Those cuts defined in increments show when a person has very little fat in this area. If there is a layer of fat on top of muscle, the only way to get rid of it is through diet and cardiovascular exercise. Since you are skaters, you've got the cardio part down. Abdominal work can be done every day. During the season our suggestion is at least three times a week alternating machines and floor.
Abdominals are crucial to skating.
Once you improve you will be able to skate lower, stronger, longer and harder. Emphasis is on strength, smaller muscles and cutting up. All exercises should be done with good form. Instead of a given number of repetitions we like to combine several floor exercises and variations of them in a routine, linking them together for anywhere from 10 to 20 minutes depending on your fitness level. Place your right foot over your left knee and place your left hand behind your head.