strength peaks in mid-twenties and declines thereafter.][ The decline is precipitous after 65 years of age, though few longitudinal studies exist on this topic. A direct assessment of the effects of sarcopenia, even in extremely physically fit individuals, can be seen in the age-related decline in Masters athletics (track and field) world records of muscle-intensive sports, such as weight lifting. Consensus on clinical diagnosis of sarcopenia has quickly developed over the last decade around the working definition proposed in 1998 by Baumgartner et al., which uses a measure of lean body mass as determined by dual energy X-ray absorptiometry (DEXA) compared to a normal reference population. His working definition uses a cut point of 2 standard deviations below the mean of lean mass for gender specific healthy young adults. This methodology is attractive for definitive diagnosis in clinical settings as well for several reasons. Primarily, emerging research shows it is predictive of negative outcomes and it is also a method familiar to most clinicians. This latter point is especially true for those that treat the geriatric population, given its similarity to the 1996 World Health Organization (WHO) methodology for definitive diagnosis of osteoporosis, which also uses DEXA, but uses a measure of lean mass rather than bone mineral density (BMD). DEXA is widely used already in clinical settings in developed countries to identify and monitor severity of osteoporosis. And the degree of sarcopenia can be measured using DEXA in patients being evaluated for osteoporosis, at the same time with the same scan, with no added cost or radiation exposure to the patient. Since Baumgartner’s working definition first appeared, some consensus groups have refined the definition, including the recent joint effort of the European Society on Clinician Nutrition and Metabolism (ESPEN) Special Interest Groups (SIG) on geriatric nutrition and on cachexia-anorexia in chronic wasting diseases. Their consensus definition is: 1) A low muscle mass, >2 standard deviations below that mean measured in young adults (aged 18–39 years in the 3rd NHANES population) of the same sex and ethnic background, and 2) Low gait speed (e.g. a walking speed below 0.8 m/s in the 4-m walking test). However, it can be replaced by one of the well-established functional tests utilized locally as being part of the comprehensive geriatric assessment. There remain many opportunities for further refinement of reference populations by ethnic groups, and to further correlate the degrees of severity of sarcopenia to overt declines in functional performance (preferably using verified functional tests), as well as incidence of hospitalization admissions, morbidity and mortality. Work toward this objective has already begun, and the body of research to date clearly points toward severe sarcopenia being predicative of negative outcomes, similar to those already shown to exist with the Frailty syndrome, as defined by the criteria set forth in 2001 by Fried et al. Exercise has been considered of great interest in treatment of sarcopenia. There are several reports showing increased ability and capacity of skeletal muscle to synthesize proteins in response to short term resistance exercise. Also, it has been reported exercise can improve physical performance (strength and mobility) in elderly subjects. However, there is insufficient research demonstrating such findings in long term. Currently, there are no agents approved for treatment of sarcopenia. Possible therapeutic strategies include use of testosterone or anabolic steroids, though long term use of these agents is controversial in men given concerns of prostate symptoms, and essentially contraindicated in women, given concerns of virilization. Recent experimental results have shown testosterone treatments may induce adverse cardiovascular events. Other approved medications have been shown to have little to no effect in this setting, including agents such DHEA and human growth hormone. New therapies in clinical development hold great promise in this area, including the selective androgen receptor modulators (SARMs), as evidenced by recent studies. Nonsteriodal SARMs are of particular interest, given they exhibit significant selectivity between the anabolic effects of testosterone on muscle, but apparently with little to no androgenic effects such as prostate stimulation in men or virilization in women.][ Nutritional evaluation may also be indicated if malnutrition is suspected, or current nutritional intake is insufficient to maintain adequate total body mass, although increased exercise also increases appetite. A 2012 study of 14 elderly women in Scotland had "compelling" results, suggesting the fatty acids EPA and DHA contribute to increased muscle strength. A further trial involving 60 people (males and females) received funding and was due to start afterwards.
The rectus abdominis muscle is crossed by three fibrous bands called the tendinous inscriptions (or tendinous intersections). One is usually situated at the level of the umbilicus, one at the extremity of the xiphoid process, and the third about midway between the two. These inscriptions pass transversely or obliquely across the muscle; they rarely extend completely through its substance and may pass only halfway across it; they are intimately adherent in front to the sheath of the muscle. Sometimes one or two additional inscriptions, generally incomplete, are present below the umbilicus. If well-defined, the rectus abdominis is colloquially called a "six-pack". This is due to tendinous intersections within the muscle, usually at the level of the umbilicus (belly-button), the xiphisternum, and about halfway between. An extremely well defined abdominal section can appear to be an "eight pack", as all eight sections of the abdominal muscle become defined. This definition is prominent among athletes with low body fat percentages, such as bodybuilders, boxers, mixed martial artists and track and field athletes. The tendinous intersections, in conjunction with the rectus abdominis, function to provide varying degrees of forward flexion to the lumbar region of the vertebral column, producing forward bending at the waist. Forward flexion results in a decreased angle between the trunk and lower body. The anatomical segmentation of the rectus abdominis into three pairs of muscles][ and the positioning of these three pairs of muscles at different levels along the lumbar region (which are created by the tendinous intersections) are responsible for the forward flexion of the vertebral column: The tendinous intersections define the anatomy of the rectus abdominis and assist with physiological movement. If the rectus abdominis did not have tendinous intersections, there would be one large muscle group on each side of the linea alba. This large muscle group would allow the vertebral column to flex forward, but would not permit][ a large extent of forward flexion. The forward flexion provided by tendinous intersections makes daily activities like stretching or bending over to pick up an object possible.][ The Obliquus externus abdominis. This article incorporates text from a public domain edition of Gray's Anatomy. Abdominal external oblique  Transversus abdominis/Conjoint tendon  Rectus sheath (rectus abdominis, pyramidalis)  Arcuate line  Tendinous intersection Fascia/abdominal fascia: panniculus adiposus (Fascia of Camper)  stratum membranosum (Fascia of Scarpa)  Transversalis fascia (Interfoveolar ligament) Linea alba  Linea semilunaris  Inguinal triangle Inguinal canal (Deep inguinal ring, Superficial inguinal ring, Intercrural fibers, Crura of superficial inguinal ring) fascia/pelvic fascia visceral (Rectovaginal fascia, Rectoprostatic fascia)  parietal (Obturator fascia/Tendinous arch, Piriformis fascia) floor/diaphragm: Superior fascia of pelvic diaphragm (Pubovesical ligament, Puboprostatic ligament)  Inferior fascia of pelvic diaphragm M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3)
Ripping is the stage that people, mainly body builders, go through in order to lose body fat to a very low percentage. The idea is that if ones body fat is low, then muscle tissue will be more visible and therefore a better looking body will emerge. The ripping process usually occurs once a year for those who participate in body building. In the stage of ripping, there is a change in diet and exercise in order to maintain muscle mass and, at the same time, lose a significant amount of body fat. It is the stage that body builders do not often look forward to, as it means giving up the food and drink that they enjoy in order to reach their desired change in body shape and definition. Also it may mean an increase or decrease in particular desired training routines. The ripping stage takes as long as a person wishes it to be. However, when body fat reaches such low levels, it becomes dangerous, which is why body builders don't usually continue with this process all year round. Most body builders spend on average around 12–16 weeks of ripping. In order for one to take part in the ripping stage they must change their diet, however, it may also be essential to make significant changes in their gym workouts or training routines. Extra cardiovascular exercises may be involved in order to burn fat. Their weightlifting exercises may become more faster, or less rest periods between sets may be an addition to the increase in heart rate, therefore an increase in fat burning. Body builders take many steps in order to rip up for a competition or to look good for the summer. It is important for body builders to maintain muscle size during the ripping stage, however, the loss of muscle may be inevitable without careful analysis on which foods are consumed or how or when cardiovascular exercise is conducted. Too much cardiovascular exercise can directly affect muscle tissue if it is used excessively and without eating the correct food. The reason for this is because if the human body doesn't have sufficient energy stored in the form of glucose, then it will begin using energy from other sources, i.e. muscles. So for example, eating a little extra carbohydrates (which eventually transforms into glucose) will help the body to divert away from muscle tissue and extract energy from the glucose supplies. The time in which one eats is an important factor in ripping where cardiovascular training is concerned. Particular foods take a certain amount of time to extract the glucose in the digestive system. This means that there is limited amount of time to use the glucose before it gets stored as fat. Also there is a certain amount of time after cardiovascular exercise is being performed when the body's energy source runs out. This is when the process of muscle breakdown comes in to play also. Ripping is considered a slow and sometimes painful process due to diet and exercise. A body builder will have to sacrifice many of their pleasures in life, in addition to increasing there workout intensity. But the goals in which they wish to achieve are far from easy, and it is known that some body builders may use performance-enhancing drugs or anabolic steroids to assist them along the way. There are many types of performance enhancers that can help with the loss of fat and the maintenance of muscle tissue. Of course, it is extremely unlikely that any performance enhancers or steroids will have an effect unless the person taking them is taking part in exercise or a specific diet plan. It is very likely that body builders will, at some stage, use supplements to help them rip up. When taking part in such a low carbohydrate, low sugar diet, it can affect energy levels in addition to changing ones mood. A person with such a diet and low energy levels may choose to take supplements that contain caffeine, which increases alertness and motivation. Or they may decide to take a supplement with nitric oxide in it, therefore expanding blood vessels and increasing blood flow, thus increasing oxygen levels around the body. Any supplements, performance enhancers, or anabolic steroids are used in order to assist a body builder or athlete in their journey to achieve the goals they aim for. But they are not necessary for ripping, or fat loss. The main concern in ripping is considered the way the person eats. In ripping, it is considered that dieting that has the largest involvement, second to the workout. It is not just what food to eat that becomes a concern but it is the time in which one should consume that food that is equally important. The main principles that are adhered to are that fat and sugar should be completely avoided, and carbohydrates and salt should be kept at a minimum. Protein is always to be quite high during any stage of body building as it has a major involvement in muscle repair and maintenance. The time in which carbohydrates are eaten are usually in the morning with breakfast and thereafter in very small portions with meals. It is common for those ripping to have a protein shake after a workout as it helps with the muscle damage that has taken place during the workout. During the ripping period, the protein shake that is consumed usually contains zero or very little amounts of carbohydrates. Most meals usually contain a piece of meat or fish with vegetables. If the person ripping wishes to include carbohydrates then it would often be foods low in fat like potato, rice or pasta fruits and vegetables often in smoothie (blended) form. After the ripping stage has passed, it is likely that diet will change back to the same as before, and the old training routine may return also. Less cardiovascular exercise may be used and a change in supplements might take place. Some body builders lose around a 20 or more pounds at the peak of the ripping period, and they would then gain it all back again, sometimes with the desire to put on extra weight. If they wish to put on weight then it is usually muscle. It might be a goal for them to lose 20 pounds of fat next year but be a few pounds heavier than they were before, indicating an increase in muscle growth.
Muscle is a soft tissue found in most animals. Muscle cells contain protein filaments that slide past one another, producing a contraction that changes both the length and the shape of the cell. Muscles function to produce force and motion. They are primarily responsible for maintaining and changing posture, locomotion, as well as movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system via peristalsis. Muscle tissues are derived from the mesodermal layer of embryonic germ cells in a process known as myogenesis. There are three types of muscle, skeletal, cardiac, and smooth. Their actions can be classified as being either voluntary or involuntary. Cardiac and smooth muscles contract without conscious thought and are termed involuntary. Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules which are used to power the movement of the myosin heads. The term muscle is derived from the Latin musculus meaning "little mouse" perhaps because of the shape of certain muscles or because contracting muscles look like mice moving under the skin. The anatomy of muscles includes gross anatomy, which comprises all the muscles of an organism, and microanatomy, which comprises the structures of a single muscle. Muscle tissue is a soft tissue, and is one of the four fundamental types of tissue present in animals. There are three types of muscle tissue recognized in vertebrates: Cardiac and skeletal muscles are "striated" in that they contain sarcomeres that are packed into highly regular arrangements of bundles; the myofibrils of smooth muscle cells are not arranged in sarcomeres and so are not striated. While the sarcomeres in skeletal muscles are arranged in regular, parallel bundles, cardiac muscle sarcomeres connect at branching, irregular angles (called intercalated discs). Striated muscle contracts and relaxes in short, intense bursts, whereas smooth muscle sustains longer or even near-permanent contractions. Skeletal (voluntary) muscle is further divided into two broad types: slow twitch and fast twitch: The density of mammalian skeletal muscle tissue is about 1.06 kg/liter. This can be contrasted with the density of adipose tissue (fat), which is 0.9196 kg/liter. This makes muscle tissue approximately 15% denser than fat tissue. All muscles derive from paraxial mesoderm. The paraxial mesoderm is divided along the embryo's length into somites, corresponding to the segmentation of the body (most obviously seen in the vertebral column. Each somite has 3 divisions, sclerotome (which forms vertebrae), dermatome (which forms skin), and myotome (which forms muscle). The myotome is divided into two sections, the epimere and hypomere, which form epaxial and hypaxial muscles, respectively. Epaxial muscles in humans are only the erector spinae and small intervertebral muscles, and are innervated by the dorsal rami of the spinal nerves. All other muscles, including limb muscles, are hypaxial muscles, formed from the hypomere, and inervated by the ventral rami of the spinal nerves. During development, myoblasts (muscle progenitor cells) either remain in the somite to form muscles associated with the vertebral column or migrate out into the body to form all other muscles. Myoblast migration is preceded by the formation of connective tissue frameworks, usually formed from the somatic lateral plate mesoderm. Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongate skeletal muscle cells. Skeletal muscles are sheathed by a tough layer of connective tissue called the epimysium. The epimysium anchors muscle tissue to tendons at each end, where the epimysium becomes thicker and collagenous. It also protects muscles from friction against other muscles and bones. Within the epimysium are multiple bundles called fascicles, each of which contains 10 to 100 or more muscle fibers collectively sheathed by a perimysium. Besides surrounding each fascicle, the perimysium is a pathway for nerves and the flow of blood within the muscle. The threadlike muscle fibers are the individual muscle cells (myocytes), and each cell is encased within its own endomysium of collagen fibers. Thus, the overall muscle consists of fibers (cells) that are bundled into fascicles, which are themselves grouped together to form muscles. At each level of bundling, a collagenous membrane surrounds the bundle, and these membranes support muscle function both by resisting passive stretching of the tissue and by distributing forces applied to the muscle. Scattered throughout the muscles are muscle spindles that provide sensory feedback information to the central nervous system. This same bundles-within-bundles structure is replicated within the muscle cells. Within the cells of the muscle are myofibrils, which themselves are bundles of protein filaments. The term "myofibril" should not be confused with "myofiber", which is a simply another name for a muscle cell. Myofibrils are complex strands of several kinds of protein filaments organized together into repeating units called sarcomeres. The striated appearance of both skeletal and cardiac muscle results from the regular pattern of sarcomeres within their cells. Although both of these types of muscle contain sarcomeres, the fibers in cardiac muscle are typically branched to form a network. Cardiac muscle fibers are interconnected by intercalated discs, giving that tissue the appearance of a syncytium. The filaments in a sarcomere are composed of actin and myosin. The gross anatomy of a muscle is the most important indicator of its role in the body. One particularly important aspect of gross anatomy of muscles is pennation or lack thereof. In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion. In pennate muscles, the individual fibers are oriented at an angle relative to the line of action, attaching to the origin and insertion tendons at each end. Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris. Skeletal muscle is arranged in discrete muscles, an example of which is the biceps brachii. The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the tendons. In turn, the tendons connect to the periosteum layer surrounding the bones, permitting the transfer of force from the muscles to the skeleton. Together, these fibrous layers, along with tendons and ligaments, constitute the deep fascia of the body. The muscular system consists of all the muscles present in a single body. There are approximately 650 skeletal muscles in the human body, but an exact number is difficult to define. The difficulty lies partly in the fact that different sources group the muscles differently and partly in that some muscles, such as palmaris longus, are not always present.
The muscular system is one component of the musculoskeletal system, which includes not only the muscles but also the bones, joints, tendons, and other structures that permit movement. The three types of muscle (skeletal, cardiac and smooth) have significant differences. However, all three use the movement of actin against myosin to create contraction. In skeletal muscle, contraction is stimulated by electrical impulses transmitted by the nerves, the motoneurons (motor nerves) in particular. Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle and many smooth muscle contractions are facilitated by the neurotransmitter acetylcholine. The action a muscle generates is determined by the origin and insertion locations. The cross-sectional area of a muscle (rather than volume or length) determines the amount of force it can generate by defining the number of sarcomeres which can operate in parallel. The amount of force applied to the external environment is determined by lever mechanics, specifically the ratio of in-lever to out-lever. For example, moving the insertion point of the biceps more distally on the radius (farther from the joint of rotation) would increase the force generated during flexion (and, as a result, the maximum weight lifted in this movement), but decrease the maximum speed of flexion. Moving the insertion point proximally (closer to the joint of rotation) would result in decreased force but increased velocity. This can be most easily seen by comparing the limb of a mole to a horse - in the former, the insertion point is positioned to maximize force (for digging), while in the latter, the insertion point is positioned to maximize speed (for running). Muscular activity accounts for much of the body's energy consumption. All muscle cells produce adenosine triphosphate (ATP) molecules which are used to power the movement of the myosin heads. Muscles conserve energy in the form of creatine phosphate which is generated from ATP and can regenerate ATP when needed with creatine kinase. Muscles also keep a storage form of glucose in the form of glycogen. Glycogen can be rapidly converted to glucose when energy is required for sustained, powerful contractions. Within the voluntary skeletal muscles, the glucose molecule can be metabolized anaerobically in a process called glycolysis which produces two ATP and two lactic acid molecules in the process (note that in aerobic conditions, lactate is not formed; instead pyruvate is formed and transmitted through the citric acid cycle). Muscle cells also contain globules of fat, which are used for energy during aerobic exercise. The aerobic energy systems take longer to produce the ATP and reach peak efficiency, and requires many more biochemical steps, but produces significantly more ATP than anaerobic glycolysis. Cardiac muscle on the other hand, can readily consume any of the three macronutrients (protein, glucose and fat) aerobically without a 'warm up' period and always extracts the maximum ATP yield from any molecule involved. The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise. At rest, skeletal muscle consumes 54.4 kJ/kg (13.0 kcal/kg) per day. This is larger than adipose tissue (fat) at 18.8 kJ/kg (4.5 kcal/kg), and bone at 9.6 kJ/kg (2.3 kcal/kg). The efferent leg of the peripheral nervous system is responsible for conveying commands to the muscles and glands, and is ultimately responsible for voluntary movement. Nerves move muscles in response to voluntary and autonomic (involuntary) signals from the brain. Deep muscles, superficial muscles, muscles of the face and internal muscles all correspond with dedicated regions in the primary motor cortex of the brain, directly anterior to the central sulcus that divides the frontal and parietal lobes. In addition, muscles react to reflexive nerve stimuli that do not always send signals all the way to the brain. In this case, the signal from the afferent fiber does not reach the brain, but produces the reflexive movement by direct connections with the efferent nerves in the spine. However, the majority of muscle activity is volitional, and the result of complex interactions between various areas of the brain. Nerves that control skeletal muscles in mammals correspond with neuron groups along the primary motor cortex of the brain's cerebral cortex. Commands are routed though the basal ganglia and are modified by input from the cerebellum before being relayed through the pyramidal tract to the spinal cord and from there to the motor end plate at the muscles. Along the way, feedback, such as that of the extrapyramidal system contribute signals to influence muscle tone and response. Deeper muscles such as those involved in posture often are controlled from nuclei in the brain stem and basal ganglia. The afferent leg of the peripheral nervous system is responsible for conveying sensory information to the brain, primarily from the sense organs like the skin. In the muscles, the muscle spindles convey information about the degree of muscle length and stretch to the central nervous system to assist in maintaining posture and joint position. The sense of where our bodies are in space is called proprioception, the perception of body awareness. More easily demonstrated than explained, proprioception is the "unconscious" awareness of where the various regions of the body are located at any one time. This can be demonstrated by anyone closing their eyes and waving their hand around. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses. Several areas in the brain coordinate movement and position with the feedback information gained from proprioception. The cerebellum and red nucleus in particular continuously sample position against movement and make minor corrections to assure smooth motion. The efficiency of human muscle has been measured (in the context of rowing and cycling) at 18% to 26%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost, as can be calculated from oxygen consumption. This low efficiency is the result of about 40% efficiency of generating ATP from food energy, losses in converting energy from ATP into mechanical work inside the muscle, and mechanical losses inside the body. The latter two losses are dependent on the type of exercise and the type of muscle fibers being used (fast-twitch or slow-twitch). For an overall efficiency of 20 percent, one watt of mechanical power is equivalent to 4.3 kcal per hour. For example, one manufacturer of rowing equipment calibrates its rowing ergometer to count burned calories as equal to four times the actual mechanical work, plus 300 kcal per hour, this amounts to about 20 percent efficiency at 250 watts of mechanical output. The mechanical energy output of a cyclic contraction can depend upon many factors, including activation timing, muscle strain trajectory, and rates of force rise & decay. These can be synthesized experimentally using work loop analysis. A display of "strength" (e.g. lifting a weight) is a result of three factors that overlap: physiological strength (muscle size, cross sectional area, available crossbridging, responses to training), neurological strength (how strong or weak is the signal that tells the muscle to contract), and mechanical strength (muscle's force angle on the lever, moment arm length, joint capabilities). Vertebrate muscle typically produces approximately 25 N (5.6 flb) of force per square centimeter of muscle cross-sectional area when isometric and at optimal length. Some invertebrate muscles, such as in crab claws, have much longer sarcomeres than vertebrates, resulting in many more sites for actin and myosin to bind and thus much greater force per square centimeter at the cost of much slower speed. The force generated by a contraction can be measured non-invasively using either mechanomyography or phonomyography, be measured in vivo using tendon strain (if a prominent tendon is present), or be measured directly using more invasive methods. The strength of any given muscle, in terms of force exerted on the skeleton, depends upon length, shortening speed, cross sectional area, pennation, sarcomere length, myosin isoforms, and neural activation of motor units. Significant reductions in muscle strength can indicate underlying pathology, with the chart at right used as a guide. Since three factors affect muscular strength simultaneously and muscles never work individually, it is misleading to compare strength in individual muscles, and state that one is the "strongest". But below are several muscles whose strength is noteworthy for different reasons. Humans are genetically predisposed with a larger percentage of one type of muscle group over another. An individual born with a greater percentage of Type I muscle fibers would theoretically be more suited to endurance events, such as triathlons, distance running, and long cycling events, whereas a human born with a greater percentage of Type II muscle fibers would be more likely to excel at anaerobic events such as a 200 meter dash, or weightlifting.][ Exercise is often recommended as a means of improving motor skills, fitness, muscle and bone strength, and joint function. Exercise has several effects upon muscles, connective tissue, bone, and the nerves that stimulate the muscles. One such effect is muscle hypertrophy, an increase in size. This is used in bodybuilding. Various exercises require a predominance of certain muscle fiber utilization over another. Aerobic exercise involves long, low levels of exertion in which the muscles are used at well below their maximal contraction strength for long periods of time (the most classic example being the marathon). Aerobic events, which rely primarily on the aerobic (with oxygen) system, use a higher percentage of Type I (or slow-twitch) muscle fibers, consume a mixture of fat, protein and carbohydrates for energy, consume large amounts of oxygen and produce little lactic acid. Anaerobic exercise involves short bursts of higher intensity contractions at a much greater percentage of their maximum contraction strength. Examples of anaerobic exercise include sprinting and weight lifting. The anaerobic energy delivery system uses predominantly Type II or fast-twitch muscle fibers, relies mainly on ATP or glucose for fuel, consumes relatively little oxygen, protein and fat, produces large amounts of lactic acid and can not be sustained for as long a period as aerobic exercise. Many exercises are partially aerobic and partially anaerobic; for example, soccer involves a combination of both. The presence of lactic acid has an inhibitory effect on ATP generation within the muscle; though not producing fatigue, it can inhibit or even stop performance if the intracellular concentration becomes too high. However, long-term training causes neovascularization within the muscle, increasing the ability to move waste products out of the muscles and maintain contraction. Once moved out of muscles with high concentrations within the sarcomere, lactic acid can be used by other muscles or body tissues as a source of energy, or transported to the liver where it is converted back to pyruvate. In addition to increasing the level of lactic acid, strenuous exercise causes the loss of potassium ions in muscle and causing an increase in potassium ion concentrations close to the muscle fibres, in the interstitium. Acidification by lactic acid may allow recovery of force so that acidosis may protect against fatigue rather than being a cause of fatigue. Delayed onset muscle soreness is pain or discomfort that may be felt one to three days after exercising and generally subsides two to three days later. Once thought to be caused by lactic acid build-up, a more recent theory is that it is caused by tiny tears in the muscle fibers caused by eccentric contraction, or unaccustomed training levels. Since lactic acid disperses fairly rapidly, it could not explain pain experienced days after exercise. Independent of strength and performance measures, muscles can be induced to grow larger by a number of factors, including hormone signaling, developmental factors, strength training, and disease. Contrary to popular belief, the number of muscle fibres cannot be increased through exercise. Instead, muscles grow larger through a combination of muscle cell growth as new protein filaments are added along with additional mass provided by undifferentiated satellite cells alongside the existing muscle cells. Muscle fibres have a limited capacity for growth through hypertrophy and some believe they split through hyperplasia if subject to increased demand.][ Biological factors such as age and hormone levels can affect muscle hypertrophy. During puberty in males, hypertrophy occurs at an accelerated rate as the levels of growth-stimulating hormones produced by the body increase. Natural hypertrophy normally stops at full growth in the late teens. As testosterone is one of the body's major growth hormones, on average, men find hypertrophy much easier to achieve than women. Taking additional testosterone or other anabolic steroids will increase muscular hypertrophy. Muscular, spinal and neural factors all affect muscle building. Sometimes a person may notice an increase in strength in a given muscle even though only its opposite has been subject to exercise, such as when a bodybuilder finds her left biceps stronger after completing a regimen focusing only on the right biceps. This phenomenon is called cross education.][ Inactivity and starvation in mammals lead to atrophy of skeletal muscle, a decrease in muscle mass that may be accompanied by a smaller number and size of the muscle cells as well as lower protein content. Muscle atrophy may also result from the natural aging process or from disease. In humans, prolonged periods of immobilization, as in the cases of bed rest or astronauts flying in space, are known to result in muscle weakening and atrophy. Atrophy is of particular interest to the manned spaceflight community, since the weightlessness experienced in spaceflight results is a loss of as much as 30% of mass in some muscles. Such consequences are also noted in small hibernating mammals like the golden-mantled ground squirrels and brown bats. During aging, there is a gradual decrease in the ability to maintain skeletal muscle function and mass, known as sarcopenia. The exact cause of sarcopenia is unknown, but it may be due to a combination of the gradual failure in the "satellite cells" which help to regenerate skeletal muscle fibers, and a decrease in sensitivity to or the availability of critical secreted growth factors which are necessary to maintain muscle mass and satellite cell survival. Sarcopenia is a normal aspect of aging, and is not actually a disease state yet can be linked to many injuries in the elderly population as well as decreasing quality of life. There are also many diseases and conditions which cause muscle atrophy. Examples include cancer and AIDS, which induce a body wasting syndrome called cachexia. Other syndromes or conditions which can induce skeletal muscle atrophy are congestive heart disease and some diseases of the liver. Neuromuscular diseases are those that affect the muscles and/or their nervous control. In general, problems with nervous control can cause spasticity or paralysis, depending on the location and nature of the problem. A large proportion of neurological disorders, ranging from cerebrovascular accident (stroke) and Parkinson's disease to Creutzfeldt-Jakob disease, can lead to problems with movement or motor coordination. Symptoms of muscle diseases may include weakness, spasticity, myoclonus and myalgia. Diagnostic procedures that may reveal muscular disorders include testing creatine kinase levels in the blood and electromyography (measuring electrical activity in muscles). In some cases, muscle biopsy may be done to identify a myopathy, as well as genetic testing to identify DNA abnormalities associated with specific myopathies and dystrophies. A non-invasive elastography technique that measures muscle noise is undergoing experimentation to provide a way of monitoring neuromuscular disease. The sound produced by a muscle comes from the shortening of actomyosin filaments along the axis of the muscle. During contraction, the muscle shortens along its longitudinal axis and expands across the transverse axis, producing vibrations at the surface. Muscles have evolved at least twice, once in cnidaria and once in bilateria; they seem to have evolved from contractile cells in sponge-grade organisms. Evolutionarily, specialized forms of skeletal and cardiac muscles predated the divergence of the vertebrate/arthropod evolutionary line. This indicates that these types of muscle developed in a common ancestor sometime before 700 million years ago (mya). Vertebrate smooth muscle was found to have evolved independently from the skeletal and cardiac muscles. M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) DAP: Sarcoglycan (SGCA, SGCB, SGCD, SGCE, SGCG, SGCZ)  Dystroglycan
Dystrophin  Dystrobrevin (A, B)  Syntrophin (A, B1, B2, G1, G2)  Syncoilin  Dysbindin  Synemin/desmuslin
Myofilament (thin filament/actin, thick filament/myosin, elastic filament/titin, nebulin)
Tropomyosin M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) masseter  temporalis (sphenomandibularis)  pterygoid (lateral, medial)
occipitofrontalis (occipitalis, frontalis)  orbicularis oculi (depressor supercilii)  corrugator supercilii
levator anguli oris  levator labii superioris  zygomaticus (major, minor) orbicularis oris  risorius  buccinator M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) CN VII (superficial, PC): platysma
CN XI (deep): sternocleidomastoid C1–C6 (anterior): Prevertebral muscles: longus (capitis, colli)
C1: rectus capitis posterior (major, minor)  obliquus capitis (inferior, superior)
CN V3 (medial): mylohyoid  anterior belly of digastric CN VII (lateral): stylohyoid  posterior belly of digastric Deep cervical fascia (Pretracheal fascia, Prevertebral fascia, Investing layer)  Carotid sheath  Alar fascia pharynx: Buccopharyngeal fascia  Pharyngobasilar fascia Palatine aponeurosis M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) splenius (capitis, cervicis)  erector spinae (iliocostalis, longissimus, spinalis)  latissimus dorsi transversospinales: (semispinalis dorsi, semispinalis cervicis, semispinalis capitis, multifidus, rotatores)  interspinales  intertransversarii vertebral column: trapezius  latissimus dorsi  rhomboid (major, minor)  levator scapulae intercostales (external, internal, innermost)  subcostales  transversus thoracis  levatores costarum  serratus posterior (inferior, superior)  diaphragm
thoracic cavity: pectoralis major  pectoralis minor  subclavius  serratus anterior M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) Abdominal external oblique  Transversus abdominis/Conjoint tendon  Rectus sheath (rectus abdominis, pyramidalis)  Arcuate line  Tendinous intersection Fascia/abdominal fascia: panniculus adiposus (Fascia of Camper)  stratum membranosum (Fascia of Scarpa)  Transversalis fascia (Interfoveolar ligament) Linea alba  Linea semilunaris  Inguinal triangle Inguinal canal (Deep inguinal ring, Superficial inguinal ring, Intercrural fibers, Crura of superficial inguinal ring) fascia/pelvic fascia visceral (Rectovaginal fascia, Rectoprostatic fascia)  parietal (Obturator fascia/Tendinous arch, Piriformis fascia) floor/diaphragm: Superior fascia of pelvic diaphragm (Pubovesical ligament, Puboprostatic ligament)  Inferior fascia of pelvic diaphragm M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) deltoid  rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis)  teres major
superficial: pronator teres  palmaris longus  flexor carpi radialis  flexor carpi ulnaris  flexor digitorum superficialis
superficial: mobile wad (brachioradialis, extensor carpi radialis longus and brevis)  extensor digitorum  extensor digiti minimi  extensor carpi ulnaris
posterior: extensor retinaculum  extensor expansion
M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3) gluteals: (maximus, medius, minimus)  tensor fasciae latae
Femoral sheath (Femoral canal)  Femoral ring Adductor canal  Adductor hiatus Pes anserinus
Plantar fascia
M: MUS, DF+DRCT anat (h/n, u, t/d, a/p, l)/phys/devp/hist noco (m, s, c)/cong (d)/tumr, sysi/epon, injr proc, drug (M1A/3)

Muscle hypertrophy involves an increase in size of skeletal muscle through an increase in the size of its component cells. Hypertrophy can be broken down into two types of categories: myofibril and sarcoplasmic. Each of these specific types of muscle hypertrophy will result in increasing size of cells, but not of equal effect. Sarcoplasmic hypertrophy is focused on increasing the actual size of the muscle, and less on increasing strength. Myofibril hypertrophy will focus more on strength increase and less on an increase in the size of the skeletal muscle. A range of stimuli can increase the volume of muscle cells. Summarizing, these changes occur as an adaptive response that serves to increase the ability to generate force or resist fatigue in anaerobic conditions. Strength training typically produces a combination of the two different types of hypertrophy: contraction against 80 to 90% of the one repetition maximum for 2–6 repetitions (reps) causes myofibrillated hypertrophy to dominate (as in powerlifters, Olympic lifters and strength athletes), while several repetitions (generally 8 – 12 for bodybuilding or 12 or more for muscular endurance) against a sub-maximal load facilitates mainly sarcoplasmic hypertrophy (professional bodybuilders and endurance athletes).][ The first measurable effect is an increase in the neural drive stimulating muscle contraction. Within just a few days, an untrained individual can achieve measurable strength gains resulting from "learning" to use the muscle.][ As the muscle continues to receive increased demands, the synthetic machinery is upregulated. Although all the steps are not yet clear, this upregulation appears to begin with the ubiquitous second messenger system (including phospholipases, protein kinase C, tyrosine kinase, and others).][ These, in turn, activate the family of immediate-early genes, including c-fos, c-jun and myc. These genes appear to dictate the contractile protein gene response.][ Progressive overload is considered the most important principle behind hypertrophy, so increasing the weight, repetitions (reps), and sets will all have a positive impact on growth. Some experts create complicated plans that manipulate weight, reps, and sets, increasing one while decreasing the others to keep the schedule varied and less repetitive. Experts and professionals differ widely on the best approaches to specifically achieve muscle growth (as opposed to focusing on gaining strength, power, or endurance); it was generally considered that consistent anaerobic strength training will produce hypertrophy over the long term, in addition to its effects on muscular strength and endurance. Muscular hypertrophy can be increased through strength training and other short duration, high intensity anaerobic exercises. Lower intensity, longer duration aerobic exercise generally does not result in very effective tissue hypertrophy; instead, endurance athletes enhance storage of fats and carbohydrates within the muscles, as well as neovascularization. Several biological factors such as age and nutrition can affect muscle hypertrophy. During puberty in males, hypertrophy occurs at an increased rate. Natural hypertrophy normally stops at full growth in the late teens. An adequate supply of amino acids is essential to produce muscle hypertrophy. As testosterone is one of the body's major growth hormones, on average, men find hypertrophy much easier to achieve than women. Taking additional testosterone, as in anabolic steroids, will increase results. It is also considered a performance-enhancing drug, the use of which can cause competitors to be suspended or banned from competitions. In addition, testosterone is also a medically regulated substance in most countries, making it illegal to possess without a medical prescription. Ultimately the message filters down to alter the pattern of protein expression. The additional contractile proteins appear to be incorporated into existing myofibrils (the chains of sarcomeres within a muscle cell). There appears to be some limit to how large a myofibril can become: at some point, they split. These events appear to occur within each muscle fiber. That is, hypertrophy results primarily from the growth of each muscle cell, rather than an increase in the number of cells. Skeletal muscle cells are however unique in the body in that they can contain multiple nuclei, and the number of nuclei can increase. Cortisol decreases amino acid uptake by muscle tissue, and inhibits protein synthesis. The short-term increase in protein synthesis that occurs subsequent to resistance training returns to normal after approximately 28 hours in adequately fed male youths. Another study determined that muscle protein synthesis was elevated even 72 hours following training. A small study performed on young and elderly found that ingestion of 340 grams of lean beef (90 g protein) did not increase muscle protein synthesis any more than ingestion of 113 grams of lean beef (30 g protein). In both groups, muscle protein synthesis increased by 50%. The study concluded that more than 30 g protein in a single meal did not further enhance the stimulation of muscle protein synthesis in young and elderly. However, this study didn't check protein synthesis in relation to training; therefore conclusions from this research are controversial. It is not uncommon for bodybuilders to advise a protein intake as high as 2–4 g per kilogram of bodyweight per day. However, scientific literature has suggested this is higher than necessary, as protein intakes greater than 1.8 g per kilogram of body weight showed to have no greater effect on muscle hypertrophy. A study carried out by American College of Sports Medicine (2002) put the recommended daily protein intake for athletes at 1.2–1.8 g per kilogram of body weight. Conversely, Di Pasquale (2008), citing recent studies, recommends a minimum protein intake of 2.2 g/kg "for anyone involved in competitive or intense recreational sports who wants to maximize lean body mass but does not wish to gain weight. However athletes involved in strength events (..) may need even more to maximize body composition and athletic performance. In those attempting to minimize body fat and thus maximize body composition, for example in sports with weight classes and in bodybuilding, it’s possible that protein may well make up over 50% of their daily caloric intake." Microtrauma, which is tiny damage to the fibers, may play a significant role in muscle growth. When microtrauma occurs (from weight training or other strenuous activities), the body responds by overcompensating, replacing the damaged tissue and adding more, so that the risk of repeat damage is reduced. Damage to these fibers have been theorized as the possible cause for the symptoms of delayed onset muscle soreness (DOMS), and is why progressive overload is essential to continued improvement, as the body adapts and becomes more resistant to stress. In the bodybuilding and fitness community and even in some academic books skeletal muscle hypertrophy is described as being in one of two types: Sarcoplasmic or myofibrillar. According to this theory, during sarcoplasmic hypertrophy, the volume of sarcoplasmic fluid in the muscle cell increases with no accompanying increase in muscular strength, whereas during myofibrillar hypertrophy, actin and myosin contractile proteins increase in number and add to muscular strength as well as a small increase in the size of the muscle. Sarcoplasmic hypertrophy is greater in the muscles of bodybuilders while myofibrillar hypertrophy is more dominant in Olympic weightlifters. These two forms of adaptations rarely occur completely independently of one another; one can experience a large increase in fluid with a slight increase in proteins, a large increase in proteins with a small increase in fluid, or a relatively balanced combination of the two. Examples of increased muscle hypertrophy are seen in various professional sports, mainly strength related sports such as boxing, bodybuilding, mixed martial arts, rugby, professional wrestling and various forms of gymnastics. These athletes train extensively in strength as well as cardiovascular and muscular endurance training.
Toning exercises are physical exercises that are used with the aim of developing a physique with a large emphasis on musculature. In this context, the term toned implies leanness in the body (low levels of body fat), noticeable muscle definition and shape, but not significant muscle size ("bulk"). Research and basic anatomical knowledge implies that the notion of specific exercises to improve tone is unfounded. Exercises can aid fat loss or stimulate muscle hypertrophy, but cannot otherwise improve tone. The size of the muscle can change, as can the amount of fat covering the muscle, but the 'shape' cannot. A muscle cannot be 'lengthened' or 'shortened' because neither the insertion of the muscle at the joint, nor the length of the tendons attaching the muscle to the bone, can be changed. Appearing "toned" is a common fitness goal, particularly associated with women. Exercises popularly believed to improve tone are primarily weight lifting exercises performed with high repetitions and low resistance (low weight), with short rest periods. This conventional wisdom is however criticized as poor-quality and inefficient. What is advocated is an exercise routine involving;
Spot reduction refers to the belief, long viewed as a myth, that fat can be targeted for reduction from a specific area of the body. This is a common view, although many people believe that view is misguided, that it is possible to achieve spot reduction through exercise of specific muscles in the desired area, such as exercising the abdominal muscles in an effort to lose weight in or around one's midsection. Advertisers exploit this concept when advertising exercise-related products. However, many fitness experts do not believe it is possible to reduce fat in one area by exercising that body part alone. Instead, fat is lost from the entire body as a result of diet and regular exercise. Muscle growth in the abdominal region does not reduce fat in that region. Instead, being on a caloric deficit is recommended for reducing abdominal fat. The misunderstanding may be attributed to the firming and shaping effect of muscle hypertrophy. When additional muscle is built, it takes up new space which can briefly compress subdermal fat against the skin until the skin adapts, a larger bulging muscle shape is also more easily seen through the layer of fat on top of it. This can give the illusion of fat being reduced when it has not. For example, triceps hypertrophy firming the back of the arm. A 2006 study published in the American Journal of Physiology seemed to indicate that spot reduction may be possible, although to what degree is unclear. In the study, conducted at the University of Copenhagen (Denmark), scientists had male subjects perform single-leg extensions with light weight for 30 consecutive minutes. The researchers then measured the amount of blood flow to the subjects' subcutaneous fat cells in both the exercising and resting thighs, as well as the amount of lipolysis from those fat cells. The scientists observed increases in blood flow and lipolysis in the exercising leg when compared to the resting leg. The study suggested that during exercise, body fat is preferentially used from the area being trained.

The muscular system is an organ system consisting of skeletal, smooth and cardiac muscles. It permits movement of the body, maintains posture, and circulates blood throughout the body. The muscular system in vertebrates is controlled through the nervous system, although some muscles (such as the cardiac muscle) can be completely autonomous.

Exercise physiology is the study of the acute responses and chronic adaptations to a wide range of physical exercise conditions. In addition, many exercise physiologists study the effect of exercise on pathology, and the mechanisms by which exercise can reduce or reverse disease progression. Accreditation programs exist with professional bodies in most developed countries, ensuring the quality and consistency of education. In Canada, one may obtain the professional certification title - Certified Exercise Physiologist for those working with clients (both clinical and non clinical) in the health and fitness industry.

An exercise physiologist's area of study may include but is not limited to biochemistry, bioenergetics, cardiopulmonary function, hematology, biomechanics, skeletal muscle physiology, neuroendocrine function, and central and peripheral nervous system function. Furthermore, exercise physiologists range from basic scientists, to clinical researchers, to clinicians, to sports trainers.

Muscle

In anatomy, the term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body, not being bone. Soft tissue includes tendons, ligaments, fascia, skin, fibrous tissues, fat, and synovial membranes (which are connective tissue), and muscles, nerves and blood vessels (which are not connective tissue).

It is sometimes defined by what it is not. For example, soft tissue has been defined as "nonepithelial, extraskeletal mesenchyme exclusive of the reticuloendothelial system and glia".

The body fat percentage of a human or other living being is the total mass of fat divided by total body mass; body fat includes essential body fat and storage body fat. Essential body fat is necessary to maintain life and reproductive functions. The percentage of essential body fat for women is greater than that for men, due to the demands of childbearing and other hormonal functions. The percentage of essential fat is 2–5% in men, and 10–13% in women. Storage body fat consists of fat accumulation in adipose tissue, part of which protects internal organs in the chest and abdomen. The minimum recommended total body fat percentage exceeds the essential fat percentage value reported above. A number of methods are available for determining body fat percentage, such as measurement with calipers or through the use of bioelectrical impedance analysis.

The body fat percentage is a measure of fitness level, since it is the only body measurement which directly calculates a person's relative body composition without regard to height or weight. The widely used body mass index (BMI) provides a measure that allows the comparison of the adiposity of individuals of different heights and weights. While BMI largely increases as adiposity increases, due to differences in body composition, it is not an accurate indicator of body fat; for example, individuals with greater muscle mass will have higher BMIs. The thresholds between "normal" and "overweight" and between "overweight" and "obese" are sometimes disputed for this reason.]citation needed[

In biology, adipose tissue /ˈædɨˌps/ or body fat or just fat is loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells (i.e. adipose tissue macrophages (ATMs)). Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from hormonally inert, adipose tissue has in recent years been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and the cytokine TNFα. Moreover, adipose tissue can affect other organ systems of the body and may lead to disease. Obesity or being overweight in humans and most animals does not depend on body weight, but on the amount of body fat—to be specific, adipose tissue]citation needed[. The two types of adipose tissue are white adipose tissue (WAT) and brown adipose tissue (BAT). The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue, more specifically brown adipose tissue, was first identified by the Swiss naturalist Conrad Gessner in 1551.

In humans, adipose tissue is located beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow (yellow bone marrow) and in breast tissue. Adipose tissue is found in specific locations, which are referred to as adipose depots. Apart from adipocytes, which comprise the highest percentage of cells within adipose tissue, other cell types are present collectively termed stromal vascular fraction (SVF) of cells. SVF includes preadipocytes, fibroblasts, adipose tissue macrophages, and endothelial cells. Adipose tissue contains many small blood vessels. In the integumentary system, which includes the skin, it accumulates in the deepest level, the subcutaneous layer, providing insulation from heat and cold. Around organs, it provides protective padding. However, its main function is to be a reserve of lipids, which can be burned to meet the energy needs of the body and to protect it from excess glucose by storing triglycerides produced by the liver from sugars, although some evidence suggests that most lipid synthesis from carbohydrates occurs in the adipose tissue itself. Adipose depots in different parts of the body have different biochemical profiles. Under normal conditions, it provides feedback for hunger and diet to the brain.

Strength training is a type of physical exercise specializing in the use of resistance to induce muscular contraction which builds the strength, anaerobic endurance, and size of skeletal muscles.

When properly performed, strength training can provide significant functional benefits and improvement in overall health and well-being, including increased bone, muscle, tendon and ligament strength and toughness, improved joint function, reduced potential for injury, increased bone density, increased metabolism, improved cardiac function, and elevated HDL ("good") cholesterol. Training commonly uses the technique of progressively increasing the force output of the muscle through incremental weight increases and uses a variety of exercises and types of equipment to target specific muscle groups. Strength training is primarily an anaerobic activity, although some proponents have adapted it to provide the benefits of aerobic exercise through circuit training.

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In journalism, a human interest story is a feature story that discusses a person or people in an emotional way. It presents people and their problems, concerns, or achievements in a way that brings about interest, sympathy or motivation in the reader or viewer.

Human interest stories may be "the story behind the story" about an event, organization, or otherwise faceless historical happening, such as about the life of an individual soldier during wartime, an interview with a survivor of a natural disaster, a random act of kindness or profile of someone known for a career achievement.

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