Runners often ask, should I stretch? I cannot answer that for you without looking at your muscle length. Only a problematic, tight muscle truly needs to be stretched, otherwise you are better off spending time on mobility and rolling. However, if a tight muscle is noted by your therapist or trainer, this approach is an extremely effective and simple way to increase muscle length. The contract-relax muscle energy stretch resulted in the greatest change of muscle-tendon stiffness compared with static stretching and maximal isometric contraction interventions. As a side note, I believe just about ALL runners would benefit from the last stretch in this series for the hip external rotators.