Have you noticed that Olympic sprinters have insane shoulders? Not only are they large in size, but they are also even developed, have impressive flexibility and almost never get injured. According to a study, 36 of all resistance training related injuries occur at the shoulder. They identified the biggest risk factors as a muscle strength imbalances, front shoulder instability and loss of mobility, which is the complete opposite of what nearly every Olympic sprinter has. In this post we’re going to try to figure out why do Olympic sprinters have insane shoulders.

Here’s the problem. There isn’t research specifically on this topic. So the next best thing would be to look at the available research on shoulder development and see what theories make the most sense. Sure we could point to genetics or steroids and call it a date. Those are valid points and we wouldn’t argue that those play a large role, especially at the elite level. However, our purpose is to look at the variables which we may benefit from, that are within our control and don’t involve illegal substances.

Research shows that in terms of muscle fiber type, the shoulders are a mix of fast twitch and slow twitch fibers. This suggests that in order to effectively train the muscle fibers of the shoulder we need a combination of low reps at a high intensity and high reps at a low intensity. If this is true, it’s possible that the initial arm swings, which are performed at a high intensity for a few repetitions per sprint start, may stimulate growth in the fast twitch fibers of the shoulder. These are the largest arm swings that occur throughout the entire sprint with the back elbow reaching far above the head for the first one to five steps. Meanwhile the arm swings may stimulate growth in the slow twitch fibers of the shoulder. As the Olympic sprinter takes on average 44 steps during a 100 meter race, this equals to 22 arm swings per arm. This means depending on the distance, during a sprint they’re performing anywhere between 22 and 88 repetitions per arm each round. Not to mention these numbers are for a world championship race. In their training they’re moving at a lower speed taking more steps and, therefore, performing more arm swings. The combination of high intensity and high volume arm swings could arguably be providing an optimal stimulus for shoulder size and strength.

Based on research, we know that hypertrophy occurs through three mechanisms, one of those being mechanical loading. This occurs when there is tension on the muscle, either in a shortened or lengthened position, which happens to your shoulders when you’re holding the start position. Because it seems that the rear shoulders are lengthened while the front shoulders are shortened as they work together to keep your body in that start position. The first time you got into one of these starting blocks, maybe you was genuinely impressed by how exhausting it was just to hold that position. When watching you guys on TV, they make it look very easy. It’s sort of like a plank, but instead of being flat on the ground, your legs are at an angle on a piece of metal with most of your weight on your arms, which is being supported only by your fingers.

Elite sprint coach Tom Tellez talks about how all sprinters should be able to hold the setup position for hours. In this clip Usain Bolt was warming up before going on to break the 200 meter world record at the 2008 Olympics, and we can see that he’s doing starts going through that start setup and initial arm swing over and over.

So even though they only start once in a race, in their training they’re doing many repetitions of the start setup and initial arm swing, all that time under tension. There’s actually a study for that. Using rats the University of California found that isometric, shortening and lengthening exercises led to essentially equivalent levels of muscle hypertrophy. Another thing that science has shown us is that ballistic stretching is an effective way of increasing our range of motion without decreasing our strength.

We define a ballistic stretching as quick movements that use momentum to push our body beyond its normal range of motion.

With that being said, we could argue that the arm swings are technically a form of ballistic stretching which could explain why sprinters seem to have healthy flexible pain-free shoulders. In this clip of Asafa Powell’s training we can see that even at the age of 38, the range of motion he has in his shoulders is crazy. This is better than most 20 year olds at the gym.

A study conducted on muscle activation during the bench press found that as the torso incline increases, the activation of the front shoulder increases as well. While it may not be the exact same thing during the set start position, the torso is at a steep incline. Now to go a step further, this study examined which hand position elicits the highest amount of muscle activation for the rear shoulder. They tested neutral versus palms down. Can you guess which one created the highest amount of muscle activation? This study found that rear shoulder activation was significantly greater in the neutral hand position which, as it turns out, is the exact hand position used during the arm swing.

You may agree with some or none of these theories, and that’s perfectly fine because beyond talking about steroids or genetics, no one has addressed this topic. So we have more specific research to confirm or deny these theories. It’s very probable that these are the reasons why they have such insane shoulders.

Bibliographic references:

• Palacios C. [The Sprint Project]. (2021). Why Do Olympic Sprinters Have Insane Shoulders? [Video]. Recovered from https://youtu.be/NBtOpWKCHg8?si=W_6DQUZt9sUG3nHo
• Kolber, M. J., Beekhuizen, K. S., Cheng, M. S., & Hellman, M. A. (2010). Shoulder injuries attributed to resistance training: a brief review. Journal of strength and conditioning research, 24(6), 1696–1704. https://doi.org/10.1519/JSC.0b013e3181dc4330
• Srinivasan, R. C., Lungren, M. P., Langenderfer, J. E., & Hughes, R. E. (2007). Fiber type composition and maximum shortening velocity of muscles crossing the human shoulder. Clinical anatomy (New York, N.Y.), 20(2), 144–149. https://doi.org/10.1002/ca.20349
• Konrad, A., & Tilp, M. (2014). Effects of ballistic stretching training on the properties of human muscle and tendon structures. Journal of applied physiology (Bethesda, Md. : 1985), 117(1), 29–35. https://doi.org/10.1152/japplphysiol.00195.2014
• Barnett, Chris, Kippers, Vaughan, and Turner, Peter (1995). Effects of variations of the bench press exercise on the EMG activity of five shoulder muscles. Journal of Strength and Conditioning Research 9(4) 222–227. https://doi.org/10.1519/00124278-199511000-00003
• Schoenfeld, B., Sonmez, R. G., Kolber, M. J., Contreras, B., Harris, R., & Ozen, S. (2013). Effect of hand position on EMG activity of the posterior shoulder musculature during a horizontal abduction exercise. Journal of strength and conditioning research, 27(10), 2644–2649. https://doi.org/10.1519/JSC.0b013e318281e1e9