Physical Activity Monitors: A Clinical Tool for Motivating Knee OA Patients

 In Orthopedics, Pain Medicine

Ju Young Yoo, BSc
Adam Gratton, MSc, ND

Student Scholarship – Honorable Mention Research Review

Osteoarthritis (OA) is the most common form of arthritis, affecting more than 10% of Canadians aged 15 years or older.1,2 The cost associated with OA in Canada was estimated to be $27.4 billion in 2010 and is projected to be $894 billion by 2030.2 The knee is the most commonly affected joint in OA, and studies have reported that knee OA reduces the quality of life by negatively impacting physical and mental health, limiting daily activities, and lowering employment.3-5

Once believed to constitute a loss of hyaline articular cartilage of the knee joint, knee OA is now considered a disease of the whole joint and its associated structures.6 The etiology of knee OA depends on many different systemic factors (including age and gender) and local factors (including employment and weight). Older age has been shown to increase the risk of knee OA,7 and women are more likely than men to develop knee OA.8 Additionally, occupations involving heavy physical activities,9 as well as high body mass index, increase the risk of developing knee OA.10

Despite medical advances over time, there is no known cure for knee OA; however, treatments are available to reduce the symptoms.11 First-line treatment for knee OA is physical activity,12 which has been shown to decrease pain and improve quality of life.13 Increased physical activity is particularly important for people living with OA given their increased risk of cardiovascular diseases.14 Reducing sedentary time can also improve physical function in adults with knee OA.15 The Canadian Physical Activity Guidelines, put forth by the Canadian Society for Exercise Physiology, recommends at least 150 minutes of moderate-to-vigorous physical activity per week in bouts of 10 minutes or more for people with arthritis, to maintain good health.16 However, a meta-analysis reported that only 13% of patients with hip or knee OA met this guideline,17 which may be due to lack of motivation18 or lack of advice from health professionals regarding exercise.19

Behavior-Changing Techniques in PA Monitors

Currently, 1 in 6 consumers in the United States use wearable technology, which includes pedometers and physical activity monitors.20 Results of a systematic review suggest that pedometers in combination with behavior-change-based interventions, consisting of various daily step goal-setting strategies and individual-based performance feedback, were most effective at increasing physical activity levels among the musculoskeletal disease populations.21 In addition, pedometers have shown benefit in patients with knee OA in terms of increasing overall activity,22,23 improving functional ability,23 and relieving pain,23,24 and could be used as a motivational tool for increasing step goals.22

Several commercially available physical activity monitors represent an improved technology over pedometers, as they are equipped with clinical behavior interventions that may improve physical activity.25,26 From Coventry, Aberdeen, and London, this refined (CALO-RE) taxonomy contains 40 items specific to behavior-changing techniques, as described in Table 1.27 The physical activity monitors are outfitted with some of these 40 items, and according to a systematic content analysis of 13 wearable monitors, the monitors allow users to track their own behavior, set goals, and compare their behaviors to those goals.25 A critical analysis reported that the number of behavior-changing functions in the monitors varied from 10 to 23, with the most common behavior-change interventions found in them being goal setting, self-monitoring of activity, historical review of past activity, and optional interaction with other users for social support,26 which has been shown to motivate inactive older adults living with OA to be more active.28

The physical activity monitors also provide visualization of the physical activity levels that may facilitate the patient’s disease management.29 The monitors are also equipped with gamification techniques, which include rewards, praise, and reminders that help motivate users to reach their daily goal.29 It has been systematically reported that rewards for successful behavior constitute one of the most effective behavior-changing techniques to improve physical activity in older adults.30 Overall, physical activity monitors have been demonstrated to be a positive behavior modification tool for promoting physical activity among older adults with chronic illness, including arthritis.31 In addition to the behavior tools, when a physical therapist supplemented the physical activity monitors with activity counseling for patients with knee OA, a trend of improvement in moderate-to-vigorous physical activity was noted.32

Table 1. Definitions of Behavior Change Techniques – CALO-RE Taxonomy27

1. Provide information on consequences of behavior in general Information about the relationship between the behavior and its possible or likely consequences in the general case
2. Provide information on consequences of behavior to the individual Information about the benefits and costs of action or inaction to the individual or tailored to a relevant group based on that individual’s characteristics
3. Provide information about others’ approval Involves information about what other people think about the target person’s behavior. It clarifies whether others will like, approve, or disapprove of what the person is doing or will do.
4. Provide normative information about others’ behavior Involves providing information about what other people are doing, ie, indicates that a particular behavior or sequence of behaviors is common or uncommon among the population or among a specified group
5. Goal setting (behavior) The person is encouraged to make a behavioral resolution (eg, take more exercise next week). This is directed towards encouraging people to decide to change or maintain change, but does not involve planning exactly how the behavior will be done and either when or where the behavior or action sequence will be performed.
6. Goal setting (outcome) The person is encouraged to set a general goal that can be achieved by behavioral means, but is not defined in terms of behavior (eg, to reduce blood pressure or lose/maintain weight), as opposed to a goal based on changing behavior
7. Action planning Involves detailed planning of what the person will do, including, as a minimum, when, in which situation, and/or where to act
8. Barrier identification / Problem solving This presumes having formed an initial plan to change behavior. The person is prompted to think about potential barriers and identify ways of overcoming them.
9. Set graded tasks Breaking down the target behavior into smaller, easier-to-achieve tasks and enabling the person to build on small successes to achieve target behavior. This may include increments towards a target behavior, or incremental increases from a baseline behavior.
10. Prompt review of behavioral goals Involves a review or analysis of the extent to which previously set behavioral goals (eg, take more exercise next week) were achieved
11. Prompt review of outcome goals Involves a review or analysis of the extent to which previously set outcome goals (eg, to reduce blood pressure or lose/maintain weight) were achieved
12. Prompt rewards contingent on effort or progress towards behavior Involves the person using praise or rewards for attempts at achieving a behavioral goal. This might include efforts made towards achieving the behavior, or progress made in preparatory steps towards the behavior, but not merely participation in intervention.
13. Provide rewards contingent on successful behavior Reinforcing successful performance of the specific target behavior. This can include praise and encouragement as well as material rewards, but the reward/incentive must be explicitly linked to the achievement of the specific target behavior.
14. Shaping Contingent rewards are first provided for any approximation to the target behavior, eg, for any increase in physical activity
15. Prompting generalization of a target behavior Once a behavior is performed in a particular situation, the person is encouraged or helped to try it in another situation
16. Prompt self-monitoring of behavior The person is asked to keep a record of specified behavior(s) as a method for changing behavior. This should be an explicitly stated intervention component, as opposed to occurring as part of completing measures for research purposes.
17. Prompt self-monitoring of behavioral outcome The person is asked to keep a record of specified measures expected to be influenced by the behavior change, eg, blood pressure, blood glucose, weight loss, physical fitness. It must be reported as part of the intervention rather than only as an outcome measure.
18. Prompting focus on past success Involves instructing the person to think about or list previous successes in performing the behavior (or parts of it)
19. Provide feedback on performance This involves providing the participant with data about their own recorded behavior
20. Provide information on where and when to perform the behavior Involves telling the person about when and where they might be able to perform the behavior, eg, tips on places and times participants can access local exercise classes
21. Provide instruction on how to perform the behavior Involves telling the person how to perform a behavior or preparatory behaviors, either verbally or in written form. Examples of instructions include: how to use gym equipment (without getting on and showing the participant), instruction on suitable clothing, and tips on how to take action.
22. Model/demonstrate the behavior Involves showing the person how to perform a behavior, eg, through physical or visual demonstrations of behavioral performance, in person or remotely
23. Teach to use prompts/cues The person is taught to identify environmental prompts that can be used to remind them to perform the behavior (or to perform an alternative, incompatible behavior in the case of behaviors to be reduced)
24. Environmental restructuring The person is prompted to alter the environment in ways that support the target behavior, eg, altering cues or reinforcers
25. Behavioral agreement Must involve written agreement on the performance of an explicitly specified behavior, so that there is a written record of the person’s resolution witnessed by another
26. Prompt practice Prompt the person to rehearse and repeat the behavior or preparatory behaviors numerous times. Note: this will also include parts of the behavior, eg, refusal skills in relation to unhealthy snacks.
27. Use of follow-up prompts Intervention components are gradually reduced in intensity, duration and frequency over time, eg, letters or telephone calls instead of face to face, and/or provided at longer time intervals
28. Facilitate social comparison Involves explicitly drawing attention to others’ performance to elicit comparisons. The fact that the intervention takes place in a group setting, or that an individual has been placed in groups on the basis of shared characteristics, does not necessarily mean social comparison is actually taking place.
29. Plan social support/social change Involves prompting the person to plan how to elicit social support from other people to help him/her achieve a target behavior/outcome
30. Prompt identification as role model/position advocate Involves focusing on how the person may be an example to others and affect their behavior, eg, being a good example to children
31. Prompt anticipated regret Involves inducing expectations of future regret about the performance or non-performance of a behavior. This includes focusing on how the person will feel in the future and specifically whether they will feel regret that they did or did not take a different course of action.
32. Fear arousal Involves presentation of risk and/or mortality information relevant to the behavior as emotive images designed to evoke a fearful response (eg, “smoking kills!” or images of the grim reaper)
33. Prompt self-talk Encourage the person to talk to him/herself (aloud or silently) before and during planned behaviors, to encourage, support, and maintain action
34. Prompt use of imagery Teach the person to imagine successfully performing the behavior or to imagine finding it easy to perform the behavior, including component or easy versions of the behaviour
35. Relapse prevention / Coping planning This relates to planning how to maintain behavior that has been changed. The person is prompted to identify in advance those situations in which the changed behavior might not be maintained, and to develop strategies to avoid or manage those situations.
36. Stress management / Emotional control training This is a set of specific techniques (eg, progressive relaxation) that do not target the behavior directly but which are designed to reduce anxiety and stress to facilitate the performance of the behavior
37. Motivational interviewing This is a clinical method including a specific set of techniques involving prompting the person to engage in change talk in order to minimize resistance and resolve ambivalence to change (includes motivational counseling)
38. Time management This includes any technique designed to teach a person how to manage their time in order to make time for the behavior. These techniques are not directed towards performance of target behavior, but rather seek to facilitate it by freeing up times when it could be performed.
39. General communication skills training This includes any technique directed at general communication skills but not directed towards a particular behavior change
40. Stimulate anticipation of future rewards Create anticipation of future rewards without necessarily reinforcing behavior throughout the active period of the intervention

Recommendations to Naturopathic Doctors

Naturopathic doctors could take advantage of the technology of these monitors in practice to promote physical activity for individuals living with knee OA. Although promising, behavior-changing techniques pertaining to self-efficacy, or individuals’ ability to maintain their physical activity, were missing in the physical activity monitors, as shown in Table 2.26 Motivation counseling is one of the techniques absent from these monitors. It was reported in a systematic review that motivation counseling, along with providing information on where and when to perform the behavior, are among the techniques promoting greater self-efficacy.30 Physical activity monitors cannot solve the personal barriers related to the knee OA. However, using motivational counseling, naturopathic doctors can begin to address many of the comorbid psycho-emotional factors, thus allowing them to practice other behavior-changing techniques such as stress management, emotional control training, and relapse prevention, which were all missing techniques from the physical activity monitors.26 Thus, by supplementing physical activity monitors with lifestyle and motivational counseling, naturopathic doctors can provide many behavior-changing strategies that help to increase the physical activity levels of their patients.

Table 2. Behavior-Change Techniques Absent from Wearable Activity Trackers26

Barrier identification or problem-solving
Set graded tasks
Prompting generalization of a target behavior
Environmental restructuring
Behavioral agreement
Use of follow-up prompts
Prompt identification as role model or position advocate
Prompt anticipated regret
Fear arousal
Prompt self-talk
Prompt use of imagery
Relapse prevention or coping planning
Stress management or emotional control training
Motivational interviewing
General communication skills training

The most popular daily step goal of 10 000 steps per day may not be realistic for people with knee OA. More than 6000 steps per day may be a more attainable goal, as it also prevents the development of functional limitations in individuals with or at risk of knee OA.33 By working together to set the daily goal, doctors can provide a realistic opinion on the patient’s daily physical activities: if the goal is set too high, the patient may not meet it, resulting in demotivation. However, when daily step goals are met, patients may stay motivated and increase their physical activity in the future. The step goals should be tailored to the patient’s limitations. As activity data are stored online, doctors can remotely access the data, which provides flexibility to both patients and naturopathic doctors.

Limitations of Physical Activity Monitors

Although these physical activity devices are commercially available, the accuracy and the privacy of the patient’s data may be a concern. As the research evidence on the validity of these devices is currently limited,20 naturopathic doctors should only use these devices as a motivational tool rather than an objective measuring tool. As new devices and features are continuously released by the companies, more research examining the validity of these devices is warranted. Also, the software upgrades may change the algorithms of the calculations of the daily activities variables, which may negatively impact the accuracy or reliability of these trackers. Thus, if used in their practice, naturopathic doctors must stay up to date with the news of the physical activity monitors. The privacy of the data may also be problematic, as patients and doctors do not own the patient’s physical activity data.20 Rather, these data are stored by the manufacturer, who then can sell it to third parties.20

The physical activity monitors are designed to be affordable, fashionable, and user-friendly. One particular device is priced as low as $14.99 (USD) and tracks steps, calories, distance, sleep, and more. It also allows daily goal setting. Moreover, many of these monitors are offered in various colors with different patterns and designs. For example, one of the best known manufacturers offers 8 different types of trackers and additional accessories. The user-friendliness of these devices provides an opportunity for older adults with OA to benefit from these devices. One study reported that physical activity monitors were easy to use, useful, and acceptable for older adults aged 70 to 90 years and older.34 Also, most recently released smartphones have an accelerometer that can track daily activities. It has been previously reported that smartphones with activity-tracking applications were as accurate as physical activity monitors at measuring steps.35 Although the research evidence on the accuracy of the physical activity monitors is limited, it may be a better measurement tool than self-report measures by the patients, which has reported both higher and lower levels of physical activity than objectively measures.36


In summary, physical activity monitors are affordable and user-friendly, and allow flexibility for both patients and doctors, as the activity data is available online. These monitors are programmed with behavior-changing techniques that provide opportunities for naturopathic doctors to promote healthy and active lifestyle to individuals living with knee OA to be more physically active.


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Image Copyright: <a href=’’>rawpixel / 123RF Stock Photo</a>

Ju Young Yoo, BSc, is a 2nd-year student at the Canadian College of Naturopathic Medicine, in Toronto, Ontario. He has a passion for research and is always willing to learn in order to provide the best care for patients.



Adam Gratton, MSc, ND, is a naturopathic doctor and full-time faculty member at the Canadian College of Naturopathic Medicine, where he leads the pharmacology and research curriculum. He has a special interest in dermatology and conducts an evidence-based practice in Toronto, Ontario.

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