Are Tight Hamstrings and Knee Pain Connected?
The single most consistent complaint I hear from my patients who come to see me for knee arthritis or low back pain is that they have tight hamstrings. This creates the obvious question…Are tight hamstrings and knee pain related?
I’ve blogged a number of times on the connections between mild low back nerve irritation (that you may not notice as back pain) and chronically tight muscles like hamstrings. I’ve also written about how my tight hamstrings have caused knee meniscus issues. However, does the research support that the hamstrings may have something to do with knee arthritis and pain?
Tight Hamstrings and Their Impact on Knee Pain
A group of researchers looked at the size of the hamstrings muscle versus the quadriceps (thigh muscle). Why would size matter? A muscle gets smaller either when it’s not being used or its nerve supply is poor. Remember big strapping ex-superman Christopher Reeves? After a spinal cord injury, despite having the best electrical stimulation exercise equipment money could buy, his muscles shriveled up. This is mostly because a muscle gets naturally smaller (starts to die off) when its nerve supply is disrupted. This research group also looked at these ratios against fancy MRI images of the knee that measured early signs of cartilage and meniscus wear and tear. They found that patients with smaller hamstrings muscles versus quadriceps had more MRI signs of cartilage and meniscus swelling and degeneration. In addition, when the inside quadriceps muscle was bigger than the outside portion, the researchers found the same thing.
Why might this be happening? We’ve seen an association for years (and the research is now supporting) a big link between subtle nerve irritation in low back nerves and knee arthritis. This is discussed in more detail in our e-book, Orthopedics 2.0. The most common nerves in the low back that get irritated happen to go to your hamstrings. I believe that this leads to weak and tight hamstrings that get smaller over time and are less able to protect the knee structures like cartilage and meniscus. For example, in other common low back nerve supplied muscles like the gluts, weakness is associated with overload of the knee cap area on running.
The upshot? If your hamstrings are tight, you may want to hit the gym to see if they’re also weak. If you can do much more weight on the knee extension machine (quads) than you can do on the knee flexion machine (hamstrings), you may have a problem with muscular imbalance. You may also want to consider having a qualified specialist (like a physician from the Regenexx Network) check to see if a low back nerve may be the problem. Regardless, strengthening weak hamstrings to help your aching knees may well be worth a shot!