Body Comp Break Down

[spatts]

Body Composition For Beginners
by Jason Norcross

The measurement of body composition is an inexact science, and outside the laboratory, it becomes an even more inexact science. Many times, I've checked into the T-mag forum and seen a thread started by some frustrated guy who just got his body fat measured. The last time he got pinched by his trainer, he was 10% body fat and now his brand new bioimpedance scale says that in reality, he's 20% Crisco.

Confusion about body composition measurements is one of the most common problems seen by beginner, intermediate and advanced bodybuilders. One month you get measured by hydrostatic weighing, the second month you get your skinfolds pinched, and the third month you grab on to your handheld bio-impedance device. What's the end result? A lot of measurement variability and frustration. Am I the only one here who sees the problem?

In an effort to find an accurate, reliable and convenient way to measure body composition, most people shoot themselves in the foot by mixing methods. So before I go any further, if you take just one lesson home from this article, let it be this: Pick one method and stick with it for the duration of your training career. Later in this article, I'll explain the various methods and their pros and cons, but always remember to pick one method and stick with it (unless you want to be the next frustrated poster in the T-mag forum)!

Unfortunately, the only really accurate way to measure body composition is by dissection. I'm absolutely sure no one wants to participate in a validation study comparing the new "superduperfatologic measuring device" against dissection. The next best option is to get into a research study that uses a multi-compartment model, which combines measurements of body density from hydrostatic weighing, total body bone mineral from dual energy x-ray absorpitometry, and total body water from deuterium oxide dilution. I can assure you that it's not very likely and also not very practical. Sure, you get an accurate measure of your body composition, but what are you going to do next time?

If you plan to be in the iron game for a while, composition measurements are a must. The mirror is nice and pictures are helpful, but numbers, (i.e. pounds of fat and muscle), tell the true story of how well your diet, training and supplementation are working. In order to get these numbers, you need to find a method that's both convenient and reliable. In other words, it should be a method that's both a) readily available and b) can be duplicated over time.

What about accuracy? This isn't nearly as important as you may think (although it is vexing when a tubby comes up to you and says he's holding tight at 5% body fat). In fact, it's probably the least important consideration (after convenience and reliability) when tracking body fat measurements. Let me explain.

Let's consider how we count our calories. We rely on labels to tell us how much protein, fat and carbohydrates are in the foods we commonly eat. I've yet to meet a person who walks around with a bomb calorimeter and literally burns up an equivalent portion of everything he eats in a day just so that he can have an accurate measure of his daily calories. That would not only be expensive, but that would take the "excessive" nature of bodybuilding to a whole new level (as if overgrown men parading around in thongs isn't enough already). We rely on food labels because they don't change; they're reliable day-in and day-out. By tracking our calories in a diet log, we can see if we're eating too much or too little in accordance with our observed weight changes.

Would we have to go back and change the last three years of food logs if we found out that our daily can of tuna was really 200 calories rather than 175? NO! What if we found out that in reality, all food labels are low by 10%? It wouldn't matter, because we've been living in a world where we adjusted to the fact that the labels are low by 10%. It really does not matter if the label is in reality off by a little as long as the label itself is consistent and we've adapted our food intake to suit our goals. So, why are people so worried about getting the most accurate body-composition measurements possible? You need to find a technique that can track your body composition changes over time. It doesn't matter if it measures your body fat 5% higher than what dissection of your body would show, as long as it is always 5% higher. Are you still following? Keep going; it only gets clearer.

First of all, body-composition measurement is merely a tool you use to track your progress in the gym. Even if your measurements are a few percentage points off from your actual numbers (and your methodology is reliable), you should be able to monitor your progress via the changes you see in both your fat mass (FM) and fat free mass (FFM). This becomes incredibly important for anyone who desires to drop fat and/or to pack on muscle. You better know the composition of the weight that you're dropping or adding. How else are you going to know how to adjust your diet, supplementation and/or cardio? If you're losing three pounds of lean body mass a week, it's pretty obvious that it's time to increase your total calories or time to start adding Methoxy-7, MAG-10, or 4-AD-EC to your supplement arsenal.

So whether your goal is to lose fat, gain muscle or both, you're going to have to track those changes. Don't be bogged down in what you've heard about the accuracy of various body composition measurement tools. Simply find a method that allows you to check your body composition frequently, reliably and conveniently.

For the purposes of this article, I'll focus on the methods you're liable to have access to. These include:

1. Hydrostatic (underwater) weighing

2. Bod Pod

3. Girth measurements

4. Bioelectrical impedance

5. Skinfolds

There are many other methods including dual energy x-ray absorptiometry, total body electrical conductivity, radioisotope tracers, 40K counting, and nuclear imaging. But who has the time, money and access to these machines? Not many, and in reality, they don't offer much of an advantage over other available methods.


Is that a hydrostatic weighing tank or is there a hot tub in this lab?

If you walk down the hall in the university's exercise physiology lab, you'll probably find an old school, redwood-frame hot tub. Well, it's only a hot tub for those lucky grad students with keys to the lab. For everybody else, it's a hydrostatic weighing tank. The tank is usually heated to about 97-98 degrees, so it'll be consistent with total-body temperature. Other than being a comfortable place to take a soak and regenerate your sore muscles, what important purpose does this tub serve?

Hydrostatic weighing (HW) relies on Archimedes principle to measure body volume (Vb). Archimedes's principle states, "the volume of an object submerged in water is equal to the volume of the water that the object displaces" (1) and "a body immersed in fluid is acted upon by a buoyancy force, made evident by a loss of weight equal to the weight of the displaced fluid" (2). When applied to HW, the difference between a person's mass in air (MA) and mass submerged in water (MW) is the weight of the water displaced. The volume of this displaced water is obtained by dividing the mass of the displaced water by the density of the water (DW), which is based on the temperature of the water (3). The equation for Vb is as follows:

Vb = (MA - MW)/DW

Still with me? If not, drink a serving of Power Drive and then go back and reread the last paragraph. Okay, ready? Next, an additional volume that contributes to Vb must be taken into account when using HW. This additional volume, which does not contribute to overall tissue density, is the amount of air in the lungs after a maximal expiration. It is referred to as the residual volume (VR). The VR must be measured and subtracted from the Vb for the calculation of body density (Db) (3).

Db = MA/(Vb - VR)

The Db is then plugged into an equation used to predict percent body fat (%BF). An example of this is:

%BF = [(4.57/ Db) - 4.142] * 100 (4)

This conversion of body density to %BF is where many of the problems with HW begin. Contrary to popular belief, HW isn't nearly as accurate as you may have heard. To demonstrate this potential for inaccuracy, let's look at the four basic assumptions regarding HW (5):

1. The separate densities of the body compartments are additive.

2. The densities of FM, FFM and all FFM components are known and constant for all persons.

3. The components of FFM are proportionally constant in all persons, therefore,

4. Proportional differences from the "reference body" are solely due to differences in FM quantity.

Assumption #1 is true. All the components of the body add up to 100%. Assumption #2 presents a few problems, but they're minor in comparison to the significant problems seen in Assumption #3. Recall that Assumption #3 states: the components of FFM (water, fat-free muscle, mineral, and to a lesser extent, glycogen) are proportionally constant in all persons. These assumptions were derived from just three male cadavers ages, 25, 35, and 46 whose data was merged to form the "reference body" (4).

We currently have data from 51 cadavers collected over the past 150 years. The majority of the cadavers were males and females that were very old or died from chronic disease, and their average ages were 56.6 and 75.5 respectively. However, FFM composition was determined on only 5 of these cadavers. Are you ready for something that makes no sense? These five cadavers don't agree with the above "reference body" assumptions, even though the "reference body" was derived from 3 of these 5 cadavers (6,4). Therefore, assumption #3 and #4 can't be true.

If you believed all the above assumptions, you'd still believe that the only proportional difference between you, your grandmother, and Ronnie Coleman is that the three of you only differ in your proportions of body fat. Think about it! Do Ronnie Coleman's bones grow in proportion to his huge increases in muscle mass and water? No! I could go into much more detail, but you get the point. Assumptions #3 and #4 can be problematic.

The problems seen with HW's accuracy also spill over into its reliability as a technique. The most common change among bodybuilders is fluid variation. If you've been in the iron game for any amount of time, you know the importance of adequate hydration. In other words, you drink a ton of water and experience a fairly large shift in fluid balance from hour to hour. Why is this a problem? A one-liter change in total-body water (TBW) (which is very easy to do and quite common) can lead to a 0.7% change in percent body fat (7).

Other problems with HW include that fact that it's expensive; it's problematic to have it done frequently; it's inconvenient; and few places have the equipment to measure residual volume. This lack of equipment is significant, as a variation of 600 ml in the calculation of VR can produce a change of up to 8% in the final %BF calculation (8). As you can see, there are several reasons why you should avoid HW.


Nanu! Nanu! Welcome to the Bod Pod


Anyone remember the TV show, Mork and Mindy? When you see the Bod Pod, images of Robin Williams shouting "Nanu! Nanu!" will instantly come to mind. The Bod Pod is a large egg-shaped device that also measures body volume. Instead of using water displacement, air pressure changes are used to determine the body volume of the subject contained in the egg. Body weight is divided by body volume, giving you body density.

Body density is plugged into the same equations that HW uses. Therefore, all of the "reference body" problems that were seen with HW will be seen with the Bod Pod. The Bod Pod is also sensitive to changes in ambient room temperature and pressure. Basically, it needs its own room to work optimally. The Bod Pod is also expensive, inconvenient and very uncommon. Plus, you have to wear a speedo and swim cap while you're in there.


The Old Fashioned Tape Measure

Checking girth measurements and deriving %BF equations from these measurements is the cheapest method used to determine body composition. Trouble is, it doesn't work well for bodybuilders because no differentiation is made between increases in girths due to fat gain versus muscle gain. The 20-inch arms belonging to Krispy Kreme patrons are 20-inch arms alright, but are quite different from the "Great Guns" earned after Ian King's 12-week program.

Variations in girth measurements can also happen without a change in fat or muscle. Fluctuations occur frequently with fluid variations and/or changes in muscle glycogen content. Another consideration is the amount of tension on the tape measure. There are a few different models that are designed to control the amount of tension with each measurement and these would be a must for any type of reliable girth measurement.

Overall, this is a technique that has minimal research behind it due to its weakness as a good predictor of percent body fat. For these reasons, I don't feel it is necessary to include an example equation. It may work well for other things like assessing risk for coronary heart disease or fitting pants, but it's not ideal for tracking body composition.


Bioelectrical Impedance — Is This Going To Shock Me?


Another popular method is bioelectrical impedance (i.e. the Tanita scales and hand held analyzers). Bioelectrical impedance devices measure the body's resistance to an electrical current. Unless you have a pacemaker or some other electrical implant, you won't feel a thing. If you look closely at a Tanita™ scale, you'll see four metallic electrodes. Two of those electrodes generate a voltage and the other two measure the residual voltage that remains after the current passes through the body.

The ratio between the starting and ending voltages is called impedance. To determine how to convert impedance values into a %BF, validation studies were done with HW or better yet, multi-compartment body composition models. The impedance value was combined with things like weight, height, and sex to create a complicated algorithm that converts all these factors into a percent body fat. (9) Okay, that may sound reasonable, but here are some problems that we run into when we use these scales.

The problems are primarily caused by changes in total-body water (TBW). TBW is assumed to be about 73% of your FFM. Any changes to this quantity of water or to its electrolyte content will change your impedance and thus change your %BF value. So, assume that this device is measuring your TBW and that TBW is 73% of your FFM. It then calculates FFM and subtracts that mass from your body weight, leaving you with a measure of your fat mass (FM). You divide FM by body weight and that gives you a percent body fat value. If you remember the problems with HW Assumption #3, they all still apply here.

Bodybuilders and athletes are nightmares to deal with when it comes to assumptions regarding fluid balance. I drink at least two gallons of fluids a day. The people used in these studies probably drank less than a half-gallon per day. The reason this method may be better for the bodybuilder or athlete is that it's convenient, requires no third-person assistance, and isn't very expensive (aside from the initial $100-150 investment).

Impedance measurements can also be altered by changes in skin temperature, skin moisture, body posture and much more. To maximize reliability, you need to find the time of day when your skin temperature, TBW, and skin moisture are the most consistent. If you don't work out in the morning, then it's pretty easy. If you have a Tanita™ scale, wake up, go to the bathroom and hop on with no clothes on or with the same type of clothing on every single time. It's okay to measure in your underwear, but remember: clothes add to your weight and can artificially change your percent body fat. After you have this measurement, get another measurement after you've taken your morning shower and completely dried off (hair also). Track the numbers over a couple of weeks and then just use the one (before shower or after) with less variability.


Tips for Bioimpedance Measurements

1. Take 3-5 measurements each time you step on the scale and average the measurements except for the first. (Drop the first measurement because the metal electrodes are cold and often it takes most people a minute or two to adjust to not wearing any clothes.)

2. Measure yourself every day and then average the measurements over the course of the week for tracking purposes. Day to day variations will drive you nuts, but a weekly average will be very reliable. I've had great results with this technique and it correlates very well with my skinfold data.

In summary, bioelectrical impedance may not be the best choice, but with a little manipulation, it can work very well.

Next week, in Part 2 of this article, Jayson Norcross will give an in-depth tutorial on how to perform the most accurate body composition method currently available: the good ol' skin-fold test.

 

[spatts]

Last week, in Part 1 of this article, author Jason Norcross talked about the different ways commonly used to determine if you're more pork than loin, if you catch our drift. Unfortunately, most of the methods usually used to determine body fat are woefully inadequate and rife with potential problems.

If you really want to know how much fat you're packin', the tried-and-true skinfold measurement is the way to go.

Here's everything you ever wanted to know about skinfold measurements.


Skinfold Measurement - The Method of Choice

Skinfold measurements are probably one of the most misunderstood body composition methods. It's true that most skinfold body fat equations have been derived by those used for HW (hydrostatic weighing), but unlike HW, which is markedly affected by day to day fluctuations in hydration, skinfold measurements of %BF aren't nearly as affected by hydration. Skinfold calipers are also inexpensive. There are several different models available for less than $60 and a couple of different models that will run you $20. Both the Accu-Measure™ and Slim-Guide® cost about $20 and will do the trick for most people.

Skinfold measurements can be done by yourself using a 3-site method or with assistance from someone else using a 7-site method, although women will have to have a partner to do both the 3 and 7-site methods. (Women can get the thigh and suprailiac measurement by themselves, but it's pretty tough for them to get a good tricep measurement by themselves. It's possible with some calipers like the Fat-Track, but with most calipers, it's very difficult. Inclusion of the triceps measurement is pretty important, too, as many women store a fair amount of fat there. )

Anyhow, after you practice a bit, you'll find that your measurement technique will get pretty good. You won't have a lot of variability if you’re only measuring yourself or someone else.

Unfortunately, once you take the measurements, you'll have to plug the numbers into equations. Even though I recommend you use either one of two different equations, there are actually hundreds of equations, so feel free to use another one if you like. I'll present the equations later on, but in the meantime, just remember a few things:

1. More sites = better reliability and less variability

2. More samples per site (3 is minimum) = better reliability and less variability

3. Practice makes perfect. For the first week or two, measure yourself or your partner every single day or until your day to day %BF values don’t vary more than 1%. You might think that the standard error of measurement is about 4%, but remember that you're only measuring one person (yourself or your partner) and in my opinion, you should be able to replicate that measurement with little variation.

4. Measure yourself every week and preferably on the same day and at the same time. One week may not be enough to see a change, but being able to make a graph that plots 52 measurements over a year will clearly show you the picture.

5. Finally, the leaner you are, the more reliable skinfold measurements become. Any measure over 20mm is subject to a lot of variability. If you keep seeing several of these high measurements, then fat loss needs to become a priority right away.


Skinfold How-To’s

1. All measurements should be made on the same side of the body. While it probably doesn't matter all that much, small differences may occur between opposite sides of the body.

2. The calipers should be placed 1/2 inch below where you pinch the thumb and finger, perpendicular to the skinfold and halfway between the crest and base (the part that is closest to your fingertips is the base and the part that is closest to your hand is the crest).

3. The pinch should be maintained while reading the caliper (unless using a model like the Accu-Measure™ where you read the number after you hear it click).

4. Wait 1-2 seconds (no longer) to take and read the measurement.

5. Rotate through the different sites to give the skin adequate time to return to normal. (This one's very important because it forces you to also learn the anatomical landmarks for skinfold measurement.)

6. Take a minimum of 3 measurements at each site and average the measurements; then add the averages together and plug them into the equations presented later on in this article.


Skinfold Sites

1. Abdominal: vertical fold, 1-inch to the right of the umbilicus.

This one is very straightforward. You can have someone measure it for you (left picture) or you can do it yourself (right picture). One thing to note is the different hand position when you do it yourself. The key is to measure the same point each time so stay in line with the umbilicus.

2. Triceps: vertical fold, posterior midline of upper arm, halfway between the olecranon (elbow) and the acromion processes (bony point on top of the shoulder).




Using your hands as a measurement tool, find the midpoint of the triceps. Spread your thumb and middle finger from both hands to the maximum distance. Lock one of the digits on the top and bottom anatomical landmarks. Then bring them together in the middle of the triceps to find the skinfold site. Mark that site and have the person flex their triceps. By flexing, the subject separates the muscle from the fat. This isn't usually a problem for most well-conditioned men and women, but it’s a nice trick to know anyway. As the person relaxes their triceps, grab the skinfold and take the measurement.

3. Chest (men): diagonal fold, halfway between the anterior axillary line (on the front of the body at the point where the arm inserts into the torso) and the nipple.

There isn't much to explain here other than to make sure you're on the lateral aspect of the pectoral muscle. These pictures show me using both types of calipers. This will probably be the toughest measurement to do on yourself, so here's a tip: If you're right handed, grab the skinfold of your left pectoral with your left hand and take the measurement with your right.

4. Chest (women): diagonal fold, 1/3 of the distance from the anterior axillary line to the nipple

5. Midaxillary: vertical fold, on the midaxillary line (a vertical line descending directly from the center of the armpit) at the level of the xiphoid process (the bony nub at the bottom of the sternum).
It's helpful to have your subject place his arm on top of his head while taking this measurement.

6. Subscapula: diagonal fold, 1/2 to 1-inch below and in line with the inferior (lower, inside) angle of the scapula.

The longer line marks the inside edge of the scapula. The other line is drawn to demonstrate where the bottom tip of the scapula is. This one's also pretty straightforward. Just don’t try to do this one by yourself; it’s virtually impossible unless you’re a hyperflexible circus freak.

7. Suprailiac: diagonal fold, in line with the natural angle of the iliac crest (hip), just above the the iliac crest at the anterior axillary line (an imaginary line down the front of the body from where the arm inserts into the torso).

Just feel for the bony prominence near the front of the pelvis. You should feel it just before the pelvis begins to slope upward (as demonstrated by the line in the first picture). Find the anterior axillary line, grab and measure the fold right above the pelvic line. Be careful with this one. The closer you are to the ASIS, the smaller the measurement, but as you travel along the pelvic line, the folds will only get bigger. Just try for utmost consistency from week to week.

8. Thigh: vertical fold, on the anterior (front) midline of the thigh, half the distance between the proximal (nearest to body) aspect of the patella and the inguinal crease (line where leg inserts into trunk). It helps to have the subject rest the foot of the leg being measured on a box, chair, or Smith machine bar. (See, the Smith Machine does have some utility!) Once you find the vertical midpoint, make sure that you're even from a horizontal standpoint and not shifted medially or laterally. You can have the subject push down with the elevated foot to separate muscle from fat and then grab the fold and measure it.


Other Skinfold Observations

Skinfold measurements change primarily when there is a change in skinfold thickness (i.e., you gain or lose fat). A minor problem to watch for is dehydration, because this will decrease skinfold thickness also. You can minimize this potential for error by measuring in a hydrated state and by measuring at the same time of day each week.

Another advantage of skinfolds is the tangible feeling of grabbing on to your body fat, which you don’t get with any of the other methods. Finally, skinfold calipers are also cheaper, readily available and more convenient. For instance, try scheduling a weekly or even monthly appointment with the same tester at the same time of day for HW or Bod Pod! It'll take a lot of effort and financially it would add up very quickly. That’s money better used on good food and supplements.


Skinfold Equations (Jackson-Pollack method)

Don't worry. If you're mathematically challenged, go to this great site to have all your calculations done for you:
www.enforcergraphics.f2s.com/bodyfat.htm.
However, if you're a "hands-on" guy, here are the equations:

NOTES: SUMS refers to the sum of the average skinfold thickness (mm) of the prescribed skinfold sites. Db refers to body density.


Male 3-Site Equation (SUM3 = chest, abdomen, thigh)

Db = 1.10938 - (0.0008267 * SUM3) + (0.0000016 * SUM32) - (0.000257 * AGE)

%BF = [(4.57/ Db) - 4.142] * 100



Male 7-Site Equation (SUM7 = chest, midaxillary, tricep, subscapula, abdomen, suprailiac, thigh)

Db = 1.112 - (0.00043499 * SUM7) + (0.00000055 * SUM72 ) - (0.00028826 * AGE)

%BF = [(4.57/ Db) - 4.142] * 100


Female 3-Site Equation (SUM3 = tricep, suprailiac, thigh)

Db = 1.0994921 - (0.0009929 * SUM3) + (0.0000023 * SUM32) - (0.0001392 * AGE)

%BF = [(4.57/ Db) - 4.142] * 100


Female 7-Site Equation (SUM7 = chest, midaxillary, tricep, subscapula, abdomen, suprailiac, thigh)

Db = 1.097 - (0.00046971 * SUM7) + (0.00000056 * SUM72 ) - (0.00012828 * AGE)

%BF = [(4.57/ Db) - 4.142] * 100

Why is age included in these formulas? As normal people (not T-mag readers!) age, there's an increase in intra-abdominal fat, a decrease in total muscle mass, and a decrease in bone density (12). These equations try to account for these changes by adding body fat as we age. Of course, this doesn't apply nearly as much to people who train with weights. Anyhow, whether you choose to put your actual age or choose to call yourself a 20-year old is up to you. Personally, I think anybody who trains hard with weights would do better to plug 20 in as their age, as it more accurately reflects your true muscle mass.

Let me put it this way: if your sum of seven skinfolds was 50mm when you were 25 and is still 50mm now that you're 35, then I’m pretty confident that your body fat hasn't increased markedly. You could still use 25 years in the equation. I suggest that you use the age at which you started to seriously train. Once again, it’s up to you, just be consistent with what you do.

In conclusion, most methods are expensive, inconvenient, unreliable and don’t improve on the accuracy of skinfolds. Skinfolds allow you to track your body composition as often as you want without burning a hole in your wallet. Just remember to pick one skinfold equation and stick with it. If that doesn’t suit you for some reason, pick up a higher end Tanita™ bioimpedance scale and follow my recommendations form part 1 of this article. Finally, don't ever go back and forth between methods unless you want frustration and bad data.

Good luck and happy measuring!


References

1. Lukaski, H.C. Methods for the assessment of human body composition: traditional and new. Am. J. Clin. Nutr. 46:537-56, 1987.

2. Behnke, A.R. Comment on the determination of whole body density and a resume of body composition data. In: Techniques for Measuring Body Composition. J. Brozek and A. Henschel (Editors). Washington DC: NASNRC, 1961, pp. 118-133.

3. Goldman, R.F. and E.R. Buskirk. Body volume measurement by underwater weighing: description of a method. In: Techniques for Measuring Body Composition. J. Brozek and A. Henschel (Eds.). Washington DC: NASNRC, 1961, pp. 77-89.

4. Brozek, J., F. Grande, J.T. Anderson, and A. Keys. Densitometric analysis of body composition: revision of some quantitative assumptions. Ann. N.Y. Acad. Sci. 110:113-140, 1963.

5. Going, S.B. Densitometry. In: Human Body Composition. A.F. Roche, S.B. Heymsfield, and T.G. Lohman (Editors). Champaign, IL: Human Kinetics, 1996, pp. 3-23.

6. Clarys, J.P., A.D. Martin, M.J. Marfell-Jones, V. Janssens, D. Caboor, and D.T. Drinkwater. Human body composition: A review of adult dissection data. Am. J. Hum. Biol. 11:167-174, 1999.

7. Martin. A.D. and D.T. Drinkwater. Variability in the measures of body fat. Assumptions or technique? Sports Med. 11:277-288, 1991.

8. Heyward, V. Evaluation of body composition: current issues. Sports Med. 22:146-156, 1996.

9. National Institutes of Health (NIH). Bioelectrical Impedance Analysis in Body Composition Measurement. Technology Assessment Conference Statement, Dec. 12-14, 1994. http://odp.od.nih.gov/consensus/
ta/015/015ta_statement.pdf

10. Jackson, A.S. and M.L. Pollack. Practical Assessment of body composition. Physician Sport Med 13:76-90, 1985. (As published in: Nieman DC: The Sports Medicine Fitness Course. Bull Publ. Palo Alto, 1986, pp. 101)

11. American College of Sports Medicine. ACSM’s Guidelines For Exercise Testing and Prescription 5th Ed. Media, PA: Williams & Wilkins, 1995, pp 56-57

12. Bemben, M.G., B.H. Massey, D.A. Bembem, R.A. Boileau and J.E. Misner. Age-related patterns in body composition for men aged 20-79. Med. Sci. Sports Exerc. 27(2):264-269, 1995.

 

[SAGAT]

that was loong. btw, you're hot