CANTON, Mass. (Dow Jones/AP) – Reebok International Ltd. Thursday reported a 31 percent increase in third-quarter earnings and said that President and Chief Operating Officer Jay Margolis resigned.

Margolis, 55 years old, joined the Canton-based shoe company when Chairman and Chief Executive Paul Fireman was experiencing health problems, which resulted in coronary bypass surgery two years ago.

Fireman, 60, is now healthy and will assume operational responsibilities after a brief transition period. He has committed to sign a new long-term contract and will work with the board to groom an internal successor.

Reebok spokeswoman Denise Kaigler called Margolis’ resignation a “mutual decision.”

In a release, Margolis said “We have discussed the future of the company and are in agreement that (Fireman) stepping back in to directly run the business is the best decision for the company and its shareholders at this time.”

Reebok reported third-quarter net income of $81.8 million, or $1.36 a share, for the period ended Sept. 30. That’s up from the prior year’s $62.7 million, or 96 cents a share.

Analysts surveyed by Thomson First Call had forecast, on average, third-quarter earnings of $1.18 a share.

Sales grew 12 percent to $1.165 billion from $1.04 billion, coming in ahead of First Call’s projected $1.13 billion. Reebok said sales were boosted by its acquisition in June of The Hockey Co., a Canadian maker of hockey apparel and equipment, as well as by exchange-rate fluctuations.

On a constant-dollar basis, third-quarter sales increased 9 percent from the prior year.

For the first nine months of the year, net income rose to $144.7 million, or $2.34 a share, from the prior year’s $129.1 million, or $1.99 a share.

Net sales climbed 6.4 percent to $2.81 billion from $2.64 billion.

Reebok shares closed at $36.37, up 76 cents, or 2.1 percent, on the New York Stock Exchange.