Nearly 5,400 former congressional staffers have left Capitol Hill to become federal lobbyists in the past 10 years, according to a new study that documents the extent of the revolving door between Congress and K Street.

The data published by the online disclosure site LegiStorm found close to 400 former U.S. lawmakers also have made the jump to lobbying.

The report, which tallies a greater number of workers moving between Congress and lobbying than found in previous studies, underscores the symbiotic relationship: Thousands of lobbyists are able to exploit experience and connections gleaned from working inside the legislative process, and lawmakers find in lobbyists a ready pool of experienced talent.

Of the 5,400 lobbyists with recent Hill experience, the study found that 2,900 were registered to lobby on behalf of clients this year. Twenty-five powerhouse firms and organizations employ 10 or more former Hill workers. The largest number are at the Podesta Group, followed by the U.S. Chamber of Commerce, which employs at least 21.

“People who are experienced in Washington tend to be better at doing this kind of work than people who have never worked in the government before,” said Tony Podesta, founder and chairman of the Podesta Group, one of Washington’s most prominent lobbying firms.

The study also documents the reverse movement, finding 605 former lobbyists who have taken jobs working for lawmakers in the past decade.

“For every person the American people have elected to sponsor legislation of public benefit, special interests have more than one former legislative advocate now working on the inside in Congress,” said Jock Friedly, founder of LegiStorm. “That represents a large network of people to influence decisions and to provide valuable intelligence.”

In the House, the study found at least 11 former lobbyists working on the Republican staff of both the Energy and Commerce and Ways and Means committees. Democratic members of those committees together employ five former lobbyists.

That could be the result of a recent hiring spree by Republicans after they took over control of the House in the 2010 elections. After the 2006 elections, when Democrats took control of both the House and the Senate, 207 lobbyists took jobs on the Hill, most of them Democrats.

LegiStorm compiled the figures by matching names in its congressional salary database with lobbying records available from the House and the Senate.

About 14,000 people work on the Hill, and about 11,700 people are registered to lobby this year, according to the Center for Responsive Politics.

A study last year from the London School of Economics found 1,113 lobbyists who had formerly worked in the personal offices of lawmakers.

Lobbying firms and companies are looking for either connections or policy experience when they hire staffers to sway their old bosses, said Mirko Draca, a research economist at the school and one of the authors of the study.

The data on current and former staffers are part of a new subscription service launched Tuesday by LegiStorm that could reignite a debate from several years ago, when the Web site published public documents with staffers’ home addresses. The new service includes a database of congressional staff, and in some cases, personal information, including work histories, birthdays, spouses’ names, family connections, hobbies, and links to personal pages on social-networking sites such as Facebook, Twitter and LinkedIn. Similar information has been available from other publications and leadership directories, although Legi­Storm is collecting data on a broader array of staffers.

The site previously came under fire from lawmakers and their staffs for posting some public documents that detailed staffers’ personal financial information, which previously had been available only in hard copies. In 2008, LegiStorm agreed to redact portions of the documents, including staffers’ signatures and home addresses, after the House agreed to pay the cost of the work.