Body Composition Tools

Written by Jesse. Posted in Coaching Thoughts

While we’re all enjoying some holiday eating before the New Year, I thought it would be a good time to talk about body composition!

Anyone who has worked with me or understands my approach to coaching knows I take a very holistic approach. That is, I don’t like to leave many details to other “specialists”. I believe that in many cases, a mixed “team approach” of specialists can confuse the athlete and make them feel as though they are being pulled in too many directions. Because of that, I have learned, think about, and develop most pieces of triathlon preparation including nutrition. One major piece related to that area is body composition management which is the focus of this writing. Primarily I’d like to discuss two very important toolsI use in this area (this isalso theevaluation method that I teach QT2coaches and dietitians):

1) Body fat (BF) measurement with calipers. This gives us a sense of what body fat is available to remove (ie, what dead weight we are carrying). The available weight to remove through body composition tweeks is based on current body fat and how low that can go based on gender and age (better to stay conservatively high here versus even a little too low).

2) Calculation of Body Mass Index (BMI) AFTER correcting weight to optimal race weight (based on optimal BF determined in #1) is super useful for determining if an athlete is strength limited or too muscular (more muscle than the sport of triathlon requires to power you forward). This is calculated simple by (body weight x 703)/(height in inches)^2.

The benchmarks I like to use for triathlon are a BMI of 21-23 for males, and a BMI of 20-22 for females, both assessed at optimal BF. The lower end of these ranges is reserved for the elites and world class professionals. Being below these ranges typically means the athlete is strength limited (to be verified by other metrics) and therefore requires strength work with heavy focus on protein while above these BMI’s means the opposite (too much muscle).

As you can see by this, its not one of the two tools that’s useful to make body comp assessments as many think. Instead, its about using both available tools to reach a very educated decision and approach to optimal performance.

Here’s an example:
Joe is 5′-11″ at 160 pounds and 15 percent body fat. He is 25 years old and wants to race elite.

1) First, we correct his weight to optimal BF (where we plan to be on race day). For him, this is 6 percent meaning he needs to lose 9 percent. In terms of weight, this means 0.91 x 160 equals 145 (assuming no muscle loss occurs).

2) At this weight and height, his BMI is 20.2 which is well below the range defined above meaning he requires a heavy strength focus, combined with adequate protein intake to help him gain some muscle mass.

Based on this example, we can see that Joe needs to lose 15 pounds of fat, and try to put on about 5-7 pounds of muscle to race at optimal body composition.

If only a BMI assessment was carried out, we’d think he only needs to just lose weight when in reality, he needs to lose some weight that’s not helping him and gain some that will. If we had just used BF measurement, we wouldn’t have identified a potential strength limiter and the need for a focused strength routine.

I hope this post was helpful in clearing up some of the misconception between these two both very useful body composition metrics. Happy Holidays!