Diligent practice of hip stretches—what in yoga we often call "hip openers,” as though they are key to unlocking the secrets of the hips—can dramatically increase your flexibility and range of motion around the hip joints. If you are athletically minded, this can be a good thing. But as with many good things, too much can be overdoing it. The key for athletes is to develop or maintain balance between stiffness and openness, which the Yoga Sutra calls sthira and sukha: a balance of strength and flexibility in the muscles around the hips. This balance can change depending on both the athlete’s body and on sport-specific needs.
Depending on your sport, too much flexibility can be detrimental to your sports performance, as it can reduce your snappiness. Consider, for example the stiffness a runner needs for efficient transfer of energy to the ground. A floppy runner, one whose hips sag with each step, will have to work harder than one who springs lightly over the ground. But you need enough flexibility to move fluidly through your stride, without a hitch that can lead to an overuse injury. Poses that mimic the running stride, like lunges, can help you stay flexible through the range of motion used to run, and hip stretches that target the external rotators (for example, Eka Pada Rajakapotanasana (One-Legged King Pigeon Pose) and Gomukhasana (Cow Face Pose)) can help avoid overuse injuries like Iliotibial Band Syndrome and Piriformis Syndrome.
On the other hand, athletes need vastly more flexibility in the hips for engaging in activities like rock climbing, curling (think of the very deep lunge position as the rock is thrown), or playing positions like catcher in baseball or softball. An asana practice for athletes in these activities can look very different from a practice for athletes who require more springy stiffness in their bodies; athletes who need to take deep squats can enjoy the full range of hip stretches, including poses that move deep into flexibility, like Hanumanasana (Monkey Pose; i.e., the splits) and Kurmasana (Tortoise Pose).
Consider where you fall on this spectrum as you choose poses for your home practice, and as you attend classes. There may be a very good reason hip openers frustrate you, or a good reason for you to love and enjoy them. Either way, the process gives you an opportunity to consider what you can change and what you can’t, and to practice focusing your energy on creating useful change and accepting the unchangeable.