Lack of ankle rocker
When your foot hits the ground, the ankle needs to dorsiflex, meaning your lower leg must be able to progress over your foot past perpendicular (greater than 90 degrees). Loss of motion means less shock absorption and decreased step length. Tight calves, bad mechanics and weak glutes contribute to this problem.
Fix it: Muscular tightness is often a protective measure to replace weakness. Stretch your calf muscles and do shin-strengthening exercises such as walking on your heels with your toes pointed upward.