As longer you do sprint with or without a weapon in your hand, you should be slowed down a bit.
Like it is in ArmA 2. If you run normal nothing changes, because you are jogging. In DayZ that would be normally running without sprinting. If you are sprinting you are very fast in the beginning but then you get slowed down because no person has the power to sprint infinitly.
That should be so in the Standalone too. It forces you to take a rest and not running 10km in one part.