The three windsurfers before attempting to cross the Straits of Florida
The article which included this photo indicated they took a year preparing for the journey, doing resistance exercises and strength training in addition to spending several hours exercising without water to help their bodies to adapt.
Henry Vergara Negrin is interviewed about his experience (in Spanish)
http://www.cubaenmiami.com/balseros-...a-de-windsurf/