The bridge is frequently compared to the deadlift in terms of which muscles the exercises work, and as such the bridge could be considered the bodyweight exercise equivalent to the weight training deadlift. Just like its weight training counterpart, the bridge primarily works muscles which are part of the posterior chain, but also many important muscles of the anterior chain. A major difference between these two exercises is that the bridge tends to emphasise the upper, superior portion of the posterior chain, while the deadlift in turn heavily empasises the lower, inferior portion of the posterior chain. The following list of muscles only includes the largest and most significant muscles worked in the movement, and is not exhaustive.
Spinal erectors
The erector spinae muscles are the ones primarily worked during bridging. These muscles stretch all the way down the spine and work to extend the spinal column when they contract. The spinal erectors are also considered to be the posterior core muscles, and counteract the contraction of the rectus abdominis in order to stabilise the core region during bridging.
Rectus abdominis
The rectus abdominis, colloquially the abdominals or "abs", works to counteract the contraction of the spinal erectors in order to stabilise the core region.
Deltoids
An effect which is almost unique to the bridge is that it works the posterior head of the deltoideus muscle, being the only common compound exercise to do so with the exception of the weight training row.
Gluteal muscles
Similar to the deadlift, the bridge also works the gluteal muscles which work to extend the spine as well as the femur.
Hamstrings
The second large muscle group primarily worked by the bridge, although with less emphasis than the deadlift, are the hamstring muscles. They extend from the ischial tuberosity of the pelvis to the heads of tibia and fibula, and work to flex the knee joint.
Quadriceps
Just like with the core muscles, the quadriceps muscles work to counteract the contraction of the hamstring muscles in order to stabilise the femural region.
Variations
The bridging exercise is not a singular movement, but includes a wide range of variations and progressions. There is no single agreed upon "standard" variation of the bridge like with other common bodyweight exercises.
Bridge hold
The bridge hold is a static variation of the bridge exercise that involves getting into the full bridge as shown at the top of the article and holding the position, either for time or until exhaustion. This variation is possibly the most frequent variation of the bridge around the world, but is most commonly used in Calisthenics circles to build strength in order to progress to some of the more difficult bridge variations.
Bridge push-up
The bridge push-up involves lying on the ground on the back with the feet pulled up to the buttocks and palms of the hands against the ground on either side of the head, followed by "pushing" the entire body upwards with both arms and feet. The practitioner then pulls the body back to the original position and repeats the whole movement for a set amount of repetitions, or until exhaustion. This is also one of the ways to get into the bridge hold position, along with the closing bridge below.
One-armed bridge push-up
A great amount of further difficulty can be introduced to the regular bridge push-up by executing the movement only supported by one arm. This also introduces unilaterality to the movement, primarily working only one side of the spinal erectors, and especially only one of the deltoids.
One-legged bridge push-up
Just like above, the bridge push-up can also be executed with one leg extended. When this is done, not only is unilaterality introduced, but the hamstrings and glutes are worked far more.
Wall walking
Wall walking is another popular bridge variation that involves standing with one's back to a wall at a varying distance, followed by leaning backwards until one can press one's palms into the wall from behind. The practitioner then proceeds to "walk" with their hands along the wall all the way down to the floor. To make the exercise more difficult, one can also finish the movement by proceeding to "walk" all the way back up again, then pushing off the wall with the arms back into the original standing position. This can be done for several repetitions.
Closing bridge
The closing bridge involves standing straight up with varying foot distance, then slowly leaning further and further backwards with the arms reaching back, until one comes all the way down into a standing bridge. This is the typical way that gymnasts go into the bridge hold position above, but is also an excellent strength exercise in itself when done for multiple repetitions.
Stand-to-stand bridge
This variation is considered by some to be the most advanced variation of the bridge, and is by far the one that requires the most strength. It involves performing a full closing bridge as above, followed by "opening" the bridge again by either pushing off the floor with the arms or coming back into standing position relying solely on the muscles in the torso and legs. Furthermore, unilaterality can be introduced to this variation by performing the whole movement with only one arm.
