Assuming that the man is standing still on a flat, horizontal surface and neglecting air resistance, the normal force produced by the ground upwards on the leg would be equal in magnitude to the weight of the man, which is given as approximately 84 kg.
Therefore, the normal force being produced by the ground upwards on the leg would be approximately 84 kg multiplied by the acceleration due to gravity (9.81 m/s^2), which gives a value of approximately 823.44 N (Newtons).
So the normal force being produced by the ground upwards on the leg is approximately 823.44 N.