... is very important for soccer players but is often overlooked.
The core is the bridge between the upper and lower body and consists of the abdominal and low back muscles, diaphragm, pelvic muscles, hip flexors, latissimus dorsi and the gluteal muscles. Together they stabilize the spine while moving the limbs.
During movements, the core transfers forces and power between the upper and lower body. The core needs to be solid to avoid energy leaks.
Worse, a dysfunctional core will put more strain on the limb muscles and tendons which could lead to overuse injuries.
Especially in soccer, where abrupt changes of direction and duels require a high degree of balance and body control, mandates a well conditioned core to stabilize the body's centre of mass. So a solid core helps to maintain a good posture, improves balance, enhances performance and prevents injuries.
To develop the core one has to do more than the usual crunches. Lots of exercise variety focussing on flexion, rotation, lateral flexion and the posterior core is needed.
The core can also be strengthened without isolating them. During push-ups, inverse rows, chop and lifts, Olympic lifts, and others, the core is highly activated to stabilize the body with proper form.