What running does to the knees, according to a large survey of marathon runners

Many runners are warned that continuous pounding of the pavement will cause knee damage. However, a recent study has found that this is not necessarily true. The study discovered that runners who ran longer, faster, and more frequently were not more susceptible to developing hip or knee osteoarthritis.

Osteoarthritis is a prevalent condition among older adults, affecting over 32.5 million adults in the United States. It is a condition where cartilage at the joint’s end wears down, causing pain, stiffness, and sometimes disability. Unfortunately, there is no known cure for osteoarthritis. Once cartilage is damaged, it cannot be replaced.

The study surveyed 3,804 recreational runners who participated in the 2019 or 2021 Chicago Marathon. The survey included questions on their running history, average running pace, and whether they had family histories of arthritis. The Northwestern University researchers, including lead author Dr. Matthew Hartwell, found that running does not increase the risk of developing osteoarthritis.

The participants in the survey were typically around 44 years old and ran an average of 27.9 miles per week at an 8-minute and 52-second mile pace. While some respondents had been running for as little as one year, others had been running for up to 67 years. The researchers found no link between the risk of hip or knee arthritis and the number of years someone had been running, the number of marathons completed, their weekly running mileage, nor their running pace.

The researchers said that because the survey respondents had a wide range of weekly mileages, ages, paces, and cumulative years of running, the results could apply to average runners who never get close to marathon-level distance. This study is a significant departure from previous research focused on elite-level Olympians.

The new study’s findings should encourage runners, according to Dr. Vehniah Tjong, who stated that they “refute the current dogma that long-distance running predisposes an individual to arthritis of the hip and knee.” Of the 3,804 recreational runners surveyed who participated in the Chicago Marathon, 7.3% reported ever being diagnosed with hip or knee osteoarthritis. However, Dr. Matthew Hartwell cautioned that the incidence of arthritis is higher than 7% in a 44-year-old on average.

Interestingly, nearly 25% of all runners surveyed, regardless of their level, had been advised by their doctors to reduce their mileage or stop running altogether.

Many doctors have traditionally viewed osteoarthritis as a “wear-and-tear” condition, comparing it to a car. However, this perspective fails to consider how running can improve joint health and offset deterioration. According to Jeffrey Driban, an osteoarthritis researcher at Tufts University, running can enhance muscle function around the joints and encourage the production of synovial fluid, which lubricates the joints.