One of the first things I noticed when I started swimming with DragSox (aside from how hard I had to kick to keep moving forward) is that DragSox forced me to develop better rhythm and timing. Because DragSox add resistance, any dead spots in my stroke were quickly exposed. Every time I had a dead spot, I felt like I stopped moving forward and had to work much harder to accelerate to gain speed again. This slowing down and accelerating wastes a lot of energy. I took it as an indicator that I needed to work on my rhythm to make my stroke smoother and more efficient.