After having both knees replaced & going thourgh PT I have started doing a fitness routine to build my leg muscles back to diving trim. I tired my fins the other day & could only swim maybe a 100 yards, not good. So I asked my twin, (Seal) for help. He says to use tyhe treadmill with a decent speed & incline to get me high stepping then go to the stair stepper and squats. I've been doing the treadmill & squats.Any other suggestions to get back in the water.