Archive for the ‘Weight Training’ Category

The Physiology of Fat Loss

by: Len Kravitz, PhD , Christine Mermier, PhD and Mike Deyhle

From the fat cell to the fat furnace, find out exactly what causes the body to burn fat.

Fat may seem like the enemy of civilized people—especially sedentary ones. Yet we cannot live without it.Fat plays a key role in the structure and flexibility of cell membranes, and it helps regulate the movement of substances through those membranes. Special types of fat, known as eicosanoids, send hormone-like signals that exert intricate control over many bodily systems, mostly those affecting inflammation or immune function.

Of course, the best-known function of fat is as an energy reserve. Fat has more than twice the energy-storage capacity of carbohydrate (9 calories per gram vs. 4 calories per gram). It has been estimated that lean adult men store about 131,000 calories in fat (Horowitz & Klein 2000), enough energy to keep the average person alive for about 65 days.

For fitness professionals, the prime concern arises when the body’s fat-storage function works too well, hoarding unwanted fat that makes people unhealthy and self-conscious about their appearance. Understanding how fat travels through the body can help personal trainers work with clients to reduce excess body fat and improve athletic performance.

The Journey of a Fatty Acid to Muscle

THE ADIPOCYTE

p38 ImageFat resides primarily in designated fat-storage cells called adipocytes. Most adipocytes are just under the skin (subcutaneous fat) and in regions surrounding (and protecting) vital organs (visceral fat). Nearly all fat in adipocytes exists in the form of triacylglycerols (TAGs or triglycerides). Each TAG consists of a backbone (glycerol) with three fatty-acid tails (see Figure 1).

Depending on energy supply and demand, adipocytes can either store fat from the blood or release fat back to the blood. After we eat, when the energy supply is high, the hormone insulin keeps fatty acids inside the adipocytes (Duncan et al. 2007). After a few hours of fasting or (especially) during exercise, insulin levels tend to drop (see Figure 2), while levels of other hormones—such as epinephrine (adrenaline)—increase.

When epinephrine binds to adipocytes, TAG stores go through a process called lipolysis (Duncan et al. 2007), which separates fatty acids from their glycerol backbone. After lipolysis, fatty acids and glycerol can leave the adipocytes and enter the blood.

p39 ImageFatty Acids in the Blood

Because fat does not easily dissolve in water, it needs a carrier protein to keep it evenly suspended in the water-based environment of the blood. The primary protein carrier for fat in the blood is albumin (Holloway et. al. 2008). One albumin protein can carry multiple fatty acids through the blood to muscle cells (Horowitz & Klein 2000). In the very small blood vessels (capillaries) surrounding the muscle, fatty acids can be removed from albumin and taken into the muscle (Holloway et al. 2008).

Fatty Acids Going From the Blood Into Muscle

Fatty acids must cross two barriers to get from the blood into the muscle. The first is the cell lining of the capillary (called the endothelium), and the second is the muscle-cell membrane (known as the sarcolemma). Fatty-acid movement across these barriers was once thought to be extremely rapid and unregulated (Holloway et al. 2008). More recent research has shown that this process is not nearly as fast as once thought and that the presence of special binding proteins is required at the endothelium and sarcolemma for fatty acids to pass through (Holloway et al. 2008). Two proteins that are important for fatty-acid transport into the muscle cells are FAT/CD36 and FABPpm.

Two Fates of Fat Inside Muscle

Once fat is inside the muscle, a molecule called coenzyme A (CoA) is added to the fatty acids (Holloway et al. 2008). CoA is a transport protein that maintains the inward flow of fatty acids entering the muscle and prepares the fatty acid for one of two fates:

  • oxidation (in which electrons are removed from a molecule) to produce energy or
  • storage within the muscle (Holloway et al. 2008; Shaw, Clark & Wagenmakers 2010)

The majority (80%) of fatty acids entering the muscle during exercise are oxidized for energy, while most fatty acids entering the muscle after a meal are repackaged into TAGs and stored in the muscle in lipid droplets (Shaw, Clark & Wagenmakers, 2010). Fatty acids stored in muscle are called intramyocellular triacylglycerols (IMTAGs) or intramuscular fat.

There are two to three times more IMTAGs stored in slow twitch muscle fibers (the slow oxidative fibers) than there are in fast-twitch muscle fibers (Shaw, Clark & Wagenmakers 2010). Shaw and colleagues note that even though this IMTAG supply makes up only a fraction (1%–2%) of the total fat stores within the body, it is of great interest to exercise physiologists because it is a metabolically active fatty-acid substrate especially used during periods of increased energy expenditure, such as endurance exercise.

Fatty Acids Burned for Energy

Fatty acids burned for energy (oxidized) in the muscle can come either directly from the blood or from IMTAG stores. For fatty acids to be oxidized, they must be transported into the cells’ mitochondria (see Figure 3). A mitochondrion is an organelle that functions like a cellular power plant; it processes fatty acids (and other fuels) to create a readily usable energy currency (ATP) in order to meet the energy needs of a muscle cell.

Most fatty acids are transported into the mitochondria via the carnitine shuttle (Holloway et al. 2008), which uses two enzymes and carnitine (an amino acid-like molecule) to do the transporting. One of these enzymes is called carnitine palmitoyltransferase I (CPT1). CPT1 may work with one of the same proteins (FAT/CD36) used to bring fatty acids into the muscle cells from the blood (Holloway et al. 2008). Once inside the mitochondria, fatty acids are broken down through several enzymatic pathways—including beta-oxidation, the tricarboxylic acid (TCA) cycle and the electron transport chain—to produce ATP.

Fatty-Acid Oxidation During a Single Bout of Exercise

At the start of exercise, more blood flows to adipose tissue and muscle (Horowitz & Klein 2000), releasing more fatty acids from adipose tissue and delivering more fatty acids to the muscle.

Exercise intensity has a great impact on fat oxidation.We burn the most fat when exercising at low to moderate intensity—that is, when oxygen consumption is between 25% and 60% of maximum (Horowitz & Klein 2000). At very low exercise intensities (25% VO2max), most of the fatty acids used during exercise come from the blood (Achten & Jeukendrup 2004). As exercise increases to moderate intensity (around 60% of VO2max), most of the fatty acids oxidized appear to come from IMTAG stores (Horowitz & Klein 2000).

p39 ImageAt higher exercise intensities (>70% VO2max), total fat oxidation falls below the levels observed at moderate intensity (Horowitz & Klein 2000). This reduction in fatty-acid oxidation is coupled with an increase in carbohydrate breakdown to meet the energy demands of the exercise (Horowitz & Klein 2000).

We often overemphasize the fatty-acid contribution to calories burned during a bout of exercise. It’s also important to consider recovery from a bout of exercise, as well as training adaptations to repeated bouts, if you’re helping clients meet their fat-loss goals.

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Food Mistakes

By Cynthia Sass

Whether you earn your living working up a sweat, or squeeze in workouts when you can, it’s easy to fall prey to eating errors that unintentionally hold you back from getting the most out of your workouts. Here are five common missteps I see, and how to correct them to reap the rewards of your hard work.

Eating Too Little Fat Despite my recommendations to include good fats at every meal, like avocado, nuts, seeds and coconut oil, some of my clients remain fat phobic, and will scale back, fearing that fat is “fattening.” But the truth is, getting enough fat is a smart strategy for both sports nutrition and weight control, because fat: delays stomach emptying, so you feel fuller longer; increases satiety, to shut off hunger hormones; boosts antioxidant absorption, which in emerging research is related to leanness; and ups metabolic rate, to help you burn more calories. In fact, fat is one of the most vital nutrients in your diet, because it’s a structural part of your cells, which means you can’t heal a cell or construct a new one without enough fat to perform these important jobs. Cutting back too much can result in fatigue, chronic hunger, or a lack of satiety, irritability, depression, a weaker immune system and an increased injury risk. So even if you’re trying to reduce your body fat percentage, don’t be afraid to add almond butter to a smoothie, top your salad with avocado, and sauté your veggies in extra virgin olive oil. Filling the fat gap can be the key to finally seeing results.

Using A Sports Drink When You Really Don’t Need One If you sweat heavily, work out for more than 90 minutes, or exercise in hot, humid conditions, reaching for a sports drink rather than plain water is a smart way to keep hydrated, stay fueled and replace the electrolytes lost in sweat. But if you’re exercising for less than an hour and a half, in a climate-controlled gym, plain water should be fine. The carbs in sports drinks are designed to keep you going when you can’t stop to eat, but if your muscles don’t need the fuel, just one 20 ounce bottle means consuming a surplus 35 grams of sugar, the amount in about 20 gummy bears. And while unsweetened coconut water is a little lower, an 11-ounce jug still contains 15 grams of potentially unneeded carbs.

Not Eating After A Workout Because You’re Afraid To “Eat Back” What You’ve Burned While it’s true that overcompensating for a workout by eating too much can prevent you from shrinking your fat cells, striking the right balance is key. Working out takes a toll on your body, and having the right raw materials to heal and repair the wear and tear is important for seeing results. In other words, it’s not just the training itself, but the healing from the training, that mends muscles, boosts metabolism and makes you more toned and fit. So while a good hard workout isn’t a license to sit down to a big plate of pasta, or eat dessert every night, you should be eating something afterwards, with a goal of delivering the nutrients your body needs to properly recover.

Only Eating Protein Post Workout While protein is a key recovery nutrient, it’s only one piece of the puzzle. In addition to a lean protein source, like a smart phone-sized portion of fish or chicken or a scoop of lentils, you should aim for plenty of produce (to replenish nutrients and supply antioxidants), a healthy fat source (which also helps muscles heal and optimizes circulation), a small serving of a whole grain, like wild rice or quinoa (to replete glycogen, the carbohydrate stored in muscle tissue, which serves as a primary fuel source during exercise) and of course fluid, preferably good old H2O (to rehydrate). If you exercise after work, a great post-workout recovery dinner would be a stir-fry made with chicken, shrimp or organic tofu, along with a variety of colorful veggies, over a small portion of whole grain rice, topped with sliced almonds or black sesame seeds. For a simple aromatic stir-fry sauce, that’s not loaded with sugar, whisk together a few tablespoons of brown rice vinegar, with a splash of fresh squeezed citrus juice (like tangerine or blood orange), and a dash each of fresh grated ginger, minced garlic and crushed red pepper.

 

Doubling Up On Recovery Meals For my pro athlete clients, I highly recommend eating something like an all natural bar or shake within 30 minutes of the end of a game or a tough training session whenever possible, because starting the recovery process within a half hour has been shown to help maximize healing. But employing this strategy if you’re not a pro can wind up working against you. For example, if you munch on a bar or grab a smoothie on the way out of the gym, then go home and eat dinner, you may be in recovery overkill. While it might not register as a meal, a bar with 30 grams of carbohydrate, 5 grams of fat, and 10 grams of protein is like eating a small turkey sandwich with mayo. And a smoothie can be the equivalent of three to four handfuls of fruit, plus a container of yogurt. Downing these “snacks” just an hour or so before eating a regular dinner, can mean giving your body far more than it needs for recovery, which results in feeding your fat cells, rather than shrinking them. If you’re going to be eating a meal with an hour of leaving the gym, skip the bar and shake. And if it’s going to be a little longer, munch on something like almonds, which supply some protein, good fat and nutrients, to tie you over.

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A toned, flat tummy is a goal many of us strive to achieve in time for bathing suit season, but endless crunches and ditching all your favorite foods until July 4th isn’t the right–or fun–way to do it. A sculpted core and trim tummy can be attained by incorporating small changes into your day, like holding in your abs while you walk and adding the right healthy fats to your diet. In our lean belly guide, you’ll get diet and exercise tips that will help you eliminate hard-to-reach ab flab and reveal a sculpted, sexy midsection. Here, learn 25 ways to flatten your belly by summer.

Take Your Gossip Session On A Walk
Instead of catching up with friends over food and drinks, suggest a reunion on the move-you’re likely to work out 104% harder if you have an exercise buddy. Suggest a weekly walk-and-talk session, form a friendly fitness club, or take advantage of gym specials together. You’ll motivate everyone to get moving while you grow even closer.

Deflate Your Muffin Top With The Roll-Up
Hold a resistance band taut between hands and lie on the floor face up, with legs extended and arms overhead. Pull abs in, tuck your chin, lift arms toward the ceiling, and roll head, shoulders, and torso up and over your legs as far as you can. Keep heels firmly on the floor and reach hands towards your feet. Pause, then slowly roll back down. Do 5 to 8 reps with 30 minutes of cardio 5 to 6 times a week.

Make Time For Cardio

If you want to burn the most belly fat, a Duke University study confirms that aerobic exercise is the most effective in burning that deep, visceral belly fat. In fact, aerobic training burns 67% more calories than resistance training or a combination of the two, according to the study. 

Try Out Spidey Moves
Eliminate spillover spots with the Spiderman Climber: Get into plank position with arms and legs extended, hands beneath shoulders, and feet flexed. Keeping your abs tight, bend your left leg out to the side and bring the knee toward the left elbow. Pause, then return to start. Switch sides. Do 20 reps, alternating sides, with 30 minutes of cardio 5 to 6 times a week.

Fight Fat With Fiber
For every 10 grams of fiber you eat daily, your belly will carry almost 4% less fat. Thankfully, there are more enjoyable ways to increase your fiber than scarfing down a box of bran flakes: Two apples, ½ cup of pinto beans, one artichoke, or two cups of broccoli will all give you 10 grams of belly-flattening fiber.

Be Pushy At Restaurants
Saying, “I’ll go last” when the waiter comes around could be adding bulk to your belly. A recent study showed that a normal-weight woman was more likely to mimic a thin woman’s eating habits than an obese woman’s. So when you’re out for girl’s night, order first. You’ll keep yourself, and maybe even a friend or two, on track to a flatter tummy. 

Do the Windshield Wiper.
Lie face up with arms out to your sides, palms down, and legs bent at 90 degrees so feet are off the floor. Keep abs tight and slowly lower legs to the left as far as possible, keeping shoulders on the floor. Pause, then return to start. Repeat to the right. Do 20 reps, alternating sides. 

Clean Your House

One more reason to start your spring-cleaning: Vacuuming is a great ab workout. Tighten your abdominal muscles while you push back and forth for a tighter tummy while you clean.

Cut Back On The Pretzels
Too much salt will make you retain more fluid, which contributes to a puffy appearance and extra water weight.

Fry Fat With The Boat Move
Target your deepest ab muscles with The Boat: Lie face up on a mat with arms straight up over chest. Lift your upper body off the ground by rolling through the spine. At the same time, raise your legs so that you’re balancing on your butt, knees bent and shins parallel to the ground. Slowly roll back down onto the mat, lowering legs. That’s 1 rep. Do 5 reps per set, resting 30 to 60 seconds between sets.

Add This Green Fruit to Your Diet
Just half an avocado contains 10 grams of MUFAs (monounsaturated fatty acids), which halt blood sugar spikes that tell your body to store fat around your belly. Eat these in ¼ cup servings to ward off belly fat without overdoing it. 

Play Catch
Get into a crunch position-lie on your back, knees bent, feet flat on the floor, shoulders and head off the floor with your abs contracted. Then have someone throw an exercise ball (or basketball) to you-first to your left side so you have to twist and reach to catch it, and then to your right. Do this as many times as is comfortable, and try to increase the number each week.

Skip Your Daily Soda Habit
Where do you think all those bubbles from carbonated drinks end up? They gang up in your belly! Swap soda, diet soda, and seltzer for water or water with lemon juice.

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Older Man MusclesThe older you get, the more you may have to work to maintain your muscles, according to a new study.

Researchers report that men and women over the age of 60 have to lift weights more often than younger adults to maintain muscle mass and muscle size.

“Our data are the first to suggest that older adults require greater weekly maintenance dosing than younger individuals to maintain resistance-training-induced increases in muscle mass,” study co-researcher and physiologist Marcas Bamman, PhD, of the University of Alabama, Birmingham, says in a press release.

The study is published in Medicine & Science in Sports & Exercise.