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The Fast Lane: contains:
Home
HOME has a news page, a contact page and a site map for a quick overview.
Training
A complete overview of training principles, building blocks, scheduling and phasing, completed with scientific articles and real-life tips & examples. CONTENT:
Racing
Advice for optimizing your performance, via clever tactics or a perfect preparation, Evaluate your performance with the Hungarian Scoring Tables. CONTENT:
Drugs & Medicine
Racing faster is more than just training more and harder. Live a healthy life. CONTENT:
Discussion
Post your opinion and discuss training, nutrition etc. with others.
Links
Discover the world of Athletics via these cool hyperlinks. CONTENT:
My Running
There's more to it than theory. Try it yourself! Or would you rather check out my schedules and results first?
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Body Fat Body Fat Percentage vs. Performance A lot of people are obsessed by their weight. Today's fashion models and fashion magazines inspired millions of adults and adolescents to lose weight and to aim for the ideal weight. However the final objective should not be losing weight, but reducing body fat. Body weight itself does not tell us a lot: a person that weighs 80kg (175 lbs.) can be overweight, underweight or have a normal weight. If he has a large muscle mass, as a result of regular exercise, he could appear to be overweight using a height & weight table. The right weight not only depends on an individual's heigth, or body type (e.g. athletic or not), but also on his body composition. The same goes for athletes: weight is not a such an important factor in athletic performance. Athletes of various sizes have won races before. Generally sprinters tend to be heavier than distance runners, which can be explained by the fact that the former tend to have more muscle mass. Weight might not be such an important factor in performance, but body composition definitely is. A very important factor is the percentage of body fat one has. Good athletes almost never have a high body fat percentage. And if they do, there is a lot of room for improvement. This is particularly true for (middle-) distance athletes, but top sprinters have a low percentage as well. VO2Max is an athlete’s maximum oxygen uptake ability, and is one of the most important factors in determining distance athletes' aerobic performance. When the racing distance gets longer, the VO2Max usually plays a bigger role. Research has shown that there is a direct correlation between an athlete's body fat percentage and his VO2Max. In other words, the lower his body fat percentage, the better his oxygen uptake.
You can gain weight and still lose fat. Or your weigth can remain status quo, but you can gain fat. Some people that follow special low-calorie programs to lose weight, often lose weigth at first, which they usually regain fairly quickly. But in fact they might have lost - besides perhaps fluids - muscle mass in the process, as some unbalanced diet programs will compensate a lack of proteins by 'eating muscles'. After such a rigid diet the body might overcompensate, and store extra energy (fat). So you end up with more or less the same weight, but with more body fat and less muscles. Body fat percentage for healthy men is generally believed to be under 18%, for women it should be under 25%. People are believed to be overweight and 'at risk’'if they have 35% or 40% body fat respectively. The minimum percent body fat considered safe and acceptable for good health is 5% for males and 12% for females. Body fat percentage levels for top male athletes tend to be between 5% and 10%, between 12% and 18% for women.
Most athletes would like their body fat level to be as low as possible. However, athletes often try to seek a body fat level that is arbitrarily low and this can increase the frequency of illness, increase the risk of injury, lengthen the time the athlete can return to training following an injury, reduce performance, and increase the risk of an eating disorder. Body composition values should be thought of as numbers on a continuum that are usual for a sport. If an athlete falls anywhere on that continuum it is likely that factors other than body composition (training, skills acquisition, etc.) will be the major predictors of performance success.
Although athletes should be careful not to eat too much fat, they do need fat. Every body needs a certain amount of fat in order to survive. This is called essential fat. Essential fat is necessary for temperature regulation, shock absorption, and regulation of essential body nutrients, e.g. to absorb vitamins such as A, D, E, and K. Nonessential fat is the result of taking in more calories than you burn. When nonessential fat accumulates in excessive amounts, an individual may become overweight. It's the nonessential fat that can undermine your VO2Max. However, not all fats are the same. Athletes can choose from saturated, mono-unsaturated, and poly-unsaturated fats. Without going into detail, it is generally considered that the saturated fats (found in animal fat) should be avoided. Poly-unsaturated fats like olive oil is generally considered as healthier. Calculating Body Fat percentage Body composition can be measured indirectly by several methods, including hydrostatic weighing, skinfold and girth measurements (applied to a nomogram or prediction equation), bioelectrical impedance analysis (BIA), dual-energy x-ray absorptiometry (DEXA), ultrasound, computerized tomography, magneticresonance imagery, isotope dilution, neutronactivation analysis, potassium-40 counting, and infrared interactance. The most common of the methods now used to assess body composition in athletes are skinfold measurements, DEXA, hydrostatic weighing, and BIA. While hydrostatic weighing and DEXA are considered by many to be the 'gold standards' of the indirect measurement techniques, there are still questions regarding the validity of these techniques when applied to humans. Since skinfold-based prediction equations typically use hydrostatic weighing or DEXA as the criterion methods, results from skinfolds typically carry the prediction errors of the criterion methods plus the added measurement errors associated with obtaining skinfold values. Popular because of its non-invasiveness and speed of measurement, but results from this technique are influenced by hydration state. Since athletes have hydration states that are in constant flux, BIA results may be misleading unless strict hydration protocols are followed. In general, all of the commonly used techniques should be viewed as providing only estimates of body composition, and since these techniques use different theoretical assumptions in their prediction of body composition, values obtained from one technique should not be compared with values obtained from another technique.
Perhaps the most convenient method for measuring body fat and checking it regularly is via the Skinfold Method. Calipers measure the thickness of skinfolds at a specified site in order to calculate how much subcutaneous fat (fat underneath the skin) a person has. These skinfold measurements are then put into an equation to estimate body fat percentage. Most skinfold equations use two or more skinfold measurements to predict body fat percentage. The skinfold method is not perfectly accurate. First of all, because body fat is not measured directly but estimated via the use of formulas. Over the years dozens of formulas have been used. Some formulas use only 3 skinfold locations in their formulas, other use 7 or more locations on the body. These formulas often use parameters that are targeted at specific ethnic groups, body styles or ages. When they are used for measuring body fat in persons from other ethnic groups or with a different body style, the results will be less accurate. Different body types differ as to the locations on their body where fat is distributed, and some methods are particularly suited for one body type, but not for another. Second, the accuracy and precision of skinfold measurements is highly dependent on technician skill, type of skinfold caliper, and client factors. It takes a great deal of time and practice to develop skill as a skinfold technician, and standardized procedures must be carefully followed. Small measurement errors can have a huge impact on the outcome. Generally skinfolds should not be measured immediately following exercise due to the possible accumulation of extracellular fluid (edema) in the subcutaneous tissue. Also, the skinfold method is not recommended for assessing body composition of obese individuals. However, when properly done, skin fold measurements can give reasonable accurate results, and it’s also fairly simple and inexpensive. The skinfold method may be used to estimate body fat percentage of children (black and white) and adults from diverse ethnic groups (blacks, Hispanic and white), as well as female and male athletes. On average these equations will predict body fat percentage within +/- 3.5%.
Some equations relate to specific populations with specific characteristics. Young people usually store half of their body fat under the skin, but as they grow older a greater proportion of their body fat is stored internally. So if the skinfold measurements for a young and old person were exactly the same, their actual body fat percentage would still be considerably different (i.e. the older person would probably have a greater body fat percentage). And there are more differences than just age: gender, ethnic group, fitness level and the amount of total body. No equation will probably suit you 100%. Therefore you may want to use more than one. When using more than one, you’ll see that the estimates may differ several points. But the skinfold method is also useful to track the skinfold thickness and monitor their evolution over time. The most-used equation is the Jackson-Pollock 7-site equation. It considers 7 skinfold locations and age.
Skinfolds measurements are usually taken by someone else as some formulas require measurements on the back. Find out the precise locations of each skinfold site. Experienced people will get better measurements. Measurements should be taken several times, and an average should be used for calculating your body fat. Using the tips (not the flat part) of your forefinger and thumb, firmly pinch the skin in the area to be measured. The skinfold should be pinched firmly. The jaws of the calipers should be placed closely to the fingertips. Once the jaws of the calipers have settled into place under the proper pressure, you can read the measurements. The following procedures will increase your reliability and precision when doing SKF measurements yourself (Harrison, G.G. et al., (1988) : Skinfold thicknesses and measurement technique): 1. Take all skinfold (SKF) measurements on the right side of the body. Calculating Your Body Fat percentage Download the Body Fat Calculator and measure your Fat percentage using a skinfold caliper and various formulas. All you need to do is to enter the skinfold measurements (in mm). Body Fat percentage, lean mass, and body fat is calculated automatically using several formulas. A 'record button' (excel macro) stores the actual data - skinfolds, percentages and date - on a special History page. Just Use it!
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Drugs & Medicine: contains: - The 6 types of Nutritients - Creatine Phosphate - The IOC List of Prohibited Substances and Methods - Achilles Tendinitis - The 3 Muscle types
- Body Fat Percentage vs. Performance
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Copyright 2001 - http://thefastlane.borghoms.com Last updated on 17 July 2002 |
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