Muscle Strength

 

There are unavoidable changes associated with aging; degenerative joints or loss of skin elasticity, for example.  We can preserve muscle strength and size.  Our muscles grow when we are developing from childhood to adulthood.  Once we reach adulthood, any further “growth” is referred to as hypertrophy.  We exercise or exert ourselves and any muscular work done against a challenging load leads to increases in muscle mass and cross-sectional area.  This is referred to as muscle hypertrophy.  The increase in dimension is due to an increase in the size (not length) of individual muscle fibers.  Both cardiac (heart) and skeletal muscle adapt to regular, increasing work loads that exceed the preexisting capacity of the muscle fiber. With cardiac muscle, the heart becomes more effective at squeezing blood out of its chambers, whereas skeletal muscle becomes more efficient at transmitting forces through tendinous attachments to bones.

      When we begin a new regimen of exercise the muscles “learn” the new movements and accommodate the new weight loads we impose.  This is a function of neural inputs and physiologically is known as “neural learning”.  For approximately two weeks neural learning serves as the main mechanism for strength building and muscle training in any new exercise routine.  With continued exercise, the muscles’ synthetic contractile protein mechanism becomes upregulated, through stimulation of the family of immediate-early genes, including c-fos, c-jun and myc. These genes appear to dictate the contractile protein gene response and through this response the muscles gain strength (how this occurs is still scientifically poorly defined).    Finally additional contractile proteins become incorporated into the myofibrils resulting in increased muscle fiber size.   The muscle fibers sustain mild trauma from the overload of exercise and this trauma stimulates a component of the muscle fiber, their “satellite” cells, to proliferate.  These cells are located on the outer surfaces of the muscle fibers and are usually dormant..  When these satellite cells proliferate in response to injury, their daughter cells are drawn to the damaged muscle site They then fuse to the existing muscle fiber, donating their nuclei to the fiber, which helps to regenerate the muscle fiber. It is important to emphasize the point that this process is not creating more skeletal muscle fibers (in humans), but increasing the size and number of contractile proteins (actin and myosin) within the muscle fiber.   This injury regeneration process continues for up to 48 hours.  By exercising repeatedly every other day or so, one can keep the process ongoing, maximizing muscle hypertrophy.  But there is a limit to how massive each myofibril will grow.    There are numerous growth factors that have been identified that play some role in muscle hypertrophy including insulin-like growth factor, fibroblast growth factor, hepatocyte growth factor, growth hormone and testosterone.  To date though there are no successful ways to use any of these factors to safely control human muscle hypertrophy.

Keep Cool, Stay Healthy

The human body maintains a fairly constant internal temperature, even though it is being exposed to varying environmental temperatures. To keep internal body temperatures within safe limits, the body must get rid of its excess heat, primarily through varying the rate and amount of blood circulation through the skin and the release of fluid onto the skin by the sweat glands. These automatic responses occur to maintain a temperature of 98.6oF and are controlled by the brain, specifically by the hypothalamus.   In this process of lowering internal body temperature, the heart begins to pump more blood, blood vessels expand or dilate to accommodate the increased flow, and the microscopic blood vessels (capillaries) that thread through the upper layers of the skin begin to fill with blood. The blood circulates closer to the surface of the skin, and the excess heat is lost to the cooler environment. If heat loss from increased blood circulation through the skin is not adequate, the brain continues to sense overheating and signals the sweat glands in the skin to shed large quantities of sweat onto the skin surface. Evaporation of sweat cools the skin, eliminating large quantities of heat from the body. As environmental temperatures approach normal skin temperature, cooling of the body becomes more difficult. If air temperature is as warm as or warmer than the skin, blood brought to the body surface cannot lose its heat. Under these conditions, the heart continues to pump blood to the body surface, the sweat glands pour liquids containing electrolytes onto the surface of the skin and the evaporation of the sweat becomes the principal effective means of maintaining a constant body temperature. Sweating does not cool the body unless the moisture is removed from the skin by evaporation. Under conditions of high humidity, the evaporation of sweat from the skin is decreased and the body's efforts to maintain an acceptable body temperature may be significantly impaired. These conditions adversely affect an individual's ability to function in the hot environment. With so much blood going to the external surface of the body, relatively less goes to the active muscles, the brain, and other internal organs; strength declines; and fatigue occurs sooner than it would otherwise. Alertness and mental capacity also may be affected.

Mental acuity, comprehension and retention of information are often lowered.  Increased body temperature and physical discomfort promote irritability, anger, and other emotional states that impair judgment and function.  Time spent in a hot environment may lead to heat-induced disorders; transient heat fatigue, heat rash, fainting, heat cramps, heat exhaustion, and heat stroke.  Heat stroke, the most serious of the conditions, occurs when the body's temperature regulatory system fails and sweating becomes inadequate.  A heat stroke victim's skin is hot, usually dry, red or spotted. Body temperature is usually 105oF or higher, and the victim is mentally confused, delirious, perhaps in convulsions, or unconscious.  Heat exhaustion is caused by the loss of large amounts of fluid by sweating, sometimes with excessive loss of salt.  A person suffering from heat exhaustion still sweats but experiences extreme weakness or fatigue, giddiness, nausea, or headache. In more serious cases, the person may vomit or lose consciousness. The skin is clammy and moist, the complexion is pale or flushed, and the body temperature is normal or only slightly elevated.   Heat cramps are painful spasms of the muscles that occur among those who sweat profusely in heat, drink large quantities of water, but do not adequately replace the body's salt loss. The drinking of large quantities of water tends to dilute the body's fluids, while the body continues to lose salt. Shortly thereafter, the low salt level in the muscles causes painful cramps. The affected muscles may be part of the arms, legs, or abdomen, but tired muscles are usually the ones most susceptible to cramps. Cramps may occur during or after heat exposure.  Standing erect and immobile in a hot environment for a prolonged period may cause fainting.  With enlarged blood vessels in the skin and in the lower part of the body due to the body's attempts to control internal temperature, blood may pool in the legs rather than return to the heart to be pumped to the brain. If the brain senses that it is not getting enough blood, it causes a series of reactions that will lead to dizziness and fainting.   Heat rash, also known as prickly heat, is likely to occur in hot, humid environments where sweat is not easily removed from the surface of the skin by evaporation and the skin remains wet most of the time. The sweat ducts become plugged, and a skin rash soon appears. When the rash is extensive or when it is complicated by infection, prickly heat can

be very uncomfortable.  Transient heat fatigue refers to the temporary state of discomfort and mental or psychologic strain arising from prolonged heat exposure. People unaccustomed to the heat are particularly susceptible and can suffer, to varying degrees, a decline in task performance, coordination, alertness, and vigilance. The severity of transient heat fatigue will be lessened by a period of gradual adjustment to the hot environment (heat acclimatization).  Humans are, to a large extent, capable of adjusting to the heat. This adjustment to heat, under normal circumstances, usually takes about 5 to 7 days, during which time the body will undergo a series of changes that will make continued exposure to heat more endurable. Treatment involves moving to a cool environment, resting and replacing lost fluids and salts.  For the more severe conditions, medical attention may be required, as the effects of heat stroke can become severe very quickly and in extreme cases, can be fatal.  People with heart problems or those on a low sodium diet who spend an excessive amount of time in hot environments require special consideration.  The efficacy of certain medications, or our body’s metabolism of medications may also be affected by elevated temperatures.  One should speak to their doctors about the risks of heat affecting their treatments or active diseases.  Clothing inhibits the transfer of heat between the body and the surrounding environment so wearing appropriate fabrics can reduce adverse heat effects.  The effects of heat can truly be extreme and everyone must take the time to recognize and acknowledge their individual needs in a hot environment.  It is foolish to insist that one is strong enough to withstand a hot day.  Learn to recognize the signs and symptoms of heat-induced body changes and tend to them as quickly as possible.‚

The Semantics of Balance

 

     The second leading cause of falls in the elderly population is a fear of falling. Among the general population, we psych ourselves, react badly, become easily distracted or, simply just accidentally fall. The leading cause of falls among the elderly is medication, and among the general population, well, certainly we fall when under the influence of substances that alter our sensorium. True disorders of balance are rare. Balance may be defined as a state of bodily equilibrium; to bring to or hold in equilibrium; or to arrange, adjust, or proportion the parts of symmetrically. 



     Increasingly these days people report more problems with balance, or are being told by physical therapists and exercise trainers that they have problems with balance. We interpret this to mean that we are having some neurologic disturbance, assume that as we age we lose dexterity and agility and for some minority of us, this is true. But for most of us, consider another possibility. Independent of age, related solely to conscious choice, most of us perform a limited number of similar actions daily, using the same motions, the same muscle groups repeatedly. We bend forward often, but backwards rarely. We lift loads upwards, but hardly press loads downwards. We practice moving our joints and muscles in only a fraction of their intended motions functionally. Over time, we develop an “imbalance” in strength and in flexibility. We are more practiced in moving forward than backwards, moving to the right than to the left (for the majority of us), climbing up versus descending downward and when we move in the more practiced directions we feel more surefooted.
This is in part neurologic but it is also strength, agility and cognitive feedback together contributing to a more complex motor planning.

Add impact activities like skipping

     In the absence of a true neurologic disorder, the most effective plans to improve our balance involve restoring normal mobility across the major joints and balancing the strength of the major muscles that pull across the joints. Performing exercises that use muscles in a functional capacity allows the muscles to be trained as well as strengthened. Muscle and nerve fibers have the capacity to “learn” and “remember” and we should capitalize on this concept. If one just walks for exercise, than all one is training for is walking. By adding some impact activity, by shifting direction, changing pace or plane in space, one trains the muscles, joints and proprioceptive neurons to remember that they all really do know how to do all those things.

Move against resistance in varied planes

Whooping

 

     In 1957, an Australian company began making wood rings for sale in retail stores. The item attracted the attention of Wham-0, a California toy manufacturer. The next year Richard P. Knerr and Arthur K. Melin, of Wham-O, manufactured a plastic hoop in a variety of bright colors. The Hula-Hoop was an instant success. Before the 1950s people were doing much the same thing with circular hoops made from grape vines and stiff grasses all over the ancient world. More than three thousand years ago, children in Egypt played with large hoops of dried grapevines. The toy was propelled along the ground with a stick or swung around at the waist.

 

       A common practice in medicine, we look back to our past for ways to improve our futures. Using a hoop, or hooping, allows for a number of health benefits making hooping worth re-visiting. The circular and side-to-side motion helps restore segmental spinal mobility. Like a chiropractor mobilizing the spine manually, the gentle repetitive swing hooping introduces safely increases each vertebras’ slide over its neighboring bone undoing the soft tissue restrictions we develop through limited motions and long times spent in static postures. Anything that restores mobility acts in a similar way to stretching, so the spine’s flexibility is enhanced. 

 
     The Cooper Institute, in Dallas, Texas is a nonprofit institute that has provided research and educational programs focusing on exercise physiology, behavior change, health communication, children's health, obesity, nutrition, aging, diabetes, hypertension, physical activity intervention, and health promotion. According to a study run by the Cooper Institute, one minute of hooping burns as many calories as running an eight-minute mile or taking part in a high impact aerobic class (though I add a caveat that baseline condition might influence this). So hooping can supplement regular low impact cardio workouts, increasing cardiac stamina. Hooping will definitely promote aerobic exercise within the metabolic fat burning exertion ranges so offers alternative to walking.   Hooping places milder stresses on the knee, ankle and foot joints than walking so might be attractive for people who prefer a true low impact exercise.   It is a great compliment to traditional abdominal workouts by toning abdominal muscles, the muscle of the hips and adding curves to the waistline.

       According to research conducted by Consumer Reports, hooping for 5 or 10 minutes at a time is categorized as brief bursts of activity or harder exercise intervals that can help you meet the new, more-demanding federal exercise guidelines. It’s more than standing in a room swinging a ring of plastic around your hips; the hoop can also travel the arms, legs and torso and may include jumps and tosses should you be so inclined. It’s great for the abdomen, but the rest of the body benefits as well.

 

 

Your hoop should stand about 1" above your belly button.

 

    There is an emotional benefit to hooping as an adult. For most hoopers there is a surge in endorphins promoting in a natural chemical way a sense of well-being. Endorphins also provide a natural analgesic further enhancing the benefits achieved. Hoops used by adults to enhance fitness are larger ( greater than 36” diameters) so that they will rotate more slowly around the body. They are heavier than a child size hoop and have friction tape or a sticky foam to make them cling to the body instead of sliding down around the user’s ankles. It is actually easier to hoop as an adult than many found it as a child, because adults have more strength.

You Should Not Limp.

   Touted as an excellent form of exercise, walking is something we all do, and that most of us take for granted as an activity we need no training in. But of course we were trained, it was just at a time we no longer remember. 

    More than an exercise, it is a basic activity of daily living. We bear weight, we transport and we maintain our body’s equilibrium. The human gait cycle is more complicated than most of us appreciate, but perhaps that is because few of us take time to think about it. A normal gait supports our weight as we move with minimal energy expenditure. The lower limbs are adapted for stability rather than range of motion and that stability is achieved at the major joints of the lower limb through the use of strong ligaments and tight fitting bony surfaces rather than the expenditure of energy in the form of muscle contraction. 

 

 

 

 

 

 

 

 With each step we shift our weight to an ideal position supported by the surfaces of our bony joints. 

 

 

 

 

 

 

 

 The wide surfaces of the knee joints, and the arches of the foot and ankle bear the majority of the weight. The ligaments stabilize the joints with amazing strength providing support. The goal is to maintain an ideal center of gravity, and this is done instinctually. 

 

     The two main phases of gait are named stance and swing and the structures of the lower limb move differently during each. In stance phase the limb is weight bearing and in swing phase the limb is non-weight bearing. During stance phase, the pelvis moves over the thigh (femur), the thigh moves over the lower leg (tibia) and the lower leg moves over the foot. During swing phase, the motion is opposite, ie the thigh moves under the pelvis etc. 

 

     The muscles act to control the rate of motion and the size of each step. They accelerate and decelerate the bones to maintain the ideal center of gravity and support our weight as we move. Any deviation away from the instinctual pattern increases the work each limb must do at a higher energy expenditure. 

 

    If a muscle is weak, a ligament damaged, a bone misshapen or in the presence of neurologic disease, we subconsciously adjust our gait pattern to accommodate the dysfunctional part. Said another way, we limp. Most people think that if they have an injury limping will protect the impaired body part from further strain and this may be true but consider the rest of the body. For example, if an ankle is sprained, the normal compensatory instinct is to walk on the ball of the affected foot minimizing motion across the ankle joint. But walking on the ball of the foot, eliminating the part of gait when the heel hits the floor, causes excess strain on the calf muscles and hip, knee and toe joints and their ligaments. The time for each step on the injured leg is reduced and the healthy limb must bear weight longer than normal, thus straining the muscles and joints. And the muscles we do not use by walking on the ball of the foot get weaker.

    
   When we limp, protecting the one injured part, we cause strain and misuse of many other portions of each limb. And this strain and misuse happen all the time, with every step. The risks of limping to the entire limb far outweigh any benefit limping might offer a single injured portion of a limb. The damage begins almost immediately so that even a single day of limping may cause substantial injury. When injured it is essential that we adjust the way we walk to maintain a normal gait pattern. Reducing the speed of our walking is one efficient way to restore a normal gait pattern. When this is not enough, using a cane or crutch to reduce our body weight can restore gait to normal.

Athletes' Heart A Benign Syndrome

 

The heart is comprised of cardiac muscle fibers, which differ from the skeletal muscle fibers of the limbs or the smooth muscle fibers of the internal organs. The specialized muscles fibers allow the heart to function as a reliable pacemaker that proves remarkably accurate and strong.
Heart muscle develops as an athlete trains. The changes in cardiac muscle fibers, and heart function as a result of training do not parallel those changes seen in the skeletal system exactly. There are a collection of fairly typical changes that occur that have been named as a clinical syndrome called Athlete’s Heart. Athlete’s Heart is an asymptomatic condition associated with common clinical signs including bradycardia (slow heart rate), a systolic murmur and extra heart sounds that, in an athlete, are usually considered acceptably normal. The vigorous, repetitive training regimens that athletes routinely endure lead to characteristic physiologic and anatomic changes, including enhanced diastolic function, larger left ventricular dimensions and mass, and right ventricular dilatation and systolic dysfunction. These are all basically enlargements of the heart chambers or thickenings of the muscular chamber walls.

Normal Heart

Athlete's Heart

 These changes allow the heart to beat less to pump out the same or greater amounts of blood to surrounding tissues used in exercise. In the first six to 12 weeks of training, the resting heart rate decreases by five to 10 percent. The resting heart rate slows, a sign that the heart is pumping blood with greater efficiency. The large volume of blood flowing through the heart results in a slower, stronger pulse (which can be felt at the wrist and elsewhere on the body) and sometimes heard as a heart murmur. These murmurs, which are specific sounds created as blood flows through the valves of the heart, are no dangerous. The heartbeat of a person with athletic heart syndrome may be irregular at rest but becomes regular when exercise begins. Premature heartbeats may occur occasionally at rest. Blood pressure is virtually the same as in any other healthy person. The myocardial changes that characterize an athlete’s heart are influenced by the type of sport practiced. The physiologic responses to static and dynamic training lead to different adaptations to sustain the specific compulsory demand During aerobic exercise, the consistent exposure of the left ventricle of the heart to increased volume during episodes of sustained elevation in cardiac output causes the ventricular enlargement. Increased afterload during strength and weight training has a propensity to initiate ventricular wall thickening.

Calf Pain When Stepping

 

Many runners use the elliptical or arc trainers as alternative exercise choices when they are rehabilitating injuries. The indoor training apparatuses allow challenging aerobic workouts without the same potentially harmful physical impact experienced when running. But outdoor runners are practiced at using a normal running “gait” pattern than their colleagues who usually exercise indoors on treadmills, ellipticals and arc trainers. Thousands of people have climbed onto trainers without any “training” in their proper use. Treadmills, ellipticals and arc trainers do not come equipped with instructions attached to each machine as to how your feet should move. Though the physiologic effects of indoor cardio workouts may be very similar to running, the actual leg motions vary in specific ways, dictated by the aparatus being used. With ellipticals and arc trainers, the foot patterns are obviously different from outdoor running since the feet rarely rise off the footplates. Calf fatigue or pain or tingling during a aerobic exercise session on a treadmill or elliptical trainer are common complaints. These specific symptoms result from the way people use their legs when exercising on the machines compared with when they run or walk on the ground.

Normal gait

Running gait

 Usually with walking or running the foot lands on the heel (heel strike) and rolls forward. When you walk faster, your stride length (the length of each step) naturally increases. Your leg muscles prime themselves to extend further and your heels reach farther to take that longer step. This cannot happen natrually on a treadmill or elliptical machine where the distance available for the next step is fixed. Your foot hits the ground prematurely, landing on the ball of the foot instead of the heel, unless you make a conscious effort to place the heel first. With practice the you can and should use the more normal heel strike pattern. Repeated stepping on the ball of the foot will exercise predominantly the calf muscles, the gastrocnemius and soleus muscles, instead of the larger and stronger thigh and buttock muscles (hamstring, quadriceps and gluteal muscles). The calf muscles fatigue quickly and cramp. Lactic acid builds up and you feel painful tightness and resistance as the muscles fight against the work you are asking them to do. Essentially, it is as if you are walking or running on your toes. You want to make sure your weight is firmly on the heel of your foot when you begin stepping down on a leg. This places your body weight properly with your center of gravity more posterior and will use you muscles and energy more efficiently.

An Effective Cardiac Workout

 

As a muscle, a heart needs exercise to remain in conditioned. Exercise helps improve heart health, and can even reverse some heart disease risk factors. As a result of exercise, a heart can pump more blood through the body with every beat and continue working at maximum level, if needed, with less strain. The resting heart rate of those who exercise is slower, because less effort is needed to pump blood.

Exercise benefits the heart and circulation (blood flow throughout the body) by improving cholesterol and fat levels, reducing inflammation in the arteries and helping to keep blood vessels flexible and open. For the greatest heart protection, it is not the duration of a single exercise session that counts but the total weekly amount of energy expended. The American Heart Association recommends that individuals perform moderately-intense exercise for at least 30 minutes on most days of the week (2008 recommendations - now recently updated in 2018 to greater than 150 minutes weekly). Similar exercise guidelines have been issued by the Centers for Disease Control and Prevention, and the American College of Sports Medicine (30-60 minutes 3-5 days/week). These organizations are recommending aerobic exercise, but resistance (weight) training has also been associated with heart protection. It may offer a complementary benefit to aerobics. And studies show that yoga and tai chi, an ancient Chinese exercise involving slow, relaxing movements, may lower blood pressure almost as well as moderate-intensity aerobic exercises. So know that there are options when designing your ideal exercise program.
 
     Consider the logic of this concept, that for optimal cardiac conditioning, creating a routine combining low intensity aerobic, moderate intensity aerobic and resistance training sessions each week provides the most functionally relevant conditioning. The benefits of such a program affords us with a heart that is well equipped to deal with any and all forms of stressors we encounter in our daily activities. Ultimately, this is what we are training our hearts to do.

     With any exercise program safety is an issue. To reduce the risk of injury or complications and make exercise more enjoyable there are a few things we must all do (or at least consider doing if we develop any possible risks). If over 40 years old it is recommended that you speak to a doctor first before starting any new exercise program. Chose a type of exercise you are more likely to stay with over the long-term. Perform your activity at a level in which you can carry on a conversation while exercising. This "talk test" provides a general rule of thumb to help you determine if a particular activity is too strenuous for you (the proper intensity of your workout).
 
     The specific design of an individual exercise program depends on the person, their age, level of fitness, basic health and personal interests. Doing something is proven better than doing nothing at all, so no one should abandon all exercise if they feel they cannot meet suggested guidelines. Knowing the guidelines provides a target for educated structure. Use these to create a program you can enjoy. Run, dance, walk, lift weights, and plan these activities with friends or alone, in a gym, in a park, at a nightclub or at home. Be creative, but be active.

BODY FAT

A body is composed of water, muscle, bone, vital organs and fat.  Adipose tissue (body fat) is a normal constituent of the human body that serves the important function of storing energy as fat for metabolic demands.

There are different types of fat cells that make up fat tissue.  What most people are referring to when they speak about the biology of “fat” are white fat cells, especially those located just under the skin (i.e. subcutaneous fat).

Large white blobs (termed “lipid droplets”) in the white fat cells are what house our triglycerides (TAGs). The lipid droplets grow and shrink as TAGs are used by the body metabolism.   

 

 

 

Chemically speaking, TAGs come in different varieties, but are always made up of a glycerol molecule plus three fat molecules.    

 

You may have heard of Omega-3 Fatty Acids, which have the third carbon from the right with a double bond. To clarify “saturated” versus “unsaturated” fat: This terminology has to do with the “saturation” of hydrogen atoms around the carbon atoms.  Unsaturated fat has double bonds between one or more of its carbon atoms (i.e. the double line things) and saturated fat are those that don’t.

 

 

 

 Know that your body needs both to function properly.

 

 

 

 

 

What causes TAGs to accumulate in lipid droplets within white fat cells?  High blood glucose levels, mainly

In order for our bodies to start pulling TAGs out of lipid droplets, the appropriate signals need to be sent to receptors on the surface of fat cells.  When glucose resources are low, this activates a wide variety of hormones including (to varying degrees and roles) epinephrine, norepinephrine, corticotropin (ATCH), thyroid stimulating hormone (TSH), cortisol, ghrelin, testosterone, human growth hormone (HGH), adiponectin, cholecystokinin (CCK), glucagon, and leptin.

To lose weight all you need to do is keep glucose levels down, make sure that these hormones are triggered effectively, and eat fewer calories than you burn.

 This simple concept would be ideal but a body never functions relying on a single process.   The blood glucose levels alone do not control metabolism.   Everyone has a different “metabolism” (i.e. the rates and efficiencies of the metabolic pathways and biochemistry described above), and these factors always change as we get older.  In addition to how we actively manage glucose, genetic and environmental factors will influence body mass index despite “classic” diet and exercise, and most Americans are destined for an increasing BMI until the age of 60 or so.  Said plainly, by just limiting calories, one will probably still carry excess body weight. 

In Lyn Genet’s work, she explains how inflammation affects metabolism, influencing weight gain and loss.   Her book, The Plan is an excellent resource for details.   Paraphrased from her blog; ‘elevated cortisol produces glucose, which leads to increased blood sugar levels. This will start to increase yeast growth as they have specialized glucose sensors and their growth in population will alter gut flora affecting your body’s defense system.  A high yeast population means never ending sugar and carb cravings (and high sugar and carb intake is definitely a factor behind the high rates of type 2 diabetes in the US).  Altered gut flora leads to a weakened immune response as the balance of our intestinal bacteria is thrown off’.   Here you have just a single example of the multiple factors working to manipulate glucose metabolism.

Fat metabolism is defined as the biochemical process by which fats are broken down, incorporated, and used by the cells of the body. Fats provide more food energy (9 kcal/g) than carbohydrates (4.1 kcal/g). Fat catabolism begins with the hydrolysis of fats (triglycerides) into glycerol and fatty acids.

Losing one pound of body fat is equivalent to 3,500 calories. To lose two pounds per week, you must eliminate 1,000 calories per day (all approximations).

The concentration of glucose in your blood is the critical switch that places your body into a “fat-storing” or “fat-burning” state.

As you eat carbohydrates, you metabolize them, and eventually store them as fats.  With energy expenditure, your body will draw on the fat stores, and you burn fat.  If your intake of carbohydrate is lower than your fat burning energy expenditure, then overall you will lose fat. 

 

In general though cardiovascular exercise rarely has a significant impact on the overall quantity of TAGs in your fat cells because  while  you expend energy and burn through glycogen and fat when you workout for long enough , your body adjusts for this via increased hunger and consumption of carbohydrates, fats, proteins, etc.   Building muscle does  raise your basal metabolic rate (so it’s a good idea to weight train). But again, your body adjusts to this new rate by compelling you to eat more.  In fact, in order to gain muscle you need to be in energy-positive situation and let insulin do its work of bringing in energy and amino acids in for “muscle building.”   It is essential to eat smart for exercise to assist with fat burning.   Selecting foods to eat with lower glycemic indices  may help a bit with balancing the caloric need/energy expenditure.   The Glycemic Index (GI) is a relative ranking of carbohydrate in foods according to how they affect blood glucose levels.  Carbohydrates with a low GI value (55 or less) are more slowly digested, absorbed and metabolized and cause a lower and slower rise in blood glucose and, therefore insulin levels.  There exists an exhaustive set of resources  presenting foods and their glycemic ratings  to assist in making smart food choices.   

 

Normal healthy values usually quoted for total body fat are 15% (12-19%) of body mass for young men and 27% (25-30%) for women, both increasing by about 5% from late teens to sixties.  Essential fat in the tissues and organs (including bone marrow, nervous system and muscle) averages 3% body mass for men and 12% for women (extra related to reproductive function); it is not a labile energy reserve, but a vital component for normal structure and function. Storage fat represents the energy reserve that accumulates as adipose tissue beneath the skin and in visceral depots, averaging 12% body mass for men and 15% body mass for women.  Methods most commonly used for estimating percentage fat are: measurement of skinfold thickness at prescribed sites, body density measurement, usually hydrodensitometry (the Quetelet index) and bio electrical impedance analysis.  None of these methods provides a precise indicator of body composition, but bioelectrical impedance is the simplest, least expensive, and most nearly accurate.

Understanding body fat empowers one to manage their metabolism, weight and health more realistically and responsibly.  There is so much more at stake than the prefect bikini body.  Lower body fat has been associated with lower risks of diabetes, cardiovascular and heart disease.  Improved metabolic rates  enhance energy, improve mobility and strength reducing the effects of osteoarthritis and osteoporosis.  Overall, we just feel better with lower body fat percentages and idealized body fat ratios mainly because we are using more efficient energy stores.