Abstract
Objective:
To evaluate the relationship of a history of strength training with symptomatic and structural outcomes of knee osteoarthritis (OA).
Methods:
This study was a retrospective, cross-sectional study within the Osteoarthritis Initiative (OAI), a multicenter prospective longitudinal observational study. Data was collected at four OAI clinical sites: Memorial Hospital of Rhode Island, The Ohio State University, the University of Pittsburgh, and the University of Maryland/Johns Hopkins. 2607 participants with complete data on strength training, knee pain, and radiographic evidence of knee OA were included (male=44.2%; age=64.3±9.0 years; body mass index=28.5±4.9 kg/m2). We used a self-administered questionnaire at the 96-month OAI visit to evaluate the exposure of strength training participation during four time periods throughout a participant’s lifetime (ages 12–18, 19–34, 35–49, and ≥50 years old). The outcomes (dependent variables) were radiographic OA (ROA), symptomatic radiographic OA (SOA), and frequent knee pain.
Results:
The fully adjusted odds ratios (95% confidence interval) for frequent knee pain, ROA, and SOA, among those who participated in strength training any time in their lives were 0.82 (0.68–0.97), 0.83 (0.70–0.99), and 0.77 (0.63–0.94), respectively. Findings were similar when looking at the specific age ranges.
Conclusion:
Strength training is beneficial for future knee health, counteracting long-held assumptions that strength training has adverse effects.
INTRODUCTION
The World Health Organization and the United States Department of Health and Human Services encourage everyone 5 years or older to perform muscle-strengthening activities at least two days a week to benefit from an array of health benefits (e.g., enhanced functional capacity, increased bone strength) (1, 2). Unfortunately, less than 1 in 3 adults (31%) in the United States meet the 2018 muscle-strengthening activity guidelines (3). We speculate that a common concern may be limiting participation in this activity, that increased joint loading could contribute to joint pain or arthritis in weight-bearing joints. Understanding the relationship between strength training and osteoarthritis (OA), the most common type of arthritis worldwide (4), could help to address the concern that strength training may be harmful to weight-bearing joints.
Concerns about the long-term safety of strength training may be anchored in previous data showing that elite male weightlifters are at high risk for knee OA (5, 6). However, results from these elite male weightlifters (5, 6) should not be generalized to the general population because their exposure (load per repetition, number of repetitions, and type of loading) differs from strength training activities in the general population. For example, the general population does not commonly perform clean and jerk or a snatch in a typical strength training session and are unlikely to approach loads experienced among elite weightlifters (e.g., 142 kg with a Snatch and 172 kg with a clean and jerk)(7).
There is substantial reason to believe that strength training is safe for most individuals. OA treatment guidelines often advocate individualized strength training programs to optimize joint health after a knee injury to prevent OA (8). Strength training can improve muscular strength, power, and neuromuscular control, helping optimize joint biomechanics, reduce the risk of joint injury, and protect articular structures(9, 10). Furthermore, strength training can improve mobility and physical function, contributing to promoting weight maintenance(10, 11).
The Osteoarthritis Initiative (OAI), a community-based cohort, which was not initially recruited based on strength-training status. The OAI staff collected data on exposure to strength training over a lifetime and comprehensive data on symptomatic and structural outcomes of knee OA. Thus, this was an ideal opportunity to evaluate the relationship between a history of strength training (exposure) and knee OA outcomes. We hypothesized that a history of strength training would not increase the risk of radiographic OA (ROA), symptomatic radiographic OA (SOA), and frequent knee pain.
PATIENTS AND METHODS
Osteoarthritis Initiative
The OAI is a multicenter prospective longitudinal observational study that enrolled individuals from 2004–2006 who (1) had no knee OA, (2) a high risk of developing symptomatic knee OA, or (3) had existing symptomatic knee OA (definite tibiofemoral osteophyte with pain, aching or stiffness on most days of a month in past year)(12). Participants were recruited from four clinical sites: Memorial Hospital of Rhode Island, The Ohio State University, the University of Pittsburgh, and the University of Maryland/Johns Hopkins.
This study received ethical approval from each OAI clinical site (Memorial Hospital of Rhode Island Institutional Review Board, The Ohio State University’s Biomedical Sciences Institutional Review Board, the University of Pittsburgh Institutional Review Board, and the University of Maryland Baltimore – Institutional Review Board), and the OAI coordinating center (Committee on Human Research at University of California, San Francisco). The OAI adhered to the ethical standards in the 1964 Declaration of Helsinki and its later amendments. All persons gave their informed consent before their inclusion in the study.
All publicly available data can be accessed through the OAI website (https://nda.nih.gov/oai/).
Study Design
We conducted a retrospective, cross-sectional study within the OAI. For this study, we included individuals who completed the Historical Physical Activity Survey Instrument, which was administered at the OAI 96-month visit, and provided information on the exposure of strength training. Additionally, as part of the OAI parent study, radiographs and knee pain questions were collected at the OAI 48-month visits, the latest time point with the largest number of radiographic readings and data points available.
Patient and Public Involvement
We had no public or patient involvement in this project.
Historical Physical Activity Survey Instrument
We mailed a modified version of the Historical Physical Activity Survey Instrument (13) to participants, similar to what was previously done that demonstrated good reproducibility of the instrument over one year (14). Within the OAI, we have demonstrated good construct validity of the instrument for various physical activities (e.g., American football, swimming, running)(15–17). Participants completed the self-administered version as a take-home survey before their 96-month visit to ascertain exposure to strength training. If the survey was incomplete at the 96-month visit, clinic staff asked participants to complete it at the clinic visit. If participants required assistance or additional clarification on completing the survey, clinic staff were present to help. The survey data were acquired between September 12, 2012, and October 31, 2014.
In the questionnaire, participants were asked to think about 37 leisure physical activities, including “Strength or weight training.” Participants were asked to identify all activities they performed “at least 20 minutes within a given day (these do not have to be consecutive minutes) for at least 10 times” during four age periods: ages 12 – 18, 19 – 34, 35 – 49, and ≥ 50 years old. We then asked them to identify the three most frequently performed activities during those four age periods. For example, “Please refer to Page 16, Question #36, Age Range #1 for activities performed during ages 12 to 18 years. Please list the top 3 most frequently performed during ages 12 to 18 years.” Only those who identified strength training as a top 3 activity were classified as individuals who participated in strength training dichotomously. For each period, they answered additional questions regarding the number of years, months per year, and times per month they engaged in their top three activities. Estimates for the number of times the participants engaged in an activity were based on those answers, which were used to divide participants into low, middle, and high tertiles of participation in strength training. The tertile groupings were used to provide dose-response evaluations of strength training with the outcomes of interest.
Knee Radiographs
We obtained bilateral, fixed-flexion, weight-bearing posteroanterior knee radiographs from the 48-month visit. At the time of analysis, the 48-month visit was the most current OAI visit with the largest number of radiographic readings. If the 48-month radiographs were missing, we used radiographs from the 36-month visit. If the 36-month radiographs were unavailable, then the most recent radiographs were incorporated (at the baseline, 12-, 24-, or 36-month visit). In total, 2289 participants had radiographs from the 48-month visit, 209 (8%) from the 36-month visit, and 109 (4%) from the baseline visit. Based on the Osteoarthritis Research Society International Atlas (18), central readers scored the radiographs using Kellgren-Lawrence grades (0–4)(19). Radiographic OA (ROA) was defined as Kellgren-Lawrence ≥ 2. The reliability (read-reread) was good (weighted kappa for intra-rater reliability was 0.71)(20).
Pain Assessment
We defined frequent knee pain based on a positive response to a standardized question at the 48-month visit: “During the last 12 months, have you had pain, aching, or stiffness in or around your right/left knee on most days for at least one month? By most days, we mean more than half the days of a month”(21). Similar to knee radiographs, if the 48-month visit responses were unavailable, we used the responses from the most recent prior in-person visit (baseline, 12-, 24-, or 36-month visit). For frequent knee pain, 99% derived from the 48-month visit (leaving 13 from the 36-month visit, 4 from the 24-month visit, and 3 from the 12-month visit).
Outcome Measures (Dependent Variables)
In this study we focused on frequent knee pain, radiographic OA (ROA), and symptomatic OA (SOA). Participants with self-reported frequent knee pain answered affirmatively to the knee pain question in at least 1 knee. ROA was defined as KL ≥ 2 in at least one knee. SOA required at least one knee to have both ROA and frequent knee pain. Anyone who reported a total knee replacement was classified as having all outcomes: ROA, SOA, and frequent knee pain. We excluded participants if they had a knee with missing outcome data and the other knee was not classified as having the outcome of interest.
Participant Characteristics
Participant characteristics of interest were age, body mass index, and prior history of injury. The ages of participants were calculated using the date of birth and current date at the time of the 48-month visit. At the 36-month visit, height and weight were both measured to calculate body mass index (BMI) as weight divided by height squared (kg/m2). The most recent annual visit was used to calculate BMIs for individuals missing measurements at the 36-month visit. Prior history of knee injuries was self-reported at baseline and all annual visits up to the 48-month visit.
Statistical Analysis
To evaluate the association of strength training with the prevalence of radiographic knee OA (ROA), frequent knee pain, and symptomatic knee OA (SOA), we performed unadjusted and adjusted knee-based logistic regression analyses where the predictor was any history of strength training. Two adjusted analyses were performed; one included age and sex, and the other included age, sex, and prior history of injury. We did not adjust for other physical activities because no activity correlated with strength training (Spearman correlation coefficient > 0.30). Trends were tested using the Cochrane-Armitage test. We also analyzed participants stratified by age when exposed (12–18, 19–34, 35–49, ≥ 50 years). Strength training was defined dichotomously: those not exposed to strength training and those exposed to strength training. Within the exposure group, results were also tertiled into a low, middle, and high exposure group based on the number of times someone did strength training.
All analyses were performed using SAS version 9.4. P-values <0.05 were considered statistically significant.
RESULTS
Figure 1 visualizes how we selected 2,607 participants from the 4,796 OAI participants. In brief, 3,954 participants attended the 96-month visit. 3,239 participants attended the visit after we started distributing the Historical Physical Activity Survey. Among those participants, 2,637 completed the survey, and 2,607 additionally had complete data for knee pain and radiographs.
Figure 1.
Flow Diagram Reflecting How 2,607 Participants Were Selected from the Original 4,796 Osteoarthritis Initiative Participants.
Of the 2607 participants, 44% were male, and the average age was 64.3 (8.9) years of age with a mean body mass index of 28.5 (4.9) kg/m2 (Table 1). 39% had frequent knee pain, 58% had ROA, 28% had SOA, 4% had a TKR, and 49% had a history of prior injury at the 48-month visit. Within the total participant group, 1789 participants were not exposed to strength training, and 818 were exposed to strength training (Table 1).
Table 1.
Characteristics of Those With No History of Strength or Weight Training, Any History of the Exposure, and All Participants.
| Participant Characteristics | Not Exposed to Strength or Weight Training (n = 1789) |
Exposed to Strength or Weight Training (n = 818) |
All Participants (n = 2607) |
|---|---|---|---|
| Age (years) | 65.5 (9.1) | 61.7 (8.2) | 64.3 (8.9) |
| Sex (% Male) | 42.7% | 47.6% | 44.2% |
| BMI (kg/m2) | 28.7 (4.9) | 28.1 (4.8) | 28.5 (4.9) |
| Frequent knee pain (%) | 40.5% | 36.9% | 39.4% |
| ROA (%) | 60.0% | 53.1% | 57.8% |
| SOA (%) | 29.2% | 23.8% | 27.5% |
| TKR (%) | 4.2% | 3.7% | 4.0% |
| Prior Injury (%) | 47.1% | 53.1% | 49.0% |
BMI: body mass index, ROA: radiographic osteoarthritis, SOA: symptomatic osteoarthritis, TKR: total knee replacement
Table 2 depicts the pattern of participation in strength training over the different age ranges. The largest group of those who participated in strength training was those who only participated at ages 50 and older. The 2nd largest group were those who participated in the oldest 2 age groups.
Table 2.
Patterns of Participation in Strength Training Through the Lifespan Ordered from the Greatest to the Least Frequency.
| Participation Age Ranges | |||||
|---|---|---|---|---|---|
|
| |||||
| Ages 12–18 | Ages 19–34 | Ages 35–49 | Ages ≥50 | Frequency | Percent |
| 1789 | 68.6 | ||||
| X | 340 | 13.0 | |||
| X | X | 145 | 5.6 | ||
| X | 86 | 3.3 | |||
| X | X | X | 65 | 2.5 | |
| X | 48 | 1.8 | |||
| X | X | 35 | 1.3 | ||
| X | X | 30 | 1.2 | ||
| X | X | X | X | 24 | 0.9 |
| X | 19 | 0.7 | |||
| X | X | 7 | 0.3 | ||
| X | X | X | 7 | 0.3 | |
| X | X | 5 | 0.2 | ||
| X | X | 3 | 0.1 | ||
| X | X | X | 3 | 0.1 | |
| X | X | X | 1 | 0.0 | |
Cells with an “X” denote participation in strength training in that age range.
Participants with a history of strength training had a 17 to 23% decreased odds of frequent knee pain, ROA, and SOA (Table 3). For the exposure group separated by tertiles, only the high exposure group had significant results for frequent knee pain (odds ratio (OR):0.74), ROA (OR: 0.70), and SOA (OR: 0.69). Each analysis reflected a dose response. For example, for ROA, the low, middle, and high exposure groups, respectively, had adjusted ORs of 1.00, 0.85, and 0.70. The same relative trend held for frequent knee pain and SOA, all indicating a dose-response benefit to prevalent OA-related outcomes as seen by the lowest odds ratios occurring in the highest exposure groups and the p-for trend being significant.
Table 3.
Odds Ratios of Prevalence of Frequent Knee Pain, ROA, and SOA, Compared to Those Not Exposed to Strength or Weight Training (Referent), for Those Exposed to the Activity (Dichotomous) and Divided into Three Levels of Activity: Low, Middle, and High.
| Strength or Weight Training | Prevalence of Frequent Knee Pain | Unadjusted Odds Ratios of Frequent Knee Pain |
Adjusted Odds Ratios of Frequent Knee Paina |
Adjusted Odds Ratios of Frequent Knee Painb |
|---|---|---|---|---|
| Any History of the Activity | ||||
| No Exposure (n = 1789) | 40.5% | Referent | Referent | Referent |
| Yes Exposure (n = 818) | 36.9% | 0.86 (0.73–1.02) | 0.83 (0.70–0.99) | 0.82 (0.68–0.97) |
| Low (n =264) | 39.8% | 0.97 (0.75–1.27) | 0.95 (0.72–1.24) | 0.95 (0.72–1.24) |
| Middle (n = 259) | 35.9% | 0.82 (0.63–1.08) | 0.80 (0.61–1.05) | 0.78 (0.59–1.03) |
| High (n = 295) | 35.3% | 0.80 (0.62–1.04) | 0.76 (0.58–0.98) | 0.74 (0.57–0.96) |
| p for trend=0.04 | p for trend=0.01 | p for trend=0.008 | ||
| Prevalence of ROA |
Unadjusted Odds Ratios of ROA |
Adjusted Odds Ratios of ROAa |
Adjusted Odds Ratios of ROAb |
|
| Any History of the Activity | ||||
| No Exposure (n = 1789) | 60.0% | Referent | Referent | Referent |
| Yes Exposure (n = 818) | 53.1% | 0.75 (0.64–0.89) | 0.86 (0.72–1.02) | 0.83 (0.70–0.99) |
| Low (n =264) | 55.7% | 0.84 (0.65–1.09) | 0.99 (0.76–1.30) | 1.00 (0.76–1.30) |
| Middle (n = 259) | 54.4% | 0.80 (0.61–1.03) | 0.89 (0.68–1.17) | 0.85 (0.65–1.11) |
| High (n = 295) | 49.5% | 0.65 (0.51–0.84) | 0.73 (0.57–0.94) | 0.70 (0.54–0.90) |
| p for trend=0.0003 | p for trend=0.02 | p for trend=0.006 | ||
| Prevalence of SOA |
Unadjusted Odds Ratios of SOA |
Adjusted Odds Ratios of SOAa |
Adjusted Odds Ratios of SOAb |
|
| Any History of the Activity | ||||
| No Exposure (n = 1789) | 29.2% | Referent | Referent | Referent |
| Yes Exposure (n = 818) | 23.8% | 0.76 (0.63–0.92) | 0.79 (0.65–0.96) | 0.77 (0.63–0.94) |
| Low (n =264) | 24.6% | 0.79 (0.59–1.07) | 0.84 (0.62–1.13) | 0.84 (0.62–1.14) |
| Middle (n = 259) | 24.7% | 0.80 (0.59–1.07) | 0.82 (0.61–0.96) | 0.79 (0.58–1.07) |
| High (n = 295) | 22.4% | 0.70 (0.52–0.93) | 0.71 (0.53–1.02) | 0.69 (0.51–0.93) |
| p for trend=0.005 | p for trend=0.01 | p for trend=0.006 | ||
Adjusted for age and sex.
Adjusted for age, sex, and prior history of injury.
ROA: radiographic osteoarthritis, SOA: symptomatic osteoarthritis.
p for trends were tested using the Cochrane-Armitage test.
The age stratified results are available in Supplemental Tables 1-3. In general, more individuals participated in strength training in the older age ranges. The association of strength training with less frequent knee pain, less ROA, and less SOA was most evident in the older age ranges.
DISCUSSION
This is the first epidemiologic study to examine the impact of strength training on knee health in a community-based sample not selected for a history of elite weight lifting. Participants with a history of strength training had a lower prevalence of frequent knee pain, ROA and SOA than those who did not, indicating that strength training is associated with better knee health. Those in the highest exposure group might receive the greatest benefit. The benefits of strength training may be attributable to improved biomechanics/neuromuscular control, reduced risk of injury, promoting weight maintenance, improved or preserved mobility and physical functioning, similar to the benefits seen with physical therapy(11, 22–28).
A strength of this study is that it was conducted in a cohort who were not selected for their exposure to strength training. The level of participation is much closer to the general population, making the findings more pertinent. This is particularly important because previous studies have indicated former elite competitive weightlifters had an increased risk of developing knee OA (5, 6). Though these findings are meaningful and apply to the activity of strength training, these findings cannot be generalized to the wider population. Because our observational study is more reflective of the general population that participates in recreational strength training, our findings showing a lower association of knee pain, ROA, and SOA are extremely valuable for most of the general population
Adjusting for injury status strengthened the associations; we speculate this is likely because prior injury status might initially predispose individuals to participate in strength training. For example, after an injury someone may complete a supervised exercise training program (including strength training) and be advised to continue to do their exercises after they complete formal rehabilitation. Thus, these individuals are inherently more likely to have all the outcomes of interest because of this indication.
In our study, we found that the association between strength training and knee OA was most robust in the older age groups with convincing dose-response relationships seen across all outcomes of interest. Exercise trends over the past few decades may have influenced results. Strength training has become increasingly popular over the past few decades. Exposure to strength training at younger ages was less common (table 2) and may predate the widespread adoption of strength training machines in local fitness centers. Participants in this study would have been around ages 12–18 in the 1950’s when fitness gyms with a focus on strength training were not ubiquitous. It would be many years later, around the 1980’s, before this would happen. In the last several decades, there has been a notable change in the patterns of strength training with many individuals engaging in this activity at younger ages. Thus, future studies allowing a greater understanding of the associations between strength training and knee OA, particularly during younger age ranges, are needed.
There are some limitations to this study. This was an observational study and individuals involved in strength training were all self-selected. Our definition of participation in strength training may be liberal (at least 20 minutes 10 or more times). But we also required that participants identify this as a top three activity they engaged in for at least one of the time periods. This definition represents how individuals may engage in strength training and would likely bias our results to the null. Hence, it is more likely that we may be underestimating rather than overestimating the benefits of sustained recreational strength training. Based on our study design, we cannot rule out reverse causation or confounding by indication. Participants might reduce or stop participating in strength training levels if they develop symptoms (reverse causation). Alternatively, individuals with OA may be advised to do strength training exercise (confounding by indication). Confounding by indication would lead to evidence that strength training increases the chance of knee OA outcomes. But instead, we find the opposite. Particularly in the older age range, strength training was associated with less frequent knee pain, ROA, and SOA. Recall bias is also a potential concern due to the retrospective nature of the design, where participants had to classify their present and past exposures based on prior time periods in their lives. However, the specific questions of the study were unknown to the study participants, reducing the likelihood of this bias in this study.
As the natural history of knee OA is very long, occurring over many decades, understanding the relationship between a lifetime of leisure physical activity and OA outcomes would be a costly endeavor if performed prospectively from the time of childhood until participants developed knee OA. Thus, studies such as this one, are needed to provide observational data supportive of associations that are anticipated. As findings from this study indicate that strength training is associated with less frequent knee pain, OA, and SOA, prospective studies confirming a benefit of strength training to knee health are warranted.
Our study represents a potential paradigm shift that strength training throughout a lifetime is beneficial for knee health. This finding adds to the growing body of observational evaluations that indicate the possible benefits of running, swimming, and gardening, and the possible harms of American football and soccer towards knee health (15, 16, 29–31). Our findings support the idea that the medical community should proactively encourage more people to participate in strength training to help reduce their risk of osteoarthritis and other chronic conditions.
Supplementary Material
Acknowledgments
Dr. Lo was supported by K23 AR062127, an NIH/NIAMS funded mentored award, providing support for the design and conduct of the study, analysis, interpretation of the data, and preparation and review of this work. This work was supported in part with resources at the VA HSR&D Center for Innovations in Quality, Effectiveness, and Safety (#CIN 13-413), at the Michael E. DeBakey VA Medical Center, Houston, TX. This research was supported in part by generous donations to the Tupper Research Fund at Tufts Medical Center. The Osteoarthritis Initiative is a public-private partnership comprised of five contracts (N01-AR-2-2258; N01-AR-2-2259; N01-AR-2-2260; N01-AR-2-2261; N01-AR-2-2262) funded by the National Institutes of Health, a branch of the Department of Health and Human Services, and conducted by the Osteoarthritis Initiative Study Investigators. Private funding partners include Merck Research Laboratories; Novartis Pharmaceuticals Corporation, GlaxoSmithKline; and Pfizer, Inc. Private sector funding for the Osteoarthritis Initiative is managed by the Foundation for the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, the National Institutes of Health, or the Department of Veterans Affairs. We also confirm the independence of researchers from funders and that all authors, external and internal, had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis is also required. The sponsors had no role in the collection, analysis, and and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.
Footnotes
Timothy E. McAlindon declares that he is a consultant for Remedium-Bio, Anika, Chemocentryx, Grunenthal, Kolon Tissue Gene, Novartis, BioSplice, MEDIPOST, Organogenesis, and Pfizer Inc. C. Kent Kwoh declares that he received grants or contracts from Abbvie, EMD Soreno, Lilly, Cumberland, Pfizer, and GSK. CKK also served as a consultant for Trial Spark and Express Scripts and received payment or honoraria from Focus Medical Communications. The other authors state they have no conflict of interest with regard to this work.
STATEMENTS AND DECLARATIONS
TRANSPARENCY STATEMENT:
Grace H. Lo affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
ETHICS APPROVAL:
All human studies have been approved by the appropriate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The Institutional Review Boards at all clinical sites and at Baylor College of Medicine (#H30423) approved this study.
CONSENT TO PARTICIPATE:
All individual participants gave their informed consent prior to their inclusion in the study.
CONTRIBUTIONS AND GUARANTOR STATEMENT:
The first draft of the manuscript was written by Grace H. Lo. Grace H. Lo is the corresponding author, as well as the guarantor; she accepts full responsibility for the work and/or the conduct of the study, had access to the data, and controlled the decision to publish. The corresponding author also attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. All authors contributed to the conception and design of the work or the acquisition, analysis, or interpretation of data for the work. All authors were involved in revising it critically for important intellectual content and each individual read and approved the final manuscript. Authors agree to be held accountable for all aspects of the work to ensure that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Of note, Dr. Rebecca Jackson, physician scientist at The Ohio State University, also assisted with data collection and other aspects of authorship, but she recently passed away. We greatly appreciate the contribution she made to the project.
DATA AVAILABILITY AND SHARING:
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. The authors of this study have full control of all primary data and they agree to allow the journal to review the data if requested. Datasets from the main Osteoarthritis Initiative are publicly available on the website: https://nda.nih.gov/oai/
REFERENCES
- 1.World Health Organization. WHO guidelines on physical activity and sedentary behaviour Geneva: World Health Organization; 2020. [PubMed] [Google Scholar]
- 2.Piercy KL, Troiano RP, Ballard RM, Carlson SA, Fulton JE, Galuska DA, et al. The Physical Activity Guidelines for Americans. JAMA 2018;320(19):2020–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Elgaddal N, Kramarow EA, Reuben C. Physical Activity Among Adults Aged 18 and Over: United States, 2020. NCHS Data Brief 2022(443):1–8. [PubMed] [Google Scholar]
- 4.(IHME) IfHMaE. GBD Summaries: Osteoarthritis — Level 3 cause 2019. [cited 2022 12/23/2022]; Available from: https://www.healthdata.org/results/gbd_summaries/2019/osteoarthritis-level-3-cause
- 5.Kujala UM, Kaprio J, Sarna S. Osteoarthritis of weight bearing joints of lower limbs in former elite male athletes. BMJ 1994;308(6923):231–4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Kujala UM, Kettunen J, Paananen H, Aalto T, Battie MC, Impivaara O, et al. Knee osteoarthritis in former runners, soccer players, weight lifters, and shooters. Arthritis Rheum 1995;38(4):539–46. [DOI] [PubMed] [Google Scholar]
- 7.Venkat R Weightlifting in Olympics: Everything you need to know 2023. 06/27/2023 [cited 2023 08/07/2023]; Available from: https://olympics.com/en/news/weightlifting-olympics-rules-history-snatch-clean-and-jerk [Google Scholar]
- 8.Whittaker JL, Culvenor AG, Juhl CB, Berg B, Bricca A, Filbay SR, et al. OPTIKNEE 2022: consensus recommendations to optimise knee health after traumatic knee injury to prevent osteoarthritis. British Journal of Sports Medicine 2022;56(24):1393. [DOI] [PubMed] [Google Scholar]
- 9.Munukka M, Waller B, Rantalainen T, Häkkinen A, Nieminen MT, Lammentausta E, et al. Efficacy of progressive aquatic resistance training for tibiofemoral cartilage in postmenopausal women with mild knee osteoarthritis: a randomised controlled trial. Osteoarthritis Cartilage 2016;24(10):1708–17. [DOI] [PubMed] [Google Scholar]
- 10.Chiu JK, Wong YM, Yung PS, Ng GY. The effects of quadriceps strengthening on pain, function, and patellofemoral joint contact area in persons with patellofemoral pain. Am J Phys Med Rehabil 2012;91(2):98–106. [DOI] [PubMed] [Google Scholar]
- 11.Fragala MS, Cadore EL, Dorgo S, Izquierdo M, Kraemer WJ, Peterson MD, et al. Resistance Training for Older Adults: Position Statement From the National Strength and Conditioning Association. J Strength Cond Res 2019;33(8):2019–52. [DOI] [PubMed] [Google Scholar]
- 12.The Osteoarthritis Initiative [cited 2019; Available from: https://nda.nih.gov/oai/
- 13.Friedenreich CM, Courneya KS, Bryant HE. The lifetime total physical activity questionnaire: development and reliability. Med Sci Sports Exerc 1998;30(2):266–74. [DOI] [PubMed] [Google Scholar]
- 14.Chasan-Taber L, Erickson JB, McBride JW, Nasca PC, Chasan-Taber S, Freedson PS. Reproducibility of a self-administered lifetime physical activity questionnaire among female college alumnae. Am J Epidemiol 2002;155(3):282–9. [DOI] [PubMed] [Google Scholar]
- 15.Lo GH, McAlindon TE, Kriska AM, Price LL, Rockette-Wagner BJ, Mandl LA, et al. Football Increases Future Risk of Symptomatic Radiographic Knee Osteoarthritis. Med Sci Sports Exerc 2020;52(4):795–800. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Lo GH, Ikpeama UE, Driban JB, Kriska AM, McAlindon TE, Petersen NJ, et al. Evidence that Swimming May Be Protective of Knee Osteoarthritis: Data from the Osteoarthritis Initiative. PM R 2020;12(6):529–37. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Lo GH, Driban JB, Kriska AM, McAlindon TE, Souza RB, Petersen NJ, et al. Is There an Association Between a History of Running and Symptomatic Knee Osteoarthritis? A Cross-Sectional Study From the Osteoarthritis Initiative. Arthritis Care Res (Hoboken) 2017;69(2):183–91. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Altman RD, Gold GE. Atlas of individual radiographic features in osteoarthritis, revised. Osteoarthritis Cartilage 2007;15 Suppl A:A1–56. [DOI] [PubMed] [Google Scholar]
- 19.Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis 1957;16(4):494–502. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Osteoarthritis I Project 15 Test-Retest Reliability of Semi-quantitative Readings from Knee Radiographs Updated November 22, 2016. https://ndanihgov/oai/study_documentationhtml.
- 21.O’Reilly SC, Muir KR, Doherty M. Screening for pain in knee osteoarthritis: which question? Ann Rheum Dis 1996;55(12):931–3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Baker KR, Nelson ME, Felson DT, Layne JE, Sarno R, Roubenoff R. The efficacy of home based progressive strength training in older adults with knee osteoarthritis: a randomized controlled trial. J Rheumatol 2001;28(7):1655–65. [PubMed] [Google Scholar]
- 23.Bennell KL, Messier SP. Osteoarthritis: Strength training, self-management or both for early knee OA. Nat Rev Rheumatol 2010;6(6):313–4. [DOI] [PubMed] [Google Scholar]
- 24.Ettinger WH Jr., Burns R, Messier SP, Applegate W, Rejeski WJ, Morgan T, et al. A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST). Jama 1997;277(1):25–31. [PubMed] [Google Scholar]
- 25.Hovis K, Stehling C, Pialat J-B, Nevitt M, McCulloch C, Link T. Association of Exercise, Strength Training, and Knee-Bending Activities with Knee Cartilage T2 Values and WORMS Using 3T MRI in Asymptomatic Subjects with and without Osteoarthritis Risk Factors. Radiologic Society of North America 2010: 96th Scientific Assembly and Annual Meeting Chicago, IL; 2010. p. Abstract LL-MKS-Mo2B. [Google Scholar]
- 26.Imoto AM, Pardo JP, Brosseau L, Taki J, Desjardins B, Thevenot O, et al. Evidence synthesis of types and intensity of therapeutic land-based exercises to reduce pain in individuals with knee osteoarthritis. Rheumatol Int 2019;39(7):1159–79. [DOI] [PubMed] [Google Scholar]
- 27.Jansen MJ, Viechtbauer W, Lenssen AF, Hendriks EJ, de Bie RA. Strength training alone, exercise therapy alone, and exercise therapy with passive manual mobilisation each reduce pain and disability in people with knee osteoarthritis: a systematic review. J Physiother 2011;57(1):11–20. [DOI] [PubMed] [Google Scholar]
- 28.Rogind H, Bibow-Nielsen B, Jensen B, Moller HC, Frimodt-Moller H, Bliddal H. The effects of a physical training program on patients with osteoarthritis of the knees. Arch Phys Med Rehabil 1998;79(11):1421–7. [DOI] [PubMed] [Google Scholar]
- 29.Lo GH, Musa SM, Driban JB, Kriska AM, McAlindon TE, Souza RB, et al. Running does not increase symptoms or structural progression in people with knee osteoarthritis: data from the osteoarthritis initiative. Clin Rheumatol 2018;37(9):2497–504. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Petrillo S, Papalia R, Maffulli N, Volpi P, Denaro V. Osteoarthritis of the hip and knee in former male professional soccer players. Br Med Bull 2018;125(1):121–30. [DOI] [PubMed] [Google Scholar]
- 31.Freiberg A, Bolm-Audorff U, Seidler A. The Risk of Knee Osteoarthritis in Professional Soccer Players—a Systematic Review With Meta-Analyses. Dtsch Arztebl Int 2021;118(4):49–55. [DOI] [PMC free article] [PubMed] [Google Scholar]
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