How Does Body Fat Affect Sports Performance?
As an ageing athlete the all too familiar weight gain of middle age beckons and for some of my friends is in full swing. Back in 2018 prior to the World Masters Athletics Championships in Malaga, I had suffered an injury after the indoor season and had unfortunate put on 5 extra KG in fat!
I lost that weight and managed to get myself in good shape without sacrificing any health, the performance benefits I gained of course were personally good for me, as I won the M35 400m title
- Have you ever wondered how your body fat affects your athletic performance?
- How much faster could you run if you lost 5 pounds of pure fat?
I never knew how important getting lean is to athletic performance until I learned the information in this article. With a lower body fat percentage, your athletic performance can improve significantly.
But first take a look at this PDF from way back in the 80s which describe the importance of Un-wanted mass on the body and how it effects performance, as a quick reference a mere 1kg of extra mass around the waist adds a detrimental element of performance of 1% economy loss, and this increases the more distal this weight is added.Effect of Mass
So lets take a look at this in action
How Body Fat Affects Athletic Performance
Lecture by Penn State exercise professor Dr. Todd Miller entitled:
Dr. Todd took it upon himself to analyse the data, which he later published in a research paper. As expected, he noticed that athletic performance tended to decrease throughout the season as players decreased overall training volume and increased sports-specific preparation for competitions.
On further review, Dr. Todd noticed that one team in particular – the women’s soccer team – experienced significantly decreased performance in-season relative to the other teams. He also noticed that while the average weight of the female soccer players stayed roughly the same from pre to post-season (136 pounds vs. 134 pounds respectively), body fat increased 3% translating into 6 pounds of muscle loss and 4 pounds of fat gain.
Immediately after reviewing this information, Dr. Todd formulated a questions that would guide the rest of his presentation – “How do changes in body composition affect athletic performance?”.
The Insight: How Much Weight Slows Down A Horse?
After exhaustive research, Dr. Todd could not find any academic papers that answered his simple and important question of how body composition affects athletic performance.
He did learn, however, that the horse racing community understood how adding weight to a horse would affect the horse’s running speed. In fact, horse racers had it down to a science.
A race horse is an amazing physical specimen that typically weighs 1300 pounds at around 5-6% body fat and can run up to 45 mph.
With this in mind, see if you can answer the following question:
How much weight do you need to add to a horse to slow it down?
Yes, a horse is a 1300lb animal, but…
- If you guessed 200lb, you would be wrong.
- If you guessed 50lb, you would be wrong again.
- What about 30lb? Nope, that’s not right either.
The answer is 2-5lb is all the extra weight needed to slow down a horse so that it loses a race. In fact, only 2lb extra will slow down a horse roughly 8 feet, or one horse length.
The Analysis: Testing Body Fat & Performance With A Weighted Vest
After learning this intriguing information about race horses, Dr. Todd reasoned even gaining a few pounds of fat for an athlete could have significant performance implications.
He decided to put his reasoning to the test by loading 170 pound athletes with 3.4 pounds (or 2% body fat) and having them complete power related tests, which he published in a research paper.
Here’s a very quick summary of the results:
For a 170 pound athlete, a fat gain of 3.4 pounds (2%), could result in a vertical jump height loss of 2 inches, and a 40 yard dash time increase of 0.26 seconds. If you are not familiar with the 40 yard dash, 0.26 seconds is an eternity. And in the world of Track and Field this is the difference between making the final and not even getting out the heats!
This is the same sprint test all NFL football players must do at the NFL Combine, which tests the athletic ability of all the athletes before entering the league. A 0.1 second difference can mean millions of dollars.
Going back to those Penn State female soccer players, recall that there was a 4 pound increase in fat (2.9% of body mass) and a 6 pound loss in muscle (4.4% of body mass). We’re talking MAJOR decrease in performance.
The Conclusion: Lose Fat Without Losing Muscle To Boost Athletic Performance
What happens if you are a triathlete, or competitive runner with 20% body fat and a good 10-20 pounds of fat to lose?
Well you are essentially carrying the equivalent of a 10-20 pound dumbbell with you at all times, which is going to have a massive impact on your athletic performance, let alone your joints. One could make the argument that losing the excess fat (without losing muscle of course) would help performance more than logging extra miles.
What about increasing weight by adding muscle mass. Does that hurt performance?
The short answer is no, adding muscle typically helps athletic performance. The power/weight ratio, which is meticulously measured by the cycling community is improved when muscle is gained. The power derived from 2 pounds of muscle will more than offset the detriment of adding the 2 pounds of weight.
In some cases, because of aerodynamics, losing overall body mass (muscle mass and fat) can sometimes help a cyclist go faster, but this has not been proven with sprinters and other power related athletes.
What are the key takeaways about increasing athletic performance so you can run faster, jump higher, improve quickness, and also power in a relatively short period of time? The first and most important is:
Here’s the last slide of Dr. Millers’ presentation with his key takeaways:
- Small increases in body fat lead to profound decrements in anaerobic performance
- Untracked changes in body composition can mislead one into believing that his/her program is responsible for changes in performance. Therefore, body composition must be taken into consideration for optimal program design.
- Keep lifting/training volume high during the competitive season
- Monitor athletes’ body composition over the course of the season
- Educate athletes about dietary behaviours
I hope this was an enlightening article for you, because learning this information was a real shocker to me. I always wondered about the athletic performance implications of increases in body fat, but never saw the affect quantified, until it effected me personally and could really see the benefit of being at a healthy weight, and losing the extra weight I had gained.