Physical Activity Levels and Their Associations With Postural Control in the First Year After Stroke
- C.U. Persson, PT, PhD, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Per Dubbsgatan 14, 3rd Fl, Gothenburg, Sweden.
- P-O. Hansson, MD, PhD, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg.
- G. Lappas, MSc, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg.
- A. Danielsson, PT, PhD, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, and Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg.
- Address all correspondence to Dr Persson at: carina.persson{at}neuro.gu.se.
Abstract
Background There is limited research concerning the physical activity levels over time of people who have survived stroke.
Objective The study objectives were: (1) to describe self-reported physical activity levels at 3, 6, and 12 months after stroke onset and (2) to analyze whether there was an association between self-reported physical activity level and postural control.
Design This was an observational and longitudinal study.
Methods Ninety-six participants with a first-ever stroke were assessed for self-reported physical activity levels with the Physical Activity Scale for the Elderly (PASE) in the first year after stroke. Postural control also was assessed with the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS).
Results The raw median PASE scores at 3, 6, and 12 months after stroke were 59.5, 77.5, and 63.5, respectively. The model-estimated relative changes in mean PASE scores (as percentages) followed the same pattern, independent of age, sex, and SwePASS scores. Between 3 and 6 months after stroke, PASE scores increased by 32%, with no significant change between 3 and 12 months and between 6 and 12 months after stroke. For each unit increase in the SwePASS score at baseline, there was a 13% increase in the PASE score during follow-up.
Limitations The sample size was limited. Although the PASE is based on the metabolic equivalent of the task, the actual physiological intensity of a person's performance of the activities is unknown.
Conclusions Self-reported physical activity levels were low in the first year after stroke. Good postural control in the first week after stroke onset was positively correlated with higher levels of self-reported physical activity in the first year after stroke.
Physical activity is defined as any bodily movement produced by the skeletal muscles and resulting in increased energy expenditure.1 A low level of physical activity is considered to be a risk factor for stroke2 and is more common in people who have had a stroke than in the general population.3,4 Explanatory factors are complex and may be both psychological and physical in nature at individual and environmental levels. In guidelines for stroke care,5 regular physical activity and exercise are recommended to improve function and independence in daily life and to reduce the risk of developing cardiovascular disease.
Previous studies indicated that the initially very low physical activity level after stroke increases up to 6 months after stroke onset.6,7 During the years after the cessation of rehabilitation, there is a risk for mobility decline.8–11 Falls12–15 and balance disability16,17 are common after stroke and have been shown to affect the abilities to independently manage daily activities and to walk.18 Recently, activity and participation after stroke were shown to be more strongly associated with balance self-efficacy than with performance measures of balance, walking capacity, or walking speed.19 In addition, positive associations between physical exercise level and enjoyment20 and between physical activity level and the Barthel Index have been shown.21
To date, studies with accelerometers have shown low activity levels in an acute stroke ward22 and during the first 6 months after stroke.7 However, the measurement of physical activity with technical equipment is not always feasible in a clinical setting; therefore, self-report is an alternative. The Physical Activity Scale for the Elderly (PASE) is a self-report questionnaire on exercise, home, and work-related physical activities performed during the preceding week.23 The PASE has been shown to be reliable and valid in different populations of people between 65 and 100 years of age23–28 and after stroke.29 The PASE has been shown to correlate positively with physical measures of strength, aerobic endurance, and balance after stroke.29
In a study on people 7 to 10 years after stroke, 21% of the variation in PASE scores was explained by walking distance30; 1 to 3 years after stroke, 31% of the variance in PASE scores was explained by balance self-efficacy, mobility measures, and health-related quality of life.17 However, there is limited research concerning the physical activity levels of people who have survived stroke over time; in 2 studies, the PASE was used to assess physical activity longitudinally in people who had survived stroke.17,31 In the ExStroke Trial,31 in which the PASE was used as an outcome measure for an intervention regarding physical activity, no significant change in physical activity during a 2-year follow-up period was observed.31
In the effort to predict and minimize decline and to provide individual advice concerning physical activity, it is essential for a physical therapist to understand typical changes in physical activity during specific periods of stroke recovery. In addition, it may be important to identify people who have survived stroke and have the greatest risk of low levels of physical activity and to be aware of the factors that increase that risk. Postural control is one of the conditions that enables everyday activities; thus, it is routinely assessed in the acute stage after a stroke because it is significant in the planning of interventions. Moreover, there is strong evidence that postural control is improved by physical therapy in people with stroke.32 Therefore, we were interested in studying the association of postural control with physical activity.
The aims of the present study were: (1) to describe self-reported physical activity levels at 3, 6, and 12 months after stroke onset and (2) to analyze whether there was an association between self-reported physical activity level and postural control. On the basis of previous studies,6,7,23,29,33 the hypotheses were that physical activity levels would increase up to 6 months after stroke and that postural control would be positively associated with physical activity level.
Method
This observational study is a substudy of the Postural Stroke Study in Gothenburg,15 with recruitment, data collection, and follow-up from 2003 to 2005. The study size was calculated in accordance with the main study. During the study period, we aimed to include people admitted consecutively to a stroke unit. Potential participants were identified through examination of the patient register and were recruited 4 to 7 days after stroke onset at the stroke unit of Sahlgrenska University Hospital, Östra, Sweden. At the time of the study, the stroke unit had 14 inpatient beds.
The inclusion criterion was a first-ever stroke, defined as described by the World Health Organization.34 Exclusion criteria were comorbidities, such as severe psychiatric diseases, dementia, or leg amputation, which could interfere with the assessment of postural control. In addition, because the study included follow-up assessments, people who did not live in the vicinity of Gothenburg were excluded (ie, Sahlgrenska University Hospital should have been the primary referral hospital). For ethical reasons, people also were excluded if they were severely impaired or in a palliative state. The decision was made by the physician in charge, on the basis of a clinical assessment. Written informed consent was obtained. If a participant could not understand the information, the next of kin could give informed consent.
Postural control was assessed with the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS)15,33,35 at 4 to 7 days and at 3, 6, and 12 months after stroke onset (follow-up). The SwePASS, an ordinal scale for assessing postural control after stroke, includes 12 items of everyday activities involving lying down, sitting, and standing. Each item is scored from 0 to 3, with higher scores indicating better postural control. The maximum score that a participant can achieve is 36. The SwePASS has been shown to be valid,15 reliable,35 and responsive to change.33
A participant's self-reported physical activity levels were assessed by interviews with the PASE23,36 at 3, 6, and 12 months after stroke (follow-up). The PASE is a questionnaire with 12 structured questions on physical activities performed during the preceding week. The physical activities included in the PASE are walking; light, moderate, and strenuous sports; strength training; light and heavy household work; home repair; lawn work; gardening; caring for another person; and paid or voluntary work involving standing or walking. The type of activity (from the examples given), the frequency during the preceding week (none, 1 or 2, 3 or 4, or 5–7 days), and the time spent in each activity (<1 hour, 1–<2 hours, 2–4 hours, or >4 hours) are registered. Household activities and work are answered with “yes” or “no” responses. The time spent in an activity is multiplied by a weight based on the metabolic equivalent of the task (MET) specified for each activity. Examples of different activities and corresponding general METs are as follows: walking very slowly=2.0 METs, washing dishes=2.3 METs, dusting=2.5 METs, weight lifting or bowling=3.0 METs, walking briskly=4.0 METs, washing a car or playing golf=4.5 METs, shoveling snow=6.0 METs, and playing soccer=8.0 METs. The PASE sum score can range from 0 to greater than 400,36 with higher scores indicating higher levels of self-reported physical activity. A mean difference in PASE scores of 20 is assumed to correspond to a minimal clinically meaningful change in physical activity.37
When a participant was unable to attend an assessment session, the PASE questionnaire was distributed by mail and the participant answered the PASE with help from next of kin. The follow-up assessments were performed at the stroke unit with a time window of ±14 days. To avoid bias, the assessments were carried out by 1 of 5 study physical therapists who were involved in neither the participants' rehabilitation nor the data analysis. The 5 physical therapists who administered the SwePASS were instructed on how to perform the SwePASS and the PASE by one of the authors (C.U.P.).
For descriptive purposes, classifications with the Modified Motor Assessment Scale, Uppsala Akademiska Hospital-95 (M-MAS UAS-95),38 as well as the Trial of Org 10172 in Acute Stroke Treatment39 were applied at baseline. The M-MAS UAS-95,38 an ordinal scale including 11 items that are ranked from 0 to 5, is used to assess mobility, postural control, walking, and upper extremity function. The higher the score, the better the function or activity. The Trial of Org 10172 in Acute Stroke Treatment39 is a system for classifying ischemic stroke subtypes.
Data Analysis
The Statistical Package for the Social Sciences (SPSS) computer program (version 17, SPSS Inc, Chicago, Illinois) was used to determine the median and interquartile range for PASE scores at 3, 6, and 12 months after stroke. Data were analyzed with R version 3.0.0 and the R nlme package.40 The outcome variable, PASE, was analyzed with a random-intercept linear mixed model. Each participant was included as a random effect, and missing values were entered through dummy variables. Thus, for each missing categorical baseline variable in the statistical model, a new category value was added to signify the missing case. Participants' sex and age at onset and SwePASS scores in the first week were entered as fixed effects. Likelihood ratio tests were performed to validate the random-intercept model. In these tests, the model including fixed effects was compared with null models including only random effects. Results in which the model including fixed effects did not differ significantly from the null model were rejected. Estimated P values at a level of ≤.05 were considered significant.
Role of the Funding Source
Financial support was received through grants from the Local Research and Development Board for Gothenburg and Södra Bohuslän, the Sahlgrenska University Hospital Foundation (Heart, Blood Vessels, and Lungs), the Stroke Centre West, the Greta and Einar Asker Foundation, the National Association of Stroke Foundations and Funds, the Felix Neubergh Foundation, the Hjalmar Svensson Foundation, the Reneé Eander Foundation, the Gun and Bertil Stone Foundation, the Rune and Ulla Amlöv Foundation, and the John and Brit Wennerström Foundation.
Results
The inclusion process is shown in Figure 1. Of 116 participants in the Postural Stroke Study in Gothenburg,15 the 96 who answered the PASE questionnaire at least once were included in the study. Figure 1 also shows the numbers of participants at the various follow-up time points. At each follow-up, all but 3 participants came to the stroke unit and participated in the interview with the PASE and in the assessment of postural control with the SwePASS. For the 3 participants who did not come to the stroke unit at each follow-up, the questionnaires were received by mail.
Inclusion process and numbers of participants at various follow-up time points. POSTGOT=Postural Stroke Study in Gothenburg, PASE=Physical Activity Scale for the Elderly.
Table 1 shows the characteristics of the participants at inclusion in the study. The SwePASS was performed for 95 of the 96 participants at baseline. The M-MAS UAS-95 values were based on assessments performed during the first week after stroke onset, at a median of 2 days (interquartile range=1–4), for 83 participants. For 13 participants, the M-MAS UAS-95 assessments were incomplete or were fulfilled later than 7 days after the onset of symptoms. Of the 96 participants, 77 (80%) were discharged to their own homes, and 19 (20%) were discharged to a nursing home or an inpatient rehabilitation unit.
Baseline Characteristics of the Study Population (N=96)a
At 3, 6, and 12 months after stroke onset (follow-up), the PASE questionnaire was answered by 90, 80, and 80 participants, respectively. Table 2 shows the median PASE scores for men and women; the scores at 3, 6, and 12 months after stroke onset were 59.5, 77.5, and 63.5, respectively. In a univariate analysis, the mean PASE score was 20 units higher for men than for women (P=.058).
Median Scores on PASE Questionnaire at 3, 6, and 12 Months After Strokea
Figure 2 shows the observed and model-based PASE scores and the observed SwePASS scores during the first year after stroke. The mean SwePASS scores were 28.1 (SD=8.3), 31.6 (SD=4.9), 32.1 (SD=4.7), and 32.1 (SD=5.1) at baseline and at 3, 6, and 12 months after stroke, respectively. A ceiling effect, that is, the achievement of a maximal score, was found in 16, 25, 27, and 24 participants at the respective time points. No floor effect, that is, the achievement of the lowest score, was observed.
Observed versus model-based mean values for the Physical Activity Scale for the Elderly (PASE) and observed mean values for the modified version of the Postural Assessment Scale for Stroke Patients (SwePASS) in the first year after stroke at 3 time points.
Table 3 shows the relative change, as a percentage, in the outcome variable PASE for each 1-unit change in the explanatory variables when the mean of our outcome variable was modeled with multiple predictor variables. There was a statistically significant 32% increase in PASE scores from 3 to 6 months (P=.03), independent of age, sex, and SwePASS scores. The change seen between 6 and 12 months after stroke onset was not significant (P=.14). Moreover, Table 3 shows that there was a 13% increase (P<.001) in PASE scores across time for each unit increase in SwePASS scores at baseline. The analyses were based on 240 SwePASS assessments and 247 PASE assessments from baseline to 12 months after stroke in 96 participants.
Relative Change (as Percentage) in Outcome Variable PASE for Each 1-Unit Change in Explanatory Variablesa
Discussion
This longitudinal study showed that the level of physical activity, which was low at all time points, increased from 3 to 6 months but not thereafter. The median PASE score at 3 months after stroke was 59.5. This value was exemplified by a participant who scored 59 and who reported walking for less than 1 hour at an unknown intensity level for 5 to 7 days, in addition to household activities. There was a strong and positive correlation between postural control at baseline (measured with the SwePASS) and self-reported physical activity in the first year after stroke. The PASE scores did not correlate with sex or age when the SwePASS scores were added in multivariate modeling.
A decline in postural control toward the end of the first year after stroke has been shown.33 It is not known whether a cutoff on the SwePASS is associated with the likelihood of a very low physical activity level. It can be hypothesized that improving postural control early after stroke may have a positive impact on the physical activity level. Given this scenario, the clinical implication for physical therapists and other health care professionals may be that training of postural control is important.32 However, which physical activity levels or magnitudes of PASE scores are associated with adverse health effects are still unknown. The low physical activity levels found in the present study may not meet public health guidelines,41 although the data cannot be compared because of the use of different units.41 For the same reason, adherence to recommendations of physical activity for people who have survived stroke2,42 cannot be evaluated on the basis of data from the present study.
The strength of the present study is the longitudinal design, with repeated measures of self-reported physical activity levels and postural control in a group of consecutive participants with first-ever stroke. On the basis of a clinical point of view that an early assessment is significant for identifying participants in need of intensive training in the acute stage, we chose to study how the baseline assessment correlated with physical activity at later stages. The timing of the follow-up assessments—at 3, 6, and 12 months after stroke—was chosen to provide data from different recovery stages and to provide an even distribution of data during the first year. Possible differences in physical activity levels according to seasons presumably were leveled out because data for the sample were collected over a 2-year period.
However, there were some study limitations. First, the sample size was limited. Second, the lack of physical activity assessments before and during the first months after stroke onset gave us no opportunity to comment on either levels of or changes in physical activity during the first 3 months after stroke. Third, although the PASE scoring system is based on METs, the actual physiological intensity attained in the activities is unknown. Furthermore, the interpretation of the results was complicated by the fact that the number of participants decreased from the baseline to and through the follow-up assessments. For ethical reasons, people with the most severe impairments were not considered for inclusion. Nevertheless, excluding people with severe impairments may have created problems with truncation, which in turn may have decreased the magnitude of the correlations between SwePASS and PASE scores. In addition, it may have reduced the generalizability of the findings. Moreover, several plausible explanatory and confounding factors may have affected the physical activity level. For example, we did not include balance self-efficacy to address psychological aspects, which have been shown to be associated with physical functioning and activities of daily living.17,43,44 Other psychosocial or environmental factors that may have had an impact on the physical activity level were also not investigated. Additionally, pain, fatigue, and sleep patterns were not analyzed, although they have been concluded to influence people's daily life functioning up to 6 months after stroke.45
The assessment of physical activity levels with a self-report method in which participants are asked to state their physical activity level in the preceding week also may be questioned because of the risk of recall bias.46 Memory or other cognitive impairments also may compromise the reliability of self-report measures. Assessment with activity monitors provides more accurate information, but the use of technical devices in clinical settings has disadvantages, such as the time, costs, and requirements of technical support and the help needed for donning and removing the devices. For these reasons, the use of a questionnaire is probably the most clinically feasible solution for obtaining an approximate measure of a participant's physical activity level to serve as a basis for advocating physical activity.
The association between physical activity level and postural control is in line with the findings of 3 other studies,18,19,29 albeit not strictly comparable because of methodological differences regarding the measurement instruments used. There are also similarities between the current median PASE scores in all of the participants at 12 months after stroke and PASE scores of 64 to 69 in patients who had ischemic stroke and were 40 years old and older within the first year after stroke in the ExStroke Trial.31 In that study, however, the ability to walk independently was an inclusion criterion—not the case in the present study. At 2 years after stroke, a mean PASE score of 64 was reported in the ExStroke Trial.31 A mean PASE score of 97 (SD=66) was found in a register-based cohort study 1 to 3 years after stroke17; although low, this mean was somewhat higher than that in the present study. At a mean of 6 years after stroke, a median PASE score of 119 was found in a convenience sample of 70 people who had survived stroke and were 40 to 79 years old.47 Mean PASE scores of 7223,48 to 16147 were demonstrated in various samples from people who were healthy. For sedentary adults, higher scores were shown in men than in women, in younger people than in older people, and in people who were healthy than in those with chronic conditions.28 The median PASE scores of 60 to 78 in the present study are low compared with population-based PASE scores of 136 and 130 in 70- to 79-year-old men and women (N=27) from the same catchment area.47 One explanation for the various PASE scores may be differences in time points for assessment, age spans, and selections of participants. The nonsignificant change in the physical activity level between 6 and 12 months after stroke was similar to published results for 28 patients with a median age of 81 years, for whom no increase in the physical activity level was detected between the first month and the subsequent 5 months after stroke.7
The low physical activity levels in the present study are a challenge for physical therapists, who have central roles in both motivational interviewing and promoting and prescribing exercise. Most of all, however, low levels of physical activity are a challenge for people and society because they may correspond to a risk for further decline in function and cardiovascular complications, with consequential economic costs. Patients with poor postural control may need more attention and support to be physically active. Further research should investigate whether physical activity can be improved by individualized postural control training of specific amounts and intensities, on the basis of the initial level of postural control. Whether there is a sex difference in physical activity is unclear48 and may be a topic for future studies. In addition, perhaps greater focus on a salutogenic, health-promoting approach and on the enjoyment of physical activity is needed.20
In conclusion, self-reported physical activity levels in people who had survived stroke were low in the first year after stroke. An increase in self-reported physical activity levels was established between 3 and 6 months after stroke onset but not thereafter. The association of postural control assessed in the first week after stroke and the physical activity level during the first year was statistically significant, independent of sex and age. Low physical activity levels represent a challenge for patients, physical therapists, and society in terms of the rehabilitation and lifestyle changes needed to meet exercise recommendations to prevent further cardiovascular events after stroke.
Footnotes
Dr Persson, Dr Hansson, and Dr Danielsson provided concept/idea/research design and writing. Dr Persson, Mr Lappas, and Dr Danielsson provided data analysis. Dr Persson provided project management and fund procurement. Dr Hansson, Mr Lappas, and Dr Danielsson provided consultation (including review of manuscript before submission).
The study was approved by the Regional Ethical Review Board in Gothenburg.
Financial support was received through grants from the Local Research and Development Board for Gothenburg and Södra Bohuslän, the Sahlgrenska University Hospital Foundation (Heart, Blood Vessels, and Lungs), the Stroke Centre West, the Greta and Einar Asker Foundation, the National Association of Stroke Foundations and Funds, the Felix Neubergh Foundation, the Hjalmar Svensson Foundation, the Reneé Eander Foundation, the Gun and Bertil Stone Foundation, the Rune and Ulla Amlöv Foundation, and the John and Brit Wennerström Foundation.
- Received July 7, 2015.
- Accepted March 13, 2016.
- © 2016 American Physical Therapy Association