Core strength plays a supportive, albeit critical, role in locomotive sports like skimo racing. That role is to provide a stable platform from which the arms and legs can perform their locomotive functions. While core exercises are basic and not necessarily sport specific, they can provide a needed base of support for sport-specific training.
To develop core strength is often challenging because you first need to learn how to engage some very deep muscles that are primarily used to stabilize the spine, hips, and shoulders and not for locomotion. This makes them hard to access and notice. These guys aren’t moving big joints through big angles like the quads, for instance, so don’t get discouraged with slow progress. It’s normal.
The core muscles, especially the deep stabilizers, are mainly made up of slow twitch fibers. This imbues them with a lot of endurance but not a lot of strength. Increasing their strength even a little can make a big difference for most people, and especially athletes.