By Jack Atkins, Home Gym Equipment Specialist · Updated 8 November 2026
A leg raise machine is a padded frame, usually called a captain's chair or vertical knee raise (VKR) station, where you support your weight on your forearms with your back against a pad and lift your knees or legs towards your chest. It's one of the most effective ab exercises you can do with equipment, and for home use it nearly always comes as part of a power tower, which adds a pull-up bar and dip handles to the same frame. This guide covers how to use one properly, the muscles it actually works, what to look for when buying, and the alternatives if you don't have the space.
The basic design hasn't changed in decades: two upright posts, a pair of padded armrests with handles at the front, a vertical back pad and, sometimes, a step to get on. You climb up, rest your forearms on the pads, grip the handles, and let your legs hang. From there you raise your knees or straight legs, then lower them under control.
Gyms call it a captain's chair, retailers often list it as a vertical knee raise station, and once a pull-up bar is bolted to the top it becomes a power tower. In the US, "Roman chair" is sometimes used for the same frame, which causes confusion because in UK gyms a Roman chair is the 45-degree back extension bench. If a listing shows someone hanging from their elbows, it's a leg raise station.
The forearm pads are what separate it from a hanging leg raise on a bar. Your grip isn't holding your body weight, so you can focus on the abs, and the back pad gives you a fixed reference that cuts down swinging.
Breathe out as you lift and in as you lower. If you find yourself pushing off with momentum on every rep, cut the set and rest.
The cue that matters most
Think "knees to chest, then tailbone up". Most people raise their thighs to parallel and stop, which turns the move into a hip flexor exercise. The small backward roll of the pelvis at the top is where your lower abs earn their keep.
Bent-knee raises are the starting point. A shorter lever is easier to control, so you can curl your pelvis properly and keep your back on the pad. Straight-leg raises lengthen the lever and load your abs and hip flexors much harder. Progress only once you can manage 3 sets of 12 to 15 strict knee raises; otherwise the straight-leg version usually becomes a swinging, back-arching mess.
If you'd like more ways to train the lower part of the stomach, our guide to lower ab exercises pairs well with this.
Swinging. Using momentum lets your legs fly up without your abs controlling them. Slow the lowering phase down and pause at the bottom with your legs still before each rep.
Stopping at parallel. Lifting your thighs only to horizontal is mostly hip flexor work. Keep going until your knees are close to your chest and your pelvis tilts.
Arching off the back pad. If your lower back peels away and arches as your legs drop, you've lost your brace. Reset, press into the pad and use a shorter range until you can control it.
Shrugging. Letting your shoulders creep up towards your ears puts strain on the neck and shoulders. Push down through your forearms so your neck looks long.
Rushing to straight legs. The straight-leg version looks impressive, but it's wasted if half the rep is swing. Earn it with strict knee raises first.
A simple starting plan: 3 sets of 8 to 12 bent-knee raises, two or three times a week, with 60 seconds' rest. Once you hit 3 sets of 15 cleanly, move to slow eccentrics or straight-leg raises. The NHS recommends muscle-strengthening activity on at least two days a week, and leg raises fit neatly at the end of an upper-body or full-body session.
Standalone captain's chairs are rare and expensive for home use, so most people buy a power tower. Here's what to check.
Weight capacity. Look for a stated limit comfortably above your body weight. Budget towers commonly list 150kg; sturdier ones list around 200kg. Listings can contradict themselves (our Sportsroyals power tower review found two different figures on one listing), so use the lower number.
Padding. The forearm pads and back pad take all the contact. Thin, hard foam gets uncomfortable over a few sets, and long armrests give taller users more room for their elbows.
Footprint and height. A wide base is more stable but needs space; a 100cm base is common on the steadier models. Measure your ceiling before ordering, because the pull-up bar on many towers sits at 220cm or more at full height.
Stability. Lighter frames rock when you swing or dip hard. Wider bases, more rubber feet and a heavier frame all help, and some owners rest a couple of weight plates on the base to settle it.
Multi-function value. A power tower that also handles pull-ups, dips and push-ups gives you a much better spread of upper-body training than a leg raise station alone, and usually for similar money. If you already own a squat rack with a pull-up bar, a dip station with a back pad may be all you need.
The Sportsroyals Power Tower (B07SM8VJ6P) is the steadier option. The listing gives a 204kg capacity, a 100cm-long base, a 28kg frame, six height settings and an adjustable back pad position for dips and knee raises. It was £159.99 at the time of writing. It's heavier and wider than budget alternatives, which is exactly what you want for leg raises without the frame walking across the floor.
Check the Sportsroyals Power Tower on Amazon£159.99The DH FitLife Power Tower (B09PGQ66NV) is the cheaper, more compact choice at £114.99 at the time of writing. It has a padded backrest, extra-long 42cm armrests, 10 height levels up to 230cm and an H-shaped base. The trade-off is a lower stated capacity of 150kg and a lighter frame (around 19kg), so it suits lighter users and controlled reps better than heavy dips.
Check the DH FitLife Power Tower on Amazon£114.99Neither has been through our hands; these picks are based on manufacturer specs, the Amazon listings and owner feedback. For a broader view of kit for the space, browse our home gym section.
Hanging leg raise. All you need is a pull-up bar. It trains your grip and shoulders as well as your abs, but swinging is harder to control without a back pad. Our hanging leg raise guide covers the form, and a pull-up bar is the cheapest way in.
Lying leg raise. Done flat on the floor or a bench, it needs no equipment at all and is a sensible first step for beginners. Press your lower back down and keep the range short enough that it doesn't arch.
Reverse crunch. A floor move that focuses on the same pelvic curl you're after on the captain's chair. See our reverse crunch guide.
Ab wheel. Very effective for the abs and needs a tiny amount of storage space. Start with our ab wheel rollout guide.
You'll see three names for roughly the same thing. A captain's chair is the gym term for a padded frame where you rest your forearms on armrests and lean your back against a pad while your legs hang free. A vertical knee raise (VKR) station is the same frame sold on its own, and a power tower is a VKR station with a pull-up bar and push-up handles added, which is what most home buyers end up with.
Yes. Hanging knee raises, the closest lab equivalent, were among the exercises producing the highest rectus abdominis and oblique activity in a 2006 study comparing traditional and nontraditional abdominal moves, outperforming the standard crunch and bent-knee sit-up. The catch is that your hip flexors work hard too, so you need to curl your pelvis at the top of each rep to make your abs do the finishing work.
Start with bent-knee raises. Bending your knees shortens the lever, so you can control the movement, curl your pelvis and avoid swinging. Move to straight-leg raises once you can do 3 sets of 12 to 15 strict knee raises; the longer lever makes them considerably harder, and it's easy to let your hip flexors take over if you rush the progression.
Plan for a footprint of about 100cm by 100cm for a wide-base model, plus clear space around it to step on and off. Height matters more than people expect: many towers top out at 220cm to 235cm, and a typical UK ceiling is around 240cm. If you only want the leg raise station, the armrests sit much lower, but you still need headroom for the pull-up bar on a combined unit.
For most people, yes. Your forearms carry your body weight on the pads, so grip strength stops being the limit, and the back pad stops you swinging. That makes it a better starting point for beginners and a good way to train high reps. A free-hanging leg raise asks more of your grip, shoulders and core stability.
For most people 3 to 4 sets of 8 to 15 controlled reps, two or three times a week, is plenty. Stop the set when you start swinging or can't curl your pelvis at the top. Once 15 strict reps feel easy, progress to straight-leg raises or slow the lowering phase to 3 or 4 seconds rather than chasing 30 sloppy reps.
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