Running and impact sports wear out your discs
James had completed eleven marathons before his back gave him trouble. His physio told him to stop running entirely. By the time he reached my clinic, he'd been off running for two years and was deeply miserable — and the running had almost certainly not been the problem.
What Patients SayI used to run marathons, but after my back started giving me trouble I switched to cycling. Everyone says running is the worst thing you can do for your spine — all that impact.
Where Did This Come From?
The impact theory of disc degeneration has been around for a long time. The logic goes like this: discs are cushions, impact compresses cushions, repeated compression wears cushions out. Running involves lots of impact. Therefore running wears out discs. It sounds reasonable. It's also not well supported by the evidence.
The fear of high-impact sport has been amplified by imaging technology. Once we could show people their "degenerative" discs on MRI, we had something concrete to point to. "See, your discs are wearing down — protect them." What those images actually showed, in many cases, was completely normal age-related changes that had nothing to do with running.
What the Science Actually Says
Multiple studies comparing runners to non-runners have found that long-distance running is not associated with accelerated disc degeneration. A notable study published in The Spine Journal actually found the opposite: middle-aged recreational runners had healthier disc composition (measured by MRI hydration) than age-matched non-runners. The discs responded to the load by staying better hydrated.
The discs don't have their own blood supply — they're avascular. They get nutrients through a process called imbibition: the rhythmic loading and unloading of exercise essentially pumps nutrients in and waste products out. Running, cycling, walking — all of these provide that beneficial pump. Complete inactivity does not.
Now — does this mean running can never cause a back problem? No. For elite or ultra-endurance runners, the picture is less clear — very high training volumes and individual genetic factors do play a role, and professional athletes are a different population from recreational joggers. An acute disc injury can happen during running, particularly under fatigue. And if you already have significant nerve compression, high-impact activity may not be ideal during a flare.
But for the average recreational runner without active nerve symptoms, running is not destroying your discs. It may be helping them.
The Verdict
Running and impact sports don't wear out healthy discs — the evidence actually suggests regular moderate-impact activity is beneficial. There are specific scenarios (active nerve compression, specific structural pathology) where guidance differs.
What To Do Instead
- Get a proper diagnosis before switching sports permanently — know what you're actually dealing with
- Work with a physiotherapist and running coach on form analysis — poor running mechanics can contribute to spinal loading issues
- Gradual return to running after a back episode, starting with walking, then walk/run intervals, then building back up
- Strengthen the core and posterior chain — the muscles that support the spine during running
Yellow Flags — Worth Monitoring
- Leg pain or numbness that comes on specifically with running and resolves with rest — possible neurogenic claudication, worth checking
- Pain that's significantly worse after longer runs but fine with shorter efforts — may indicate a load threshold issue to manage with a physio
- Pain that's different in character when running versus other activities — worth noting for your clinician
Red Flags — Get Checked Immediately
- Sudden severe back pain during a run with immediate leg weakness — stop running, seek urgent assessment
- Running triggering saddle area numbness (inner thighs, genitals, buttocks) — possible cord or cauda equina involvement
- Belavý DL et al., "Running exercise strengthens the intervertebral disc," Scientific Reports, 2017. Videman T et al., "Associations of back pain history with disc degeneration," Spine, 2003.