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Smith machine ab exercises: Bent knee hip raise, crunch, hanging leg raises and more!

By Lee Thomas
Last Updated on 8th July 2020

I don't care what the gurus say, direct ab training should be part of any Smith machine workout program.

man performing behind the back shrugs

While some people think that weighted ab training will make their midsection look blocky, this simply isn't the case. In fact, the only thing that'll give you a thick waist is excess fat...oh, and growth hormone. But let's not go down the whole roid rabbit hole today.

Instead, let's check out the most effective Smith machine ab exercises for sculpting a chiselled core.

Top 7 Smith machine ab exercises

1. Smith machine crunch

Main muscles: Upper rectus abdominis, transverse abdominis

Performing an ab crunch on Smith machine stations is one of the best ways to overload your rectus abdominis and make your six-pack more pronounced. This exercise was actually created by Jim Stoppani (creator of Pre-JYM), and it's by far my favourite mass-builder for the abs [1].

Step 1: Lie on a bench with your feet together.

Step 2: Centre the bar over your upper abs and grab it with a shoulder-width grip.

Step 3: Draw your belly button towards your spine (pre-stretches the abs).

Step 4: Crunch up with the bar by contracting your abs. Make sure that your shoulder blades come off the bench.

Step 5: Hold the contraction for a second and then lower the bar under control by stretching your abs. Repeat for 2-4 sets of 8-10 reps—and always lift explosively.

2. Smith machine sit up

Main muscles: Rectus abdominis, transverse abdominis

The sit-up is one of the most effective Smith machine core exercises for building more blocky abs. It's essentially the same as the Smith machine crunch, except that you're performing the movement on an ab mat rather than on a bench. As such, it's great for time-pressed people (or for when you can't get a bench). [2]

Step 1: Lie in the sit-up position—back flat, eyes looking straight up, feet shuffled close to your hips.

Step 2: Set the bar so that when your arms are extended overhead (while laying down), you can easily grab it.

Step 3: Grab the bar firmly and then crunch up with your abs until there's roughly a 90-degree angle at your hips.

Step 4: Hold the contraction for a second and then lower yourself down to the ground until your back is completely flat—repeat for 2-4 sets of 8-10 reps.

3. Smith machine bent knee hip raise

Main muscles: Lower rectus abdominis, transverse abdominis

This exercise has many different names: Smith machine leg lifts, Smith machine knee raise, Smith machine hip raise. Anyway, the idea is to raise your hips and legs off the ground using nothing more than your abs.

It sounds easy in theory, but many people let their hip flexors take over—or worse, they use momentum to swing their legs back. However, by initiating each rep with your abs, you can ensure that your six-pack muscles are doing all the work.

Step 1: Set the bar to the lowest position.

Step 2: Lie in the sit-up position with your head a good few inches away from the bar.

Step 3: Garb the barbell with an underhand grip. This allows you to maintain your stability so that you can focus purely on working your abs.

Step 4: Straighten your legs out and then raise them a couple of inches off the floor.

Step 5: Tuck your knees towards your chest and then raise your hips off the ground until your thighs are hovering over your chest—avoid using momentum to achieve this position. Remember, your legs only move as a consequence of you contracting your abs.

Step 6: Lower your hips and legs back down to the ground, straightening your legs out in the process. Repeat for 2-4 sets of 10-15 reps and perform the exercise with straight legs once you become proficient at the bent-knee variation.

Also consider using ankle weights to increase the challenge. With the extra resistance, it makes a great Smith machine hip raise alternative.

4. Smith machine hanging leg raise

Main muscles: Lower rectus abdominis, transverse abdominis

Grip giving out during hanging leg raises? Then try doing hanging leg raises on Smith machine stations instead. This uncommon Smith machine leg raise takes the pressure off your wrists and shoulders while making it easier to activate your abs by allowing for more precise isolation [3].

Step 1: Set the bar to upper chest height and place a thick bar pad on the middle of the barbell.

Step 2: Place the back of your upper arms onto the pad and then cross your arms as if you were setting up for a front squat.

Step 3: Place all of your weight onto the bar and bend your knees slightly. Make sure that your back is straight and that you have a forward eye gaze.

Step 4: Raise your legs and hips upwards by crunching your upper and lower abs together.

Step 5: Keep going until your hips curl forwards and then lower your legs under control. Repeat for 2-4 sets of 10-12 reps before adding weight.

If the leg raise variation is too hard, then you can also do the Smith machine hanging knee raise. This version reduces the resistance because the moment arm is shorter (your legs don't have to travel as far).

5. Smith machine reverse crunch

Main muscles: Lower rectus abdominis, transverse abdominis

Besides using ankle weights, performing the reverse crunch on Smith machine systems is one of the most convenient methods for adding resistance to this traditionally "bodyweight-only" ab exercise.

Step 1: Set the safety catches about halfway down the Smith machine—make sure that they're positioned well above your torso.

Step 2: Lie on a bench and position your midfoot (of both your feet) against the bar.

Step 3: Push the bar up by lifting your hips off the ground via an ab contraction. Don't try to leg press the bar, let your abs take the strain.

Step 4: Pause for a good second in the contracted position and then lower your hips back down onto the bench. Repeat for 2-4 sets of 10-15 reps.

The setup will feel a bit tricky at first. But you'll soon learn why this is one of the most effective Smith machine lower abs exercises after a while.

6. Smith machine oblique side bend

Main muscles: Obliques

When you're training abs Smith machine style, it's easy to forget about the obliques. After all, everyone wants to add mass to their six-pack muscles to make them more prominent. However, the obliques are a critical muscle group for both aesthetics and core strength. When developed, they give you those "v-lines" and make your waist look more streamlined.

Step 1: Set the bar to just below hip height.

Step 2: Stand side on to the bar inside the machine.

Step 3: Grab the bar one-handed with a neutral grip.

Step 4: Place your other hand on your head or hip for balance.

Step 5: Lower the bar down by stretching your oblique (bending your waist), while keeping your hips as still as possible.

Step 6: Come back up just past the starting position by contracting your oblique. Repeat for 12-15 reps

7. Smith machine decline sit up

Main muscles: Upper rectus abdominis, transverse abdominis

Try the decline sit-up if you want to spice up your Smith machine ab workouts with some intensity. The form is exactly the same as on the regular sit up. However, this advanced exercise is much harder than the vanilla version since your abs start in a highly stretched position (muscles are weakest when they're highly stretched or contracted).

Step 1: Lie on a decline bench and grab the Smith bar with a shoulder-width grip.

Step 2: Explode up with the bar by contracting your abs forcefully. Stop once there's (roughly) a 90-degree angle at your hip joint. You know that you've come high enough when you feel your abs tense up.

Step 3: Hold the contraction for a full second and then lower your torso back down onto the bench. Repeat for 2-4 sets 10-15 reps, and start off with a moderate decline.

Smith machine ab exercises: Are they legit?

Performing an ab workout Smith machine style is not only fun, but it's also an incredibly effective way to build more visible, blocky abs.

Plus, you can save yourself a ton of time by doing your entire ab workout on the Smith machine. So there's really no excuse to have underdeveloped core muscles these days.

young man performing barbell squats

I personally work my abs after legs and back because my core is already slightly fatigued after training those muscles. But you can train them after any body part—or on their own separate day if abs are a weak muscle group for you [4].

What're your favourite Smith machine ab exercises?

Let me know in the comments. I'm always interested to hear how other people sculpt their six-packs!

Lee Thomas
Ey Up! I'm Lee, a Leeds-based strength and conditioning coach who's been helping serious trainees achieve their physical potential for the past 20 years. In my time, I've been a competitive physique athlete and a national powerlifter. I hope you enjoy my exercise guides.
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