An important part of recovery from any injury is an understanding of tissue change and how quickly turnover can happen. Practically, this question is asked: “how long will this tissue take to heal”? Typically, we often think that muscle heals fastest, followed by other structures such as bone, tendon, ligament, cartilage, or meniscus. In some instances, such as with cartilage or meniscus, it is often assumed that tissue turnover doesn’t happen very much at all.
In a recent study published by researchers out of The Netherlands, these tissues were assessed based on protein synthesis(1). We can look at the rate of protein synthesis and make some assumptions about how quickly tissues are capable of healing or repairing. While this is obviously not a direct correlation, it can raise some interesting points!
In this study, researchers took patients who were going in for a knee replacement and utilized some brilliant biochemistry and science to assess the rates of protein synthesis in tissues all around the knee.
They found some interesting results. We know from previous studies that skeletal muscle remodels at a rate of 1-2% per 24 hour period – which is why we are able to put on muscle or lose it at quite significant rates. But with this study, researchers found no significant difference between the rate of muscle protein synthesis and protein synthesis rates of tendon, bone, cartilage, ligament and meniscus! This is a much higher rate of plasticity than previously believed.
So what does this mean for you? Well it means that some tissues previously thought to heal slowly, or not at all, may actually be working behind the scenes. Now, this study certainly has some limitations and we cannot assume that it now proves everything injured will heal at the same rate of muscle. But, it does give us some reason to think that if tissues are injured, there is a non-zero chance of recovery or tissue improvement!
Perhaps the most significant finding of this study was the ability to differentiate a difference between types of protein synthesis occurring. While this study was not able to determine what amino acids were more active in different tissues, it does raise some important suggestions for additional research. Perhaps if we know what types of amino acids are more active in certain tissues, maybe we could supplement those to improve healing rates! We will certainly have to continue following the research as it develops.
Thanks for reading!
1 . Smeets, J. S., Horstman, A. M., Vles, G. F., Emans, P. J., Goessens, J. P., Gijsen, A. P., ... & van Loon, L. J. (2019). Protein synthesis rates of muscle, tendon, ligament, cartilage, and bone tissue in vivo in humans. PloS one, 14(11).