Beginning this year, swimmers are banned worldwide from wearing polyurethane and neoprene suits during competition.
FINA, the world governing body of swimming, issued the regulations earlier this year after an unprecedented number of swimmers broke world records after the high-performance swimsuits were introduced in 2008. The regulations went into effect Jan. 1, 2010.
Since their introduction in 2008 the suits, which cut down on fatigue and give swimmers more buoyancy and speed, have led to nearly 200 world records. Last year, 43 world records were set at last summer's world championships in Rome. Phelps wore the Speedo LZR, a full-body, 50-percent polyurethane swimsuit during the Beijing Olympics, where he won eight gold medals. Phelps broke seven world records in Beijing.
"I'm glad they're banning them, but they should have done them almost two years ago, before the damage was done to the history of swimming," said veteran sports journalist Christine Brennan in an interview with ABC News.
"Unfortunately, it has rendered its record book worthless. It sadly is a joke because so many records have been broken with the new suit. These records will not be touched for years, if ever, because they were broken by swimmers using suits that will now be illegal."
USA Swimming, the national governing body for swimming as a sport, welcomes the new regulations. It banned the suits in the United States October 2009.
"We have been in support of swimsuit regulations and worked together with other nations and with FINA on these regulations, and USA Swimming felt so strongly about the importance of creating an even playing field that we adopted these regulations on Oct. 1," Jamie Olsen, communications director for USA Swimming, told ABC News.
Since then, some swimmers, including Phelps, have been competing in the older, textile, navel-to-knee-length suits for men, and in textile, shoulder-to-knee-length suits for women. Textile fabric is defined by USA Swimming as "material consisting of natural and/or synthetic, individual and non-consolidated yarns used to constitute a fabric by weaving, knitting and/or braiding."
Phelps and other USA team members have already started high-altitude training in Colorado. Phelps' next big swim race is in the Southern California Grand Prix on Jan. 15 -- the first big race where all swimmers will be wearing the old suits.
A list of approved swimsuits exist on the FINA Web site.
"One of things we started pushing for last November was for FINA to look very carefully at a scientific evaluation of these swimsuits, because it's difficult for you and I to look at things [such as] permeability and flotation," Olsen said.
Leading competitive swimwear manufacturer Speedo issued a press release about the ban earlier this year, supporting the July 28, 2009, FINA ruling, saying that the recent introduction of 100 percent non-permeable buoyant wetsuits and their impact on performance has "cast a shadow over the sport" and "put swimmers in a very compromising position."