Nairobi, Aug. 22 -- When most people her age are winding down, swapping gym shoes for walking shoes and easing into quiet evenings, Ruth Ngei is stacking plates on the barbell. She calls it her game of numbers, and somehow the numbers keep bending her way. From South Africa to Nairobi, she has lifted past expectations, past records, and past the myths about what a woman in her fifties should look like or do.

At 55, Ruth is now preparing for the Static Monsters finals, a strongman competition set for next month. In February this year, she travelled to South Africa for the qualifiers. She placed first in her age category, first in Africa, first among all the ladies competing. It is the kind of result that could make anyone rest on their la...