Clenched fists and giant leaps made Mexico 1968 arguably the greatest of all Olympic Games: a high-altitude blend of passion and perfection that rang through the ages and ensured elite sports and the politics which accompany them would never quite be the same again.

When Bob Beamon launched himself down the runway for his first leap of the men's long jump final, little did he know he would achieve a distance which would take 23 years and five Olympic cycles to overhaul.

Nor could George Foreman have envisaged that his second-round knockout of Ionas Chepulis in the men's heavyweight boxing final would hasten an extraordinary professional career in which he lurched from Manila to Kinshasa, from ogre to hero, encompassing everything from Rumbles-in-Jungles to fat-free grills along the way.

They were the Games when Dick Fosbury finally convinced his remaining doubters of the practicality and legitimacy of approaching a high jump bar backwards; when Al Oerter became only the second man to win a fourth consecutive individual Olympic gold medal in the discus.

But if the sporting feats were destined to remain benchmarks for generations of future pretenders, other brave men and women seized the opportunity to stand up for noble causes, no matter the risk of sacrificing their own athletic careers in the process.

The Games began amid especially febrile political times. Ten days prior to the lighting of the Olympic flame, hundreds of protesters were killed by security forces in the Mexico City suburb of Tlatelolco.

Boycott threats had forced the International Olympic Committee to rescind an earlier invitation to South Africa to compete due to ongoing apartheid, while globally, the Cold War was raging and Soviet tanks had recently rolled into Prague.

American sprinter Tommie Smith had been one of those leading the boycott threats over civil rights issues, and when he stood on the podium for the men's 200m final, in which he won the gold medal, he prepared for the most famous protest in sports history.

Smith and his team-mate, bronze medallist John Carlos, stood shoeless during the national anthem and raised black-gloved fists. For doing so, they were vilified back home, suspended from the US team and banned from the Olympics for life.

"We were just human beings who saw a need to bring attention to the inequality in our country," said Smith years later.

Their bravery was matched by the Czech gymnast Vera Caslavska, who was controversially beaten by Soviet athletes on both floor and beam, and deliberately looked down and away as their national anthem was played.

Caslavska, who had previously been openly critical of the Soviet invasion, was banished in disgrace and effectively forced into retirement, resurfacing with honour only after the country's Velvet Revolution of 1989.

By the time Caslavska strode to comparative freedom, Smith had been inducted into the US Track and Field Hall of Fame, and Beamon's long jump record was still two more years from finally being overhauled.

In a sport which clings with increasing desperation to its once-in-a-generation heroes, Beamon remains one of its true standard-bearers, his name recognisable by almost anyone who has laced up a pair of track shoes.

The legacy of Smith and Carlos is harder to ascertain. The IOC still routinely suppresses what it considers to be overtly political sentiment, and there are those who continue to insist that - for all it inspired - there was no place on an Olympic podium for what they did.

Fifty years on, in our new age of far-right uprisings and Black Lives Matter, there will be those who prefer to take heed of one of the men who made Mexico 1968 so indelibly unique.

"In life, there's the beginning and the end," Carlos said in an interview many years later. "The beginning don't matter. The end don't matter. All that matters is what you do in between - and whether you're prepared to do what it takes to make change."