Straight Arms V-Up
Also known as: straight arm jackknife
In SetGrip: V-Up (Straight Arms)
- Primary muscleAbs
- EquipmentBodyweight
- DifficultyIntermediate
- TypeCore · Core flexion
- Secondary muscles
- Hip Flexors, Quads
- Body part
- Core
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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Reaching straight arms overhead while your extended legs rise to meet your hands creates the longest lever this family offers, and the quads have to hold the legs rigid the entire time. Compare it with the bent-knee V-up when it proves too much; shortening either the arms or the legs immediately makes the movement more forgiving.
How to do the Straight Arms V-Up
- Lie flat on your back with your legs extended and arms straight above your head.
- Engaging your abs, lift your upper body off the ground while simultaneously lifting your legs towards your chest.
- Reach your hands towards your toes as you lift your upper body and legs.
- Pause for a moment at the top, then slowly lower your upper body and legs back down to the starting position.
- Repeat for the desired number of repetitions.
Tip: Reach the hands forward along the thighs and think of peeling the spine off the floor from the top down.
Muscles worked
Primary
Abs · Core
The abs curl the torso off the floor and then control it back down, and they do the most work in the first 30 degrees of the movement before the hip flexors take over.
Secondary
- Hip Flexors — The hip flexors pull you the rest of the way up once the abs have curled the ribs, and they will dominate if the feet are anchored and the range is rushed.
- Quads
Common mistakes
- Yanking the neck — hands behind the head should support only; keep the elbows wide or cross the arms on the chest.
- Jerking up flat-backed — the spine should curl up one segment at a time starting from the head, not lift as a rigid board.
- Dropping back down — the lowering half is where the abs work hardest, so take two or three seconds to come down.
- Anchoring the feet — this lets the hip flexors do everything; if you must anchor, keep the knees bent and focus on curling the torso.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Strength | 3 × 8–12 | 60 s |
| Endurance | 2–3 × 15–25 | 45 s |
Sit-ups go at the end of a session with the other core work. Superset them with a back extension to balance the front and back of the trunk.
Variations and alternatives
Similar exercises
Without bodyweight
Frequently asked questions
What muscles does the Straight Arms V-Up work?
The Straight Arms V-Up primarily works the abs. It also involves the hip flexors and quads, which assist the movement and stabilise the joints.
Is the Straight Arms V-Up good for beginners?
It is rated intermediate, so it suits people who already train regularly. Beginners can still do the Straight Arms V-Up with light load and a spotter or coach watching the first few sessions; if it feels awkward, pick an easier variation from the alternatives below first.
What can I do instead of the Straight Arms V-Up?
If you cannot do the Straight Arms V-Up, try the Bent Knee V-Up, the V-Up or the Decline Sit-Up. Each of them trains the abs through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Straight Arms V-Up, a sensible starting point is strength: 3 × 8–12 with 60 s rest; endurance: 2–3 × 15–25 with 45 s rest. Train it at the end of a session or pair it with a lower-body lift as active rest.
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