The best way to build lean calves is by combining cardiovascular exercises with weight training. Cardio helps burns calories while you do it and weight=training exercises help tone and tighten your muscles as you lose weight.
If the cold Winter temps are keeping you indoors, you don't have to stick to a treadmill for your cardio. In fact, all you need is a jump rope to make for an effective cardio workout that burns around 330 calories in just 30 minutes.
Jump Rope Hopscotch >> Lay 2 jump ropes on the floor in an X. Begin standing with both feet in 1 of the sections, facing the jump ropes. Bend your knees and jump forward, landing in a squat position with 1 foot in each of the next 2 sections.