Optimal Performance Weight For Endurance Athletes

Using total body weight alone is
like the cover of a text book.  It
gives you some idea of what's
inside but lacks important detail.

 "Never be fooled by what you see on the outside because on the inside it's often a different story." ~Anonymous

Human performance results from a complex interaction of physical, psychological, and nutritional variables. Your "optimal performance weight" is one of those variables. Let's drill down a little deeper into the topic.

Optimal Performance Weight

Body weight is an incredibly sensitive topic to discuss. Various societal pressures have increased the prevalence of disordered eating and exercise behaviors in young people. Some estimates suggest there are approximately 30 million US adults struggling with an eating disorder with 95% of them between the ages of 12-25. Female athletes make up a disproportionate percentage of that group. Many endurance athletes have experienced an eating disorder before or perhaps are struggling with one now. It is for that reason that I approach this subject very cautiously and in the spirit of supportive guidance rather than with disapproving judgement.

Body weight is inextricable related to endurance performance. More specifically, body composition (lean body mass and fat mass) is linked to endurance performance. But no online "optimal performance weight" calculator can determine that for you. Your optimal performance body composition can only be determined by consistent data collection over time. Here's how it works.

Body Composition
Your total body weight alone is like the cover of a text book; it gives you some idea of what's inside but lacks important details. With respect to body composition those details include lean body mass and percent body fat. If you're interested in optimizing endurance performance you should consider measuring your body composition routinely. These periodic body composition assessments create body accountability and data points. When assessing body composition consider the following guidelines;

1.) Assess Monthly
More frequent assessment is less sensitive to actual changes in body composition and more sensitive to daily or weekly fluctuations in body water.

2.) Standardize
By creating the same testing conditions (time of day, clothing, etc) you significantly reduce the error associated with the testing conditions.

3.) Testing Considerations
When you test make sure that you haven't exercised or eaten for at least three hours prior to the assessment and always on an empty bladder and bowel (ideally).

Commercial body fat scales are now both widely available and affordable. Most use "bioelectric impedance" technology which has been around for decades and highly correlated with the gold standards for this procedure (skinfold and plethysmography).

Performance Outcomes
Once you are in the habit of collecting lean body mass and percent body fat data the next step is to correlate it to endurance performance. There are a few important things to consider. First, understand that body composition naturally fluctuates throughout the year and/or training cycle. Differences in eating and activity patterns during the winter months and off-seasons tend to result in natural and acceptable increases in percent body fat during these times. Secondly, we must always account for the effects of aging on both performance and body composition. That is to say, you should keep your comparison of body composition and performance to the last 3-5 years. Anything beyond that becomes an unreasonable and unrealistic comparison and sets you up for discouragement and resultant demotivation. Lastly, standardize the correlation by choosing an event or workouts that is both relevant and repeatable.

My Experience

The last four years of body fat and Orchard Cross
results clearly shows that for me; leaner is faster.

This graph is the last four years of my percent body fat and cyclocross performance. The body composition data was collected on a Tanita body fat scale once a month (I've actually been collecting the data monthly for over a decade). The performance data is from a local cyclocross race (Orchard Cross) that I've done for a number of consecutive years and represents the finish points in my Category 4/5 40+ race. For those not familiar with cyclocross, the lower the finish points the better the performance relative to the rest of the field. There are a few important things to note from the graph. The first is that you can clearly see seasonal fluctuations in percent body fat with the winter months generally representing the higher percent body fat values. Secondly, there appears to be a direct correlation to my percent body fat and my Orchard Cross results. In other words, the lower my percent body fat, the better the performance result (in lower points) at that specific race. While this really isn't a surprise, it's very helpful for me to see it in black and white (and red). This graph clearly demonstrates that my 50 year old optimal performance body composition is around 10% body fat. And just as importantly, I know exactly the dedication it takes to reach this level.

Please remember that this value is highly individualized. Your optimal performance body composition is uniquely yours and you must collect adequate amounts of data to determine that value.