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Exercise Benefits People with Osteoarthritis
Thomas, J., M.S. & Len Kravitz, Ph.D.

Osteoarthritis (OA), the nation's most common form of arthritis, is a degenerative joint disease characterized by the breakdown of cartilage and its underling bone, which eventually leads to joint pain and stiffness (Lubar, 2010). Although it has been associated with joint wear and tear, it also linked to low-grade chronic inflammation and synovitis (inflammation of the synovial membrane) (Helmark et al., 2010). According to the CDC (2011), OA affects 13.9% of adults aged 25 and older, which is about 27 million people in the US. Although OA impacts the hand, feet, and hips, the knee appears to be the joint most affected (higher in women the men), and thus the target body area of most research (CDC, 2011). Current clinical practice guidelines of OA recommend client exercise as a core treatment. Because OA is considered an irreversible condition, the treatment is focused on reducing physical disability, controlling pain, and minimizing the potentially harmful side effects of medications (Beckwee et al., 2013). Regular resistance training and aerobic exercise can improve mobility and reduce the risks of falls for OA sufferers, and provide other meaningful health benefits.

The Inflammation Connection to Osteoarthritis
OA is associated with periods of synovial membrane inflammation and increases in inflammatory markers (Helmark et al., 2010). According to Zhang et al. (2013), persons with knee OA have greater levels of tumor necrosis factor alpha, C-reactive protein, and matrix metalloproteinase-3, which are cell signaling proteins associated with elevated inflammation. Excessive joint loading in these patients can lead to an intensified inflammatory response, joint pain, and swelling (Helmark et al., 2010). However, Helmark and colleagues emphasize that regular moderate exercise like strength training, cycling, or walking is known to be advantageous in OA patients, with no sign of joint deterioration or enhanced inflammation. Zhang et al. (2013) found that in knee OA patients, 4 weeks of dynamic and isometric exercises 4 times per week led to a reduction in these inflammatory chemicals in the knee joint synovial fluid. Thus, research suggests that regular moderate intensity exercise may actually have an anti-inflammatory effect, positively reducing the deleterious consequences of osteoarthritis.

Why is Muscle Strengthening Exercise Good for People with Osteoarthritis?
Having weak lower extremity muscles makes a person more vulnerable to joint injury. Beckwee et al. (2013) summarize data that suggests the contraction of opposing muscles about a vulnerable OA joint, which leads to an eventual gain in strength, greater level of physical activity, better functional movement capability and fewer compression force-related joint injuries. The researchers continue that an improvement in strength of muscles involved in weight bearing exercise will better maintain optimal gait patterns, and thus minimize lower body skeletal misalignment.

What Type of Resistance Training Program Works Best for Persons with Osteoarthritis?
As noted earlier, consistent moderate intensity exercise has been recommended to be most advantageous (Helmark et al., 2010) for men and women with osteoarthritis. Fukumoto and colleagues conducted a very applied research study that provides some valuable guidance in designing resistance training exercise for women with osteoarthritis. In the Fukumoto et al. (2013) study, 46 women (ave age = 52 years) with hip osteoarthritis completed four exercises daily (at home; although exercises were taught by a physical therapist) of the lower limbs. The exercises were hip abduction in supine position, hip extension in prone position, hip flexion in a sitting position, and knee extension in a sitting position. Each exercise was performed using elastic resistance, with subjects completing exercises at a perceived 'somewhat hard' intensity. Subjects had different elastic bands to use to progress in intensity to attain the 'somewhat hard' intensity. Two sets of 10 repetitions of concentric and eccentric contractions through the full range of motion were performed for the first two weeks, and three sets of 10 repetitions were performed there after for 6 weeks (study length 8 weeks). Participants were further divided into a high-velocity group, who were taught to perform the concentric phase of each repetition as rapidly as possible and then return (to start) with a 3-second eccentric contraction. Participants in a low-velocity group performed both the concentric and eccentric phases in 3 seconds. Several outcome measures were analyzed including isometric muscle strength, muscle power, muscle thickness, maximum walking speed, timed up and go test, 3-minute walking test, and hip pain. Interestingly, both groups progressed equally in all measures with the timed up and go test being superior in the high-velocity group. This study provides great insight for personal trainers developing resistance training programs for clients with osteoarthritis.

What Type of Cardiovascular Training Program Works Best for Persons with Osteoarthritis?
Mangione and colleagues (1999) recruited thirty-nine male and female adults (71 ± 6.9 years old) who had been diagnosed with OA in the knee. Subjects were randomly assigned to either a high-intensity (70% heart rate reserve) or low-intensity (40% heart rate reserve) exercise group. Study participants cycled for 25 minutes, 3 times per week for 10 weeks. Before and after the exercise intervention they completed a standardized overall pain assessment, timed chair rise, 6-minute walk test, gait test, and graded exercise treadmill test. Acute pain was reported daily using a pain-severity scale. The results of this study revealed that participants in both groups significantly and equally advanced in aerobic capacity, the 6-minute walk test, and the timed chair rise. Pain relief also similarly lowered for both groups. Cycling, a repetitive lower extremity exercise, may be considered an appropriate exercise modality for patients with knee OA. Additionally, low-intensity cycling was as effective as high-intensity cycling in improving aerobic capacity and decreasing pain. In another study, Lau et al (2013) recruited twenty subjects (average age 72 years) who had suffered from osteoarthritis of the knee for at least 3 years and with mild-to-severe knee pain. Volunteers completed a 10-week aquatic exercise program (2 times a week) designed and led by physiotherapists. Results indicated beneficial changes in range of motion, knee strength and psychosocial functioning.

Exercise and Lifestyle Guidelines
About 10 years ago, the Centers for Disease Control and Prevention and the Arthritis Foundation launched The National Arthritis Action Plan: A Public Health Strategy. This collaboration resulted in a landmark document with a consensus of lifestyle and exercises guidelines for people who suffer from chronic arthritis. Here is a synthesis of their physical activity recommendations. The most effective and safest physical activities for adults with OA (of the lower extremities) are low impact, moderate intensity aerobics, including water exercise, walking and cycling. Depending on the pain of the client, cycling and water exercise may be less stressful. Muscle strengthening exercises that use different forms of resistance (i.e., band, body weight, free weight and fixed form machine) are recommended. Overall, a minimum of 150 minutes (2.5 hours) of moderate intensity aerobics throughout the week with two days of muscle strengthening exercise per week is recommended to lessen OA pain and symptoms, while enhancing body function and helping to manage chronic health conditions.
In addition, the The National Arthritis Action Plan document addressed the concern that a higher body mass index (BMI) is associated with OA. Being overweight may consistently overload the pressure on the weight-bearing joints, leading to joint inflammation and pain. Overweight and obesity are a major risk factor for diabetes, cardiovascular disease, some cancers and premature death. However, people who maintain a healthy weight are less likely to develop OA of the knee. Modest weight loss in people with OA has been shown to lead to improvements quality of life, physical function, pain symptoms and self-reported disability.

Final Thoughts
Lack of physical activity is associated with muscle weakness, pain, joint stiffness, and reduced range of motion, fatigue, decreased function and general deconditioning in clients with OA. In addition, exercise may have an anti-inflammatory effect. Clients need clear messages about the benefits of exercise for people with OA and need to be assured that moderate intensity exercise, of the type and amount recommended for health, has not been shown to cause or worsen arthritis. In fact, the opposite is true. Personal trainers should recommend that their clients engage in exercise that utilizes proper progression and rest. Strength training (at least 2x/week which is not excessive) should be recommended for development of muscle mass, muscular strength and function. Aerobic exercise (at least 3x/week) should be advocated to better control disease activity and function as well as inflammatory markers. A combination of strength and aerobic exercise (e.g. circuit training) may also be beneficial and convenient for a client's lifestyle. Introducing non-weight-bearing exercise may be a good strategy when introducing exercise to a physically inactive OA sufferer. Progress gradually to include weight-bearing exercise. Keep moving.

Jenny Thomas, M.S. has a Masters in Exercise Science from the University of New Mexico, Albuquerque. She works as a Health Educator at Sandia National Laboratories in Albuquerque, and her clinical and research interests include clinical populations, disease prevention, functional mobility, functional strength, and stress management.
@bio:Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, Albuquerque, where he won the Outstanding Teacher of the Year award. He has received the prestigious Can-Fit-Pro Lifetime Achievement Award and American Council on Exercise Fitness Educator of the Year.

Beckwee, D., et al. (2013) Osteoarthritis of the knee: Why does exercise work? A qualitative study of the literature. Ageing Research Reviews. 12(1), 226-236.
CDC (2011): Osteoarthritis
Accessed January 22, 2014
Fukumoto, Y., et al. (2013). Effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in individuals with hip osteoarthritis: a randomized controlled trial. Clinical Rehabilitation. Epub ahead of print: DOI: 10.1177/0269215513492161
Helmark, I.C., et al. (2010). Exercise increases interleukin-10 levels both intraarticularly and peri-synovially in patients with knee osteoarthritis: a randomized controlled trial. Arthritis Research & Therapy. 12, R126.
Lubar, D., et al. (2010). A national public health agenda for osteoarthritis, Seminars in Arthritis and Rheumatism, 39(5), 323-326.
Mangione, K.K., et al. (1999). The effects of high-intensity and low-intensity cycle ergometry in older adults with knee osteoarthritis. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. 54(4), M184-M190.
Zhang, S.L., et al. (2013). Effects of exercise therapy on knee joint function and synovial fluid cytokine levels in patients with knee osteoarthritis. Molecular Medicine Reports. 7(1), 183-186.
Helmark, I.C., et al. (2010). Exercise increases interleukin-10 levels both intraarticularly and peri-synovially in patients with knee osteoarthritis: a randomized controlled trial. Arthritis Research & Therapy. 12, R126.