The Sigmoid Curve

Did you already read my latest blog post ‘How to set the optimal training load’?

If you haven’t read it yet, please click here to read it. Otherwise, you would not understand what I am going to talk today.

In the last blog post, I told you the simple equation to know your optimal training load.

However, I also told you that the equation wasn’t perfect and today I want to explain more about why it is not perfect.

Roughly speaking, training is stimulus and reaction. More roughly speaking, everything is stimulus and reaction.

You see something tasty, so you eat it.

You see something tasty, so you drink it.

You work, so you are tired now.

You saw my blog post in the past, so you are reading my blog post now.

You saw a beautiful girl, so you fell in love with her.

You saw an interesting book, so you bought it.

Very roughly speaking, everything in this world is stimulus and reaction. And training is no exception. The question is which kind of stimulus you need to cause an ideal reaction from your body. This is all about training.

And before we think about it, we need to know how our body reacts to stimulus generally. And the relationship between stimulus and reaction of our body is shown as the Sigmoid curve.

Even if you have never seen the Sigmoid curve, don’t worry about it because I can explain you what the point is clearly by words.

What that means is very simple. In terms of our human bodies, no matter if you are black, white or yellow person, too small stimulus and too much stimulus doesn’t make any change to our bodies.

Imagine, you drink a cup of coffee every day. Then, if I put 1mg sugar into your coffee, do you notice the difference?

In other words, is your coffee sweeter now?

Probably not.

You can’t notice the sweetness of 0.001g sugar.

Then what about if I put 2mg sugar into your coffee?

How about 3mg sugar into your coffee?

How about 4mg sugar into your coffee?

How about 5 mg sugar into your coffee?

Probably you don’t feel the sweetness of sugar at all.

What if I put one tablespoon of sugar into a cup of coffee?

Now, you feel the sweetness a little bit and the more tablespoons of sugar into your coffee, you feel more sweetness.

But probably, after I put 10 tablespoons of sugar into a cup of coffee, no matter how many more tablespoons of sugar into a cup of coffee, you can’t feel the difference anymore because it is already too sweet.

You cannot feel the difference with a cup of coffee with 10 tablespoons of sugar and 15 tablespoons of sugar.

This is not because you are stupid, but because our body cannot feel something too little and too much.

I will give you another example. Imagine, now your room temperature is 15 degrees in Celsius and I turn on the heater. Now, the room temperature is 16 degrees, but you feel no difference. Now, 17 degrees and you feel no difference. Now 18 degrees, you feel no difference.

But once the room temperature reaches 25 degrees, you start sweating.

After the room temperature is over 30 degrees, 1 degree has a significant effect on your body. The higher the room temperature is, the more you sweat.

But once the room temperature reaches 70 degrees, no matter how much I increase your room temperature, it makes no difference anymore because you are already dead. It doesn’t change your body reaction at all.

Sometimes the same principle works in psychological field.

If you are single now. One beautiful woman makes you so much happier than now. Two beautiful women make you so much happier than having one beautiful woman. And three beautiful women make you much happier than having only two beautiful women.

However, 100 beautiful women do not change your happiness at all unless you are Tiger Woods. There is no difference between having 99 beautiful women and 100 beautiful women.

I’m a bit joking, but you know what I mean if you experience being poor and rich. If you are poor, 100 US dollars have a big impact on your life. The more you earn, the happier you get.

However, once your annual income reaches one million US dollar, money doesn’t impact on your happiness much anymore unless you are greedy like crazy.

Anyway, the relationship between the stimulus and our body reaction is shown as the Sigmoid curve. And training stimulus is completely same.

Too easy training stimulus does not make any difference.

For example, you walk one hour every day. You hardly get faster in a full marathon. Of course, it is better than sitting on a couch and watching Netflix. But it hardly affects your race performance.

What about high intensity and low volume training?

Look at sprinters. They run much faster than we do. But their training has almost no training effect on your race performance in a full marathon.

In the former example, the intensity is too low and in the latter example, the volume is too low, so it doesn’t cause your body's reaction.

What about intensity and/or volume is too high?

It’s the same.

Even if you run 70km, it does not make a big difference with 40km run if you are a marathoner, in other words, you are not an ultra-marathoner.

Also, in this case you do 70km long run, the intensity tends to be too low.

Intensity is the same.

High intensity training is important. But once you train enough hard, it doesn't make any differences even if you train even harder.

Generally speaking, if you run faster than 110% of your race pace, extra effort is in vain. I don’t mean, the moment your pace reaches 111% of your race pace, training effect becomes 0, but if you are already running 108% of your race pace in your interval workout, it doesn’t make sense to push yourself harder because it is already enough fast.

Too easy training doesn’t get you faster and also once you reach the point, it doesn’t make sense to train extra harder. Extra harder training after you passed the point doesn’t get you faster. And that point is easier than most people think.

So far, there is no way to point out this point 100% objectively.

However, in my experience if you cannot do that workout consistently once a week alone, that workout is too hard for you.

Or, if you cannot do that workout with more than 90% confidence, it is too hard for you.

There is nothing bad to train with someone who is faster than you. But, if you cannot do that workout alone once a week with more than 90% confidence, it’s too hard for you. And that means, there is no excuse that you cannot run faster because you don’t have any training partners.

And once you understand the Sigmoid curve, you’ll understand why moderate volume moderate intensity with high frequency is the best training method.

And also, you’ll understand why high intensity short time interval is not as effective as many people say especially if you are a half marathoner or full marathoner.

The problem here is, how hard we should train.

In terms of training effect, too easy training makes nothing and once you train enough hard, it makes no difference to train extra harder.

While fatigue and risk of overtraining and injuries, if it is easier than your homeostasis function, in other words recovery ability, it makes almost no difference.

But once you train harder than your homeostasis function, in other words your recovery ability, the harder you train, the more risk you have to get slower or get injured.

And the relationship between how hard you train and the possibility to get slower and get injured is not proportional, but exponential until your body is completely broken down. Once your body is broken down, it makes no difference anymore no matter how harder you train.

The problem of my equation is that my equation doesn't consider this. Anything higher than moderate intensity or moderate volume is plus 1. And high intensity high volume training is plus 2.

However, considering that extra harder effort increases the training load exponentially, this simple math is not perfect.

If your moderate volume is 10km a day and you run 40km a day with moderate intensity, probably the training load is not plus 1, but plus 2, 3 or 4.

But based on my simple calculation system, this training load is only plus 1.

The point is, if you understand why my equation is not perfect, you can use my equation very well. I mean, my equation is 80-90% right, but you need to arrange the rest of 10-20% by yourself by feeling yourself.

While if you don’t understand why my equation is not perfect and follow my equation blindly, you make a mistake, a big mistake.

And also, if you know the Sigmoid curve, you can understand why moderate volume moderate intensity with high frequency is a golden rule.

I hope this article helps you a lot.

Lastly, if you want to learn more about how to run faster without overtraining and injuries, please click here to download my free ebook ‘Three things you should know to get faster dramatically without any injuries and overtraining’.