12/05/2025
How important are genes to your potential. Warning, this is solely about competing at at high level in sport. We aren't talking about your local Park Run.
I had this discussion during a training session. One of the athletes said some people can't jump but surely it's down to training. Yes and no. We are nowhere near our potential, but there are ceilings (in my opinion) to what is possible.
Let's look at a simple concept of raw speed and sprinting. Every athlete who has been tested has the presence of a gene called ACTN3. This is found in fast twitch muscle fibres. It stands to reason, to be the fastest person on the planet you need the presence of fast twitch muscle fibres. You Also need a favourable distribution of fast twitch muscle fibres to be a good sprinter. This will make your body look and adapt differently to training. You will be more muscular, particularly in your lower body and you will respond to explosive training better.
When looking at jumping sports, most athletes will have a longer, slimer calf muscle. This provides more force at the joint (fulcrum - ankle) which means you can produce more force into the ground than a shorter calf/achilles tendon. It's like using a long spanner vs a short spanner to unscrew a tight bolt. You can get around this with a shorter-bulkier calf but it will need to be significantly bigger than someone who has a longer calf muscle.
It's been long thought in gym circles that calf shape and development is down to training. I have been in and around research and training methods for decades and I can tell you calf development is nearly 100% down to genetics. People look at someone with slimer calf muscles and say they must have skipped leg day, or they need to put on weight. However, when you see how much force they can generate with a jump, it will far exceed (mainly) someone with bigger calf muscles. This is a generalisation and there will be exceptions.
People often don't like the mention of genes as they think we are talking about fate; we aren't. People don't like the idea that there are things we simply can't do. We have no issue when looking at a 7ft basketball player, but do when looking at less obvious differences.
So what role does training have? In sprinting, if you could get to 14/13 seconds as a child/youth athlete, you can get to11 seconds with constant training. I could get most men to 13 seconds and most women to 14-15 seconds. However, you may have to accept that this is close to your limit. What you can't do is get someone all the way down to 10 or 11 seconds with just training alone. You can't get to the elite level without a genetic element. Elite of the elite is about genes + long-term training.
What about the stories of the marathon runners who started running through lockdown and are now running sub 3 hour marathons? There are some people who have untrained favourable genes. This is not the case for most people and I think knowing and appreciating your limit is much healthier. There is also a lot of body shaming from the layperson to athletes. I see this more with endurance athletes. Women are told they are too skinny; as if an athlete is remotely concerned about how they look to others. They would most likely look like this if they didn't train, albeit with slightly more bodyfat. There is a famous saying, "you can't fatten a greyhound."
There are many pieces in the puzzle but one last important one is time. Athletes have a window where they are at their physical peak (17 - 28). Their training, recovery and adaptation cycle is much quicker. They can learn skills quicker and their potential is higher. Starting sports as a teenager gives you more time during this peak period and gets you to your goal quicker. More importantly, before you start to notice a decline. Even if you don't carry on with sport, I advise all young people to play (don't train) different sports.
If you are starting to feel there is no hope with such a negative post, I need to add some balance. Despite your potential falling, I feel many people aren't even at 50% of their potential. They can experience improvements into their 30s, 40s, 50s and 60s. This has nothing to do with genetics and it will feel amazing. It's solely down to training. However, if you think you can jump as high as someone who naturally has favourable genes to jump high, you can't.
You can't compare yourself to anyone other than who you were yesterday.
