Too much tension across a joint can be damaging. Extra tension leads to too much pressure and too much friction. All this extra force makes the bits and pieces that make joints work smoothly wear out before their time. But the usual prescription may not be what’s needed to fix the problem.
It’s usually assumed that the problem is that there are stronger muscles overpowering weaker muscles. If your hip flexors are weaker than the hamstrings and lower back, then the hip flexors will be overpowered and you’ll have joint problems. Then if you strengthen you hip flexors, problem solved.
But I would guess more often than not the real problem is tighter muscles and over stretched muscles. Here in the developed world we have chronically shortened hip flexors from spending most of our time sitting. These shortened muscles cause the pelvis to rotate out of position.
The body can try to counteract this rotation by tightening the abs and hamstrings. This can compensate as long as the hip flexors aren’t too short, but it greatly increases the muscle tension in the hips and lower back. And BANG! The recipe for worn out joints is complete!
If we focus on strengthening the hip flexors, they’re still short and we just increase the muscles tension. So by trying to solve the problem we’ve actually made it worse. More strength probably isn’t what we’re looking for here.
So what’s the real solution if it isn’t strengthening the weak muscles? In this example, the solution is to lengthen the hip flexors. As they return to the normal length, all of the muscles that are contracting to counteract the tension will relax. This will reduce the cross joint tension to normal levels.
Remember it isn’t always about weaker or stronger. It’s about tension and relaxation. Efficiency is about using the minimum amount of tension required and the maximum amount of relaxation allowed to complete a movement.
And this cross joint tension applies to all joints, not just hip flexors.