Clinical Scenario

According to the American College of Sports Medicine and the American Heart Association, it is recommended that adults aged 18–65 years should spend a minimum of 30 minutes per day for 5 days each week participating in moderate physical activity or 20 minutes per day for 2 days each week participating in vigorous physical activity.^1,2 Furthermore, the recommended average daily steps needed to maintain health for an adult is 10,000 steps per day³; however, a study conducted in 2008 estimated that less than 10% of adults meet the recommended guidelines for daily physical activity.² It is important that adults reach these recommendations, as physical activity can aid in the prevention of coronary heart disease, type 2 diabetes, and different types of cancer as well as prevent recurring or chronic injuries.⁴ One factor that may cause adults to participate in less physical activity is musculoskeletal injury including injuries to the knee^5–7 and ankle.⁸ Most often subjective measures of physical activity have been utilized in these populations, including the Tegner activity scale⁹ and the Marx activity scale.¹⁰ However, most recently objective measures of physical activity have been used to determine physical activity levels in patients with a history of musculoskeletal injury. These findings are pertinent to patient care, as an understanding of how these injuries may affect a person’s physical activity can help clinicians educate their patients on the importance of participating in physical activity to reduce the risk of chronic disease development associated with physical inactivity.^4,6–8 Therefore, the purpose of this critically appraised topic (CAT) was to synthesize and critically appraise the current research that examines objectively measured physical activity levels in patients who have a history of ankle or knee injury compared with healthy controls.

Focused Clinical Question

Do individuals with a history of ankle or knee injury participate in less objectively measured physical activity compared with healthy controls?

Search Strategy

A computerized search was completed in October 2018. The following search terms were used:

1. •Patient/Group: Lower-extremity injury (knee OR ankle OR knee injury OR ankle injury OR knee pain OR ankle pain)
2. •Intervention: None
3. •Comparison: Healthy controls OR healthy (not osteoarthritis OR arthritis OR elderly OR older OR amputation OR aging OR diabetes OR stroke)
4. •Outcomes: Objective measured physical activity OR step counts OR moderate to vigorous physical activity OR MVPA OR pedometer OR fitness tracker AND physical activity

Evidence Quality Assessment

Validity of the articles found was determined using the strengthening the reporting of observational studies in epidemiology (STROBE)¹¹ statement. Prior to review, the authors met and discussed each item on the STROBE. It was decided that numbers 17 and 22 would be removed from the instrument prior to appraisal due to not being applicable to the purpose of this CAT. The maximum number of quality points on the STROBE was 20. Two authors (A.B. and J.H.) reviewed and scored each article independently. Following the independent review, the 2 authors met and reached agreement on the appraisal and quality of each study. If a disagreement arose, a third reviewer (S.B.) was consulted to discuss and come to a consensus.

Results of Search

The search of the literature yielded 49 studies (Figure 1). After a review of the abstracts, 45 studies were excluded as they did not meet the inclusion criteria for this CAT. Four studies^5–8 were included, 3 case–control studies and 1 cross-sectional study. Characteristics of these studies are detailed in Table 1.

—Summary of search history and included studies.

Citation: Journal of Sport Rehabilitation 29, 2; 10.1123/jsr.2018-0486

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—Summary of search history and included studies.

Citation: Journal of Sport Rehabilitation 29, 2; 10.1123/jsr.2018-0486

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—Summary of search history and included studies.

Citation: Journal of Sport Rehabilitation 29, 2; 10.1123/jsr.2018-0486

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Results of Evidence Quality Assessment

The scores on the STROBE ranged from 16 to 19. None of the included articles^6–8 discussed any efforts to address sources of potential bias. Bell et al,⁶ Hubbard-Turner and Turner,⁸ and Glaviano et al⁵ did not provide a proper description of the setting, locations, or relevant dates of the study. Also, Hubbard-Turner and Turner⁸ did not provide a hypothesis or explain how their study size was arrived at.

Clinical Bottom Line

There is consistent, high-quality evidence that demonstrates individuals with a history of ankle or knee injury participate in less objectively measured physical activity compared with healthy individuals. Due to nature of study designs of the included articles in this CAT, we recommend a grade of B as recommended by the Oxford Centre of Evidence-Based Medicine.¹²

Implications for Practice, Education, and Future Research

The results of this CAT revealed consistent, high-quality evidence that compared objectively measured physical activity between patients with a history of ankle or knee injury with healthy controls. Two studies^6,7 investigated moderate to vigorous physical activity (MVPA) levels with similar methodologies using a wrist-worn accelerometer, specifically an ActiGraph wGT3X-BT unit (ActiGraph Corp, Pensacola, FL). Bell et al⁶ investigated the differences in average time spent in MVPA and daily step counts in patients who have been cleared to return from an anterior cruciate ligament reconstruction (ACLR) and healthy controls. The authors secondary purpose was to investigate the relationship between MVPA levels step counts and subjective measures of physical activity. The participants wore the ActiGraph accelerometer for 7 consecutive days for at least 10 hours per day. The authors observed patients with a history of ACLR spent overall less time in MVPA (79.37 [23.95] min/d) and had fewer daily step counts (8158 [2780] steps/d) than the healthy controls (93.12 [23.94] min/d and 9769 [2785] steps/d). There were no relationships between objective measures of physical activity (MVPA or step counts) and subjective measures of physical activity (Marx or Tegner scale).⁶

Kuenze et al⁷ observed the relationship between objectively measured MVPA and self-reported physical activity and knee function in patients who have undergone ACLR and included a secondary aim to investigate differences in MVPA levels between those with a history of ACLR and healthy controls. In similar methodology to Bell et al,⁶ the participants wore an ActiGraph wGT3X-BT (ActiGraph Corp) accelerometer for 7 days for a minimum of 10 hours per day. The participants also completed self-report measures (the International Knee Documentation Committee Scale and the Knee Osteoarthritis Outcome Score, along with subjective measures of physical activity and knee strength measures. Interestingly, there were no relationships between self-reported measures of knee function (International Knee Documentation Committee Scale and the Knee Osteoarthritis Outcome Score), subjective measures of physical activity or knee strength measurements. The authors determined that patients included in the ACLR groups spent less time (553 [175] min/wk) in MVPA than the healthy controls (658 [161] min/wk).

Glaviano et al⁵ examined the difference in physical activity levels in patients with a history of patellofemoral pain compared with healthy controls. All participants wore a FitBit Charge HR (FitBit Inc, San Francisco, CA) on their wrist for 2 consecutive weeks, and the authors assessed each participant’s steps per day and minutes of mild, moderate, and high activity levels. It was observed that the patients in the patellofemoral pain group took fewer overall steps per day (8629.7 [1665.3] steps/d) and completed fewer minutes of mild (163.3 [38.1] min/day), moderate (11.6 [6.7] min/d), and high (17.8 [7.9] min/d) activity levels per day compared with the healthy controls (12,042.2 [3878.7] steps/d, 203.7 [38.7] min/d, 16.0 [6.1] min/d, and 27.9 [12.3] min/d, respectively).

Finally, Hubbard-Turner and Turner⁸ assessed the difference in total steps taken in a week between healthy controls and participants with CAI, the difference of total weekly steps between male and female participants with CAI, and the relationship between physical activity levels and ankle laxity. Each participant wore a pedometer for 7 days on their hip. Participants were instructed to wear the pedometer at all times except for sleeping, swimming, or showering and were instructed to keep a daily step log to document their steps each day. The results indicated the CAI group took fewer steps (6694.47 [1603.35] steps/d) when compared with the controls (8831.01 [1290.01] steps/d). There was no significant difference found between sexes, and ankle laxity was overall greater for the CAI group and was correlated to physical activity levels.

Objectively measured physical activity appears to be more accurate than subjective reports. Bell et al⁶ found that patients after ACLR are less physically active than healthy individuals, spend less time in MVPA, and have a lower step count when measured objectively. However, there were no differences in subjective measures of physical activity between these 2 groups.⁶ Furthermore, both studies that included ACLR participants found that there was no relationship between subjective and objective measures of physical activity.^6,7 Both authors recommended that objectively measured physical activity levels be incorporated into the rehabilitation process for patients following an ACLR to aid in obtaining the treatment goals.^6,7 The authors of these studies used ActiGraph wGT3X-BT units to measure physical activity levels; however, there are other less expensive or easily accessible options. For example, smartphones and smartwatches often have a built-in pedometer that patients could use to track their steps per day. Also, a standard pedometer can be very inexpensive, averaging cost about $5 per unit. Glaviano et al⁵ utilized a FitBit Charge HR (FitBit Inc) that average cost about $75 to $150 per unit. Although there are a range of options and costs for equipment to objectively measure physical activity, the addition of an objective measure into a treatment plan will ensure clinicians that patients true activity levels are being measured and that they are meeting the recommended guidelines for physical activity.

The results of this CAT suggest patients who have sustained an ankle or knee injury become less physically active and thus may be at risk for negative health consequences associated with physical inactivity. However, patients may not be aware of the risks associated with an inactive lifestyle. Therefore, it is important that clinicians educate their patients on the benefits of a physically active lifestyle, with the impetus to either improve their patient’s participation in physical activity or promote the maintenance of their patient’s physical activity levels to maintain a healthy lifestyle. Clinicians should monitor physical activity levels with objective measures of physical activity as subjective measures may not be entirely representative of the patient’s true physical activity levels. Future research should examine mechanisms to improve physical activity in larger populations of people with a history of musculoskeletal health conditions. This may include educational strategies to improve physical activity participation, which has been done in the osteoarthritis literature.¹³ Future research should also make efforts to address bias that may occur when utilizing an objective assessment of physical activity. Finally, future research should consider the time of year that the data are collected, as the time of year may impact physical activity practices.