Quite often you'll face a workout that's just a little out of your reach that day. It might be a matter of residual fatigue from previous training, some missing freshness following a night of poor sleep or maybe you're just a little distracted and thus lacking your usual level of motivation.
Whatever the reason, you still need your workout and you're not too tired to need a recovery day. In this case, modifying your workout in a small way, on-the-fly is probably the best way to maintain the workout's intent as well as keep your training on track.
Bailouts vs Alternate Versions
Workout "bailouts" are the best way to reduce the demand of the workout once you've begun the workout, i.e. on-the-fly, and recognize that you just aren't as sharp as you might have hoped.
Alternate workout versions, on the other hand, are better suited to situations where you know ahead of time that a modification - decreasing or increasing the workout's demands - is your best bet in terms of extracting the most benefit from the day's workout.
Alternate versions are covered in their own article aptly titled, "Alternate Workout Versions".
When to Bailout & When to Gut It Out
Before delving too far into the how's of bailing out, it's important to first cover the why of the matter.
Bailouts are not encouragement to take the easy road when intensity and suffering are the order of the day. Intervals by their very nature hurt, and when you bypass this discomfort, it will come at the expense of your training progress.
The take-home message is to use these sparingly, only when you need them and not simply when you want them - big difference.
Types of Bailouts
Bailouts come in a number of forms depending on the situation in which you find yourself, but they basically fall into 4 main categories: extended warmup, extended recovery/reduced interval duration, intensity reduction and intermittent backpedals.
I'll explain each bailout type briefly, but keep in mind that each type of bailout is only a framework inside of which you have flexibility; they're shapeable based on the type of workout and the intervals within the workout.
If, from the very start of the workout you recognize that the first interval is going to crush you, reduce the Workout Intensity as much as 10%. More often than not, this will prevent you from derailing your entire workout and barely affect the workout's objectives if it affects them at all.
You can then gradually raise the intensity of the workout as you progress through shorter, numerous intervals, e.g. 10x1-minute repeats, or you can do so as you progress through a longer, e.g. 12-minute, interval to bring yourself back up to full-dose, Target Power.
For further example, during a 4x8-minute Threshold workout you feel you'd be best off by extending the warmup by easing into the first 8-minute interval. Before the interval begins, reduce the Workout Intensity to 90%. Two minutes later, increase it to 95% and then 2 minutes after that raise it back to the full 100% prescribed intensity.
This will only have a slight effect on the workout's overall stress & intensity and it may very well save your workout by rendering the remaining intervals that much more productive since you warmed more thoroughly and are then able to keep your power more steadily on target.
This approach doesn't just apply to days when you're feeling a little off. This is an excellent approach to any workout where the warmup isn't sufficient for your personal warming needs.
Extended Recovery/Reduced Interval Duration
Once you're further into the workout and still not quite keeping things on track, lengthening the recovery valleys in between intervals & cutting into the intervals themselves offer an on-the-fly bailout.
The gist is that you recover longer than allotted by trimming the duration of the work interval thereby trading recovery for work.
This option will have a greater effect on the workout's overall intensity and total stress but will retain the prescribed interval intensity and consequently most of the desired training stimulus.
A suitable situation would be a 6x3-minute VO2 Max workout where you work for 3 minutes and then have 3 minutes of recovery before working for another 3 minutes.
Say you make it about 2 minutes into the first interval before you start falling apart but hang in there for another 30 seconds before pulling the plug.
This might simply be a matter of first-interval brutality and all subsequent intervals will be slightly more manageable, or it might be an invitation to perform a 6x2.5-minute workout - it's up to you to decide.
Should you decide to trim them down, simply backpedal (discussed further a little later on) when the wind goes out of your sails. In this case, start backpedaling at the 2:30 mark and begin pedaling forward as soon as you reach the recovery valley.
Then, make yourself hang in there to that same 2:30 mark for all remaining intervals, i.e. don't keep trimming a 3-minute interval down, down & down until you're only riding hard for a minute.
Perhaps the most obvious bailout would be a workout-long reduction in intensity, but this bailout falls lowest on the list of recommended modifications since you might miss the overall objective of the workout.
If, for example, you're slated to perform a Sweet Spot workout in the 88-94% FTP range but drop the Workout Intensity by 10% making the workout a Tempo workout, you've altered the workout's primary objective.
Is Tempo training a waste of time? Certainly not, but it might only serve to postpone the recovery your body needs and miss the intended muscle endurance work in the process.
In this case, an easy Endurance workout or recovery day might be a better solution.
But intensity reductions can come on a smaller scale and only affect a handful of intervals, e.g. a couple early intervals, 1 or 2 mid-workout intervals or perhaps an interval or two at the tail-end of the workout.
For example, a 16x1-minute Anaerobic workout might see you start out strong but fade toward the middle or end. A brief reduction in Workout Intensity of 10% could be just the slight reduction necessary to help you get all 10 intervals completed, most of them at full power.
Whether the reduced-intensity intervals happen at the start for an extended warmup, in the middle when your motivation dips a little, or at the end when you're simply running low on go-juice, 2 or 3 less-intense intervals out of 16 means you kept things highly productive for 13 or 14 intervals while the other 2-3 were only slightly off the mark but still very productive.
A personal favorite of mine, backpedaling, is probably the most malleable bailout in our repertoire of recommended workout modifications.
Whether you apply it in conjunction with another bailout, e.g. backpedaling through a 30-second recovery extension, or on its own as a quick, 10-second break to dispel some muscle burn, backpedaling keeps your muscles active but with virtually no stress.
Quite simply, turn the pedals backwards for the intended duration.
In the case of short, VO2 Max or Anaerobic intervals, backpedals might be relatively long but during longer, Threshold or Sweet Spot intervals they're probably going to be brief, very brief.
So a 3-minute VO2 Max interval might include a 30-second backpedal while a 10-minute Sweet Spot interval might contain 2 or 3 backpedals lasting no more than 10 seconds each.
Try to only backpedal for as long as necessary to maintain a high level of productivity. This is again a matter of only resting as long as you need to, not as long as you want to.
To Bailout or Bail Out
Finally, there are simply some days where you need rest more than a down-modified version of your workout. Determining this line of demarcation is matter for you and/or your coach, but as you learn more about yourself as an endurance athlete you'll gain a better understanding of where that line exists.