Another way to look at it, if you stretched a short and tight muscle and it regained length, it shouldn’t get tight again, should it? Whereas if the muscle wasn’t technically “tight” but rather holding excessive tone in order to keep your spine from looking more like a losing game of Jenga, stretching it will just give more opportunity for low back pain, and quickly lead to the muscle tensing up again to defend the spine. This is the problem with conventional hip flexor stretches.
Of course, you know what it feels like to have a tight muscle. But tight hips aren't just uncomfortable—they can lead to all sorts of other aches and pains, especially in the lower back. "People focus on the hips and say their hips are tight, but we don't always think about the fact that the lower back connects to our legs at the hip," Charlee Atkins, C.S.C.S., instructor at Soul Annex in New York City and creator of Le Stretch class, tells SELF. Tight hip flexors make it harder for your pelvis to rotate properly, which can cause your lower back to overcompensate, "and this can be a setup for lower-back injury," Teo Mendez, M.D., an orthopedic surgeon at NY Orthopedics who focuses on operative and non-operative management of sports-related injuries, musculoskeletal injuries, and arthritis, tells SELF.