The first thing you need to understand is the Theory of Supercompensation. This theory states that you start at a certain baseline. To take from Patrick Ward we will refer to this as the starting point of our stress bank account. We start at a base line level and we invest that money into some product for our workout. That investment then puts us at a low in our bank account until we get some return from that investment. It then puts us in the positive once it begins to pay us back.
So if we apply this directly to the model above we get the following. We start at baseline and we apply a stress to our body like a workout, riding or racing. This stress then depletes our reserve to a certain point and now our body compensates to that stress and we then have a slightly greater capacity. If you put this into light of a workout its really simple. If I want to improve my bench press, I lift and challenge myself. The next day my arms and chest may be sore and a bit weak but, a couple of days later I'm just a little bit stronger.
Now a big thing to recognize is that there are different kinds of stressors and of different intensities. These different stressors can impact the length of time it takes to come back up above baseline. Below is a good example of this extracted from Olbrecht (2000).
The chart here shows how these different types of stress impact the time that it takes for your stress bank account to go positive from your physical investment. The big thing you need to disseminate from the titles on the chart are this. Extensive refers to a greater amount and duration but maybe not as intense for your overall capacity. Intensive refers to very high intensity like big heavy lifts or a max but, you cant do these for a long duration or for many reps.
Now there are an insane amount of what ifs and modifications that can be made to this model and idea based on your own genetic abilities, your physical fitness and quality of life related to stressful events not directly associated to physical activity. For now just assume that you meet the this chart at it's very basic level.
Each time you go riding the stress that your body endures can be pretty severe. A full race weekend is equivalent to the last box of Intensive/Strength Training/Competition. It can take you between 48 to 72 hours to fully recover. Now when you ride really hard even when training, you incur this same kind of stress. However most of the time your not riding at 100% all out effort which means you may be more along the Sprints/Short Sets on medium intensity riding days or in the Extensive/Anaerobic to Intensive Anaerobic range; depending on your intensity of riding that day. So riding at a decent pace to help improve your ability to race will land you somewhere between 30 to 60 hours to fully recover. Don't think that just going out and riding the track and hitting some jumps for fun meets this. We all know when we're riding hard and when we're just letting the bike work for us to hit some jumps and have a good time.
So now back to why does rest matter so much? You have a necessity for rest every day and I think we all understand each week also. Most people leave 1 day as their rest day. However us motocrosser's don't have that same luxury. We ride Saturday and Sunday just to get any amount of track time and then we return to the stress of the regular week. Now think about that accumulating day after day, week after week and month after month. Now your trying to work out during the week to get your fitness up to get faster. How do you think that looks over time?
Eventually if you compile this together across time you realize all that stress adds up. At a certain point your body cant return back above its baseline and adapt to make you better. This is when we apply an unload week. In strength training periodization this is a very formal process that occurs somewhere around the 4th or 5th week depending on different variables. However if you think about it, we work out maybe 2 or 3 times a week and ride maybe 1 or 2 times in the week for a total of about 4 of 5 days of training focus; then we try to get some rest. We just did 3 or 4 weeks of hard work why don't we get a week of rest just the same?
This doesn't mean that we take a whole week off by any means but we definitely reduce the overall volume of our work. We still give it some stress to make sure that we don't lose our progress we just achieved, but we allow our-self to fully recover and improve. This becomes a huge factor long term because of how intense motocross can be.
I don't know this for a scientific fact but I assume that guys racing outdoor nationals can take up to 5 days to fully recover. The reality is that certain types of stress can go beyond the models above for time of recovery. Doing a true max lift for something like squats or deadlift's could take you up to 5 to 7 days to recover completely. Now think 30 minutes +2 laps twice while its 100 degrees out, you better believe that's equivalent.
The last major thing is that people don't realize your body makes its adaptations during rest and especially sleep. When you sleep your body is able to fully repair itself. The other really cool thing that happens when you sleep is the movement patterns that you just practiced or learned become ingrained into your permanent memory bank. All sorts of cool things happen in our sleep. Just check out this Discovery Channel excerpt below.
The real take home points are this, plan yourself some rest time. It is important to improving your overall performance. This doesn't mean quit exercise completely for a whole week, just scale back the total volume of work. Think about the type of stress your body is undergoing and better plan your training. You can use the chart above with the different times as a general guideline to improve your training. Then go ahead and start adapting this chart to fit you and create some personal zones based off your own intensity and observations. Then you're able to better plan your overall training and better plan your rest to improve performance.
