My question revolves basically around how much energy would be required for a person to exert to remain at a constant speed. While exact numbers would obviously not be possible without a specific example (and would probably be impossible even with a specific example), I am thinking more relative figures. For example, for a 50 kg individual to move at 5 m/s, the Newtonian kinetic energy required would be 625 J (based on Ke=1/2mv2). I wouldn't think that the individual (ignoring air resistance) would essentially have to exert 625 J per step (as they are not starting from 0 each time), but I also would think that it would be quite a good chunk of the 625 J, as running 10 m is quite a bit less strenuous than running 100 m. I am a physics beginner who is simply interested, so I apologize if there are any fallacies in the scenario I have laid out. I appreciate your help!