It is natural to move your arms while walking to counterbalance your leg motion. But if you keep your arms stiff and straight at your sides, they act like a long pendulum, slowing you down. You can add power and speed by using you arms effectively and more naturally, by bending them and letting them swing naturally forward and back as you walk.
If you keep your arms straight down at your sides while walking, you may notice that your hands swell quite a bit while walking, especially in warm weather.
The cure: Bend your arms 90 degrees and swing them naturally back and forth opposite the leg motion.
Walking Arm Motion