Beyond the traditional sit-ups and crunches, learn about 4 valuable core strengthening exercises. From the NSCA’s Performance Training Journal.

The core is a key component in building an athletic base. Many common misconceptions of how to activate the core can lead to wasted time and possible injury. Targeting specific muscle groups effectively can build core endurance, increase strength, and reduce injury. 
A majority of athletes describe core exercises as “doing crunches or sit-ups.” While these exercises do activate muscles in the core, they are not necessarily core exercises. The core can be considered the surrounding muscles that support your spine, provide stability, and help generate power during athletic movements. They consist of not just a specific muscle group, but a multitude of muscles that work together to provide optimal support and function. The primary muscles consist of the rectus abdominis, internal oblique, external oblique, erector spinae, latissimus dorsi, transverse abdominis, iliocostalis, and multifidus. In order to activate these muscle groups, one must perform a variety of exercises that target the muscles efficiently. Athletes must also be aware that traditional “core” exercises (e.g., crunches) may increase injury risks. Following the exercises below may help reduce those risks.
There are four important exercises that can be integrated into any practice or workout that provide core activation. These exercises are the curl-up, alternating quadruped, lateral bridge, and plank. The curl-up (Figure 1) is a modified version of a traditional crunch. Electromyography studies have shown that the rectus abdominis, internal obliques, and external obliques are activated during a curl-up with limited hip flexor activation, which can overcompensate during a traditional crunch (1). Research has also found that the curl-up minimizes spinal loading when compared to a traditional crunch or sit-up (1,2). To begin a curl-up, lie supine with the hands supporting the low back. Bend the knees so that the feet are flat. Concentrate on contracting the abdominal wall and bending the thoracic spine without bringing the neck or chin forward. Leave the elbows on the floor and slowly lift the head and shoulders off the ground a few inches. Slowly return by eccentrically using the core muscles, which studies have shown is a great benefit to core strength (3). 

Figure 1. Curl-Up 
Figure 1-Curl-Up

The alternating quadruped exercise (Figure 2) concentrates more on developing the back extensors while minimizing loads on the spine (1). The alternating quadruped exercise begins in the position of all fours. Begin the exercise by raising one arm straight and simultaneously extending the opposite leg until they are both parallel with the floor. Return to the starting position in a controlled manner and repeat on the opposite side. It is important to concentrate on controlling body position and not let the hips hike, rock anteriorly, or rock posteriorly. It is recommended that a coach be used the first few times to monitor any excess motion and help correct poor technique.  

Figure 2. Alternating Quadruped

Figure 2-Alternating Quadruped

The lateral bridge (Figure 3) is another important core exercise that targets the internal and external obliques (1). There is also a component of shoulder stabilization, but in certain athletes, this can cause discomfort. The starting position of the lateral bridge begins with the athlete on their side, forearm and elbow on the ground, and the feet slightly staggered. From this position, pick the hips and legs off the ground, keep the hips extended, and minimize rotation of the torso. If shoulder pain occurs, try the exercise with the knees bent, or add a soft pad under the forearm/elbow.  

Figure 3. Lateral Bridge
Figure 3-Lateral Bridge

The last important core exercise is the plank (Figure 4). The plank can target a variety of core musculature including the rectus abdominis, internal/external obliques, latissimus dorsi, erector spinae, deltoids, and triceps. The plank position begins with the forearms on the ground beneath the shoulders. Athletes should be on their toes and lift the stomach, pelvis, and legs off the ground. The upper and lower body should be completely straight like a plank of wood. Again, it would be appropriate to have a coach present to help correct any problems such as lumbar extension or flexion of the torso or hips. Athletes can place padding under the forearms if there is irritation from the floor or ground.

Figure 4. Plank
Figure 4-Plank
Adding these four core exercises to any routine will help ensure that athletes are working the correct core muscle groups. It can also help prevent unwanted forces through the spine, which can cause pain or injury in the future. It is important to remember that endurance is an important factor for training the core (1,2). It is also important to remember that each individual is different and that these exercises may not be appropriate for every athlete.