Runners typically have weak gluteus medius muscles, more technically referred to as ‘weak bums’. Clams are a great glute activation exercise.
Preparation: Lie on your right or left side with your knees bent at 90 degrees. Legs should be stacked one atop the other.
Execution: Keeping the insides of the feet touching at all times, slowly open up your legs by engaging the glute of the upper leg. Lower down slowly until knees meet. Repeat 10-12x on each side.