The square-cube law explains why a 6'5" man is not automatically stronger than a 5'9" man, even though he is much larger. The law states Muscle strength is primarily determined by a muscle's cross-sectional area (how thick it is), which scales with the square of size. Body mass scales with volume, which scales with the cube of size. Example:A 6'5" man is about 11.6% taller than a 5'9" man.So he may have about 25% more muscle cross-sectional area. But body mass scales by the cubeSo he may weigh about 39% more. So this means that the 6'5" man is stronger in absolute terms. But he is carrying even more body mass. His strength-to-weight ratio is actually lower.