Long Post Warning: I’m going to give my experience with lower back pain on high intensity rides. I know this can be pretty individual, but I also know how desperate one can be when dealing with seemingly never ending injury issues. So i never know who it could potentially help.
I’ve had reoccurring low back issues for the past 2 years. I am a triathlete, so I am doing multiple disciplines. However, Vo2 max workouts always seem to be the issue. The first time I threw it out it was the evening after a Vo2 session. A few months later, the same thing. Once it was while doing front squats. But Vo2 sessions on the bike have been a major issue for me the past 2 years. The worst 2 episodes were complete devastation. Couldnt stand/walk for 2 days. 4-6 weeks off of working out. It was like a full on muscle strain. The pain was always really difficult to pin point. Its always my left side…but difficult to differentiate between hip flexor, erector spinae, glute med, psoas, etc.
Regardless, it always seems like it would start with a tight left hip. Like a restriction in my hip flexor, hip capsule, maybe a tight psoas or something. I would carry that into a Vo2 session and it would seem as if this hip tightness would cause my back to be overused during the workout. Then later on that day, those muscles would start to revolt and eventually go out on me. Because of this perceived hip tightness I was trying everything in the book to resolve that: core work, hip mobility stuff, hip strength, low back strength stuff, etc. I was so dedicated to all of this work (which we all know can get really old really quick) but regardless of any temporary relief I would experience from all this stuff, it was always just that: temporary.
MY SOLUTION: I say “my solution” because again this can all be individual. But the issue for me was neuromuscular. I had really poor movement patterns through my pelvis and low back. I’ll try to explain.
We always hear how important it is to “level your pelvis.” And coming from a running background (where you are mostly upright) leveling of my pelvis has always been a major focus of mine. You dont want anterior tilt and you dont want posterior tilt. You want to stay nice and level so that your glutes are engaged and blah blah blah. This is all well and good when you’re body is upright. As good as this focus is, it got me into trouble when performing activities that are not upright (like squating, deadlifts, riding in aero).
So here’s the issue: I would visualize “leveling” my pelvis as keeping it level with the floor…Like the analogy of not spilling the bowl of water. However, when you lean your torso you need to bring your pelvis with it. If you do not bring your pelvis along with the torso, and instead keep it level with the floor, you will bend into a pretty bad posterior tilt. You need to maintain the relationship between your pelvis and torso, not pelvis and ground. So when I’m doing big efforts in a Vo2 bike session, and I tip my torso forward to get in aero, I was keeping my pelvis level to the ground (keeping my sit bones grounded to the saddle). But what this would do if you were looking from the side is cause an extreme posterior tilt. This results in a body hinge going right through your lumber spine rather than your hips. It turns off your glutes, robs power, and puts an extreme load on your back and back muscles.
Then thinking back to the time I threw it out doing squats, it was the exact same movement pattern. Standing with the bar on my back/shoulders, I level my pelvis so that my entire body is aligned. When I begin the actual squatting movement i was focusing on “not spilling the water” by keeping my pelvis level to the ground. But when my torso leans forward slightly, as it does during a back squat, my body would hinge at the lumbar and extremely bad things happen.
I believe this has always been an issue for me, especially on the bike. But the most devastating results would only occur after Vo2 max sessions because thats when you’re producing the most power. I could get away with it during lesser efforts. It wasnt efficient or safe during lesser efforts, but it wouldnt result in injury.
Ever since focusing on correcting this movement pattern, i have had zero issues. I wish you the best in your journey. I know it can be very frustrating.