I don’t remember ever hearing anything about Bolt doing a single leg front squat. We’ve seen Powell use step-ups, lunges, bench press and apparently he also uses the hang clean.
I’d be extremely hesitant to attribute the performance increases to something as general as a weight room lift, especially a single leg front squat (basically a weighted pistol?).
80 kg person lifts 50 kg of weight in a single leg squat = 130 kg load on the leg
80 kg person lifts 180 kg weight in a two leg squat = 260 kg weight total = 130 kg each leg
Load aside the version of single leg front squat I use probably encapsulates all that step-ups, lunges, and hang clean facilitate and all in one exercise. Leaves plenty of time for other training (swinging a golf club in my case).
I am just trying to provide some guidance so that we can quantify the improvements to the Jamaican sprinters – aside from the extra motivation and self-belief that comes from having not one or two but now half the country of medalists. I would love to carry out experiments on the high knee drill up a hill, “fast stretching”, high-knee resisted drill and measure a cause and effect. These would likely have more influence on sprint performance as weight room stuff hasn’t shown to correlate much to sprint improvement although I would state that it is because the exercises are not movement or motor recruitment pattern or velocity specific enough.