Exercise as it relates to Disease/How knee osteoarthritis in older adults can be improved from home

This page is a critical analysis of "The Efficacy of Home Based Progressive Strength Training in Older Adults with Knee Osteoarthritis: A Randomised Controlled Trial" by Baker et al (2001).

What is the background for this research?
Osteoarthritis is a irreversible, chronic, and progressive condition occurring when joint cartilage wears down, typically due to ageing, obesity, or joint related injuries. It is the most common joint disease in adults around the world and occurs in the hands, hips, and spine, but most commonly in the knee. The estimated lifetime risk for knee osteoarthritis is 47% in women and 40% in men, with between 19-28% of adults actually exhibiting the condition.

The study aims to test how strengthening the musculature acting on the knees, particularly the quadriceps, affects the clinical signs and symptoms of knee osteoarthritis. Previous research has concluded that quadriceps weakness is the greatest predictor of lower limb functional limitation and that strengthening the quadriceps improves pain and function of those with knee osteoarthritis. However, those same studies showed little, to no, strength gains in the participants. Improving strength, psychological well-being, or maintaining cartilage integrity have been stated to have potential beneficial effects on knee osteoarthritis, but are yet to be evaluated. Therefore, this study aims to fill this gap in knowledge through testing these pathways and their benefits when the goal of the program is to actually improve strength.

This research is important due to the potential real world application of a home-based strength program for elderly adults, as an exercise program like the one in the study can be easily accessed and replicated by all those suffering from knee osteoarthritis.

Where is the research from?
The baseline and final tests were completed at the Jean Mayer USDA Human Nutrition Research Centre on Ageing at Tufts University. It was also partly supported by grants from the Arthritis Foundation, American Federation of Ageing Research, Life Fitness Academy, The Farnsworth Trust Medical Foundation, Brookdale Foundation, USDA Cooperative Aggreement-58-1950-9-001, and National Institutes of Health Grant AR20613. However, there is no evidence of bias from such organisations.

All six authors have previous research on topics revolving around osteoarthritis, nutrition, exercise programs, cartilage damage, and pain management.

What kind of research was this?
The study was a randomised controlled trial (RCT) where participants were placed in either a home-based exercise program (intervention group) or a home-based nutrition program (control group). The participants were blinded to the active intervention and the results of both groups were compared.

The use of a RCT provides reliable evidence regarding the effectiveness of the intervention when compared to other study types (e.g. cohort study, cross-sectional study, case-control study). This is because other study types only find correlations between groups, rather than conclusive evidence like a RCT.

What did the research involve?
The research in this study involved elderly adults who were randomly placed in either the intervention or control group. Eligibility criteria for these participants included:
 * ≥55 years old
 * BMI ≤40kg/m2
 * Pain on one or more days of the past month during walking, going up/down stairs, standing upright, or in bed,
 * Radiographic evidence of knee osteoarthritis
 * Cleared to exercise
 * No inflammatory arthritis
 * Had not participated in a exercise program within the last six months

There were 56 potential participants, however due to withdrawals during the treatment period, only 38 participants completed the full intervention.

The home-based exercise program included seven exercises, including bodyweight squats and step-ups, and knee extensions/flexions, hip extensions, and hip abductions/adductions with ankle weights. The squats and step-ups had three and four progressions respectively, meaning the exercises increased in difficulty with technique changes rather than load increases. Whereas the other exercises progressed with heavier ankle weights. Each participant performed two sets of twelve repetitions, three times per week for each exercise. The intensity of each exercise was determined using a modified 10 point Borg scale rating of perceived exertion (RPE). Participants began with an RPE of 3-5 until proper form was achieved, then increasing to RPE 8 for the remainder of the intervention. Patients were visited twice a week in the first three weeks, once in the fourth, and then once every two weeks from thereon.

The nutrition program included keeping a food log on three nonconsecutive days every two weeks, which were evaluated with each home visit. Additionally, specific nutritional goals were set each visit, e.g. increasing fruit and vegetable intake.

The methodology used had both strengths and weaknesses. The weaknesses lie in the sample size being small, and the risk of food log inaccuracies. Due to the nature of knee osteoarthritis and high-intensity exercise, the selection criteria had to be specific to avoid harm to the participants, and explains the small sample size. Additionally, food log inaccuracies are unavoidable due to potential errors in self-reporting and a low number of recorded days. The strengths are using an RPE system, not progressing until proper form was learned, and employing steady progression for each exercise, allowing for individualised and safe development for each participant.

What were the basic results?
Pain, physical function, knee extension 1 repetition maximum (1RM), knee flexion 1RM, leg press 1RM, and quality of life factors were measured both at baseline and after the four-month intervention.

NOTE: Pain and physical function were measured using the Western Ontario/McMaster Universities Osteoarthritis Index (WOMAC), where higher scores indicate worse pain or function.

Findings show that strength training greatly improved all measures compared to the control group. Not seen in the table, but there were improvements in quality of life factors, including social functioning, mental health, bodily pain, vitality, general emotional health, and walking self-efficacy.

The implications of their findings were not over emphasised as the conclusions made by the authors are supported and can be comparable to previous studies (mentioned in the report), although limitations are acknowledged. The authors interpreted the benefits of their intervention as almost entirely a result of increased muscular strength, however they do believe that psychological factors also play a role in pain management and the mechanisms in which increased muscular strength improve knee osteoarthritis are still inconclusive.

What conclusions can we take away from this research?
The study proves that high-intensity, at-home, progressive strength training programs can improve the physical function, pain, self-efficacy, and the quality of life of elderly adults with knee osteoarthritis through increasing muscular strength. However, since osteoarthritis cannot be reversed, only managed, four months is a relatively short period of time when considering sufferers will be managing pain and function for years, and as such, long term adherence and benefits of a strength program are yet to be evaluated. Thus, the long term benefits of a strength program needs further investigation before proper judgement is made. Nevertheless, the findings are still extremely promising due to the number of lifestyle related aspects that improved as muscular strength increased.

Practical advice
The research shows that a home-based, strength training program can have significant effects on knee osteoarthritis. A program like the one in the study can be easily replicated by elderly adults due to minimal required equipment and the simplicity of the exercises. Although, it is important to be cleared by a health professional prior to beginning exercise (via an ESSA pre-exercise screening tool) and proper form needs to be learnt before increasing intensity to reduce the risk of harm. Furthermore, exercise should be ceased if any pain or discomfort occurs at any stage. Once these considerations are met, a home-based strength program can be achieved by those suffering from knee osteoarthritis.

Further information
For further information on osteoarthritis, please visit:
 * 1) Mayo Clinic - Osteoarthritis: https://www.mayoclinic.org/diseases-conditions/osteoarthritis/symptoms-causes/syc-20351925
 * 2) What is knee osteoarthritis?: https://www.arthritis-health.com/types/osteoarthritis/what-knee-osteoarthritis#:~:text=Knee%20osteoarthritis%20is%20a%20condition,from%20joint%20friction%20and%20impact.
 * 3) The effect of dynamic versus isometric resistance training on pain and functioning among adults with osteoarthritis of the knee: https://doi.org/10.1053/apmr.2002.33988
 * 4) Cost-effectiveness of aerobic and resistance exercise in seniors with knee osteoarthritis: http://doi.org/10.1097/00005768-200009000-00002