When does "fitness" happen?

As Nick said, you don't get stronger from what you "do", you get stronger by recovering from what you "do". Simply "doing" more (whether it's longer or harder) just tears you down more. Your recovery well is only so deep, and after that the risk of injury and/or illness goes up exponentially. Finding the balance of work and recovery is an individual pursuit.

And remember that all stress digs into that recovery well. Work stress, family stress, lack of sleep, poor nutrition... It all affects your ability to recover.

^^^This^^^

Our "fitness" is never static.  At all times, we're either gaining or losing.  During training, we're breaking our bodies down.  When recovering from training, we're gaining fitness through what's called supercompensation.  This is the idea that after we create damage through training, our bodies repair the damage, plus a little bit more to insure against future damage.  Rest too long beyond the time when those repairs have occurred, and fitness begins to deteriorate. That's why consistency in training is so important.  Cycling back and forth between doses of training stress and recovery that are in balance with each other is the objective of training.  Too much or too little of either one will impair your improvements.

That's the principle of specificity.  The training concepts of stress and recovery to achieve supercompensation are the same for both.

It's a bit of a semantics issue, but I don't think you're really asking about "fitness" as much as structuring your training to be able to perform at an optimal level for your  targeted event.  In other words, how to "peak" at the right time.

No short answer.  It depends on the individual and the event they are training for.

When I first started doing serious triathlon training twelve years ago  I attended a weekend clinic with Joe Friel and adopted his periodization strategies pretty much straight out of his The Triathlete's Training Bible, but with some modifications to compensate for my age and my need for more recovery time.  Some of Friel's stuff is considered outdated these days, but a lot of the underlying theory still holds to be true.

I'm primarily focusing on swimming this year and am using Ernie Maglischo's Swimming Fastest to guide my training.  It not only deals with stroke technique, but also goes in-depth into the physiology of training and adaptation.  Great stuff, but it reads like a college textbook and at nearly 800 pages, it's not something you can get through without some effort.

Mark 

Why?

It depends.  If you race frequently, you should not taper for each one.  Racing is training.

Not tapering does not equal not doing well.  An easy day or two prior to racing should be enough taper to have a good race.  (Likewise, an easy day or two after should be enough to recover.)  Just as an example (and, admittedly, not entirely applicable since not a pure endurance race) in high school and college I was a rower.  In the Spring, we would race almost every weekend.  An easy day on Friday, race on Saturday, off on Sunday.  Hard, regular training Mon-Thurs.  Tapers came only before the championship events--our main goal races for the season.  I assure you, we were trying our best to win every race we had.  We were simply looking for our peak performances to come at the end of the season.  Trying to taper before each race would have meant not developing as great an increase in fitness prior to our 'A' races--a bad trade-off for the chance of winning a few less important races.

The point is that if you really do race frequently, you cannot expect to peak for each race.  Therefore, you should not taper for each race.  You can take a 'different approach', but only at the cost of long-term progress.

No.  An 'easy' day is not a taper.  It is just that, an easy day.  Any training program should have easy days around hard days.  Racing is a hard day.  You put easy days around it.

Edit:  I should note in the above example that Sunday was always an off day for us.  So it was not an extra rest day to account for a race.  It was there for the race plus the other work we had done during the week (as well as for 'non-training' reasons--we were students, not just athletes).

Most people can do a lot better in terms of rest, recovery, and taper by looking at all the non training things they are doing and optimizing that.  Especially sleep.  Often times we get into a mindset that training time and intensity is the only factor in how we will improve fitness (by training more or harder), or recover (by training less or easier).  The reality is that the other 20+ hours of the day that we are not training counts too in terms of the quality of rest and recovery we are getting.

For most of my "B" or "C" races I don't adjust training all that much.  Maybe slightly easier in the days leading up as Johnny mentioned, but I do make a more conscious effort to get more sleep and stay off of my feet as well.  IME, that works just as well as taking complete days off of training but not optimizing sleep and time on my feet.

I'm not trying to be difficult or argue just for the sake of it.  But a taper has an actual definition in exercise physiology.  And it is not an easy day.  It's OK if you consider an easy day a taper, just like it's OK if you want to consider a lemon to be an orange.  It hurts no one and may not make an actual difference in what you do--so it seems to you to just be semantics.  But when you offer someone a slice of your 'orange', don't be surprised when they look at you like you're nuts.  :-)

And maybe to try to get back on point, racing frequently can be excellent training.  I don't do it anymore because the logistics of racing (travel, waiting around for start times, etc.) take up too much of my (un)available time.  But, when you can, racing is some of the best training you can do.  It can be a great catalyst for fitness to 'happen'.

Ha ha!  I missed that when I wrote it. You got me!

I'll go suck on an orange now.

Since we're running off the rails anyway...I know JK knows this, so I'm not disagreeing with him, but just trying to help explain... in general, a good taper doesn't consist of easy days.  It's primarily short sessions at about the intensity of the planned race, but at a drastically decreased volume.  So, if you're racing sprints and olys, the meat of taper sessions is going to be at pretty high intensity.  Nothing easy about that at all.

In the case of someone who wants to race a lot, it can help to use an A, B, C race approach.

'A' races are the ones where you really want to knock it out of the park, and be in your best condition for.  For the average AGer, this can only be achieved about twice a year on average.  Genetically gifted professional athletes are more likely to be able to achieve this about 3 times a year.

'B' races are ones that you want to do well, but they're not as important as 'A' races.  For these, you'll do a partial taper, and go into them fairly well rested, but not at peak fitness.

'C' races are the lowest priority.  They are just part of your training, and done with no taper at all.  They're a good opportunity to hone your racing skills for the higher priority races.

IMO, using this approach can be an effective way to develop your annual training plan.