Weighted Decline Sit-Up (Arms Straight)

The Sit-Up is a 'classic' abdominal exercise (see technique). The exercise contains two important elements: rounding the back and bringing the upper body upward.

The rectus abdominis (the basis of the 'six-pack') draws the sternum toward the pelvis by rounding the back.

The rectus femoris brings the thigh toward the pelvis and the lower part of the spine, and vice versa. It is a so-called hip flexor and, in a standing position, brings the thigh forward from the hip joint. In the lying position of the Sit-Up, this brings the entire upper body toward the legs. The weaker sartorius assists the rectus femoris. Shorter muscles connecting the pelvis to the thigh, the psoas major and iliacus, also play an important role in flexion from the hip.

The oblique abdominal muscles on the sides stabilize the core throughout the exercise by resisting lateral tilting and rotation. The transversus abdominis (beneath the oblique abdominal muscles) draws the abdominal wall inward and thus acts as a natural weightlifting belt to stabilize the core.

The reclined position ensures that tension is maintained for longer throughout the movement. In this variation, you add extra weight by holding a weight plate. This can be done with straight arms, or with the weight plate (high) against the chest. Keeping the arms straight requires the shoulders to engage.

Weighted Decline Sit-Up (Arms Straight)

Active muscles:

Abdomen:

Rectus abdominis (straight abdominal muscle)
Obliquus externus abdominis (external oblique muscle)
Obliquus internus abdominis (internal oblique muscle)
Musculus transversus abdominis (transverse abdominal muscle, or 'corset muscle')

Pelvis:

Psoas major
Iliacus

Legs:

Rectus femoris
Sartorius

Execution:

Remove any weight plate from the rack.
Lie down with the weight plate on the decline bench and make sure your lower legs are firmly secured between the leg pads.
Extend your arms with your hands at chest height. This is your starting position.
Bring your chest toward your pelvis by contracting your abdominal muscles. Focus on curving the spine (rounding the back). Keep looking upward to prevent your neck from curving along with it. Your upper back has now lifted off the bench.
In a smooth movement, continue raising the rest of your upper body until you feel little resistance.
Slowly bring your upper body back down and backward.
Stretch your back until you almost touch the bench.

Notes:

For a six-pack or injury prevention?

Strong abdominal muscles are indispensable for a strong core and preventing, among other things, lower back complaints. In practice, many people mainly perform abdominal exercises for a better-looking abdomen. Often with a flat stomach or six-pack as the ultimate goal. In most cases, you do not need to perform abdominal exercises for a flat stomach or six-pack. These are mainly caused by a low body-fat percentage. You cannot specifically burn fat in the abdominal region, not even with abdominal exercises. So, as the old saying goes, you mainly build a six-pack in the kitchen.

At a low body-fat percentage, abdominal exercises can make a visual difference. Thicker muscle bellies in the rectus abdominis then create deeper lines in the abdomen. However, the abdominal muscles are used and therefore trained during many different exercises and daily activities. For most people, a low body-fat percentage is therefore enough for a six-pack. In some exceptional cases, the muscle bellies (the 'blocks') in the rectus abdominis are so flat that they are barely visible, even at a low body-fat percentage. Very superficial tendons between the muscles and a linea alba dividing the muscle bellies can also contribute to this. In those cases, performing abdominal exercises for appearance may be worthwhile.

Sit-Ups or Crunches?

As mentioned, you can divide the Sit-Up into two movements. In the second part of the movement, the aforementioned muscles in the legs and pelvis play an important role. Sit-Ups are often performed for stronger or better-looking abdominal muscles. The Sit-Up also places a higher load on the spine, while the abdominal muscles themselves work less hard than during a Crunch. In this case, 'a classic exercise' therefore partly means 'outdated'. Sit-Ups have lost considerable popularity in favor of the Crunch, which is effectively only the first part of the Sit-Up.

At a glance