BEIJING (AFP) - China is sending its largest team to an overseas Olympics, but forecasters predict the 416 athletes will fail to match the country's greatest medal haul.

Eight years after leading the world with 100 medals at Beijing 2008, China is expected to win 89 medals in Rio de Janeiro, according to a study from Dartmouth College.

Of those, 38 are predicted to be gold, behind an expected US tally of 48, said Camila Gonzales of Dartmouth's Tuck School of Business.

In traditional strengths such as table tennis, badminton, weightlifting, shooting, gymnastics and diving, ageing or injured stars and fiercer competition have dampened expectations.

Fans are pinning their hopes on figures such as Ma Long, the world's top-ranked table tennis player, and controversial star swimmer Sun Yang.

The towering 1.98m Sun will be the most recognisable member of China's team after winning the 400m and 1,500m freestyle at London 2012, but his current form is largely unknown after he missed the national championships in April with a foot injury.

The 24-year-old's biggest challenger could be Italy's Gregorio Paltrinieri, 21, who registered the second-fastest swim in history - just three seconds behind Sun's 2012 world record - when winning the European Championships 1,500m this year.

Ma, who has dominated the ping-pong rankings, was controversially omitted by China's selectors for the 2012 Olympics singles. The 27-year-old finally won a global singles title at his fifth world championships last year, after a career that has raised questions about his mental resilience in showpiece finals.

Lin Dan, the 32-year-old badminton gold medallist in 2008 and 2012, looks to complete a golden hat-trick in his fourth and almost certainly final Olympics.

He will probably have to defeat his eternal rival Lee Chong Wei of Malaysia, who is back atop the world rankings after returning from a doping ban last year.

Lin beat Lee in both the Beijing and London Olympic finals but they are drawn to meet in the semi-finals in Rio, with world No. 2 Chen Long seeded to face Lee in the final.

China have won the men's gymnastics team golds at both the last two Games, but will face a Japan line-up who won the world championships last year.

In golf, Feng Shanshan and Lin Xiyu have strong medal hopes for the women while Wu Ashun and Li Haotong, who have both won on the European Tour in 2016, will fancy their chances of getting on the men's podium.

On the track, the men's 4x100m team, who won silver at the 2015 World Championships in Beijing, aim to become the first Chinese team to reach the Olympic sprint relay final.

China came second in the medal table four years ago in London, with 88 in all, 38 of them gold.

The Dartmouth forecast represents a marginal improvement, but the authorities have sought to dampen expectations, with Gao Zhidan, China's deputy chef de mission, telling the official Xinhua news service the country faces diminishing returns from its investment in training programmes.

"After Beijing was selected as the (2008) host city in 2001, China started a long-term talent training plan for the Games," he said, adding that while the plan continues it "is not as vigorous as then".

Reports in the state media have also highlighted problems in the country's state-run sports academy system, which takes in children at a young age and trains them intensively in sports such as gymnastics.

Academies have supplied 95 per cent of China's Olympic gold medallists, the state-run Global Times newspaper reported.

But Chinese parents are more reluctant to take their children from an academic track and send them to the gruelling institutions.

Except for the rare stars who have lucrative corporate sponsorships, long-term career prospects for athletes are dim, retirement benefits are limited, and athletes who have not attended conventional schools can struggle for years to secure normal jobs.

China's anti-doping procedures have also been in the spotlight, after the World Anti-Doping Agency (Wada) suspended the accreditation of its national testing laboratory in Beijing in April.

In March, China's state media reported that six Chinese swimmers had failed doping tests - including two who were let off with warnings for taking the banned muscle-builder clenbuterol.