Influencing walking behavior can increase the physical activity of patients with chronic pain hospitalized for multidisciplinary rehabilitation: an observational study

A high prevalence of chronic pain—around 20% of the adult population—is observed all over the world [1‐3]. This debilitating condition, which is particularly difficult to treat, causes a substantial burden to healthcare systems, economies, and societies [4]. Due to its high prevalence, complex etiology, and the need for combined therapeutic approaches, chronic pain constitutes a major challenge for practitioners, caregivers, and researchers.

Traumatic injuries and orthopedic traumas are frequent causes of chronic pain. Six month after an isolated musculoskeletal extremity injury (fracture, sprain, or strain), 10% of patients suffer chronic pain [5]. The mechanisms that explain the transition from acute to chronic pain following a trauma are still incompletely understood [6]. That said, psychological factors may explain the continuation of disability and pain after a skeletal trauma [7]. Following an orthopedic trauma, strategies that combine physical and psychological therapies may thus help prevent the occurrence and continuation of chronic pain [8].

Multidisciplinary biopsychosocial rehabilitation is the favored approach to severe chronic pain that is resistant to other treatments [9‐11]. Although analgesic medication is indeed used as a primary treatment, poor outcomes are often observed [12‐14]. Psychological and social approaches are thus required, along with biomedical care and physical therapy, to enhance patient’s ability to function with pain through coping strategies [15, 16]. Multidisciplinary rehabilitation is particularly beneficial to patients with poor prognosis when therapies are combined at high frequency, e.g., six-hour sessions 5 days per week over 4 weeks [17].

Exercise and physical therapy are key components of biopsychosocial rehabilitation [9, 18]. Exercise aims to improve cardiovascular fitness (aerobic training [19]), increase joint mobility and reduce muscle stiffness (flexibility training [20]), and enhance muscle strength (strength or resistance training [20, 21]). Exercise in general [18, 22, 23], and walking in particular [24], improve function and reduce pain. Furthermore, the WHO recommendations on physical activity and health [25] advise participation in at least 150 min per week of moderate-to-vigorous physical activity (MVPA). Indeed, a positive association exists between physical activity, health-related quality of life [26], and emotional well-being [27]. Evidence also exists that being physically active has positive effects on painful conditions [28]. Therefore, encouraging patients to walk more and to be more physically active is a desirable goal of chronic pain care. In addition to specific effects on functional capacity, physical therapy may increase the level of physical activity, which can further improve a patient’s well-being. However, the immediate effects of intense multidisciplinary rehabilitation on daily physical activity and walking behavior have not been studied, especially during hospitalization.

Knowing how patients perceive their own functioning is essential to the study of chronic pain in general [29, 30], and pain-activity associations in particular. Psychological distress and fear [31], as well as beliefs, coping and catastrophizing [32], and self-efficacy [33], also play a role in how chronic pain impairs patients’ functioning. Measuring the self-perceived interference of pain with the practice of daily-life activities is thus recommended [29].

We were interested in the immediate effects that a rehabilitation stay may have on the physical activity levels of patients suffering from chronic pain following an orthopedic trauma. We aimed at investigating the difference between habitual physical activity and physical activity during rehabilitation. Furthermore, we sought to assess the proportion of total physical activity due to walking activities (WA), and to what extent this proportion was modified during the hospitalization. Finally, we sought to determine whether pain interference with physical functioning, as well as pain localization, could modulate physical activity levels.

We studied physical activity levels and walking behaviors in 272 inpatients with chronic pain hospitalized for multidisciplinary rehabilitation. First, the results suggest that measuring days-off during a patient’s stay can serve as a proxy for habitual physical activity. Second, study participants increased their physical activity substantially at the clinic (+ 35%). This increase is mainly explained by more frequent long walks (+ 300%). Finally, self-perception of physical functioning with pain—measured by means of BPI—was associated with activity level, especially in patients with back pain.

Regarding the assessment method, we considered as MVPA all whole-body movements that induced higher accelerations than a slow gait. The classical MVPA definition relies on metabolic equivalent of task (MET), which must be higher than 3 [46]. Therefore, slow walking is categorized as sedentary-to-light physical activity, and only normal and brisk walking are classified as MVPA. The reason for not following this definition was twofold. First, patients suffering chronic pain have a limited capacity to walk fast and a lower preferred walking speed [41, 47‐50]. Second, slow walking speeds induce higher energy cost of displacement, and pain may alter walking efficiency [50, 51]; that is, pain patients may expend more energy and may be more rapidly exhausted than healthy counterparts over similar walking distance. Therefore, our definition of MVPA seems more adapted for individuals in pain and with limited walking abilities.

Considering the study’s methodology further, we experienced many missing days due to poor compliance in wearing the accelerometer, especially during weekends. We are confident that we correctly captured average activity patterns, given the large number of observed days and the use of mixed models, which are inherently robust to missing values. However, this issue should be addressed in case of individual assessment of physical activity in future clinical applications, for example by using a device that can be worn 24 h a day. Another methodological issue is that MVPA estimation might be slightly underestimated, because inpatients may practice cycloergometer and strength exercises that are poorly measured with an accelerometer fixed onto the hip.

The first study goal was to explore whether measuring days off during the rehabilitation stay could be a solution assessing habitual physical activity, because it can be logistically complicated to measure patients at home before hospitalization. The results (Fig. 2 and Tables 2 and 3) demonstrate that weekend days during the stay have similar MVPA as days measured before the stay. By measuring physical activity during days off, medical staff can therefore obtain information about patient’s habitual behavior for a better evaluation of functional status.

During days off, study’s participants spent 90% of their waking time in sedentary activities (Fig. 4). WA accounted for 57% of MVPA, i.e., 43 min per day. A substantial inter-individual variability was observed (MVPA CV = 67%, WA CV = 79%). Activity level and walking behavior are indeed labile parameters that strongly depend on occupation and personal habits, along with multiple social and environmental variables [52‐55]. Although there is no conclusive evidence that patients with chronic pain are globally less active than healthy people [56, 57], the study of Ryan et al. [53] highlighted that individuals with chronic low back pain walked less than matched controls (9 min/h versus. 13 min / hour on non-work days). For comparison, our results show 3 min/h; this lower value is likely due to the higher severity of symptoms in our sample.

Inpatients substantially increased their physical activity level when staying at our rehabilitation clinic (+ 35%) by adding each day 28 min of MVPA to their habitual level (Fig. 4). Evidence exists that biopsychosocial rehabilitation improves pain and physical function in patients suffering chronic low back pain [58] and other pain conditions [10, 47]. To date, the efficacy of extensive rehabilitation programs has been mostly attributed to the synergy between physical and psychological therapies. Here, we show that an increase of daily physical activity could also contribute to the overall positive outcome of hospitalization for biopsychosocial rehabilitation.

Our results highlight a negative relationship between MVPA and PI (Table 4 and Fig. 5) for patients with LoL and Sp pain. In other words, the patients who reported that pain interfered substantially with their daily activities were effectively less active. The absence of a significant association between PI and MVPA for patients with upper-limb pain is very likely due to the poor recording of upper-limb movements with the accelerometer fixed to the hip. Regarding LoL patients, the strength of association (− 3% MVPA per PI point change) seems relevant: A patient with a score of 8 would be 15% less active than a patient with a score of 3. This relationship is substantially stronger in patients with back pain. For these patients, a five-point difference on the PI scale would correspond to a 50% change in MVPA. Similar results have been described in the literature regarding low back pain, as reported in the meta-analysis of Lin et al. [59]. In line with these studies, our results thus support the hypothesis that a link exists between perceived physical functioning and actual physical activity level.

Study participants were more active during rehabilitation days, mainly through participation in more long walks (Fig. 4). To be more precise, participants averaged 7 min of long walking bouts during days off, and they increased this duration to 29 min during rehabilitation days (+ 22 min). Total WA and MVPA increased accordingly (+ 32 min and + 28 min, respectively). Whereas walking constituted about half of MVPA (57%) during days off, walking became dominant during rehabilitation days (72%). Modifying walking behavior seems therefore a potent mean to make patients more active.

A close examination of the data led us to conclude that the spatial organization of clinic facilities was the main explanation for the WA increase on rehabilitation days. During a typical rehabilitation day, the inpatients had to move between their bedrooms, the therapy facilities, and the restaurant. In other words, the inpatients were obligated to walk for accomplishing their rehabilitation program, even beside their therapies. Furthermore, given the relative smallness of hospital’s bedrooms, inpatients were motivated to walk indoor and outdoor for socializing and enjoying clinic leisure facilities. Given the size of the building, most of paths among therapy rooms and other facilities necessitate 50–150 m walks, which last more than 1 min; this explains the large augmentation of long walks during rehabilitation days (+ 302%).

The obligation of frequent displacements may thus be an important incentive that can push patients to be active through more long walks. In addition to prescribing exercise, adapting the walkability of a patient’s environment, as well as including more walks in a patient’s daily activities, could therefore be used to enhance physical activity. Correspondingly, changing the built environment to increase walking practice and physical activity level of populations is a very active area of research [55, 60]. Besides, it is well established that walking can reduce pain and improve self-reported physical function [24]. However, further investigations are needed to clarify whether unstructured walking practiced in many discontinuous bouts can have the same positive effects as structured walking exercises of longer duration.

The strength of the current study is that it includes a substantial number of patients assessed in a constant environment. The biopsychosocial complexity of the included patients was comparable to the average complexity of the hospitalized patients at the Clinique Romande de Réadaptation. Therefore, the study’s sample was very likely representative of the inpatient population. Furthermore, patients are referred from all the French-speaking counties of Switzerland, including both rural and urban areas. Excepting the underrepresentation of women, the study’s sample is therefore expected to accurately represent the Swiss injured population.

The first limitation of the study is that it took place in a single center. Because we assumed that changes of physical activity were mainly driven by the spatial distribution of the clinic facilities, an identical physical activity enhancement is not expected for other clinics and hospitals. Nevertheless, we are confident that the main finding of the study—that patients suffering from chronic pain can be made more active through walking incentives—is valid for other settings. Second, we focused on the immediate effects of extensive rehabilitation on physical activity levels. The potential carry-over effects after discharge should be further investigated.

Although there is compelling evidence that maintaining a high level of physical activity has positive effects, many healthcare professionals hesitate to prescribe exercise to treat chronic pain [61, 62]. The erroneous belief that excessive movements may worsen pain is widespread [34, 63]. Fear-avoidance beliefs and behaviors exist both in patients and caregivers [34, 64], who may be inclined to consider patients as unable to be more physically active. In contrast, the present study shows that physical activity levels can be enhanced via appropriate incentives, even in patients reporting a high degree of impairment in their physical functioning due to pain. This finding should further motivate healthcare professionals to promote physical activity to their patients suffering from chronic pain. In practice, adding more walking in a patient’s daily activities could be an effective strategy.