Why do sprinters have muscular arms?

Question

I would like to know why all Olympic sprinters have muscular arms. They probably have muscular arms to help them sprint, but the reason is unclear. These are the two paradoxes I cannot fathom:

• Heavy arms increases the force the legs have to supply to move the body. So it seems big arms will slow down a sprinter.
• The legs are stressed far more than the arms when sprinting, so it is common sense that legs would grow from training. However, the arms only swing against the air, so how are they stressed enough to grow?

Below is an example of how big Olympic sprinters' arms are.

Answer 1

The main role of the arms in sprinting is to stabilize the torso and provide drive forward, especially in the start (Which is critical in 100/200m races).

This stabilization allows power to be transferred through the center of mass in an efficient fashion. Since you've got to be able to oppose a significant driving force from the hips and legs, you need the strength in the arms to do so, as well as in the abdomen, lats, etc.

There is this writeup, Sprinting Mechanics that also suggests that the arm swing doesn't necessarily contribute to horizontal motion, but contributes to the vertical drive component. It also cites a couple of studies that confirm the role of the arms in stabilization (Hinrichs et al., 1987; Mann & Hermann, 1985).

Answer 2

Look closer, sprinters have muscular everything...

People tend to lump all different types of running into one category but it's more complicated than that.

Marathon runners run long distances, within an aerobic heart range (ex 133 < 152 bpm for a 30yr male), maximizing distance by decreasing load as much as possible. Typically, if you do a dedicated endurance running regiment your body will favor Type I (slow twitch) muscle mass which uses energy (oxygen, glycogen) more efficiently and reduce Type II (fast twitch) muscle mass which trades efficiency for power. That's why experienced marathon runners will typically appear very skinny.

Sprinters are the opposite. Sprinting requires exercise to be pushed into the aerobic ranges up the V02 max (ex 152 < 190 bpm for a 30yr male). The body has a limited amount of time it can maintain an anaerobic intensity due to the impurities that anaerobic metabolism create. To increase the intensity and duration you need more Type II (fast twitch) muscle mass and an increased ability to process the impurities created by anaerobic stress.

That's why you can hit the 'runners high' during an aerobic workout where you feel like you can keep going forever and you get the 'muscle burn' from doing anaerobic workouts.

So why are sprinters so muscular?

First, increase your anaerobic range to be higher by doing HIIT (High Intensity Interval Training) workouts. Basically, do short hard bursts for of activity (like sprinting) for a few minutes followed by recovery periods to allow your body to recover from the anaerobic stress. The rule is, the harder you push, the harder you will be able to push.

Second, here's where distinguishing between marathon runners and sprinters will start to make sense. HIIT training (including sprinting) uses your whole body. Make no mistake, high impact, high intensity exercises work your core and upper body as well as your lower body. Unlike endurance running, it's actually beneficial to focus on all muscle groups as long as you're not just putting on unnecessary bulk.

Third, Type II muscle burns lots of energy and I mean a lot. Not only do sprinters have a lot of Type II mass from head to toe, they also have highly optimized circulatory systems. The high energy burn and increased blood flow lead to a very low body fat percentage giving a very defined 'cut' look.

In conclusion, Type II muscle mass and upper body strength is bad for an endurance runner because it adds weight and unnecessarily consumes more energy. But, for a sprinter Type II upper body mass is generally a result of working out and also a good counter to balance the force being exerted by the lower body.

Answer 3

Despite the technical verbiage above, OP is correct to be questioning why a sprinter should have such pronounced upper body musculature. Not only would you naturally have to perform regular and intense hypertrophic exercise to develop such muscles, not the best use of energy for a sprinter, but the intense regime and diet of an Olympic athlete should really reduce any gains. As soon as you go down to that sort of body fat level you will be losing unused muscle faster than fat. The human body evolved to be efficient, not look good on a beach.

It is hard to argue that biceps stabilise the upper body, as they serve only to flex the arm and turn the wrist - and sprinters don't do this dynamically, they hold their arms in place.

It seems to me that the only way that a sprinter could gain and maintain such great (and, as you point out, counter-productive) upper arm mass is if they are cycling some kind of anabolic steroid, insulin, growth hormone, or other form of doping agent. Steroids are proven to actually stimulate muscle growth without any stimulation (i.e. exercise) and prevent muscle wastage associated with extreme training and dieting programmes. HIIT is not going to create such anabolic stimulus on its own.

We like to believe that doping is not widespread in sport, but don't forget that sport is entertainment, underneath it all. Audiences pay a lot of money for their subscriptions, athletes get paid to win. If one lumberjack uses a chainsaw, soon every lumberjack will be swapping their axe for a chainsaw.

Answer 4

Because androgen receptor concentration & sensitivity is highest in the muscles around the shoulder girdle.

Answer 5

Sprinting causes natural increases in growth hormone produced. Ideal sprinting for this effect is about 10-15 minutes of short 30 seconds sprints. With adequate rest between sprints. This increase is roughly 600% from base line growth hormone that occurs naturally. This effect doesn't happen with long distance marathon running because they do not pass the lactate threshold or in other words its not high intensity, where the heart rate reaches nearing 90% of max. It's weird, but basically short extremely intense exercise, will just naturally develop a better physique.

Answer 6

1. Sprinters need their arms to provide dynamic balance; legs don't push straight through the center of mass. Their arms have to be:
   1. strong to move fast enough (try doing a full sprinting workout; your legs will hurt the next day, but so will your arms)
   2. big so that moving them around does something (swinging a twig won't counter-balance as much as swinging an anvil).
2. Sprinting is HIIT. It will help you grow muscle.
3. Sprinters aren't randomly chosen from the population. People who put on fast twitch muscle easily will do better as sprinters, train at it, make it to competitions,... These are the people who will put on muscle if they pick up a pen.
4. Their arms look bigger than they actually are because sprinters tend to be thinner than average people (an arm looks bigger next to a small body), and have lower body fat than average (an arm looks bigger when it's shredded).
5. Some of them are probably taking steroids, but I personally have known sprinters who I'm pretty sure weren't taking anything fancier than coffee who were pretty jacked.
   1. Even if they are taking steroids, they wouldn't grow their arms past the point of utility. Look at Lance Armstrong from when he was the best cyclist on the planet and using steroids. He had arms smaller than mine (note that he got big the minute after he retired). Steroids affect how much work you need to do to get to a size/strength, they don't just make you big.

Answer 7

The question is why arms are big while they are just for balance and their moving through air.

Is swinging limbs on air easier than swinging it on the floor. We should calculate percentage of leg force that is used for swinging the leg and percentage that is used to move body forward. Since the body speed is almost constant through 90% of race and applied force is not proportional to speed and it's proportional to acceleration then I bet most of energy is not used for pushing body forward against the floor but most of it is used to just swing legs own weight back and forth. A good test would be to try to run on air. A good cadence for sprinter is about 300spm. I doubt if they can increase it more than 25% if they run through air.

So the point is swinging limbs on air is mostly as energy taking as swinging it on floor. But why 5k runners don't have such masculine arms? Because sprinters extend their arms and 5k runners bend them and also they don't swing them as aggressive as sprinters. You need more torque for extended arms.

Answer 8

In a word, anabolic steroids. Sprinters engage in anaerobic work to increase raw leg strength because this is what sprinting partly is- a measure of anaerobic leg strength- raw power. That leads to them to the weightlifting gym. For serious professional athletes (and others), that leads to steroids and steroids don't differentiate between your arm muscles and your thigh muscles.

Just giving someone steroids increases muscle mass irrespective of whether they work out or not. This is a large part of the reason why boys are boys and girls are girls in terms of strength (the rest is strictly genetic).

Steroids were introduced to the public immediately after WWII as a way for concentration camp survivors to regain loss body mass. If you look at athletes from BEFORE that era, the 1900's or 1920's say you'll notice their upper bodies while defined and muscular look nothing like today's sprinter's upper bodies. That's not because they didn't train hard; that is an across the board gross morphological change in the musculature and size of the athletes. That's steroids. Anyone telling you anything different is either naive, lying or in denial.

Answer 9

I looked trough a few videos of Usain Bolt doing strength training. In one I noticed that he did pull-ups and inclined bench press. Pull-ups indirectly trains the biceps and bench press indirectly trains the triceps.