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Weight-bearing recreational activity was associated with a 22% increased odds of developing knee osteoarthritis (OA) in a large prospective cohort study in the Netherlands, but notably, the increased risk was seen only in those with low levels of lower-limb muscle mass.
The findings point toward the value of “tailored advice” for physical activity, and suggest that “caution is needed when engaging in weight-bearing activity, especially for individuals with low levels of lower-limb muscle mass,” Yahong Wu, MD, and coinvestigators, of the Erasmus Medical Center in Rotterdam, the Netherlands, wrote in JAMA Network Open.
Investigators used data from sequential cohorts of the longitudinal Rotterdam Study, which enrolled people aged 45 and older starting in 1990. The 5003 participants in this new analysis of physical activity and knee OA had complete records of baseline recreational physical activity, baseline knee pain, and knee radiographs from both baseline and at least one follow-up exam. Those with radiographically defined knee OA at baseline were excluded.
The incident rate of radiographically defined (x-ray) knee OA among all participants was 8.4%, with a mean follow-up time of 6.33 years. Among 3492 individuals without baseline knee pain, the researchers found no increased odds of incident radiographic OA with non–weight-bearing activity (odds ratio [OR], 1.04; 95% CI, 0.95-1.15; P = .37) but a significant association of weight-bearing activity with OA incidence (OR, 1.22; 95% CI, 1.10-1.35; P < .001).
A stratification analysis of a subset of participants whose lower-limb mass had been measured by dual-energy x-ray absorptiometry (DXA) showed, however, that the association of weight-bearing activity with incident OA was limited to patients in the lowest third of lower-limb muscle mass index (LMI), who had a 53% increased likelihood of developing knee OA (OR, 1.53; 95% CI, 1.15-2.04; P = .003).
For patients in the middle and upper tertiles, there was no significant association between weight-bearing activity and the odds of incident OA (OR, 0.93; P = .73, and OR, 1.15; P = .40, respectively).
The findings are reassuring overall, said Kelli D. Allen, PhD, research professor of medicine and exercise physiologist at the University of North Carolina at Chapel Hill, who was asked to comment on the study. “The study corroborates prior research showing that for most people, weight-bearing recreational activity does not increase the risk of knee osteoarthritis. This should be encouraging for people who want to increase their physical activity,” she said.
The study also suggests that “for people with low lower-limb muscle mass, there may be some considerations to make regarding the best type of physical activity to prevent future knee osteoarthritis,” she said in an e-mail. “The best approach may include non–weight-bearing activities, which could include biking, swimming, or other water exercises, along with strengthening exercises that help to increase muscle mass.”
Other studies, Dr. Allen said, have shown that low muscle mass itself is a risk factor for knee OA.
Physical Activity Types, Other Analyses
The researchers assessed total, weight-bearing, and non–weight-bearing physical activity using two validated questionnaires (an adapted version of the Zutphen Physical Activity Questionnaire and the Longitudinal Aging Study Amsterdam physical activity questionnaire) that asked participants about the frequency and duration of various types of physical activity. Activity was quantified as metabolic equivalent of task (MET) hours per week, and weight-bearing activities were defined as those in which the knee joint bears the body’s weight.
Walking, gardening, golf, dancing, and ball sports were among the activities qualifying as weight-bearing activities. Non–weight-bearing activities included cycling, rowing, and swimming.
Sex, body mass index, and follow-up time were among the covariates adjusted for in the primary analysis. Similar results were found when adjustments were also made for educational level, alcohol intake, lipid levels, and diabetes.
While incident radiographic knee OA (measured using the Kellgren & Lawrence grading system) was the primary outcome, the researchers also looked at symptomatic knee OA, as defined by x-ray and a knee pain questionnaire, and found no significant association of its incidence with any of the exercise categories (total, weight-bearing, or non-weight-bearing).
Coauthor Joyce B. J. van Meurs, PhD, of the departments of internal medicine and orthopedics & sports medicine at Erasmus Medical Center, told this news organization that “pain as a subjective, recurrent symptom is more difficult to study … [and] a larger sample size or more precise measurements [of pain] in future studies would help to better understand the true association” of symptomatic knee OA and physical activity.
Similarly, analyses of the 1511 patients (out of 5003) who had knee pain at baseline found no significant association of weight-bearing or non–weight-bearing physical activity with incident radiographic knee OA. The trends were similar to those found in the population without knee pain, however, which suggests the analysis was underpowered, the researchers wrote, noting too that patients with baseline pain had lower activity levels than those without pain. (Low case numbers precluded a stratification analysis on LMI for incident symptomatic OA.)
Thigh Circumference as an Indicator of Muscle Mass
The findings build upon an international meta-analysis published in 2021 that found no association between total physical activity and knee OA and align with other studies suggesting a link between greater mechanical stress/strain and greater OA risk, the researchers wrote. (The meta-analysis couldn’t investigate different types of activity.)
“Although we cannot establish a causal relationship … we hypothesize that the mechanical loading on joints and cartilage could explain the association of weight-bearing activity with osteoarthritis in the low LMI tertile group,” they said.
It is possible that thigh muscle-specific strength or mass may temper the risk of knee OA, they wrote, but the lack of thigh strength data in the Rotterdam Study precluded such evaluation. Still, in everyday practice, the researchers noted, lower limb muscle function could be assessed using thigh circumference.
Dr. Allen agreed. “ ‘Gold standard’ assessment of muscle mass is not common in routine practice, but clinicians can evaluate muscle mass in other ways, such as thigh circumference,” she told this news organization, noting that measurement should align with procedures described by the National Health and Nutrition Examination Survey in its anthropometry procedures manual.
“If low lower-limb muscle mass is suspected, a referral to a physical therapist can be helpful for more formally assessing muscle mass and muscle strength,” she added, “and for instructions for a safe and appropriate exercise program for building muscle and protecting joints.”
Among other limitations of the study, according to the researchers, are an ethnically nondiverse population, the unavailability of knee injury data, and the assessment of physical activity only at baseline.
Moving forward, Dr. van Meurs told this news organization, “the main question regarding physical activity and OA is still, if people already have pain or early OA complaints, what kinds of sports they can do without hurting their joints?” This “should be tested,” she said, “in a real-life, ideally trial-like intervention study.”
The study was funded by the Erasmus Medical Center and Erasmus University as well as through various government grants. Dr. Wu also had study support from the China Scholarship Council. Two of the authors reported relationships with arthritis-related organizations. Dr. Allen reported having no disclosures relevant to her comments.
Weight-bearing recreational activity was associated with a 22% increased odds of developing knee osteoarthritis (OA) in a large prospective cohort study in the Netherlands, but notably, the increased risk was seen only in those with low levels of lower-limb muscle mass.
The findings point toward the value of “tailored advice” for physical activity, and suggest that “caution is needed when engaging in weight-bearing activity, especially for individuals with low levels of lower-limb muscle mass,” Yahong Wu, MD, and coinvestigators, of the Erasmus Medical Center in Rotterdam, the Netherlands, wrote in JAMA Network Open.
Investigators used data from sequential cohorts of the longitudinal Rotterdam Study, which enrolled people aged 45 and older starting in 1990. The 5003 participants in this new analysis of physical activity and knee OA had complete records of baseline recreational physical activity, baseline knee pain, and knee radiographs from both baseline and at least one follow-up exam. Those with radiographically defined knee OA at baseline were excluded.
The incident rate of radiographically defined (x-ray) knee OA among all participants was 8.4%, with a mean follow-up time of 6.33 years. Among 3492 individuals without baseline knee pain, the researchers found no increased odds of incident radiographic OA with non–weight-bearing activity (odds ratio [OR], 1.04; 95% CI, 0.95-1.15; P = .37) but a significant association of weight-bearing activity with OA incidence (OR, 1.22; 95% CI, 1.10-1.35; P < .001).
A stratification analysis of a subset of participants whose lower-limb mass had been measured by dual-energy x-ray absorptiometry (DXA) showed, however, that the association of weight-bearing activity with incident OA was limited to patients in the lowest third of lower-limb muscle mass index (LMI), who had a 53% increased likelihood of developing knee OA (OR, 1.53; 95% CI, 1.15-2.04; P = .003).
For patients in the middle and upper tertiles, there was no significant association between weight-bearing activity and the odds of incident OA (OR, 0.93; P = .73, and OR, 1.15; P = .40, respectively).
The findings are reassuring overall, said Kelli D. Allen, PhD, research professor of medicine and exercise physiologist at the University of North Carolina at Chapel Hill, who was asked to comment on the study. “The study corroborates prior research showing that for most people, weight-bearing recreational activity does not increase the risk of knee osteoarthritis. This should be encouraging for people who want to increase their physical activity,” she said.
The study also suggests that “for people with low lower-limb muscle mass, there may be some considerations to make regarding the best type of physical activity to prevent future knee osteoarthritis,” she said in an e-mail. “The best approach may include non–weight-bearing activities, which could include biking, swimming, or other water exercises, along with strengthening exercises that help to increase muscle mass.”
Other studies, Dr. Allen said, have shown that low muscle mass itself is a risk factor for knee OA.
Physical Activity Types, Other Analyses
The researchers assessed total, weight-bearing, and non–weight-bearing physical activity using two validated questionnaires (an adapted version of the Zutphen Physical Activity Questionnaire and the Longitudinal Aging Study Amsterdam physical activity questionnaire) that asked participants about the frequency and duration of various types of physical activity. Activity was quantified as metabolic equivalent of task (MET) hours per week, and weight-bearing activities were defined as those in which the knee joint bears the body’s weight.
Walking, gardening, golf, dancing, and ball sports were among the activities qualifying as weight-bearing activities. Non–weight-bearing activities included cycling, rowing, and swimming.
Sex, body mass index, and follow-up time were among the covariates adjusted for in the primary analysis. Similar results were found when adjustments were also made for educational level, alcohol intake, lipid levels, and diabetes.
While incident radiographic knee OA (measured using the Kellgren & Lawrence grading system) was the primary outcome, the researchers also looked at symptomatic knee OA, as defined by x-ray and a knee pain questionnaire, and found no significant association of its incidence with any of the exercise categories (total, weight-bearing, or non-weight-bearing).
Coauthor Joyce B. J. van Meurs, PhD, of the departments of internal medicine and orthopedics & sports medicine at Erasmus Medical Center, told this news organization that “pain as a subjective, recurrent symptom is more difficult to study … [and] a larger sample size or more precise measurements [of pain] in future studies would help to better understand the true association” of symptomatic knee OA and physical activity.
Similarly, analyses of the 1511 patients (out of 5003) who had knee pain at baseline found no significant association of weight-bearing or non–weight-bearing physical activity with incident radiographic knee OA. The trends were similar to those found in the population without knee pain, however, which suggests the analysis was underpowered, the researchers wrote, noting too that patients with baseline pain had lower activity levels than those without pain. (Low case numbers precluded a stratification analysis on LMI for incident symptomatic OA.)
Thigh Circumference as an Indicator of Muscle Mass
The findings build upon an international meta-analysis published in 2021 that found no association between total physical activity and knee OA and align with other studies suggesting a link between greater mechanical stress/strain and greater OA risk, the researchers wrote. (The meta-analysis couldn’t investigate different types of activity.)
“Although we cannot establish a causal relationship … we hypothesize that the mechanical loading on joints and cartilage could explain the association of weight-bearing activity with osteoarthritis in the low LMI tertile group,” they said.
It is possible that thigh muscle-specific strength or mass may temper the risk of knee OA, they wrote, but the lack of thigh strength data in the Rotterdam Study precluded such evaluation. Still, in everyday practice, the researchers noted, lower limb muscle function could be assessed using thigh circumference.
Dr. Allen agreed. “ ‘Gold standard’ assessment of muscle mass is not common in routine practice, but clinicians can evaluate muscle mass in other ways, such as thigh circumference,” she told this news organization, noting that measurement should align with procedures described by the National Health and Nutrition Examination Survey in its anthropometry procedures manual.
“If low lower-limb muscle mass is suspected, a referral to a physical therapist can be helpful for more formally assessing muscle mass and muscle strength,” she added, “and for instructions for a safe and appropriate exercise program for building muscle and protecting joints.”
Among other limitations of the study, according to the researchers, are an ethnically nondiverse population, the unavailability of knee injury data, and the assessment of physical activity only at baseline.
Moving forward, Dr. van Meurs told this news organization, “the main question regarding physical activity and OA is still, if people already have pain or early OA complaints, what kinds of sports they can do without hurting their joints?” This “should be tested,” she said, “in a real-life, ideally trial-like intervention study.”
The study was funded by the Erasmus Medical Center and Erasmus University as well as through various government grants. Dr. Wu also had study support from the China Scholarship Council. Two of the authors reported relationships with arthritis-related organizations. Dr. Allen reported having no disclosures relevant to her comments.
Weight-bearing recreational activity was associated with a 22% increased odds of developing knee osteoarthritis (OA) in a large prospective cohort study in the Netherlands, but notably, the increased risk was seen only in those with low levels of lower-limb muscle mass.
The findings point toward the value of “tailored advice” for physical activity, and suggest that “caution is needed when engaging in weight-bearing activity, especially for individuals with low levels of lower-limb muscle mass,” Yahong Wu, MD, and coinvestigators, of the Erasmus Medical Center in Rotterdam, the Netherlands, wrote in JAMA Network Open.
Investigators used data from sequential cohorts of the longitudinal Rotterdam Study, which enrolled people aged 45 and older starting in 1990. The 5003 participants in this new analysis of physical activity and knee OA had complete records of baseline recreational physical activity, baseline knee pain, and knee radiographs from both baseline and at least one follow-up exam. Those with radiographically defined knee OA at baseline were excluded.
The incident rate of radiographically defined (x-ray) knee OA among all participants was 8.4%, with a mean follow-up time of 6.33 years. Among 3492 individuals without baseline knee pain, the researchers found no increased odds of incident radiographic OA with non–weight-bearing activity (odds ratio [OR], 1.04; 95% CI, 0.95-1.15; P = .37) but a significant association of weight-bearing activity with OA incidence (OR, 1.22; 95% CI, 1.10-1.35; P < .001).
A stratification analysis of a subset of participants whose lower-limb mass had been measured by dual-energy x-ray absorptiometry (DXA) showed, however, that the association of weight-bearing activity with incident OA was limited to patients in the lowest third of lower-limb muscle mass index (LMI), who had a 53% increased likelihood of developing knee OA (OR, 1.53; 95% CI, 1.15-2.04; P = .003).
For patients in the middle and upper tertiles, there was no significant association between weight-bearing activity and the odds of incident OA (OR, 0.93; P = .73, and OR, 1.15; P = .40, respectively).
The findings are reassuring overall, said Kelli D. Allen, PhD, research professor of medicine and exercise physiologist at the University of North Carolina at Chapel Hill, who was asked to comment on the study. “The study corroborates prior research showing that for most people, weight-bearing recreational activity does not increase the risk of knee osteoarthritis. This should be encouraging for people who want to increase their physical activity,” she said.
The study also suggests that “for people with low lower-limb muscle mass, there may be some considerations to make regarding the best type of physical activity to prevent future knee osteoarthritis,” she said in an e-mail. “The best approach may include non–weight-bearing activities, which could include biking, swimming, or other water exercises, along with strengthening exercises that help to increase muscle mass.”
Other studies, Dr. Allen said, have shown that low muscle mass itself is a risk factor for knee OA.
Physical Activity Types, Other Analyses
The researchers assessed total, weight-bearing, and non–weight-bearing physical activity using two validated questionnaires (an adapted version of the Zutphen Physical Activity Questionnaire and the Longitudinal Aging Study Amsterdam physical activity questionnaire) that asked participants about the frequency and duration of various types of physical activity. Activity was quantified as metabolic equivalent of task (MET) hours per week, and weight-bearing activities were defined as those in which the knee joint bears the body’s weight.
Walking, gardening, golf, dancing, and ball sports were among the activities qualifying as weight-bearing activities. Non–weight-bearing activities included cycling, rowing, and swimming.
Sex, body mass index, and follow-up time were among the covariates adjusted for in the primary analysis. Similar results were found when adjustments were also made for educational level, alcohol intake, lipid levels, and diabetes.
While incident radiographic knee OA (measured using the Kellgren & Lawrence grading system) was the primary outcome, the researchers also looked at symptomatic knee OA, as defined by x-ray and a knee pain questionnaire, and found no significant association of its incidence with any of the exercise categories (total, weight-bearing, or non-weight-bearing).
Coauthor Joyce B. J. van Meurs, PhD, of the departments of internal medicine and orthopedics & sports medicine at Erasmus Medical Center, told this news organization that “pain as a subjective, recurrent symptom is more difficult to study … [and] a larger sample size or more precise measurements [of pain] in future studies would help to better understand the true association” of symptomatic knee OA and physical activity.
Similarly, analyses of the 1511 patients (out of 5003) who had knee pain at baseline found no significant association of weight-bearing or non–weight-bearing physical activity with incident radiographic knee OA. The trends were similar to those found in the population without knee pain, however, which suggests the analysis was underpowered, the researchers wrote, noting too that patients with baseline pain had lower activity levels than those without pain. (Low case numbers precluded a stratification analysis on LMI for incident symptomatic OA.)
Thigh Circumference as an Indicator of Muscle Mass
The findings build upon an international meta-analysis published in 2021 that found no association between total physical activity and knee OA and align with other studies suggesting a link between greater mechanical stress/strain and greater OA risk, the researchers wrote. (The meta-analysis couldn’t investigate different types of activity.)
“Although we cannot establish a causal relationship … we hypothesize that the mechanical loading on joints and cartilage could explain the association of weight-bearing activity with osteoarthritis in the low LMI tertile group,” they said.
It is possible that thigh muscle-specific strength or mass may temper the risk of knee OA, they wrote, but the lack of thigh strength data in the Rotterdam Study precluded such evaluation. Still, in everyday practice, the researchers noted, lower limb muscle function could be assessed using thigh circumference.
Dr. Allen agreed. “ ‘Gold standard’ assessment of muscle mass is not common in routine practice, but clinicians can evaluate muscle mass in other ways, such as thigh circumference,” she told this news organization, noting that measurement should align with procedures described by the National Health and Nutrition Examination Survey in its anthropometry procedures manual.
“If low lower-limb muscle mass is suspected, a referral to a physical therapist can be helpful for more formally assessing muscle mass and muscle strength,” she added, “and for instructions for a safe and appropriate exercise program for building muscle and protecting joints.”
Among other limitations of the study, according to the researchers, are an ethnically nondiverse population, the unavailability of knee injury data, and the assessment of physical activity only at baseline.
Moving forward, Dr. van Meurs told this news organization, “the main question regarding physical activity and OA is still, if people already have pain or early OA complaints, what kinds of sports they can do without hurting their joints?” This “should be tested,” she said, “in a real-life, ideally trial-like intervention study.”
The study was funded by the Erasmus Medical Center and Erasmus University as well as through various government grants. Dr. Wu also had study support from the China Scholarship Council. Two of the authors reported relationships with arthritis-related organizations. Dr. Allen reported having no disclosures relevant to her comments.
FROM JAMA NETWORK OPEN
