Distance Running and Knee Osteoarthritis
Introduction
Most runners have heard at least once, whether it be from a friend or a family member, that running is bad for your knees. Knee joint deterioration is many distance runners’ biggest fear. If the deterioration continues, the concern for knee osteoarthritis development may arise. Knee osteoarthritis is a condition in which one’s articular cartilage degenerates, leading to the femur and tibia bones rubbing against each other. “Osteo-” has a Greek root, “ostéon” which means bones; “arthro-,” Latin root, “arthus” means joints. The suffix “-itis” is also of a Greek root and means inflammation (dictionary.com, n.d.). Osteoarthritis “is the most common chronic condition of the joints, affecting approximately 27 million Americans,” and it is most commonly found in knees (Arthritis Foundation, n.d.). Many risk factors have been identified, including old age, gender (female at higher risk), obesity, joint injuries, genetics, and bone deformities; however, it is not clear whether distance running plays a role in the development of osteoarthritis.
Logically speaking, it makes sense that runners would have such concern. As they put on their mileage, their feet are pounding on the ground for miles and miles. It sounds reasonable that the continuous impacts may increase the risk of knee osteoarthritis, as the force from the foot hitting the ground carries straight to the knee joint. There is no doubt that distance running affects the knee, but does the impact increase risk of chronic conditions like osteoarthritis?
In order for a chronic condition to develop, the joint would need to experience high impacts at a rate of which the body is incapable of compensating, more than what most trained distance runners experience. Distance running has more components that it appears. Training is a huge part of the sport; runners need to know the right techniques as well as their own capabilities. They also need to provide their body enough time to rest and recover to avoid injuries. However, the body does recover from the impact of the sport at an extremely high rate, fast enough to eliminate most runners’ concern of long-term damage. The sport of distance running, if trained and performed right, although can have a temporal effect on knee joint deterioration, does not lead to knee osteoarthritis in long term.
Training
Training contributes tremendously to distance running. If not instructed correctly, all sports, running included, can be harmful to athletes. Many argue that the sport of distance running itself damages athletes’ knees. Contrary to the general belief however, running results in no damage so long as athletes have the right training.
Cartilage loss is know to cause knee problems, and while many believe distance running leads to cartilage loss, Hinterwimmer (2013) along with other researchers conducted a study regarding the “effect of a six-month training program followed by a marathon run on knee joint cartilage volume and thickness in marathon beginners.” Ten marathon beginners were put on a 6-month marathon training program. Prior to the program an initial physical examination was taken for each participant. MRI exams were taken at the beginning of the the training period and a day after the marathon.
Figures 1 and 2 respectively show the thickness and the volume of cartilage in each area of the knee, comparing the results of before and after the 6-month training program. The lines extending upwards from the bars on the graphs show the range, whereas the bars show the mean. Results show no statistically significant changes in thickness see Figure 1) or volume (see Figure 2) of knee cartilage other than a slight decrease in lateral femur (identified by “*”). Though claimed to be statistically significant, the thickness of lateral femur cartilage only declined by 1.7 ± 1.6% (Figure 1), and the volume by 3.2 ± 3.0% (Figure 2). Such small decrease is not evidential to conclude that distance running leads to knee osteoarthritis. The results overall in fact suggests no significant relationship between distance running and cartilage loss.
Figure 1 Thickness of Cartilage
Figure 2 Volume of Cartilage
The training program was supervised and designed to suite each runner, increasing their mileage by “an average of 10.5 km/week–34 km/week (range 25–60 km/week).” The program gave participants’ bodies a reasonable amount of recovery time, which is an essential part in training for distance running events. The sport of distance running although seems simple, requires technical training. Some follow a training program created for other people which may not be right for them; many neglect important techniques to avoid injuries, such as step rate manipulation (Heiderscheit, Chumanov, Michalski, Wille, & Ryan, 2011). Without the right trainings, any sport can harm your body, running included. However, when trained appropriately, distance running does not lead to increasing risk of knee injuries.
Rapid Recovery
Recovery contributes tremendously in the maintenance of our bodies. We damage our body ever so slightly as we go through our daily lives. However, because our bodies are capable of recovering, no real harm is caused, so long as the recuperation is faster than the cartilage loss. Although the common belief that distance running can reduce knee cartilage is not completely unreasonable, most people are not aware that it recovers very quickly. Many fear distance running would lead to osteoarthritis over time, but the rate at which cartilage recovers suggests otherwise.
Long-term. When it comes to long-term effects, running shows no significant negative impacts on knee joints. “Skeletal Radiology” published a 10-year longitudinal study on marathon runners’ knee joints in 2008 (Krampla, Newrkla, Kroener, & Hruby). The research concludes no permanent knee joint damage from distance running. In fact, data even suggests a possibility of a protective effect.
First, in Study 1 in 1997, initial MRI scans were done on ten male runners from Vienna city marathon, along with 24-hour and six-month follow-ups. Then, a ten-year follow-up (Study 2) was done in 2007 on eight of the runners, one of which had given up distance running (referred to as person 8). In the ten years between the studies, the participants, excluding person 8, ran distances ranging from 4,000 to 25,000 km.
In runners with no pre-existing knee damage prior to the initial scan in Study 1, no damage was shown in Study 2; the same goes for those with mild degeneration initially. For example, Figure 3a shows the medial meniscus of runner 3 from the initial scan and 3b shows the follow-up scan from Study 2. Runner 3 had a grade I degeneration in the beginning, as shown in 3a. It turned out that in the follow-up scan after 10 years, shown in 3b, no change had occurred. In Runner 2, a grade IIIA meniscal tear was observed initially, which normally increases the risk of cartilage degeneration in the area. However, the runner reported no symptoms of knee problems; both the tear and the cartilage remained the same, even after many races over the ten-year period.
Figure 3
No significant new knee joint damage was observed, aside from one case where a runner showed major damage in the initial scan. The results led the researchers to conclude that distance running is not destructive to the knees of “well-trained and healthy” runners, but rather preventative. Another study, “MR imaging of the hip and knee before and after marathon running” had similar results, showing how distance running does not damage joints in the long run, as the impact can be tolerated by the body (Hohmann, Wörtler, & Imhoff, 2004).
Misconceptions. The general public typically takes the conclusion of a study and magnifies it without considering its whole picture. According to Behzadi and associates (2016), from analyzing immediately after a 45-minute run, the T2* (“weighted gradient-echo sequence”) relaxation times suggestively reduced. Many then neglectfully concludes that distance running causes knee joint deterioration, leading to osteoarthritis in the long run. However, the research itself is titled “The immediate effect of long-distance running on T2 and T2* relaxation times of articular cartilage of the knee…,” not long-term effect. The MRI examinations were done with a delay of no more than six minutes after the run. The information does not hold much weight in regards to osteoarthritis being caused by distance running.
In 2008, the American Journal of Sports Medicine published a study, “Recovery of the Menisci and Articular Cartilage of Runners After Cessation of Exercise” (Kessler, Glaser, Tittel, Reiser, & Imhoff, 2008), where cartilage volumes of 20 male athletes measured an hour before, immediately after, and an hour after a 20 km run, were compared (see Figure 4). As shown in Figure 4, the change of cartilage shown in the slope of the graph is negative during the run (from “start” to “20 km run”) suggesting cartilage loss, but positive after (from “20 km run” to “60 min recovery”) suggesting an increase. Results show that though cartilage volume decreased as observed immediately following the run, it increased significantly after a 60-minute recovery, suggesting an incredibly high recovery rate. Data shows significant recovery in all areas. Cartilage volume of the lateral meniscus, though had decreased by 9.3% initially, increased by 6.8% after an hour. In the patella, cartilage volume had decreased by 7.0% after the run, but increased by 5.2% after the hour recovery period. Though this study’s follow-up was measured only one hour after the run, results show a major increase of cartilage volume with the tendency to continue at an expedited rate. The results caused the researchers to conclude that the impact force from distance running is compensated by the rapid recovery of the cartilage. The data suggests distance running does not lead to osteoarthritis.
Figure 4. Cartilage Volume
Some may argue any damage at all, even the temporary type, is bad. However, as our body recovers, it rebuilds to be even stronger. The concept of breaking before making better is not at all new. That is how we build muscles. Muscle damage has to occur in order for them to grow. The soreness we feel after working out is one example of how we experience muscle damage. However, it also means that we are gaining more muscles (Leyva, 2013). Though we do not have enough evidence to say that cartilage works the same way, it would not be a big leap if further studies show such data.
Lack of Correlation
Studies suggest no direct correlation between running and higher risk of osteoarthritis (Timmins, Leech, & Batt, 2017, p. 1455-1456). Though some cases show slight increase in osteoarthritis risk in runners, many others show no difference or even smaller risk in runners (Apold et al., 2014; Ageberg et al., 2012; Felson et al., 2007). Because evidence from various studies is so scattered, a correlation between running and knee osteoarthritis cannot be concluded.
A lot of times, the general public is blinded by their own beliefs and may ignore the big picture. When people find one study that supports their beliefs, they are convinced that the idea must be true. The truth is, a single study holds little weight. For an idea to be scientifically accepted, many evidences are needed; and if a number of studies may support that idea, but a reasonable amount shows otherwise, the idea cannot be concluded as a fact. Much evidence support both running being destructive and preventative of knee osteoarthritis, but it cannot be concluded one way or another.
Meta-analyses of several case studies are much more reliable. The study “Running and Knee Osteoarthritis” for instance, found many results pointing in different directions (Timmins, Leech, & Batt, 2017). The researchers then concluded that running and knee osteoarthritis have no direct correlations. In such circumstance, it is reasonable to make conclusions showing no relationship between the two, because many different studies show different results. When results are scattered, not pointing into any one direction, it is likely that running has no direct influence on the development of knee osteoarthritis. Thus, over all, runners should not be concerned.
Conclusion
Although the general public claims distance running increases the risk of osteoarthritis, a further investigation shows otherwise. It is not the running, but the incorrect training and forms, that lead to chronic injuries. When performed right, though temporal injuries may still occur, because of the body’s rapid recovery, these will not lead to osteoarthritis as many runners fear. As Dr. Ebert mentions, “joints have a wonderfully sophisticated structure that resists damage and adapts to stress” (2001). Activities involving joint impact may be shown to strengthen the cartilage overtime; however, evidence shows no correlation between distance running and higher risk of osteoarthritis. Thus, there is no need for runners to be concerned about higher risk of osteoarthritis.