Adaptation to Training

[Sean Sundwall]

My coach just sent me something he published with the USATF about the body's adaptation to training. It's a short and interesting read:

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Adaptation to Training

How your body works and what this tells us about the importance of consistency,
specificity, and incorporating easy days into your schedule.

Hard-long concept.  Your greatest adaptation actually occurs in the days
following a hard workout.  This is when your body makes the adaptive changes.
For the first day or so your body is actually weaker than before the hard workout. 
These adaptations are triggered by a hormone called growth hormone.  The more
you run, the more you work, the more growth hormone you make.  So it pays to
run long, or pretty long, the days after a hard workout.  But it is very important
to run slowly then so that you don’t tax your system while it is repairing and
remodeling itself.

A more complete explanation is that the adaptive change is a 2-step
process.  The changes are brought about as a one-two punch involving two hormones—growth hormone and insulin-like growth factor. Growth hormone is the trigger that sets the adaptation program in motion.  IGF-1 is the 2nd factor and it executes the final program, promoting the remodelling of your muscles. 

Growth hormone is made during exercise.  When you exercise your blood is diverted to the exercising muscle.  So this is a win-win situation—more growth hormone and the growth hormone made will be preferentially bound to the stressed muscle.  Growth hormone does two things to promote recovery and remodelling   First, it acts on the liver to stimulate IGF-1 secreation.  Second,  in order to get the IGF-1 into the muscle, you need to have receptors for IGF-1 on the surface of the exercising muscle.  Growth hormone’s second role is to increase the number of IGF-1 receptors on the surface of muscles, so that the IGF-1 made in the liver can be taken into the stressed muscle.  The  muscle cells have the maximum number of IGF-1 receptors a day or two following a hard workout, allowing more IGF-1 to be taken up and act in the stressed muscle.  But since the increase the number of IGF-1 receptors this takes about a day, say 16-30 hours, to occur, the final remodelling cannot occur until after this time. 

This tells us one other thing about how to train.  Because it is the growth hormone (and IGF-1) that you make on the two days AFTER your hard workout, that determines the rate and extent of the adaptive response.  So the growth hormone that you make on the two days following your workout are very important in ensuring that you recover and get stronger and faster from your hard workout. 

What is the best way to do this?  Well, it seems that running longer and slower is better than running short and fast.  You may make the same amount of growth hormone either way, but running slowly is less taxing on your body and will allow you to recover quicker, rather than trying to recover from “two” hard workouts.  In conclusion,  the best way to train is to run hard, and the follow up with long or medium long runs on the two subsequent days.



The other interesting thing to know is how long this process takes.  Usually, it takes at least 2 days and can be up to several days, depending on the intensity and volume of the training session.  Essentially no remodelling takes place within the first day.  Parodoxically, the adaptation to a hard workout occurs on your easy days and is a two-stage process that really doesn’t take place until two or more days after your hard run.  Longer or very intense training sessions can take several days to fully recover.

Finally the reason adaptation is a 2-step process is so that it can be blocked, if necessary. 
Muscle building and muscle remodelling is an elective process.  Your body may have more important priorities.  These five things can block adaptation—lack of sleep, infection, trauma, poor nutrition, and excessive alchol consumption.  Taking care of these
things are important to make sure you are getting the most out of your training.




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[Michelle Lowry]

I have read different things about how to structure your week of training.  One is from Daniels that says two hard days back to back are ok since you feel a hard workout the most two days after a hard workout.  Then there's the traditional hard-easy-hard-easy way.  If you take Sunday off, and follow this article's guidelines and have two easy/long runs after a hard workout, then your hard workouts have to be Monday and Thursday.  What about people who like to do hard stuff inside of their long Saturdays then don't workout on Sunday?  I guess that way of getting in a hard workout would not be ideal?

[Jon Allen]

I've heard some arguments for hard-medium-easy order.  Kind of follows what Sean said- the medium day would be a mid distance at a not-fast pace.

[Sasha Pachev]

Michelle:
The human body has a proven tendency to embarrass scientists who try to describe its behavior with simplistic models and insist that  because of their calculations some trivial rule has to be followed to the T. 10% mileage increase rule is one of them. Running medium long exactly one day after a hard workout to gain maximum benefits would probably fall into the same category. You would probably get the same results if you add a short run Saturday evening after long and hard Saturday morning, followed by extra sleep and full rest on Sunday, and a medium long Monday morning followed by a short run Monday afternoon. If you do this repeatedly, your body will probably learn how to maximize the benefits of such routine. In fact for that matter, I would suspect if you follow any kind of routine that is close enough to medium long after a hard workout pattern, the body will learn.