Prone Sliding

[Steve]

In the case of sliding while prone, such as running/jumping and then doing a baseball-style slide or a "John Woo Dive" that ends in a slide, would that sliding distance be determined by another movement rate like Running or Leaping? How far could a character slide if they used Leaping to push off from a wall and try to slide across muddy ground or grass?

[Steve Long]

Pages 220-23 of The Ultimate Speedster have rules for Controlled and Uncontrolled Movement, including for Skidding (what you're referring to as sliding). I think they pretty much cover the issues you raise to the extent necessary, or provide the GM with enough information to make a ruling for his campaign, but if you have further questions after reviewing that material, please post a follow-up.