An extensible implantable electrical lead includes a lead body having a proximal end and a distal end. The lead body is formed of a polymeric material that is extensible between a first length and a second length. A plurality of electrical conductors are disposed within the lead body and extend between the proximal end and the distal end. The plurality of electrical conductors are each electrically insulated from each other and form a braided coil extending between the proximal end and the distal end. The plurality of electrical conductors are electrically insulated and separated from each other and have a braided coil diameter.