Part 2:The Science

Based on the science, my take away for both males and females is this: improving body composition has its place, but it is low on the totem pole on the road to getting faster.

First, I wanted to thank everyone who reached out to me – privately or publicly – after yesterday’s post.  It is freaking scary to talk about topics that hit so close to home, but support makes the load a little less back breaking.

Second, I wanted to spend this post talking about science, our perceptions of “race weight” and what it all means for runners.  There will be some sections that are specifically meant for female runners, but male runners can definitely benefit from some science class as well. Links to my sources are given.

Okay, so I am not going to sit here and lie to everyone/jumble the science and say that lighter does not equal faster. Because technically, it does.  One main component of increasing our speed is increasing our VO2 max, or how much oxygen we consume while exercising.  Oxygen use is essential to go faster, because that oxygen is delivered to our muscles while we run (source).  Our muscles love that oxygen and the higher we can get our VO2 max, the more oxygen we can feed those hard working muscles of ours. VO2 max is measured in mL Oxygen/ kg body weight consumed; therefore, lighter bodies equate to more oxygen pumped to our muscles (source).

Image result for vo2 max and body weight

Well, that’s it folks. All you need to know. Shed those pounds because nothing else matters.

Kidding.  Anyway, it is true.  To an extent, our bodies just perform better when we are lighter.  But there is a cut off.  This is not an all or nothing thing.  And I think we (or at least I do) forget that in running and in life sometimes: the answers are never that simple.  Let’s discuss further.  In a study by Samuel Mettler, Nigel Mitchell, and Kevin Tipton, they found that as runners were shedding fat, athletes were shedding muscle as well (source).  Now, marathoners are not known for being built like body builders but also, lets take a minute to consider how FAST those elites are going (thus, how strong they have to be).  The world record marathon for men is a 2:02:57 set by Dennis Kimetto, which in case you were wondering, is 26.2 miles ran at a 4:41 minutes/mile pace (source).  You don’t do that with little muscle on your body because *cough, clears throat, shakes head* THAT IS SO FAST!

Image result for dennis kimetto

Dennis, if you wanna send some of that speed my way, I would greatly appreciate it.

Also, in a study by Cathy Zanker and Ian Swaine, the researchers found that if athletes were taking in less calories than they were burning, they  had lower levels of blood markers of bone and collagen synthesis (aka an athlete is at a risk for more bone and tendon injuries). (source).  So, periods of dieting/fasting for a while can lead to muscle loss (slower) and bone and tendon injuries (more time on the sidelines and less time training).

Now, science says athletes aren’t banned from losing weight and I totally agree; there are some instances where shedding some unnecessary fat could help (as body composition is a better indicator of health anyway)(source).  But, there are two important things to remember:

  1. Sports health professionals have provided guidelines for how much body fat a person should have or shed and that line should NOT be played with(source), as it puts an individual at risk for cardiovascular disease (your body can start to eat your heart) and muscle loss.  If you want to improve body composition, seek a medical professionals help first.  If you don’t trust your regular doctor, sports doctors or dietitians can be more sympathetic to the special needs of athletes.
Body Fat %
Age Women Men
General health <55 20-35% 8-22%
>55 25-38% 10-25%
Physically active <55 16-28% 5-15%
>55 20-33% 7-28%

2. Losing 0.5-2 pounds a week is okay but any more than that, and you are setting      yourself up for burnout, injury, or can slow your metabolism for the long haul                (causing you to put that weight right back on) (source).

Bottom line, for both male and female athletes: losing body fat is fine, but in a controlled way with the help of a medical professional and good support around you.  Furthermore, fat loss is not the complete answer for faster running: smart training, playing your game, proper nutrition, sound recovery methods, sleep, and God given talent all play a role in performance.  At the end of the day, it is the well trained (both physically and mentally) athlete with muscles that fire, passion, and miles of hard work on and off the roads that create the champion.

Finally, let’t talk about female athletes.  First and foremost, I think it is so important to educate ourselves on our unique physiology and if you want to do so, I highly recommend listening to THIS podcast and reading THIS book.  Dr. Stacy Sims puts it best when describing female athletes:

“Women are not small men. Stop eating and training like one.”

This blog would be 2000 pages long if I went into all the science and differences between male and female athletes, but I shall just write the Cliff Notes version here (based on the lessons I learned from the podcast and book).

  1. Women do not shed weight like men.  When in a famine state (aka dieting) our bodies tend to hold onto the weight, shift our metabolisms, and shut down our periods.  Our hormones go out of wack and our performance suffers.
  2. Women have a lower VO2 max than males because we are fat burners during exercise (as opposed to carb burners, a more efficient fuel, like our male counterparts).  Inefficient fuel= less oxygen getting to our bodies = slower times.  We also have smaller lungs and hearts which means less oxygen is getting pumped through our blood.
  3. Women have a harder time holding on to muscle than men and have less type II, anaerobic muscle fibers than men.  Our bodies are more prone to break down muscle post exercise because post exercise, women start to burn carbohydrate for energy.  Which would be fine, except female hormones prevent women from storing carbohydrate very well.  SO, the next best source of fuel= our muscles.
  4. Having a period is not something to be afraid of and neither is puberty- sure, our bodies shift in weight/proportion and such but females (on their period) perform more like their male counterparts because while on a period we are in a low hormone stage.

What does this all mean for the female athlete?  Well it means that proper and sufficient fueling is essential.  Don’t fuel properly after exercise, and we are at a risk for breaking down muscle that we don’t hold on to very well to begin with.  Less muscle= you have less of a chance to “chick” some dudes in a race 😉 Not fueling enough= ceased menstrual cycle, low energy availability, and a jacked up metabolism.  Not to mention, you miss out on that peak performance time= our periods.

Image result for paula radcliffe 2002 chicago

Paula Radcliffe broke the marathon record for women in 2002 in Chicago while suffering from period cramps.

This is also not to say that females cannot lose fat if they want to increase performance- but they should seek out a medical professional first, develop a good support group, and have a end goal in sight (not one that keeps getting extended).

Based on the science, my take away for both males and females is this:  improving body composition has its place, but it is low on the totem pole on the road to getting faster.

Training hard matters

Recovery matters

Eating well/ nutrient timing matters

Strength and flexibility matters

And mental strength DEFINITELY matters


I hope this was informative!

Anyone else have some good info about science and training?


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