5/3/1 Boring But Big vs First Set Last: Which Supplemental Template to Run

Short AnswerBoring But Big and First Set Last are the two standard supplemental templates in Jim Wendler's 5/3/1 - the block of volume work done after the main 5/3/1 sets. BBB is 5x10 of the same lift at 50% of your Training Max and is the hypertrophy choice: high volume, high recovery cost, best when eating enough to grow. FSL repeats the week's first work-set percentage (65/70/75% TM) for 5x5, giving heavier barbell practice at much lower fatigue - the better pick for a strength focus, a cut, or tight recovery. Both are legitimate; pick by goal and switch cycle to cycle as your goal changes.

In this article

What supplemental work is in 5/3/1

Every 5/3/1 session has three layers: the main work (three ascending sets of the day's lift, the last one an AMRAP), supplemental work (a bigger block of the same barbell lift for volume), and assistance (25-50 easy reps of chin-ups, rows, leg raises and the like). The main work is fixed. The supplemental slot is where the templates differ, and Boring But Big and First Set Last are the two Wendler templates almost everyone runs. All percentages in both are of your Training Max - 90% of your 1RM - never of your true max.

BBB vs FSL: the spec side by side

The two supplemental templates compared
	Boring But Big (BBB)	First Set Last (FSL)
Sets x reps	5x10, same lift as the main work	5x5 standard (3-5 sets of 5-8 also works)
% of Training Max	50% classic; 60-70% variants for advanced lifters	The week's first work-set percentage: 65 / 70 / 75%
Weekly rep count	50 supplemental reps per lift	~25 supplemental reps per lift
Goal	Muscle size and work capacity	Strength and barbell practice at working weights
Recovery cost	High - the squat and deadlift days are genuinely hard	Moderate - sustainable on lower calories or sleep

When BBB is the right call

BBB exists to make you bigger. Fifty reps of squats after your main squat work is a blunt hypertrophy instrument, and it works precisely because it is boring: same lift, easy weight, no decisions. It also builds work capacity that pays off later at heavier percentages. Run BBB when size is the goal, calories are at maintenance or above, and you can afford the soreness. Start at 50% TM even if it looks light - across five sets of ten it isn't, and the 60-70% variants are for lifters who have already handled 50% comfortably for multiple cycles.

When FSL is the right call

FSL keeps the bar heavy enough to feel like your work sets - 65-75% TM instead of 50% - so every rep is practice for the main lifts, at half the rep count. That makes it the default when strength is the priority, when you are cutting calories and cannot recover from 5x10 squats, or when life stress and sleep are working against you. You give up some size stimulus; you keep the skill work and most of the strength signal, and your week 3 AMRAP sets tend to stay strong because you are less beat up walking into them.

A useful rule of thumb: BBB when the scale should go up, FSL when it should go down or recovery is tight. If you are unsure, FSL is the safer default - it is much easier to add volume next cycle than to dig out of three weeks of under-recovered 5x10 squats.

Switching between them cycle to cycle

Supplemental templates are modular: the main 5/3/1 work, TM increments and week-4 deload stay identical, so you can swap BBB for FSL between any two cycles with zero transition cost.
A classic pattern is seasonal: BBB cycles while building through winter, FSL cycles while cutting for summer.
Another is blocks: 2-3 cycles of BBB for size, then 1-2 cycles of FSL to acclimate to heavier weights before testing rep PRs.
Whatever you pick, keep it for the whole cycle - judging a template on one hard week tells you nothing.

Frequently Asked Questions

Can I run BBB for upper body and FSL for lower body?

Yes, and it is a popular hybrid: 5x10 bench and press for size where recovery is cheap, 5x5 FSL squat and deadlift where 5x10 hurts most. It keeps the program's structure intact, so nothing else changes.

Is 5/3/1 BBB better than a bodybuilding split for size?

For a lifter who wants to stay strong, usually yes. BBB gives you 50 hard reps of the big lifts plus progressive main work, while a typical bodybuilding split spreads effort across many isolation moves with no strength backbone. If pure physique is the goal a dedicated split can win, but BBB builds size you can measure on the bar.

Should I run FSL or BBB while cutting?

FSL. In a calorie deficit the extra 25 reps per lift of BBB mostly buys soreness you cannot recover from. FSL keeps intensity high and volume moderate, which is exactly what preserving strength on a cut requires.

Can I do FSL as one AMRAP set instead of 5x5?

That variant exists (often called FSL AMRAP): one all-out set at the first work-set weight, stopping 1-2 reps short of failure. It is quicker but easier to overdo - the standard 5x5 is the better default and much easier to progress consistently.

The 5/3/1 Boring But Big routine is free in Hardy, with every main and supplemental set calculated from your Training Max - and if you switch to FSL for a cycle, editing the percentages takes seconds, not a new spreadsheet.

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