Sergi Constance Abs Workout: The Exact Superset in His Routine

Sergi Constance's abs workout is short and specific: a floor or cable crunch in a superset with knee raises, 4 rounds of 20 reps each, done at the end of both pull days in his 6-day split. When you complete every rep, you add 2 reps per set next time.

That's the whole block. No 15-exercise ab circuit, no daily sit-ups. Below is how to run each exercise properly, why it's enough, how it progresses, why abs only show at low body fat, and an optional extended version from our team for those who want more.

The exact ab block in Sergi's routine

One set of crunches, straight into one set of knee raises, then rest about 60 to 90 seconds. That's one round; do four. Abs come last in the session on purpose: your trunk has been bracing through chin-ups, barbell rows and back extensions, and you don't want it tired before those lifts. The rest of the pull day is in the full Sergi Constance workout plan.

Across the week that's 16 hard sets for abs (8 per session, twice a week), which sits inside the 10 to 20 weekly sets per muscle that research points to for most lifters.

Why these two exercises

The rectus abdominis, the "six-pack" muscle, does one main job: it flexes the spine, pulling your ribs and pelvis toward each other. The two exercises attack that from opposite ends.

• Crunch: the ribcage moves toward a fixed pelvis. Top-down flexion.
• Knee raise: the pelvis moves toward a fixed ribcage. Bottom-up flexion, done right.

Pairing them in a superset means 40 reps of spinal flexion per round from two angles, with no time wasted between them.

How to do the crunch right

Floor crunch

• Lie on your back, knees bent, feet flat. Hands lightly at your temples or crossed on your chest, never pulling on your neck.
• Exhale and curl your ribcage toward your hips. Think about rolling up one vertebra at a time, not sitting up.
• Your lower back stays on the floor. The range is short; the squeeze at the top is the point.
• Lower under control. Don't let your head drop and bounce.

Cable crunch

• Kneel facing a high pulley with a rope, hands holding the rope by your head.
• Keep your hips still and crunch your elbows toward your knees by rounding your spine.
• The most common mistake: sitting back onto your heels and turning it into a hip hinge. If your hips move, the weight is too heavy.

The floor version is the simpler starting point. The cable version lets you add load, which matters once 20 reps get easy.

How to do knee raises right

You can do them on a dip station (back against the pad, forearms on the arms) or hanging from a pull-up bar. The dip station is more stable; hanging also asks a lot of your grip.

• Start with your legs straight down and your body still. No swinging.
• Bring your knees up toward your chest, and at the top tilt your pelvis up, curling your tailbone forward. That last part is what turns it into an ab exercise.
• If your knees just come up to hip height and stop, the hip flexors are doing the work and your abs are mostly along for the ride.
• Lower in about two seconds. Dropping fast and rebounding makes reps easier and less useful.

Using it without the full split

If you train on a different schedule, you can still use this block as is. Put the superset at the end of two sessions a week, with at least one day between them, so the abs get roughly the same 48 to 72 hours of recovery they get in Sergi's plan, where the two pull days are three days apart. Keep it at the end of the session, not the start, for the same reason as above: a tired trunk makes heavy squats, rows and deadlifts less stable.

Two practical details. Breathe out on the way up on both exercises; exhaling helps you pull the ribs down and get a harder contraction. And if your grip gives out before your abs on hanging knee raises, switch to the dip station or use straps, so your forearms aren't what ends the set.

How to progress

The rule in Sergi's plan is simple: once you complete all 4 sets of 20, add 2 reps per set next session.

If you can't yet do 20 clean reps, do as many as you can with good form in each set, and work toward 20 before you start adding. Clean reps beat sloppy ones every time.

Why abs only show at low body fat

Everyone has abs. Whether you can see them depends on how much fat sits on top. You can have strong, well-developed abs that stay hidden under a layer of fat, and no amount of crunches will burn that specific fat off.

That's been tested. In a 2011 study, Vispute and colleagues had one group do ab exercises for six weeks and compared it with a group that didn't. The ab-training group got better ab endurance, but its belly fat didn't drop significantly more than the other group's. Spot reduction doesn't work: you lose fat across the whole body, and where it comes off first depends largely on genetics.

So the honest formula for visible abs has two parts:

1. Build the muscle: train abs hard and progressively, which is what this block does.
2. Lower body fat: a calorie deficit of about 300 to 500 kcal a day, or roughly 0.5 to 1% of body weight lost per week, while eating 1.6 to 2.2 g of protein per kg of body weight (about 0.7 to 1 g per lb) to hold on to muscle.

The exact body-fat level at which abs show varies a lot from person to person. Don't chase a number; watch the mirror and the trend over weeks. In Boost, the diet is set for each person based on their goal, so a cutting phase is planned around your numbers, not someone else's.

Optional extended version (Boost Team suggestion)

Do Sergi's superset as written, then add one or two of these on the same pull days:

Keep the extended version to 2 extra exercises at most. More ab volume doesn't make abs show sooner, and fatigue from it can carry over into your next leg day, where you need a stable trunk under a heavy hack squat.

Common mistakes

• Pulling on your neck during crunches. Hands support the head; the abs do the lifting.
• Swinging on knee raises. Momentum takes the abs out of it. Start every rep from a dead hang.
• Training abs every day hoping for faster results. Twice a week, hard, beats daily and half-hearted.
• Expecting crunches to fix the diet. They won't. Body fat decides visibility.

Abs are only one piece of the pull days. If you want the arm work that comes right before them, see Sergi Constance's arm workout.