A difficult paper in Nature Neurocience (see reference below) contains fascinating results that reveal new insights into muscle recruitment and the location and variety of muscle pools. The results do support the version of power law training that I call hierarchical sets or the 15-8-4 protocol as we call it here. They also shed light on the idea that sprinting or intense exertion is an expression of youth.
The work out I always come back to and the very best for all round strength and muscularity, not to mention leanness, is the hierarchical work out.