Some days you just aren’t feeling it. 

Your limbs feel airy, your joints ache, and your mind flits to every topic except your workout. 

BUT, your workout program says it’s leg day, or chest day, or whatever, and come hell or high water, you’re going to stick to the plan. Winners never quit and quitters never win and all that. 

So you turn up the Sabaton, grit your teeth, and grind your way through each set. And you have a shitty workout. You barely manage to match your previous week’s best. Maybe you even miss reps.

On the one hand, this is laudable and necessary. Sometimes you have to suck it up. It’s called working out for a reason. 

On the other hand, you’ve probably thought to yourself, wouldn’t it have been smarter to let your batteries recharge before draining them again so soon? If you’d put off your workout just one more day, might you have enjoyed it more and gotten better results? 

More and more scientific research shows that the little voice in your head is onto something.

In other words, you’ll likely relish your workouts more, gain muscle and strength faster, and reduce your risk of injury by following what I call flexible programming instead of standing pat with your workout plan.

What Is Flexible Programming?

Flexible programming refers to adjusting the order and frequency of your workouts based on how you feel. 

Basically, it’s applying the concept of autoregulation not just to your sets, reps, and weight, but to your workout schedule as well. 

To understand how this works, let’s see how it compares with traditional, rigid programming, which involves doing the same workouts on the same days every week regardless of fluctuations in fatigue, motivation, and so forth. 

Let’s say you’re following a push pull legs workout program, which looks like this:

  • Monday: Push
  • Wednesday: Pull
  • Friday: Legs

And every Monday, Wednesday, and Friday, you do those workouts on those days, regardless of how you feel. Most of the time you progress as planned and have no trouble recovering between workouts, but sometimes you hit a speedbump. 

Let’s say that you don’t sleep well on Thursday night, and you’re dragging anchor on Friday—leg day. With traditional, rigid programming, you’d gut it out and chalk it up as “one of those days,” and hope for better sleep next week. 

With flexible programming, though, you could push the workout back to Saturday, giving yourself an additional day to rest and recoup so you can fully profit from your efforts in the gym. 

Here’s another example.

Maybe your upper body is still feeling bushed from your push workout on Monday, so instead of doing your pull workout on Wednesday, you swap it with your leg workout on Friday. In this case, you’re still training on the same days, but you’ve rearranged the order of the workouts—going from “push pull legs” to “push legs pull.” 

That’s the essence of flexible programming: changing your workout schedule so that you can hit the weights when you’re feeling freshest, or at “peak readiness” as some sports scientists like to say.

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Flexible Programming Benefits

While many fitness fiends turn up their nose at the thought of programming their workouts based on a mushy metric like “feelings,” it’s hard to argue with the merits of this approach. 

Ultimately, your body doesn’t care how closely you hew to your workout schedule. 

All it cares about is recovering from the workouts you subject it to so it can grow stronger, fitter, and more muscular over time, and it does this on its own capricious schedule.

What’s more, sundry factors such as sleep, stress, nutrition, and supplementation can increase or decrease how quickly you recover, making it even harder to predict when you’ll be fully primed for your next workout. 

Experience, scientific research, and educated guesses will get you in the ballpark, but all things considered, there’s no way to predict exactly how fast you’ll recover from your last workout (and thus be ready to give your all in the next). 

With this in mind, does it make sense that you’ll always be optimally prepared for, say, squats on Friday after deadlifts on Wednesday? Or a hard chest workout on Monday after blitzing your triceps on Friday. Or a long run on Sunday after intervals on Thursday? 

Of course not. 

Sure, most of the time you’ll recover on a somewhat predictable schedule, but there will also be many days where your body rebels, and you’re better off giving it another day or two to catch its breath instead of lashing it onward.

Viewed in this light, your workout routine begins to look more like a to-do list than a timetable. You have your list of workouts and you need to get them all done by a certain date (the end of the week, for instance), but you can decide when and in what order you knock them out.

While athletes in various sports (especially endurance sports) have been toying with flexible programming for decades, more and more scientific research has piled up in support of the idea for weightlifting, too. 

A notable example of this is a study conducted by scientists at St. Francis College, which divided 16 beginner weightlifters into two groups: 

  1. A rigid programming group, which performed all of their workouts in the same order and on the same days each week.
  2. A flexible programming group, which was allowed to choose what workout they did each day of the week based on how they felt (for instance, swapping leg day for a chest day if they were feeling a bit ragged).

The flexible programming group gained significantly more strength than the rigid programming group, despite doing the exact same number of workouts and using the same intensity and volume over the 12-week study. 

A follow-up study by researchers at South Florida University found that powerlifters who used flexible programming only missed four workouts during the 9-week study, whereas those who used rigid programming missed eight workouts. In other words, flexible programming helped already dedicated weightlifters better stick to their program. 

Other studies show that moderating workout variables by “feel” may be more fruitful than sticking to a premade plan.

For instance, research shows that you’ll probably gain more strength by resting as long as you feel you need to between sets rather than using predetermined rest periods. Other studies have found that deciding how much weight to add and how many sets to do based on how you feel, rather than arbitrary, pre-planned benchmarks, can help you gain strength faster.

An additional benefit of flexible programming is that it can help you head off weightlifting injuries. While I’m not aware of any data to prove this, most experienced weightlifters will tell you that many of their worst overuse injuries were precipitated by a couple of “off” workouts that they knew they should have skipped.

This principle also pops up in fields far from fitness.

The Prussian military strategist Helmuth von Moltke the Elder said that, “No battle plan ever survives contact with the enemy,” Darwin put forward that the “fittest” creatures are the most adaptable, it’s a truism in business that being able to “pivot” is a prerequisite for success, and Robert Burns warned against blind faith in “The best laid schemes o’ mice an’ men.” (I’m stretching a bit here, but you get the idea).

In other words, empirical evidence, collective wisdom, and common sense suggest that tweaking your training on the fly—within limits—is probably superior to unbending adherence to The Plan. 

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Flexible Programming Downsides

The most obvious downside of flexible programming is that it requires more judgement on your part. 

Instead of running on autopilot—doing the same workouts on the same days every week—you have to assess your readiness and adjust accordingly.

You’re intentionally second-guessing your program, which can feel disconcerting. 

What if I’m just being soft? 

What if I still feel stale tomorrow? 

What if I’m actually missing an opportunity for a good workout?

These thorny thoughts can quickly lead to screw it, I’m not training this week, which is why it’s best to practice flexible programming within certain constraints (more on this in a moment). 

This is also why it pays to have an experienced coach in your corner who can help you make the right decision.

Another concern many people have with flexible programming is that they think it’ll make it harder to track their progress. For example, if some weeks they get one day of rest before a particular workout, and other weeks they get two or three days of rest, won’t that artificially dampen or boost their performance on those days? 

And to that I’d say, who cares? 

While I used to share this concern, I no longer think it’s valid. As you saw a moment ago, your body doesn’t recover on a neat schedule anyway, so if you get a bit more or less rest before workouts occasionally, the differences average out over time.

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How to Use Flexible Programming

There are many ways to make use of flexible programming, but here’s what I’ve found works best for most people in the context of weightlifting: 

  1. Pick a weightlifting routine. 
  2. Follow the default routine most of the time, but don’t be afraid to decide on the fly what days you train and what workout you do each day. It’s best if you leave at least one day of rest between workouts that train the same muscle group, but this isn’t essential. 
  3. If you aren’t able to do a workout one week, don’t try to make it up the next week. Look at each week like a blank slate. 

Here are a few examples to illustrate this concept in action. 

Let’s say you’re following the five-day Bigger Leaner Stronger program, and your normal training week looks like this: 

  • Monday: Push
  • Tuesday: Pull & Calves
  • Wednesday: Upper Body A
  • Thursday: Legs
  • Friday: Upper Body B
  • Saturday: Rest
  • Sunday: Rest

Here’s how a few weeks of flexible programming might look like: 

Monday Tuesday Wednesday Thursday Friday Saturday Sunday
Week 1 Push Pull & Calves Upper Body A Legs Upper Body B Rest Rest
Week 2 Push Legs Upper Body A Pull & Calves Upper Body B Rest Rest
Week 3 Legs Push Upper Body A Pull & Calves Upper Body B Rest Rest
Week 4 Push Pull & Calves Rest Upper Body A Legs Upper Body A Rest

As you can see, this isn’t complicated. All we’re doing is swapping a few workouts here and there, while leaving the overall rhythm and structure of the program intact. 

Let’s look at another example of flexible programming in action, this time with an upper lower workout split

Monday Tuesday Wednesday Thursday Friday Saturday Sunday
Week 1 Upper Body Lower Body Rest Upper Body Lower Body Rest Rest
Week 2 Upper Body Lower Body Rest Upper Body Rest Lower Body Rest
Week 3 Rest Upper Body Lower Body Upper Body Rest Lower Body Rest
Week 4 Upper Body Lower Body Rest Rest Lower Body Upper Body Rest

Again, all we’ve done is fiddle with the sequence of workouts. 

There’s one more example I want to share that involves a more extreme version of flexible programming: repeating the same workouts in the same order, but changing the days you train and your weekly workout frequency based on your schedule and how you feel.

For instance, if you have a particularly draining week at work, you could train only two days per week instead of three, and if you have more time and energy, you could train four or even five times per week. 

Here’s how this might look with a push pull legs workout routine: 

Monday Tuesday Wednesday Thursday Friday Saturday Sunday
Week 1 Push Pull Legs
Week 2 Push Pull
Week 3 Legs Push Pull Legs
Week 4 Push Pull Legs

This approach is very malleable, which cuts both ways. 

On the one hand, it tends to work very well for people following a fickle schedule, like shift workers, soldiers on deployment, or anyone while traveling. Your workout routine bends around your daily grind, but doesn’t break. 

On the other hand, if you’re prone to procrastination or overanalyzing, this much freedom can prove treacherous. (“I’ll have a better workout in another day or two or three,” “Is today really the most optimal time to train?” and so on).

Thus, I think this approach to flexible programming works best as a stopgap for navigating calendar kerfuffles rather than standard operating procedure.

What’s your take on flexible programming? Have you tried it before or do you plan on doing so? Let me know in the comments below!

+ Scientific References