Roller derby training camp will test your fitness.
Try to spend 30 minutes/5 days a week doing some type of cardio activity.
Strength training is great! You will need strong legs and core. Squats, lunges, calf raises and wall sits will help with legs. Planks, crunches and pushups will help your core. Don’t neglect the upper body, you will need that strong for your balance. (Check out the off-skates training