Note : these estimations & calculations are taken by average and may be variations *This estimation will be carried out by the difference between 2 individuals 1-subject (A): the short one 160 cm 2-subject (B): the tall one 190 cm Note : both of them have the same muscle mass & weight ( 80 kg ) - the example will be in shoulder abduction "this calculation can be carried in most body movement". 1- the range of movement (ROM) : - subject (A) : the arm length = 0.42 x total body height the arm length = 0.42 x 160 = 67.2 cm ( the circumference = 2πr) " the arm length = radius" -since we moved 90° for shoulder abduction (1/4 of circumference ) (π = 3.14) therefore ROM " X "= 1/4 x circumference " X "= 1/4 x (2 x 3.14 x 67.2 ) = 105.6 cm - subject (B) : the arm length = 190 x 0.42 = 79.8 cm -( the arm length = radius ) the ROM " X " = 1/4 x circumference (2πr) " X^2 " = 1/4 x ( 2 x 3.14 x 79.8 ) = 125.4 cm Conclusion...