Your wallet is one of your most taken-for-granted accessories. That’s because you’ve had one since you were in grade school, and it’s always lived in your back pocket. Whether you’re driving, sitting on the train, or sitting at your desk, it stays in the same spot. And since most guys treat a wallet like a filing cabinet for receipts and gift cards, it’s grown a lot since you were a kid. But here’s the trouble: This small oversight can lead to muscle imbalances and nerve irritation in your hips and back.
Let’s break down the chain reaction that occurs when you sit on your wallet. The bulge makes it so one side of your body is raised, so your pelvis hikes to that side, and your lumbar spine, or low back, will side-bend with it. Your thoracic spine, or mid-back, will curve left to counterbalance it because your eyes want to stay horizontal. This side-bending in the low back, although minimal, will lead to your right quadratus lumborum, and all the muscles on your right side like the paraspinals, obliques, and transversus abdominis, to become shortened, making them actively insufficient. Basically, this small shift decreases your muscle’s ability to fire and increases stress at your right sacroiliac joint. And it doesn’t stop there.
The left side of your pelvis, mainly the wing-shaped part called the ilium, does the complete opposite. Those same muscles are lengthened to the point that they become passively insufficient, which does not allow for a proper co-contraction. There's a similar effect in the mid back. The side with the curve, namely the left in the thoracic spine, will be shortened, leading to overuse, shortening, and pain. The right-sided spinal stabilizers will be over-stretched and quick to fatigue in the mid back. This will decrease your postural endurance and lead to pain when sitting at your desk.
Not only is your pelvis going to be out of whack, leading to muscle imbalance and joint strain, but also that wallet is probably pressed against your piriformis muscle and/or sciatic nerve. This strained position may eventually cause nerve irritation and pain from the nerve to travel through the glute and down the leg.
In other words, your overstuffed wallet could be the source of your lousy squat form, your slow run time, your tight back, your tight hamstrings, and your weak calves, hamstrings, and glutes.
So here’s what to do about it: Clear all the crap out of your wallet, then throw that wallet away. Get something slim that only lets you hold a few things at a time, like your ID and a couple cards (Billykirk makes leather card cases — like the 397 or the 092 — that’ll last you forever). It’ll force you to cut clutter, which you probably needed anyway. Now, most important part: Stick that thing in your front pocket, and get your body back on track.