* Herbert Hainer remains CEO until March 2017
* Contract originally due to expire in 2015
* Adidas to work with Hainer on succession plan
HERZOGENAURACH, Germany March 4 (Reuters) - Adidas has extended the contract of long-serving Chief Executive Herbert Hainer until 2017 but will work with him on a succession plan to ready the world's second-biggest sportswear company for "generation change".
Hainer has been CEO since March 2001, making him the longest serving boss among German blue-chip companies, prompting speculation over whether he might think about stepping down as he approaches his 60th birthday in July.
Igor Landau, chairman of the Adidas supervisory board, said he was pleased Hainer had agreed to extend his contract, which runs until 2015, even though the board would have liked him to stay on even longer.
"Today's decision gives us sufficient time to ensure a smooth transition at the helm of the Adidas Group and to optimally facilitate the process of succession for the company," he said in a statement.
"We will continue to pursue the generation change which has already been initiated within the Group's management team, thus preparing the company for the next era of success," he added.
A handover in 2017 would make sense as it is a relatively quiet year in terms of major sporting events, sandwiched between the 2016 Olympics in Rio de Janeiro and the 2018 soccer World Cup in Russia.
Landau noted that the value of Adidas had increased more than fivefold under Hainer's leadership and said he was sure he would continue to drive more growth at the company.
Adidas, which warned in September that 2013 sales and profits would not rise as much as expected, reports full-year results on Wednesday, which are expected to show it has fallen further behind market leader Nike.
Adidas has only recently started to turn around fitness brand Reebok that Hainer bought in 2006 in an attempt to expand into Nike's home territory.
Last October, Adidas said it was shaking up its management structures in North America and western Europe as it seeks to boost growth in these regions.
In January, Adidas appointed Eric Liedtke as new global head of brands on the five-man executive committee, to replace Erich Stamminger, who had been with the company for 30 years.
Adidas shares were up by 2.6 percent at 1425 GMT, rebounding from losses on Monday sparked by concerns over the impact of the Ukraine crisis on the company's business in eastern Europe.