Non-repetitive weight lifting wouldn't be a good example, but neither is anything in 10s of km.
Mitochondria produce ATP as energy. You can't store much¹ ATP, therefore mitochondria must be capable of producing ATP at your near peak output (say 10s average).
I'd look at anything with high >10s peak power (probably a bonus if it's aerobic). Many bodybuilding exercises would qualify.
¹ Lactic acid is a byproduct of ATP production, therefore ATP supplies surely last less, than what it takes to start producing lots of lactic acid.
