The study found there has been a drop in support for high executive remuneration. In 2012, survey respondents supported an average of 30% of pay reports, down from 38% in 2011.
However, whereas in 2012 shareholders voted down six renumeration reports, in 2013 only three reports - none of which were from FTSE 100 companies - were rejected.
The study found pay remains the issue most likely to lead to investor action, followed by board structure and capital structure issues.
TUC general secretary Frances O'Grady said shareholders should be "prepared to challenge proposals from the boardroom more frequently".
She added: "If worker representatives were allowed to sit on boards, they could improve decision making and provide an effective challenge to management."
The TUC is campaigning to have workers on company boards to curb executive pay.
