Exercise as it relates to Disease/How resistance training can help with knee osteoarthritis

This is a critique of the research article: Jan MH, Lin JJ, Liau JJ, Lin YF, Lin DH. Investigation of clinical effects of high-and low-resistance training for patients with knee osteoarthritis: a randomized controlled trial. Physical therapy. 2008 Apr 1;88(4):427-36.

What is the background to this research?

Osteoarthritis (OA) is a common musculoskeletal disorder which commonly affects hands, knees, hips, the lower back and neck. According to a 2011-12 national survey, 8% of Australians had been reported with osteoarthritis with twice as many female cases as males (10.2% and 5.6% respectively). There are many factors that have been linked to causing OA:

• Age
• Joint injury/overuse: common in both work and sporting environments
• Obesity: extra weight and forces being placed on joints
• Weak muscles: weak muscles causing instability
• Genetics
• Sex/gender

Osteoarthritis can also have a heavy impact on the lifestyle of the population. Common symptoms of osteoarthritis include pain, reduced mobility, stiffness and decreased muscle strength which may lead to decreased physical activity, and ultimately further health concerns. A decrease in physical activity has potential to lead to weight gain or obesity which then may bring upon health issues such as high cholesterol, diabetes, heart disease and high blood pressure. People living with OA are also at greater risk of falls and fall-related injuries. The National Council on Aging found that people with OA have a 30% greater chance of having a fall, and 20% greater chance of a fracture from a fall. Resistance training has been linked to reducing pain and promoting exercise in OA patients. The current literature suggests that resistance training (resulting in increased muscle strength) has been found to reduce pain and improve joint function. Another study on blood flow restriction training found a greater increase than just standard resistance training. The aim of the present study was to determine the effects of high- and low-intensity training on pain and functional scores related to knee OA. The hypothesis of the study was that the resistance training groups would present a greater functional improvement compared to the control group.

Where is the research from?

The authors of this study were

• MH Jan, PT, MS, is Associate Professor, Medical College, School and Graduate Institute of Physical Therapy, National Taiwan University, and Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital
• JJ Lin, PT, PhD, is Associate Professor, Medical College, School and Graduate Institute of Physical Therapy, National Taiwan University
• JJ Liau, PhD, is Associate Professor, Medical College, School and Graduate Institute of Physical Therapy, National Taiwan University
• YF Lin, MD, PhD, is Chairman, Department of Orthopaedics, West Garden Hospital
• DH Lin, MD, is Attending Doctor, Department of Orthopaedic Surgery, En Chu Kong Hospital, Taipei Hsien, Taiwan, Republic of China

The study was completed in Taiwan with participants recruited from the Department of Orthopaedics at the National Taiwan University Hospital.

What kind of research was this?

This study was a single-blind randomised controlled trial. The evaluation of results was performed by the same examiner, who also remained blinded to the experiment. There were three groups in this study, two exercise groups and a control group – of which participants were assigned to via a randomisation number table.

What did the research involve?

There were 102 participants split into three groups – high-resistance (HR), low-resistance (LR) and a control group. These participants needed to meet the needs of the American College of Rheumatology criteria of knee OA (hyperlink a link of needs). Participants were also excluded if they had received physical therapy in the 3 months prior to the study or had other musculoskeletal issues with the knee joint. There were 34 participants in both the resistance (high and low) groups with 30 participants featuring in the control group. All participants were required to do some pre-testing for pain and physical function. The WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) pain scale was used to compare pain levels of the participants whilst performing general housework tasks such as bathing, walking, sleeping and sitting. The physical function tests were

• Walking time over 4 different terrains: hard/level surface, a figure-eight pattern, a staircase consisting of 13 stairs and along a spongey surface

Participants were required to complete these tasks as quick as they could, time was measured in seconds.

• Knee extensor and flexor muscular torque

Participants were seated in an upright position against a backrest inclined to 15 degrees. The test required participants to either extend or flex their knee as far as possible with starting angles of the knee being at 60 degrees, 120 degrees and 180 degrees. The practical part of the study was an 8-week resistance training program that was individually prescribed and monitored by an experienced therapist. The programs all had similar total volume (resistance x repetitions x sets) and was referred from a predicted 1RM. Every two weeks the participants’ 1RM was re-tested to adjust the resistance increased 5%. The sessions consisted of:

• High resistance: participants resistance was set to 60% 1RM for 3 sets of 8 repetitions. Sessions lasting 30 minutes
• Low resistance: participants resistance was set to 10% 1RM for 10 sets of 15 repetitions. Sessions lasting 50 minutes.
• Control group: the control groups were not permitted any exercise throughout the duration of the study

For each session, there was a 10-minute stationary bike warm up and post exercise cold packs were applied to the participants knees for 10 minutes.

What were the basic results?

The results from the study was that resistance training does reduce pain and increase function of OA sufferers. Both resistance groups scored much better after the 8-week training program compared to the control group with similar results between the high-resistance and low-resistance groups. The WOMAC pain index scores decreased, the walking times for the figure-eight pattern and the spongey surface times decreased and the muscle torque for flexion and extension all improved. Some key results included the WOMAC pain subscale scores (8.5 to 4.8 and 7.8 to 4.8 in HR and LR), figure-eight pattern time (11.0 seconds to 6.1 seconds and 10.9 seconds to 6.8 seconds) and the spongey surface times (12.6 seconds to 6.3 seconds and 12.5 seconds to 7.3 seconds).

What conclusions can we take from this research?

The conclusion of the study found that both high- and low-resistance training groups are beneficial in reducing pain and increasing function in people with knee OA compared to the control group. Previous literature has stated that high-resistance training has greater results compared to low-resistance training but with the results of this current study we can see that low-resistance training can be just as effective. Between the high- and low-resistance training groups the differences in improvements for the WOMAC pain scores were quite little, but for knee function the high-resistance training proved to have a greater result.

Practical Advice

People who are experiencing pain or a loss of function in their knee(s) from OA should be doing some resistance training as part of their rehab and/or management. All through the literature there are lots of papers supporting the findings of this study. Although most OA studies have been looking at participants of the older population, the younger population can still benefit off the same style of training.

Further information/resources

Osteoarthritis Australia

Strength training with Arthritis