Somebody earlier mentioned free-fall parachuting.
I can remember being a young co-pilot in the RAF in the 1960s when we were doing HALO trials on Salisbury Plain. For those of you who are not familiar with HALO, it consisted of parachutists throwing themselves out of the back of the aircraft at high altitude and then free-falling to low altitude to then open their parachutes and hopefully, arrive unannounced.
In the beginning, the jumping beans did not have any built-in oxygen system. We carried an oxygen system that came straight out of the safety equipment section in the freight bay and that was a console made out of plywood that stood about 6 ft tall and about 10 ft long and was fed by 750 lire bottles of oxygen. The jumpers connected themselves to the oxygen console using 'H' Type masks and a cloth hat and breathed oxygen whilst we de-pressurised and opened the doors on the run in to the drop point,
They breathed oxygen until the last moment and then threw themselves over the sill.
I personally threw lots of these very special people all over the world on behalf of the British taxpayer.
Nowadays they have their own built-in oxygen system and with square parachutes to boot so things have definitely improved.
However, getting back to the thread, those original HALO guys were coming down from altitude at great speed to low level with no medical problems whatsoever.