As stated before, one of the primary hip flexor muscles is the psoas major. This muscle plays a role in core stabilization (something that is needed during running, squatting, and sitting) due to its attachment site at the spine. If there is a lack of core stability or poor movement patterns during these tasks then the hip flexor can become overworked/tired/fatigued (think what happens when your co workers or teammates don’t do their job, you have to pick up the slack and work harder, bringing you more stress and fatigue). It is when the hip flexor becomes fatigued that the sensation of tightness sets in. This is because the hip flexor has to “work harder” to compensate for other muscles not doing their job.
Firstly, let’s establish where your glutes are and what they actually refer to! Your ‘glutes’ — or your gluteal muscles, as they are more formally known — refer to the muscles in your butt. Specifically, there are three major muscles in this area: your gluteus maximus (the main, large muscle that shapes your backside), your gluteus medius and your gluteus minimus (two smaller muscles that assist the gluteus maximus in moving your body).