What Does Being Double-Jointed Have To Do With COVID? Surprising Link Discovered

LONDON — People who are double-jointed, meaning they have especially flexible fingers, legs, and arms, appear to be at an elevated risk of developing long COVID, according to a new study. More specifically, scientists from the United Kingdom found that double-jointed individuals appear to be 30 percent more likely to suffer an incomplete recovery from COVID-19 infection. They’re also more likely to experience persistent fatigue associated with long COVID in comparison to others without hyper-mobile joints.

Besides old age, the chances of developing long COVID appear greater if associated with certain underlying health conditions, including fibromyalgia, irritable bowel syndrome, migraine, allergies, anxiety, depression, and back pain.

All of those risk factors have shown an independent association with joint hyper-mobility, which refers to some or all of a person’s joints displaying an unusually large range of movement. Study authors set out to determine if double jointedness could be a risk factor for long COVID in its own right. To that end, they made use of data pertaining to 3,064 participants in the COVID Symptom Study Biobank. All of those people had a COVID-19 infection at least once.

Everyone underwent a series of surveys in August 2022 to ascertain who had hyper-mobile joints, who had fully recovered from their last bout of COVID-19 infection, and if anyone was experiencing persistent fatigue. Over four in five people (81.5%) reported having had COVID-19 at least once. Among those individuals, information on self-reported recovery was available for 2,854; a group that included 2,331 women (82%) and 2,767 Whites (97.5%), with an average age of 57.

Also, one in three participants (914; 32%) reported they had not fully recovered from their last COVID-19 infection. Among these people, 269 (just under 30%) had generalized joint hyper-mobility. Meanwhile, among the 1,940 people who said they had enjoyed a full recovery, close to one in four (439; just under 23%) had hyper-mobile joints, with 400 of them being women.

Even after researchers accounted for potentially influential factors, such as age, sex, ethnicity, deprivation level, educational attainment, and number of vaccinations received, joint hyper-mobility continued to have a strong association with not fully recovering from COVID. Those classified as double-jointed were roughly 30 percent more likely to report not fully recovering from COVID-19 in comparison to people with normal joints. Moreover, joint hyper-mobility was found to significantly predict higher levels of fatigue, which emerged as a key factor in the failure to make a full recovery.

Researchers stress this project was observational in nature, meaning no firm conclusions are possible regarding whether joint hyper-mobility plays direct role in developing long COVID. Also, the research team acknowledges numerous limitations tied to their study, such as most study participants being women and White, revealing a need for more diverse study groups. Researchers say the analysis also failed to include or correct for other potentially influential factors like duration of symptoms and coronavirus variant, as well as pre-existing conditions, such as fibromyalgia, which also happens to be characterized by fatigue and brain fog.

In summation, study authors stress it is unlikely long COVID is a single entity but a medley of intersecting immunological, inflammatory, autonomic nervous system, respiratory, and cardiovascular processes that eventually lead to distinct symptom profiles affecting both body and brain.

“However, these results suggest further exploration of whether [joint hypermobility] is linked to a particular phenotype or subtype of those not recovering fully from COVID-19, including long COVID,” the study authors write in a media release.

The study is published in BMJ Public Health.