Research Review

Gomez-Cabrera MC et. al. Oxidative stress in marathon runners: interest of antioxidant supplementation. Br J Nutr. (2006) Suppl 1:S31-3.

We have recently reported that xanthine oxidase is involved in the generation of free radicals in exhaustive exercise. Allopurinol, an inhibitor of xanthine oxidase, prevents it. The aim of the present work was to elucidate the role of exercise-derived reactive oxygen species in the cell signalling pathways involved in the adaptation to exercise in man. We have found that exercise causes an increase in the activity of plasma xanthine oxidase and an activation of NF-kappaB in peripheral blood lymphocytes after marathon running. This activation is dependent on free radical formation in exercise: treatment with allopurinol completely prevents it. In animal models, we previously showed that NF-kappaB activation induced by exhaustive physical exercise leads to an increase in the expression of superoxide dismutase, an enzyme involved in antioxidant defence. We report evidence in man that reactive oxygen species act as signals in exercise as decreasing their formation prevents activation of important signalling pathways which can cause useful adaptations in cells.

My comments: This is what happens when Pubcrawler is lame in a given week, I have to dredge out something like this. Ok, I'm being melodramatic, this is actually a topic I've been following for a while of late: the potential issue that anti-oxidant supplementation might be detrimental to certain aspects of exercise adaptation; in this case, endurance performance.

Back in the early days of both sports nutrition and longevity research (for example Colgan's "Optimum Sports Nutrition" and "Life Extension: A Scientific Approach" by Durk Pearson and Sandy Shaw), an idea that came up rather rapidly was that oxidative damage (due to the generation of free radicals, or what are now called reactive oxygen species or ROS) were a bad thing. Colgan had a list of anti-oxidant recommendations for hard training athletes and it was taken as an article of faith by the life-extensionists that

a. Oxidant damage was part of the aging process

b. High dose anti-oxidant supplementation would limit said damage (and hence the aging process).

I'm going to focus on 'a' here since I haven't looked into 'b' enough to say very much (except to say that many studies are finding that diets high in anti-oxidants do very different things than supplementing individual anti-oxidants).

We know that exercise, and I'm going to focus on endurance exercise here, increases free radical production (if for no other reason than the increased utilization of oxygen) and there is some logic to the idea that taking supplemental anti-oxidants (either habitually or right around training) might limit damage. However, this neglects the fact that ROS appear to be part of the overall signalling pathways to adapt to training (it's also known that regular training tends to bump up the body's inherent anti-oxidant defense system).

Over the last few years a number of studies have suggested that blocking the normal ROS response to endurance training might limit adaptations. For example, a very recent study (Close GL et. al.) found that vitamin C supplementation (1 gram 2 hours before and after downhill running) not only had no impact on muscle soreness but delayed recovery by limiting the production of ROS.

Mechanistically this is similar to data showing that anti-inflammatories taken before training may limit growth by decreasing the normal inflammatory response to training.

And, in hindsight, makes a certain sort of sense. Given the adaptations that occur in response to endurance training, it makes some logical sense that the production of ROS might actually be part of the signalling pathway. Blocking that response might attenuate the response seen to training.

Which is a long way around of explaining the study above which basically says exactly what I wrote: exercise increases ROS, ROS are involved in the overall adaptation/signalling to endurance exercise, preventing their production with anti-oxidant supplements might serve to limit the adaptations to training.

From a practical standpoint, based on the limited research, while I wouldn't use this to argue that no anti-oxidants should be taken or that an anti-oxidant rich diet, containing plenty of fibrous veggies and fruits should be avoided. But it looks like avoiding high dose anti-oxidant supplementation right around training might be a good idea from the standpoint of making sure that optimal adaptations occur.

Feature Article

Measuring Body Composition Part

Two weeks ago, I discussed some distinctly non-body composition methods of tracking changes in 'body composition'. These included the scale, the mirror, the tape measure, BMI and waist/hip ratio. This week, I want to discuss actual methods of measuring body composition, moving from lower to higher tech.

Circumference measurements

The tape measure is sometimes used to estimate bodyfat percentage, usually in conjunction with bodyweight. Many popular diet books advocate this method because it's fairly easy for people to do. I believe some branches of the military still use this method because it's quick and they need to measure a bunch of potential cadavers very quickly. While easy and fairly fast, body composition estimates based on circumferences alone tend to not be very accurate.

Circumference bodyfat measurement is basically BMI plus a tape measure thrown around one or two representative sites (frequently wrist or hips but others may be used). It's quick and easy, just like BMI, but it's not necessarily accurate. A lot of this will depend on what sites are used for the measurements

Someone with a wide hip structure (i.e. many women) will be vastly overestimated in terms of bodyfat, even if they are very lean (this was actually one mountain bike client of mine who I calipered in the low teens bodyfat percentage-wise but was estimated in the high 20's with a tape measure). So while circumferences can be useful to track other aspects of a diet or training program, I don't think they should not be used to track bodyfat percentage unless no other method is available. They are better than nothing, but not by much.

Calipers

Calipers are small spring loaded devices that have been used for decades to measure body composition. They are surprisingly accurate. The primary assumption that caliper measurements are based on is that anywhere from 40-60% of a person's total bodyfat is located underneath the skin (this is called subcutaneous bodyfat). There are some other assumptions about skinfolds, including assumptions about bone density, uniform fat distribution, uniform skin thickness, etc. that are turning out to be (very) incorrect. I'll address this in a future article

The basics of caliper measurements are thus: The person doing the measurement pulls the fat away from the muscle so that the sides are parallel, and applies the calipers, which give the thickness of the skinfold in millimeters. Readings are taken after 2 seconds (this is important, if you wait longer, the caliper will squeeze water out of the area and give you an artificially lower reading) and 3 readings are taken at each site; they should be within a mm or two of one another. Between readings, a short break is given to avoid squeezing water out of the area, otherwise you get progressively smaller measurements as you go.

Anywhere from 3 to 10 (or more) sites may be measured to get an idea of total bodyfat percentage and distribution and a total of 19 sites have been described in various studies. Traditionally, the right side of the body is measured. Typical sites include triceps, biceps, abdominal, iliac crest (love handles essentially), subscapular (underneath the shoulder blade), axilla (under the armpit), pectoral and thigh. You'll sometimes see calf and chin or a few others in there

Once the chosen number of sites has been measured, the numbers (which are in millimeters of thickness) are totalled and plugged into an equation, usually along with age. To be nitpicky, the equation spits out body density, which goes into a second equation to give bodyfat percentage. Lazy folks like me have lookup charts or a computer program to do the math for them. There are many online calculators

Equations exist for 3-, 4-,7- and more site measurements. While more sites can give more accuracy, it also gives the person doing the measurements more of a chance to screw up at least one of them and give you the wrong number. So there's always a tradeoff

Equipment wise, calipers range from inexpensive plastic jobs (the Slimguide are actually quite good and a steal at $30) to very expensive research grade brands (Lange and Harpendon which run to $200) to electronic versions that do the calculations for you (Skyndex can go as high as $400). Depending on the spring tension, all can give slightly different measurements, although they are usually within a millimeter or two. As long as you are using the same calipers, this is irrelevant; you'll still get consistent measurements.

As a recommendation, I would highly recommend the Slimguide calipers. I think the one click devices that are often included with other products are crap (they are cheap and not very accurate, you can bias the measurement by how quickly or slowly you close them) but most people don't need to drop $200 on research level calipers. I've checked my $30 Slimguides against a couple of different Lange calipers over the years and any difference in measurement is 1-2 mm if that. For the price they are simply unbeatable. You can get them a lot of different places, I recommend Creative Health Products; and no, I don't make any money off of their sale

Calipers also tend to underestimate very small skinfolds and overestimate very large skinfolds. As long as you always use the same set of calipers, you can at least get consistent measurements, which is what really matters.

In the hands of a trained operator, calipers are surprisingly accurate, giving values anywhere from 3-5% different from hydrostatic weighing (see next entry) which is better than most of the higher tech methods described below. In the hands of an untrained operator, they aren't very accurate at all. There are a lot of untrained operators out there.

Most health clubs and gyms, as well as a lots of other places, can do caliper measurements. Since caliper technique can vary quite a bit, it's important to have the measurements done by the same person if at all possible. With the high turnover rate of employees at most commercial gyms, this can be tough to do. I usually recommend that people learn to do at least some of their own skinfolds. That's why you should buy a pair of calipers of your own.

Since bodybuilders are more concerned with appearance than bodyfat percentage per se, it behooves them to measure a lot of areas, most of which aren't in the equations. This is especially true when they are getting started in competing. The low back, which is not a normal measurement site, can carry a lot of bodyfat in male bodybuilders. The glute area for women is similar. To reach the kinds of bodyfat percentages required to place well in competition means a skinfold of 3-4 millimeters anywhere on the body. Just because your abs are shredded doesn't mean your low back or glutes are so make sure and measure all over.

Caliper equations are problematic at best, a topic I'll address in a future article. A current trend is to simply use the sum of skinfolds and look at changes. If your skinfolds are going down, you're losing fat; if they're going up, you're gaining fat. Putting percentage bodyfat values to those measurements isn't necessarily valuable or beneficial.

Underwater weighing

I probably should have talked about underwater (or hydrostatic) weighing first since it is usually described as the "Gold standard" of body composition. Hydrostatic weighing is based on the simple principle (more or less) that fat floats. It's a little bit more technical, but that's the gist of it. Most of the other methods (especially skinfolds) are based on underwater weighing. That is, researchers will underwater weigh and caliper a group of individuals and develop a caliper equation based on the assumption that the underwater weighing was 100% accurate.

For a while underwater tanks were very popular and could be found in a lot of different places. Lately they are only found in performance labs at universities for the most part. There's a reason for that which primarily has to do with the hassle involved in doing it.

To get underwater weighed, you report to the lab in your bathing suit. First they weigh you out of water, then you get into the tank (filled with cool but not cold water). Then you breath out as much air as possible and then dunk your head under and let them weigh you again. Think about how much fun it will be to have your head underwater with no air in your lungs. I doubt many people find the idea of feeling like they're suffocating to be 'fun'.

Even then, it' s impossible to get all the air out. Researchers can use technical methods to measure residual volume (the small amount of air left over) or usually they just estimate it. That introduces another potential source of error. Some methods let you keep your head above water but this too reduces accuracy. A big gas-producing meal (such as beans) can throw off the equations and make you look leaner than you are, since the gas will make you more buoyant and you won't weigh the same underwater. I guess beans really are good for fat loss.

Underwater weighing also makes some major assumptions about bone density which aren't correct. It's not uncommon to have people report negative bodyfat percentages because of this. More on these problems in a future article.

Oh yeah, underwater weighing will usually cost you a pretty penny: $50-75 each time usually. Since you have to do at least two measurements to see if your diet is working, this can add up fast. My feeling is that unless you have a friend in an exercise physiology program who can dunk you for free, underwater weighing isn't worth the cost and hassle. It might be useful to get a caliper measurement done and get dunked on the same day to see how close to reality the calipers are. But that's about it.

Bioelectrical impedance (BIA)

BIA is another popular method, like calipers. Perhaps moreso because BIA is easier to do and requires less training. You can get BIA done at a lot of health fair types of events and any gym monkey can be trained to do it. But it's not very accurate unless you adhere to some strict guidelines, which most people don't

A typical BIA machine will have an operator hook one electrode to the back of your hand and another to your foot. Some data (age, height, weight) is entered into the machine which runs a small current through your body and times how long it takes. More recently, BIA scales have appeared that run a current from one foot to the other to make the estimation. They aren't that cheap and you have to choose between an athlete and a non-athlete model. There is also a hand-held version that runs a current from hand to hand.

BIA is measuring how much water is in your body (called, logically enough, total body water). Since muscle, fat, bone, etc contain different amounts of water, BIA can roughly differentiate how much of each you have and crank out a number, usually on a nifty little graph that at least looks very official, high-tech and accurate. Just remember that high-tech isn't the same as correct.

And that's where we run into problems: since BIA is measuring total body water, hydration state becomes critical. Both dehydration and hyperhydration can throw off BIA. This can be a real problem when people are manipulating carbohydrate intakes which causes changes in body water levels. Even a large urination or a big glass of water can throw off the values by a percent or two. This makes it impossible to really track your bodyfat percentage since a change of 2% could be because you lost fat or because your hydration state is different from last time.

Now, in BIA's defense, assuming someone kept their hydration state constant (i.e. measuring themselves every Monday after urinating but before breakfast), BIA should give at least comparative measurements. But for the cost, I still think calipers are the better buy.

Infrared reactance (IR)

While rarely seen anymore, IR had a brief stint in the sun, mostly at health fairs and some gyms. Originally developed to measure body composition in cattle, IR worked by bouncing a beam of infrared light off your upper arm bone and seeing how long it took to get back. Since infrared light travels faster through muscle than fat, the machine could estimate how much fat you had. Since it only measured the biceps (upper arm), it was quick and easy. It was also pretty inaccurate. I can't recall ever measuring anybody who had a lot of fat on their upper arm so that one measurement won't tell you much about the rest of the body. When measuring cattle to determine price at slaughter, a few percentage points aren't that big a deal. For humans, I consider IR unusable and do not recommend it.

Other high-tech methods

To round out this piece, let me mention briefly some of the high tech methods, even though most people won't have access to them unless they are involved with a lab. MRI (magnetic resonance imaging) and DEXA (dual-energy X-ray absorbitometry) are both being used in research to more accurately measure regional body composition and bone density. DEXA is kind of cool in that it will give you the amount of fat in different parts of your body, so you can look at arms versus trunk versus legs. Of course, calipers do too; or just look in the mirror.

I should mention that DEXA is becoming more prevalent (usually to measure bone density) and the cost is coming down. Scans can be had for $150-200 (going by internet prices) and insurance may cover it. Still a bit pricey to do frequent measurements but people are using it to track body composition. Like underwater weighing, you might get a DEXA scan and correlate it with caliper measurements and then just use the calipers from there on out.

Scary sounding methods like potassium-40 counting, doubly labeled water, and nitrogen balance studies are also used to get a better idea of body composition changes and metabolic rate. They aren't practical outside of the research lab.

The other current high-tech method is the Bod-Pod (tm) which is essentially a dry version of hydrostatic weighing. It measures how much air you are displacing in the machine, and uses that to estimate the volume of your body, makes some estimations about tissue density, and cranks out a bodyfat percentage. The last I looked, these were in the $70,000 range and only found in research centers and a few high-priced gyms.

In an upcoming article, I'll talk about some of the problems inherent in truly measuring body composition and give some more concrete recommendations for folks.

Questions and Answers

Q: Yohimbe: you have mentioned this in a couple of your articles. I have never heard of it, so I googled it and only found references to it as a "super sex enhancer". I don't see the connection. Could you please explain

A: In the body, there is something known as an alpha-receptor (aka alpha adrenoreceptor) of which there are two primary types: alpha-1 and alpha-2 (I'll call these a-1 and a-2). These receptors normally bind the catecholamine hormones (adrenaline/noradrenaline or epinephrine/norepinephrine depending on which side of the Atlantic you're on). For completeness, let me mention that there are also beta-receptors (of which there are at least three, beta-1, beta-2 and beta-3).

Alpha-2 receptors do a number of things in the body and their general effect is inhibitory. Sexually, they are involved in blood flow to the genitals, stimulation of the a-2 receptor decreases blood flow to the genitals. They are also involved in heart rate and blood pressure response in the heart, a-2 receptor stimulation decreases heart rate and blood pressure.

Of importance to fat loss, they inhibit lipolysis (fat mobilization). Of even more importance, certain depots of stubborn bodyfat (women's hip and thigh fat and possibly men's abdominal fat) tends to have lots of a-2 receptors and less of the pro-lipolytic receptor (the beta-1 and beta-2 receptor).

Yohimbe is an a-2 receptor antagonist which means that it blocks the effect of that receptor (I'm simplifying this a bit). What that means is that yohimbe will increase blood flow to the genitals (hence it's use for sexual purposes), it will increase heart rate and blood pressure, and it will increase fat mobilization from certain stubborn fat depots.

If this is confusing, just think of it as a double negative, or the way that multiplying two negative numbers gives you a positive number. A-2 receptors inhibit blood flow, heart rate/blood pressure and lipolysis and yohimbe inhibits a-2 receptors. When you inhibit an inhibitor, the net effect is positive.

Oral yohimbe (or yohimbine HCL) can be used to help mobilize/lose stubborn bodyfat in women's hip/thigh region and, as above, may be beneficial for men's abdominal fat

Q: First of all let me congratulate you for the incredible amount of good work you are able to produce. I have bought all of your books and I am a regular reader of your newsletter and I have to say that the quality and usability of your works is unparalleled on the net (or elsewhere). I would like to ask you a question about Clenbuterol and T3. Some believe that they are a must if you want to get ripped (six pack style) whereas ephedrine is all right if you just want to get fit (let's say in the neighborhood of 10-12 % body fat for a man). Do you agree? What is your opinion about these products? Do you think it is possible to reach extremely low (single digit) body fat levels without them?

A: If this were the even remotely the case, natural bodybuilders would never get into shape/get a sixpack (because thyroid and clean aren't allowed in natural competitions) and obviously they do. And yes, before I get silly feedback, I know that natural competitors do (gasp) use drugs. But let's assume that most aren't using clen or thyroid for natural shows; men still get plenty ripped and they do it with ephedrine/caffeine (or nothing at all).

Q: I've been putting creatine in my post-workout shakes for the past 2 years. I have heard that you should not be taking creatine continuously for such a long time. Is this the case? I've putting the normal recommended amount in my post-workout shakes, 1 tsp.

A: There's an idea out there that creatine needs to be cycled. Usually some type of argument regarding creatine synthesis or uptake is given, or people just want to pretend it's a steroid. I've seen nothing to suggest that creatine needs to be or should be cycled, nor do I see any problem with taking a continuous maintenance dose the way that you are.