Nick and Rebecca Sperling are similar to many young couples in Nevada County. The two have been married for nearly five years and wed after just six months of courtship. Rebecca is a nurse at Sierra Nevada Memorial Hospital, and Nick was a carpenter but now relishes the role of the stay-at-home dad, taking care of their 22-month-old son. The thing that separates the Sperlings from most everybody else in Nevada County is what they do after the work day is done. Nick and Rebecca are both Mixed Martial Arts fighters who train and compete out of Grass Valley. Nick …