Drink 1 to 2 cups immediately before running, then a half-cup to a cup every 15 minutes. When you run, your muscles generate enough heat to literally boil your blood. To keep that from happening, you produce sweat, which takes this unwanted heat away when it evaporates. In a sense, yes. Simply improving your fitness will do it, as this actually causes your sweat glands to enlarge.
More blood means a faster sweat rate.
When you run in a swimming pool, the water's resistance creates a full-body workout, while the buoyancy eliminates the impact on your legs. Click HERE for More Information. Sweat rate is also genetically determined, so some people sweat more than others. Regardless of your sweat rate, make sure you drink plenty of fluids before, during and after running. To find out your replenishment needs, weigh yourself before and after a training run.