Are Olympic weightlifting records based on mass or weight?

[andrewkirk]

The impact of altitude on sporting records has been officially recognised in athletics since at least the 1968 olympics in Mexico City, at which athletes set new records for jumps and sprints were broken that stood for unusually long times after that. Mexico City has altitude approx 2240m. The thin air provides a considerable advantage for jumps and sprints. For distance events, the opposite effect arose, as the shortage of oxygen slowed down the athletes. However in cycling, where air resistance has much greater importance because of the higher velocities, Mexico City became a favoured venue for attempts on the world record for distance ridden in one hour.

Apparently, official track and field world records now exclude performances at altitudes above 1000m.

This thread makes me realize that in addition to the thin air, Mexico City advantages runners by reducing their weight, since at latitude 19 degrees, Mexico City would still be materially affected by the equatorial bulge. But for distance events the weight effect would be much more than offset by the lack of oxygen. For short sprints, the advantage of lower weight would be greatest for 200m or 400m as, for 100m or 60m, the acceleration at the start plays a crucial role, and that is governed by mass rather than weight.

NOAA tells us that the Earth's surface gets furthest from its centre at Mount Chimborazo in Ecuador.

 

[swampwiz]

What is the weight difference between historical Summer Olympics locations the closest and furthest from the Equator? Just eyeballing a list, looks like Helsinki and Rio. If you are going to worry about this with weightlifting, why not pole vaulting or any other track and field event? Would not figure skating moves be easier if the skater is 0.3% lighter?

The "world's strongest man" achieved his feat in Thailand:

Even the top individual lift (clean & jerk) was done in Australia: