Amphibous Exercise for Improving Swimming (aXis) | 17 followers on LinkedIn. aXis (Amphibious Exercise for Improving Swimming) is the first every dry land strength and conditioning program designed to improve the performance of competitive swimmers. Designed by legendary swim coach David Marsh and respected members of the physiotherapy and strength and conditioning community, aXis’s mantra is injury prevention while improving strength and power. aXis will provide education and certification services to swimmers and coaches who are interested in decreasing the repetitive use injuries that plague competitive swimmers while improving their speed and power through proper technique and body line control. aXis was founded with the mission of funding philanthropic organizations that focus on athletics like the Medalist Club that supports Team Elite in Charlotte North Carolina.