The equation we want to use for this is P=1/2kx^2, with P being stored energy, K being spring constant, and x being displacement. For sprinters, the equation would be
1/2(33)(41)^2= 27736.5
And for non athletes:
1/2(33)(33)^2= 17968.5
Subtract the two and you get: 9768 J of energy