Scaling isometric mid-thigh pull maximum strength in division I Athletes: are we meeting the assumptions?

This study examined the validity of various scaling methods, isometric mid-thigh pull (IMTP) peak force using various scaling methods, and the relationships between IMTP peak force and countermovement jump height.  Fifty-one collegiate baseball and soccer athletes performed two maximal IMTPs.  Absolute peak force was compared between teams and when data were scaled using ratio (RS), traditional allometric (ALLO_Trad), and fitted allometric (ALLO_Fit) scaling.  ALLO_Trad and ALLO_Fit validity was violated because different derived exponents existed for baseball (b = 0.20) and soccer (b = 1.20).  Soccer athletes produced greater RS peak force compared to baseball (p = 0.012), while no difference existed with absolute, ALLO_Trad or ALLO_Fit (all p > 0.05) peak force.  Moderate relationships existed between body mass and absolute (r = 0.402, p = 0.003) and RS (r = -0.328, p = 0.019) peak force, while trivial relationships existed with ALLO_Trad and ALLO_Fit (both r < -0.10, p > 0.05).  Trivial relationships existed between countermovement jump height and absolute, RS, ALLO_Trad, and ALLO_Fit (all r < 0.20, p > 0.05) peak force.  The current dataset violated allometric scaling assumptions, making it inappropriate to use ALLO_Trad and ALLO_Fit scaling.  Practitioners must understand the assumptions, limitations, and purpose of scaling methods.