It's great finding new workouts that can help derby athletes, check this one out from @thighs_ontheprize. This would he perfect to work on while in off season.
The thing I’ve most practiced these past 2 seasons are what I dub at h predator pose, which is so multiuseful in roller derby. Getting used to using your tricep in defensive blocking, using it in a bracewall or in a Tripod, getting used to holding pressure and getting your wingspan up for the most track covered is really intimidating and strong! Use those traps and your strength to catch a Jammer and rotate into positions. This is a pose I do for nearly all warm ups to get my muscle memory up, and then train in the gym against resistance for core strength. Give it a shot! #rollerderbytraining