The leg tuck is a challenging, full-body exercise performed on a pull-up bar, designed to test upper body strength and core stability. It requires the participant to hang from the bar and dynamically contract the abdominal muscles and hip flexors. The movement involves simultaneously bending the elbows and tucking the knees upward until they make contact with the elbows or upper arms. Completing a repetition demands significant grip endurance and core strength.
Step-by-Step Guide to Proper Form
The exercise begins from a straight-arm, active hang position on a pull-up bar, engaging the shoulders by pulling the shoulder blades slightly down and back. A common grip is the alternating grip, where one hand faces forward and the other faces backward. This position helps stabilize the body and limits rotation during the lift.
To initiate the repetition, the hips and knees flex while the elbows bend, creating a simultaneous pulling and tucking motion. Looking up toward the bar encourages a slight lean back, which helps align the torso for a more efficient tuck. The repetition is successful when the knees or upper thighs make contact with the corresponding elbows or upper arms.
After achieving contact, the body must be lowered with control back to the starting position. Avoid dropping rapidly or relaxing into a dead hang. Maintaining active tension in the shoulders and core throughout the descent prepares the body for the next repetition and prevents excessive swinging. The body must return completely to the straight-arm hang position before beginning the next repetition.
Primary Muscle Groups Engaged
The leg tuck is a compound movement recruiting various muscle groups for the upper body pull and the lower body tuck. The upper body relies heavily on the forearm muscles for grip endurance. The latissimus dorsi (lats) are the primary drivers of the initial pull, working alongside the biceps to flex the elbow and raise the torso.
The abdominal muscles execute the tucking motion; the rectus abdominis and obliques work intensely to flex the trunk. Hip flexors, including the iliopsoas, are also engaged to lift the legs toward the torso. These core and hip muscles must coordinate with the upper body to curl the body into the required position.
Context and Scaling the Exercise
The leg tuck gained attention due to its inclusion in the U.S. Army Combat Fitness Test (ACFT) as a measure of muscular strength and endurance. Its presence in standardized testing highlights its effectiveness as a challenging, full-body assessment requiring combined pulling and core power. The exercise simulates movements needed for climbing and maneuvering over obstacles.
Regression
For those who cannot yet perform a full repetition, the exercise can be regressed to build the requisite strength. Modifications like the hanging knee raise, where the knees are simply brought toward the chest without touching the elbows, are excellent for building core endurance. Another option is focusing on the eccentric (lowering) phase of the movement, which involves jumping up to the top position and controlling the descent as slowly as possible.
Progression
Conversely, individuals seeking a greater challenge can progress the movement to exercises like the toes-to-bar or L-sits. The toes-to-bar requires the legs to remain straight and lift all the way to the bar, increasing the lever length and difficulty. L-sits involve holding the legs out straight at a 90-degree angle while hanging, which builds static hold strength necessary for overall body control.