The Myths About Endurance Running

by On Feb 2, 2020

Running is a lot like life. Only 10% of it is exciting. Ninety percent of it is slog and drudge.

The Myths About Endurance Running

I’m sure you have seen the fitness meme with a muscular Sprinter next to a skinny Marathoner in an attempt to convince you that running any longer than 10 minutes will only bring you closer to your death bed.  

In this entry I am going to go through and explain what it is lame and completely ignorant to compare the aesthetics of Elite Sprinters and Marathoners.  

You will notice that I differentiate between Elite runners and “normal” runners.  This is because there are many factors which exist that are responsible for the big differences in the body composition seen in Elite runners.  

If we were to compare “normal” runners, these differences shrink, but I will get into running and “normal” people in my next entry.  This is a condensed version so I will only present the main points.  

1. Running’s Role In The Life Of Elite Athletes

One of the biggest factors we need to consider is very simple and that is the role which running plays in the life of Elite athletes. With Elite athletes, running is their livelihood; it is how they support themselves to live a life, provide for their family, etc.  

Running is a performance sport, not an aesthetic sport, therefore elite runners are only concerned with how to run faster. That’s it. They are not going to implement training to augment their aesthetics if it takes away from their performance. Performance is their only concern and will create the optimum body for their sport.

2. Why Elite Sprinters Are Thin

Marathoners are running 42km which will take more than 2 hours at the highest level. Therefore, having any unnecessary weight will only cause a deficit to their work economy. Marathoners have no need for a big upper body and therefore benefit from having less muscle mass and being lightweight. This should be obvious. Not only does being thin improve economy, but height has been shown to also be a factor in elite runners.

A study by Arrese & Ostariz (2006) looked at the elite runners across all distances and found that long distance runners are “…lighter, and shorter” than mid and sprint distances. We can look at the fastest man in the world, Usain Bolt, who stands at 6’5” (195cm) and compare him with the greatest marathoner in the world, Eliud Kipchoge who stands at 5’6” (167cm). Having a low body weight also has another advantage. One of the best indicators for success in endurance sports is having a higher lactate threshold.

A study by Buresh, Berg, & Noble (2004) found that body mass accounts for 58% of variability of lactate threshold with a greater lactate threshold being found in runners with smaller body mass. 

Having a greater work economy and greater lactate threshold is vital for success in marathon running and if being smaller and thin are both factors, which affect these variables.  

3. Why Elite Sprinters are Muscular

On the other end, Sprinters benefit from having a larger body with more muscle mass; even if that muscle does not contribute to the mechanics of running. There are the factors which shows that having larger, muscular arms helps with arm pump, drive, and balance, but what we rarely hear about is the importance of ground force production. 

The Myths About Running Which Have Crept Up In Fitness Circles Concerning Endurance Running

In a study by Weyand, et..al (2000), it was discovered that the ability to create greater ground force was the most important factor in creating top speeds, even more than faster leg movement. Bodies with more mass are able to generate more force which translates to higher speed. 

A study by Davis & Weynard (2005) found a direct correlation with body-mass size, ground-force production, and performance in running distances. They too concluded that a larger body-mass was capable of creating a more ground force which resulted in better performance at short distances with a decline in size with longer races. 

Another study by Babic, et..al (2017) found that “sprinters with larger muscle mass and more strength had better performances.” This is interesting because, unlike many people think, muscle mass and strength are not the same thing yet this study found that both were indicators of better performance. 

So, not only does more muscle create strength, it creates more body mass which creates a heavier body that is capable of creating a greater ground force production.

4. Differences in Their Cross Training 

One variable that greatly effects the musculature of these athletes is the difference in their weight training. Sprinters engage in much more weight training and specifically one that is based on progressive overload with an aim to growing a stronger and bigger muscle. 

The Myths About Running Which Have Crept Up In Fitness Circles Concerning Endurance Running

Remember, Sprinters will benefit from an increase in fat-free mass. Marathoners engage in much less weight training and the training they do have the main goal to strengthen the muscles for injury prevention.  

Not only does their weight training differ in volume and purpose, but their bodies will react differently (see below) with Sprinters muscles being able to grow more. This is important because the claim that is made by misinformed “trainers” insinuates that marathoners are attempting to build muscle, but they can’t or all their muscle wastes away. Marathoners don’t have big muscles because they don’t want it and they don’t train for it.

5. Genetics

Genetics play a huge role, perhaps the biggest role, in the differences we see in athletes, which means that the largest factor is out of the athletes control regardless of the type of training they do. 

The Myths About Running Which Have Crept Up In Fitness Circles Concerning Endurance Running

Genetics dictate height, bone structure, muscle composition, and the body's response to the training stimulus. The most telling aspect is the composition of muscle fibres we see in marathoners and sprinters.  

A real quick physiology lesson first, our muscles are composed of different types of muscle fibres, which are suited for certain activities, Type I (Slow-twitch) and Type II (Fast-Twitch) fibres. 

Type I muscle fibres are characterised by low force production, but highly resistant to fatigue while Type II are characterised by having high force production but fatigue easily. A few other important differences are that Type II fibres are larger than Type I, Type II have a greater response to training than Type I, and Type II fibres will grow more (hypertrophy) than Type I when exposed to stressors.  

Type II obvious benefit Sprinters and Type I benefit marathoners. While the general population generally has a 50/50 split of these fibres, studies have shown that the muscle composition of elite athletes greatly skewed in favour of Type I or Type II. 

Studies have shown that elite marathoners will usually have around 79% Type I muscle fibres while elite sprinters generally have around 75-80% Type II with some athletes having been found to have up to 90% Type I or Type 2 (Costill, Fink & Pollock, 1976). 

One gene, which is recently gaining a lot of interest world of sports performance is the ACTN3 gene. The ACTN3 gene is responsible for coding actinin, alpha-3 in muscle and can dictate your muscle fibre composition and type depending on if you have the functional or functional deficient allele.  

There are 3 genotypes of the ACTN3 gene; RR (having 2 functioning alleles), RX (having 1 functioning and 1 non-functioning allele); and XX (having 2 non-functioning alleles). Having the RR genotype is a huge advantage for speed and power athletes giving them the ability to be more powerful, explosive, and have more and quicker muscle growth from the training. 

This genotype is almost exclusively seen in Elite and Olympic level speed & power athletes with 99% of these athletes having one or both alleles. 


As we can see, there are many reasons that dictate the way sprinters and marathoners look let alone the fact that sprinters don’t want to have big muscles. Even if an elite marathoner had the right genetics for muscle he still wouldn’t train for muscles. 

For example, I can find a skinny gamer who doesn’t lift, but that doesn’t mean gaming makes you skinny. Not lifting weights makes you skinny.  

Therefore, why would we expect marathoners to have a developed musculature when they don’t train for that? It would be a detriment to their performance. It’s actually really silly when you take a second to think about what is being suggested. 

This is similar to concluding that you shouldn’t eat like a sumo wrestler because sumo wrestlers are fat. Now, I am not saying that running marathons are the best for those wanting to build large amounts of muscle or that it’s even on par with sprinting. It’s not. However, if you are looking for a strong, well rounded athletic body, running is not going to waste away all your muscles if you are training correctly. 

I know plenty of individuals who run long distance and have bodies that many guys would be very happy to have, but I will get into that in my next entry. 

All I want you to take away from this is don’t let a misinformed trainers try to scare you from running and use this ridiculous comparison to try and sell their program. 

There is a huge difference from professional marathoners who regularly run 100+km a week and a fit individual running a few 10-50km a week with weight training.

Originally from America, Garett has been living in Asia for the past 7-8 years in the fitness world focusing on strength, performance, and endurance. Currently he is living in Thailand and hold a Masters in Exercise Science and CSCS.

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