Video: Meet the New America's Cup Sailor

The modern America's Cup sailboat looks nothing like the vessels used ten years ago – and the modern America's Cup sailor has changed as well.

With the advent of hydrofoils, wing sails and 45-knot top speeds, the boats need a lot of hydraulic power to move all of their control surfaces. It can't come from electricity, so the teams' grinders have been recruited into the role of human pumps – cranking as hard as they can to build the fluid pressure behind each adjustment. At the same time, the organizers have limited the crew size to six sailors with a combined weight of 525 kg (1,160 lbs), putting all of the workload on just four grinders, plus the wing trimmer and helmsman.

The work is beyond extreme. "We've never seen anything like it in sailing. It's like sprinting up a hill for 25 minutes," Oracle Team USA skipper Jimmy Spithill told CNN. "Some days you look at the heart rate data and it looks like a few guys are having heart attacks." (The video below illustrates Spithill’s point: Oracle grinder Louis Sinclair is in top shape, but the work is far from easy.)

Courtesy Oracle Team USA

To meet the power demand, Emirates Team New Zealand has swapped upper body for lower body, equipping its boat with cycling-style winches and training grinders to put out maximum power with their legs. The method is unprecedented in the America's Cup competition. "There's a substantial increase in power output using the legs. It's been about a year of hard work, we've gone through a lot of base work and now we've hit a few phases of intensive and the guys are making big jumps," said trainer Hubert Woroniecki of Emirates Team New Zealand. 

However they are providing power, the athletes behind the next America's Cup all follow intense training regimens, complete with special diets, individualized workout routines, constant vital statistics measurements and in-depth performance analytics. Grinders can hit 98 percent of their maximum heart rate in the course of a race, and often sustain an average level of 93 percent throughout. It takes extensive preparation to meet these demands, and Oracle Team USA trains its athletes 12 to 14 hours a day, six days a week. Like the boats, the regimen – and the personnel it produces – may now have more in common with the competitive triathlon than with the traditional regatta.