What causes variation in training?
Read time 6 mins
Have you wondered why your friend is stronger even though you did the same training? What is the reason behind this?
People adapt to exercise and training very differently. The biggest factor for your ability to make gains seems to be your genetics. It’s best to choose your parents wisely if you want to be the best in the world. Even though it helps a lot to have good genes, other factors also play a part.
Why training should be tailored to an individual and not the other way around? We’ll talk about differences in endurance and strength training, factors behind variation, and what to take away from all this.
What is variability in adaptations?
For example, when you and your friend do the same training program and your friend increases his bench press by 30 kg and you only by 10 kg. That’s variation in adaptation.
The factors behind these individual differences have been studied widely. We want to understand these factors better to prescribe more effective training.
High- and low-responders
Most of the research has been done in the field of endurance or strength training. Most often the change in VO2max, muscle force, or muscle size has been recorded. The studies have found that some people respond extremely well and some people might not improve at all. Most of the people land somewhere in the middle.
Variability in strength training
A study with 585 subjects looked into the variability in muscle size and strength changes after 12 weeks of training elbow flexion. They found the changes in muscle size to be normally distributed. Some of the outliers increased their muscle size by 55% while some got worse during the training period (due to injuries). (1)
What they also found was that the gains in muscle size were slightly better in men but the difference was very small.
Another study had 53 previously untrained young men train knee extensions for 9 weeks. Their aim was to quantify the range of responses to maximum force, muscle size, and specific tension. (2) They found similar results as the previously mentioned study. The results varied considerably.
Variability in endurance training
VO2max is often used as a measure in studies looking at endurance training. VO2max is your ability to transport oxygen from the air to the muscles. (3)
When discussing variability in training, the HERITAGE Family Study must be mentioned. Because it’s a classic.
It had 742 subjects from 200 families. The participants trained endurance for 20 weeks. The training responses varied from no change to increases of 1000 mL of oxygen per minute (4). It can be hard to grasp how much that is, but it’s a lot! Trust me.
The changes had large differences between individuals. Because they had recruited the participants from 200 families, they were able to model how much of the variation was inherited. Based on their model, 47 % of VO2max trainability is inherited. As a comparison, baseline fitness only explained 2 % of the variation. (4)
This is one of the first studies in sport and exercise science to look at how much of training response is inherited and how genetics are involved.
What if you are a “low-responder”?
It is important to remember that the “low-responders” gains could have been very different if they would’ve have done more or another type of training, their improvement could have been very different.
A study looked into this. They had people train endurance for 6 weeks in five groups. They trained for 60, 120, 180, 240, or 300 minutes per week. After the first 6 weeks, the people trained again, but this time they increased their dose by 120 minutes. This time there were no non-responders and everyone improved. (5)
This is pretty cool to see, because finding the ideal dose for you, is where I get my kicks.
What factors are behind variability?
We already talked about genetics which is the biggest player. We also discussed the training dose and how that can change your response to training. Lifestyle factors like sleep, nutrition, and stress levels play their own part in your ability to develop.
You want to recover between training sessions. If there is an imbalance between your overall stress and recovery, that can lead to overtraining or even burnout (6). In one of my earlier blog posts, we talked about how stress affects recovery and adaptations, you can check it out below.
Sleep & stress
We already know that high psychological stress impairs your recovery and you want to regulate your training based on your life situation. Poor sleep can lead to poor training tolerance and fatigue. It’s associated with a variety of physiological and neurological effects. (6)
It’s not exactly clear through which mechanism these are linked to training adaptation but the stress hormone, cortisol is related to impaired healing and recovery. (6) This is what we talked about in an earlier post.
Training status
If you are well-trained, you are able to recover faster from training stress. At least from high intensity training. (7) Although, like the HERITAGE study showed us, baseline fitness doesn’t seem to explain why someone improves more than the other.
As a caveat, the people in that study were healthy sedentary people. So someone really fit probably won’t improve as much as someone who just started exercising.
Practical takeaways
Well, how are we going to use this information? First of all, we can’t change our genetics so we better focus our attention somewhere else.
Finding the training volume
I would encourage you to find a suitable workload that creates adaptations for you. Based on my experience, some people do way too much and some people don’t do enough. It requires you to keep track of your training to find the right load.
The right workload also helps you to find the balance between recovery and stress.
Be flexible
I must remind you that the suitable load changes over time. If your stress levels are high and sleep is poor, you better adapt your training. You will make better long-term progress if you are flexible. Find a way to autoregulate your training so you’ll take it back when needed, but push when possible.
My way of autoregulating training is by using rate of perceived exertion. It’s a subjective measure for you to adapt your training based on your feeling.
Nutrition
Nutrition is one important piece of the puzzle even though we are not exactly sure how big the impact is on individual variation. What we do know, is that you can train more and adapt better with higher food intake. (8)
Summary
The aim of this post is to explain why one training plan won’t fit for everyone. We are so different from each other that it must be considered if you wan’t to get more out of your training.
Thank you for reading. If any of this resonates with you, send me a message on Instagram or Linkedin or leave a comment below.
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References
1.Hubal, M. J. et al. Variability in Muscle Size and Strength Gain after Unilateral Resistance Training. Medicine & Science in Sports & Exercise 37, 964–972 (2005).
2.Erskine, R. M., Jones, D. A., Williams, A. G., Stewart, C. E. & Degens, H. Inter-individual variability in the adaptation of human muscle specific tension to progressive resistance training. Eur J Appl Physiol 110, 1117–1125 (2010).
3.Joyner, M. J. & Lundby, C. Concepts About V˙O2max and Trainability Are Context Dependent. Exercise and Sport Sciences Reviews 46, 138–143 (2018).
4.Bouchard, C. et al. Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study. J Appl Physiol (1985) 87, 1003–1008 (1999).
5.Montero, D. & Lundby, C. Refuting the myth of non-response to exercise training: ‘non-responders’ do respond to higher dose of training. The Journal of Physiology 595, 3377–3387 (2017).
6.Mann, T. N., Lamberts, R. P. & Lambert, M. I. High Responders and Low Responders: Factors Associated with Individual Variation in Response to Standardized Training. Sports Med 44, 1113–1124 (2014).
7.Tomlin, D. L. & Wenger, H. A. The Relationship Between Aerobic Fitness and Recovery from High Intensity Intermittent Exercise. Sports Med 31, 1–11 (2001).
8. Hawley, J. A., Burke, L. M., Phillips, S. M. & Spriet, L. L. Nutritional modulation of training-induced skeletal muscle adaptations. J Appl Physiol (1985) 110, 834–845 (2011).