The Weapons Platform: USAMU Physical Conditioning for Highpower Shooting
An excellent article from the US Army Marksmanship Unit discussing the whys and how-tos of getting in shape for competitive riflery.
One can legitimately question some of the "equipment race" and "game" aspects of NRA Highpower shooting.
But riflery competitions come in many forms, don't they?
Physical fitness will help in every form of competitive shooting endeavor, and its absence will likely degrade or even doom your efforts, regardless of the particulars.
Read the article and then go do.
Hat-tip to the Civilian Marksmanship Program and the CMP's online magazine.