Investigating physical inactivity and associated health parameters in patients with systemic lupus erythematosus

Abstract

Background

Physical inactivity, which is highly prevalent in patients with systemic lupus erythematosus (SLE), is an independent risk factor for cardiovascular events and causes many complications. This study aimed to investigate the effect of objective measurement and physical activity level on peripheral muscle strength, exercise capacity, pain, dyspnea, fatigue, anxiety, and depression in patients with SLE.

Methods

The present cross-sectional study analyzed 41 patients with SLE. Clinical and demographic characteristics of patients were recorded. Functional exercise capacity, peripheral muscle strength, dyspnea, pain, fatigue, anxiety, and depression were assessed. The physical activity level was assessed by a wearable activity tracker (Mi Band four smart band).

Results

The number of steps measured by the activity tracker was 4384.43 ± 1558.21 steps per day in patients with SLE. Patients with physical activity levels below 5000 steps exhibited elevated levels of fatigue, along with diminished functional exercise capacity and knee muscle strength, in comparison to those who were above the 5000-step threshold. Physical activity levels correlated with functional exercise capacity (6MWT), physiological parameters (maximum heart rate, Δ heart rate, Δ dyspnea, QFM fatigue, Δ QFM fatigue), and knee extension muscle strength. The functional exercise capacity and knee extension were identified as significantly and dependently associated with physical activity levels in SLE patients.

Conclusion

Physical activity level is associated with functional exercise capacity and knee muscle strength in patients with SLE.

Keywords

Systemic lupus erythematosus physical activity muscle strength functional exercise capacity fatigue

Introduction

Systemic lupus erythematosus (SLE) is a chronic, autoimmune, and inflammatory rheumatic disease that causes tissue damage through autoantibodies and immune complexes. In the disease, constitutional complaints are seen together with skin, hematological, renal, musculoskeletal, and pulmonary involvements. There is considerable evidence of a significant prevalence of physical inactivity in patients with SLE.^1,2 The European League Against Rheumatism (EULAR) states that physical inactivity in patients with SLE increases cardiovascular disease and other complications. However, there is a lack of comprehensive research on reduced physical activity and its physical and emotional associations in SLE patients. Physical and mental impairment caused by organ involvement and resultant damages in SLE may seriously affect patients’ ability to fulfill life goals, impair social functioning, and lead to work disability, leading to psychosocial stress.³ The prevalence of depression and anxiety in patients with SLE is twice as high as that in the general population. These psychological challenges, alongside fatigue, may lead to a decline in physical activity. Various studies have demonstrated correlations between fatigue, decreased sleep quality, and anxiety.^4,5 Regular physical activity can reduce psychological symptoms, reduce the level of fatigue, and improve the quality of life in patients with SLE.^1,2 In light of these benefits, it is hypothesized that the heightened levels of fatigue, depression, and anxiety observed in SLE patients are linked to their relative physical inactivity. Nevertheless, to date, no study has explored the effect of physical inactivity on anxiety, depression, and fatigue patients with SLE.

The level of physical activity can exert a significant impact on muscle function. Studies have demonstrated a positive correlation between physical activity and muscle strength in patients with SLE.⁶ There are limited studies that have investigated the effect of physical activity on peripheral muscle strength in patients with SLE, and subjective assessment scales were used in these studies. The fact that the scales-evaluating the level of physical activity are subjective and the energy consumption is not examined according to the type of activity causes limitations in these studies.^6,7 No study objectively measures the effect of physical activity level on peripheral muscle strength and shows the difference in muscle strength according to physical activity level. Additionally, in patients with SLE, physical inactivity leads to a decrease in exercise capacity and oxygen consumption. Pinto et al. demonstrated that the aerobic capacity of physically inactive patients with SLE decreased significantly compared with healthy individuals.⁸ It is worth noting that there are no studies showing the relationship and effect between exercise capacity, dyspnea, and physical activity in patients with SLE.

The physical inactivity experienced in SLE is important due to the relationship between muscle strength, fatigue, depression, anxiety and resulting in reduced quality of life.^1,8 Yet, to our knowledge, no study has examined the impact of objectively measured physical activity levels on peripheral muscle strength, exercise capacity, dyspnea, depression, anxiety, and fatigue. Therefore, the aim of this study was to investigate the effect of objective measurement and physical activity level on peripheral muscle strength, exercise capacity, pain, dyspnea, fatigue, anxiety, and depression in patients with SLE.

Methods

Study design

This was a cross-sectional study that was conducted in patients with SLE. The study was approved by the local ethics committee (Date: 18/07/2022, No.: 22/15). Before the evaluations, the patients read the informed consent form and signed it, declaring that they accepted the study. The study was complied with the principles of the Declaration of Helsinki.

Patients

The study included patients with SLE who were diagnosed based on the criteria established by the EULAR/the American College of Rheumatology (ACR) and who were under regular follow-up. The inclusion criteria comprised the following: 1) individuals aged between 18 and 65; 2) recipients of standard medical treatment; 3) stable general health condition for the previous 6 months (defined as having no significant illnesses or laboratory abnormalities that require hospitalization or major treatment modifications); 4) provision of informed, voluntary consent. The exclusion criteria were as follows: 1) inability to cooperate with the measurements; 2) presence of orthopedic or neurological conditions that could impact the assessment of functional capacity; 3) pregnancy; 4) use of sedating medications that cause fatigue; 5) have comorbidities such as fibromyalgia, mood disorders, or sleep disorders.

Patients with stable medical conditions were assessed by a rheumatologist and were subsequently referred to physiotherapy and rehabilitation services. The evaluation of these patients was conducted by a physiotherapist who specialized in rheumatic diseases.

Outcome measures

Demographic information (sex, age, body mass index, smoking history, education), disease characteristics (disease duration, morning stiffness, organ involvement), and current treatment of all the SLE patients were recorded. Disease activity was evaluated by the Systemic Lupus Erythematosus Disease Activity Index-2K (SLEDAI-2K). Higher scores show higher disease activity.⁹

Physical activity level

Physical activity level was evaluated using the Xiaomi Mi Band four smart wristband device (Xiaomi Corp., Beijing, China). The Xiaomi Mi Band four smart wristband device measures movements in three dimensions. Parameters were measured using the device, including total energy expenditure (kcal/day), physical activity time (min/day), number of steps (h/day), time spent lying down (min/day), deep sleep time (min/day), light sleep time (min/day), and sleep duration (min/day). A mobile application, Mi Fit (Huami Co., Ltd, Hefei, China), was installed on the participants’ smartphones. The Mi Band four was connected to Mi Fit via Bluetooth, and the results were recorded. Individuals wore the device on their non-dominant wrist for 24 h a day, continuously for five consecutive days (Monday–Friday).¹⁰

Functional exercise capacity

Functional exercise capacity was assessed using the 6-min walk test in accordance with the criteria established by the European Respiratory Society and the American Thoracic Society (ATS/ERS). Patients were instructed to walk as fast as possible at their self-determined pace for a duration of 6 min along a straight 30-m corridor. Prior to starting the test, patients were informed that if they experienced excessive dyspnea, chest pain, or overwhelming leg fatigue during the test, they had option to rest; however, any rest period would be included in the total test duration. Throughout the test, patients were periodically informed of the time remaining per minute, in accordance with ATS/ERS criteria, and received standardized motivational feedback, such as “You are doing very well.” Heart rate, peripheral oxygen saturation, respiratory frequency, dyspnea, fatigue, and perception of quadriceps muscle fatigue (assessed using the modified Borg scale) were all recorded both before and after the test, as well as at the 1-min recovery point. The Modified Borg scale is a categorical scale used to assess levels of fatigue and dyspnea, ranging from 0 (not at all) to 10 (extremely). Differences between post-test and pre-test values (Δ) for physiological parameters (heart rate, peripheral oxygen saturation, respiratory frequency) and modified Borg scale scores were calculated. On the same day, the test was repeated with a half-hour interval between each session, and the maximum distance achieved was selected for subsequent analysis.¹¹

Peripheral muscle strength

The patient’s knee extension muscle strength was assessed using a portable digital handheld dynamometer (Lafayette Hand-Held Dynamometer Model-01,165, USA). The test was performed three times for both the right and left sides in each region, and the highest value was recorded in Newtons (N).¹²

Dyspnea

Dyspnea experienced during activities of daily living was assessed using the Modified Medical Research Council (mMRC) Dyspnea Scale. The mMRC dyspnea scale categorizes the severity of dyspnea in daily activities into ordinary levels ranging from 0 to 4. As a patient’s score on the scale rises, their perception of dyspnea increases. A change of one point on the mMRC dyspnea scale is considered to be of minimal clinical significance.¹³

Pain

The pain levels were evaluated using the Numeric Rating Scale (NRS), which is a validated and reliable tool for assessing pain severity. The NRS is a numerical adaptation of the visual analog scale, where patients are instructed to indicate the number that best represents their level of pain. It consists of an 11-point numerical scale, with 0 indicating “No pain,” and 10 indicating “The worst pain imaginable.” Patients were specifically requested to provide feedback on their average pain intensity.¹⁴

Fatigue

The severity of fatigue was assessed using the Turkish version of the Fatigue Severity Scale, comprising nine questions. Each question is rated on a scale from one to 7. An elevation in the total score on the scale indicates an escalation in the patient’s fatigue severity. The total score ranges from seven to 63, with a total score of 36 or higher signifying severe fatigue.¹⁵

Anxiety and depression

The anxiety and depression levels of the patients were assessed using the Turkish adaptation of the Hospital Anxiety and Depression Scale (HADS). The scale is further divided into two subgroups: anxiety (HADS-A) and depression (HADS-D). Comprising 14 questions, the odd-numbered ones evaluate anxiety, while the even-numbered ones assess depression. The minimum score attainable in both subgroups is 0, while the maximum score is 21.¹⁶

Statistical analysis

The statistical analysis of the study was conducted using SPSS Version 22.00 (SPSS Inc., Chicago, IL). The normality distribution of the data was evaluated through visual (histograms/probability graphs) as well as analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk tests). Continuous variables were summarized using mean and standard deviation (SD) or median (interquartile) values, while categorical variables were presented as counts and percentages. Group comparisons were made using the independent samples t test or Mann whitney U tests. For the evaluation of correlations Pearson or Spearman analyzes were applied, with interpretations as follows: negligible (0 to 0.29), poor (0.30 to 0.49), moderate (0.50 to 0.69), good (0.70 to 0.89), and excellent (0.90 to 1.00).¹⁷ Linear regression analysis was carried out using the enter model to identify independent variables associated with the level of physical activity (functional exercise capacity, muscle strenght, dyspnea, pain, fatigue, anxiety and depression). A level of p < 0.05 was accepted for statistical significance in all analyses.

Post-hoc power analysis for the sample size of the study was analyzed utilizing G*Power 3.1.9.2 software. The 6-MWT was chosen for post-hoc analysis in the independent sample t test. The power of the study was found sufficient statistical power (1-β = 95%, α = 0.05; total sample size = 41; Df = 39).

Results

A total of 41 patients followed up with the diagnosis of SLE were included in the present study. Of the patients with SLE, 40 (97.6%) were female and 1 (2.4%) was male. Clinical and demographic characteristics of the patients were as follows; the mean age was 35.80 ± 10.72 years, the mean disease duration was 10.82 ± 6.61 years, and the mean SLEDAI-2K score was 4.78 ± 4.32. In the patients, there were 4 (9.8%) lung, 17 (41.5%) renal, 2 (4.9%) hematologic, 1 (2.4%) neurologic, 2 (4.9%) ocular, and 1 (2.4%) cardiac involvements. Detailed demographic and clinical characteristics of patients with SLE are stated in Table 1.

Table 1.

Patient characteristics in the study.

Characteristics	n (%) or mean ± SD
Gender
Female	40 (97.6)
Male	1 (2.4)
Age (years)	35.80±10.72
BMI (kg/m ² )	24.99±5.24
Dominance
Right	41 (100)
Education
Elementary school	10 (24.4)
High school	12 (29.3)
University	19 (46.3)
Current smoker	16 (39)
Disease duration (years)	10.82±6.61
SLEDAI-2K	4.78±4.32
Morning stiffness	10 (24.4)
System involvements
Respiratory	4 (9.8)
Renal	17 (41.5)
Hematologic	2 (4.9)
Neurologic	1 (2.4)
Cardiac	1 (2.4)
Current treatments
Mycophenolate mofetil	6 (14.6)
Corticosteroids	19 (46.3)
Hydroxychloroquine	32 (78.0)
Azathioprine	2 (4.9)
Physical activity level
<5000 steps/day	30 (73.2)
>5000 steps/day	11 (26.8)
Outcome measures
Physical activity level	4384.43±1558.21
6-MWT (m)	530.20±88.43
Peripheral muscle strength
Knee extension (right), (N)	211.69±69.91
Knee extension (left), (N)	203.27±64.81
mMRC dyspnea score	0 (0-1)^a
Pain-VAS	0 (0-0)^a
Fatigue severity scale score	46.12±10.58
Hospital anxiety depression scale
HADS-A	9.12±4.68
HADS-D	7.31±5.13
Total score	16.19±8.61

n: number. BMI: Body-mass index. SLEDAI-2 K: Systemic Lupus Erythematosus Disease Activity Index-2K. X ± SD: Mean ± Standard deviation. IQR25th-75th: interquartile range 25-75. 6-MWT: 6-min walk test, VAS: VisualAnalogScale. mMRC: the Modified Medical Research Council dyspnea scale. HADS-A: Hospital Anxiety and Depression Scale-Anxiety, HADS-D: Hospital Anxiety and Depression Scale-Depression. All correlations are statistically significant with p < 0.001.

The number of steps measured using the Xiaomi Mi Band four smart wristband device in the patients of SLE was 4384.43 ± 1558.21 steps/day. Patients with physical activity level below 5000 steps/day had significantly lower 6-MWT distance (p < 0.001) and knee extension strength (right) (p = .018) compared to patients with a physical activity level above 5000 steps/day. In addition, fatigue levels were higher in the physical activity level below 5000 steps/day compared to the physical activity level above 5000 steps/day (p < 0.05). The pain, dyspnea, knee strength (left), anxiety, and depression measures were similar between groups (p > 0.05) (Table 2).

Table 2.

Comparison of patients with SLE according to physical activity levels.

	Number of steps (<5000 steps)	Number of steps (>5000 steps)	p-value
6-MWT (m)	507.35±89.61	592.54±46.43	<0.001
Peripheral muscle strength
Knee extension (right), (N)	196.30±60.72	253.68±78.80	0.018
Knee extension (left), (N)	195.32±65.95	224.94±59.01	0.199
mMRC dyspnea score	1 (0-1)	0 (0-1)	0.477^a
Pain-VAS	0 (0-0)	0 (0-0)	0.424^a
Fatigue severity scale score	47.93±11.18	41.18±6.95	0.028
Hospital anxiety depression scale
HADS-A	8.66±4.95	10.36±3.74	0.310
HADS-D	7.50±5.39	6.81±4.53	0.711
Total score	15.83±9.19	17.18±7.11	0.663

Independent samples t test.

^aMann–Whitney U Test, Variables are presented as mean ± Standard deviation and interquartile range 25-75, p < 0.05.

6-MWT: 6-min walk test, VAS: VisualAnalogScale. mMRC: the Modified Medical Research Council dyspnea scale. HADS-A: Hospital Anxiety and Depression Scale-Anxiety, HADS-D: Hospital Anxiety and Depression Scale-Depression.

Physical activity had poor to moderate correlations with 6-MWT distance (r = 0.493, p = 0.002), maximum heart rate (r = 0.319, p = 0.042), Δ Heart rate (r = 0.420, p = 0.006), Δ Dyspnea (r = −0.309, p = 0.049), QFM Fatigue (r = 0.314, p = 0.046), Δ QFM Fatigue (r = −0.611, p < 0.001), knee extension (right), (r = 0.539, p < 0.001) and knee extension (left) (r = 0.464, p = 0.002) in patients with SLE. The results showed that physical activity level was associated with 6-MWT distance, maximum heart rate, Δ Heart rate, Δ Dyspnea, QFM fatigue, Δ QFM fatigue, knee extension (right), and knee extension (left). Table 3 indicates the correlation coefficients between the physical activity level and other study outcomes.

Table 3.

Correlations of physical activity in patients with SLE.

Physical activity level
	r	p
6-MWT (m)	0.493	0.002
Heart rate, beats/min (resting)	0.162	0.346
Maximum heart rate,%	0.319	0.042
Δ Heart rate, beats/min	0.420	0.006
Dyspnea, (MBS) 0–10 (resting)	−0.130	0.451
Δ dyspnea, (MBS) 0–10	−0.309	0.049
Fatigue, (MBS) 0–10 (resting)	−0.095	0.583
Δ Fatigue, (MBS) 0–10	−0.280	0.076
QFM Fatigue (MBS) 0-10 (resting)	0.314	0.046
Δ QFM Fatigue (MBS) 0-10	−0.611	<0.001
Peripheral muscle strength
Knee extension (right), (N)	0.539	<0.001
Knee extension (left), (N)	0.464	0.002
mMRC dyspnea score	−0.236	0.138^a
Pain-VAS	−0.276	0.081^a
Fatigue severity scale	−0.258	0.103
Hospital anxiety depression scale
HADS-A	0.237	0.136
HADS-D	−0.067	0.679
Total score	0.078	0.630

Pearson correlations analyze.

^aSpearman correlations analyze. Bold values are significant at p < 0.05.

6-MWT: 6-min walk test, Δ: Differences between post-test and pre-test values. MBS: Modified Borg scale VAS: VisualAnalogScale. mMRC: the Modified Medical Research Council dyspnea scale. HADS-A: Hospital Anxiety and Depression Scale-Anxiety, HADS-D: Hospital Anxiety and Depression Scale-Depression.

The linear regression analysis showed that the 6-MWT distance (R² = 0.214, p = 0.002), knee extension (right) (R² = 0.290, p < 0.001), and knee extension (left) (R² = 0.216, p = 0.002) were significant and dependent predictors of the physical activity level in patients with SLE. The regression model was accepted as adequate since both F values and p-values were significant and the residual distribution was random (Table 4, Figure 1). If the Durbin and Watson values range between 1.5 and 2.5, It reveals no autocorrelation problems within the model. In the present study, the Durbin and Watson values presented a range from 1.745 to 2.406. According to the findings of the study, there was no autocorrelation problem, as detailed in Table 4.

Table 4.

Results of linear regression enter model analysis: The effect of physical activity in patients with SLE.

Independent variable	Dependent variable	β	t	p	F	R²	Durbin-watson	95% confidence interval (lower-upper)
Physical activity level	6-MWT (m)	0.463	3.259	0.002	10.622	0.214	1.960	0.010–0.043
	Knee extension (right)	0.539	3.992	<0.001	15.933	0.290	1.745	0.012–0.036
	Knee extension (left)	0.464	3.275	0.002	10.728	0.216	1.843	0.007–0.031
	mMRC dyspnea score	−0.233	−1.498	0.142	2.245	0.054	1.843	0-0
	Pain-VAS	−0.297	−1.057	0.297	1.117	0.028	2.082	0-0
	Fatigue severity scale	−0.258	−1.670	0.103	2.789	0.067	2.406	−0.004–0
	HADS-A	0.237	1.522	0.136	2.317	0.056	2.174	0–0.002
	HADS-D	−0.067	−0.417	0.679	0.174	0.004	2.107	−0.001–0.001
	HADS total score	0.078	0.486	0.630	0.236	0.006	2.291	−0.001–0.002

Discussion

The main findings of the present study indicated that physical activity level was found to be associated with exercise capacity, maximum heart rate, Δ heart rate, Δ dyspnea, QFM fatigue, Δ QFM fatigue, and knee extension muscle strength. It also showed that physical activity had a significant association with these parameters. In addition, SLE patients, who had physical activity levels under 5000 steps, had more pain and fatigue, lower functional exercise capacity, and knee muscle strength compared to physical activity levels higher than 5000 steps. In the study, we focused on assessing the effects of physical activity level on peripheral muscle strength, exercise capacity, pain, dyspnea, fatigue, anxiety, and depression.

Physical inactivity is an independent risk factor for cardiovascular events and is highly prevalent in SLE. Moreover, physical inactivity has shown to be associated with fatigue, anxiety, and depression, which all have a high prevalence in patients with SLE, resulting in a decrease in quality of life.⁸ Pinto et al. stated impaired aerobic capacity and quality of life when compared with healthy individuals matched by physical inactivity.⁸ Andrews et al. found that extremity muscle strength was lower in physically inactive individuals in their study on female patients with SLE.⁶ Several studies demonstrated that the number of daily step counts was considerably lower in patients with SLE as compared to the healthy individuals.¹⁸ It has been stated that <5000 steps/day may be used as a sedentary lifestyle index in the literature.¹⁹ Tudor-Locke et al., a systematic review of 32 studies, emphasized the imp/ortance of 5000 steps/day for patients living with disabilities and chronic diseases.²⁰ The current study demonstrated that the number of daily step counts was substantially decreased in the patients with SLE. In fact, 73.2% of our patients had a sedentary lifestyle. A physically inactive sedentary lifestyle (<5000) may lead to increased fatigue, decreased exercise capacity, and quadriceps muscle strength (right). The reason behind the observed difference solely in the strength of the right quadriceps muscle appears to be associated with the prevalent dominance of the right side among the patients. Furthermore, the absence of complaints related to dyspnea or pain among the patients contributed to the lack of a notable difference between the groups. Therefore, theoretically, If physical activity levels increase in patients with SLE, fatigue, exercise capacity, and muscle strength might be improved. Based on the current findings, patients with SLE should be adviced for physical activity counseling.

The 6-MWT, a current test for the evaluation of functional capacity and exercise tolerance in patients and healthy individuals, is a straightforward, safe, and inexpensive method.²¹ In several studies, the functional exercise capacity in SLE patients has been assessed using the 6-MWT.^18,22–24 However, these studies have mostly been utilized for cardiac or pulmonary evaluations.^25,26 Nevertheless, the correlation between physical activity and the 6-MWT has been objectively demonstrated in certain chronic diseases.^27–29 Similar to these studies, we found a positive correlation between physical activity and 6-MWT, maximum heart rate, Δ heart rate, and QFM fatigue. At the same time, there was a negative correlation between physical activity and Δ dyspnea, and Δ QFM Fatigue. As far as we know, studies demonstrating the relationship between exercise capacity and physical activity in SLE patients have evaluated exercise capacity through subjective methods. Hence, the current study is the first to objectively demonstrate the relationship between physical activity and exercise capacity as well as its physiological parameters in patients with SLE. There are limited studies related to the relationship between physical activity and muscle strength in SLE.^6,30 Andrews et al. stated that decreased muscle strength was strongly related to physical disability.⁶ Another study demonstrated that reduced strength in the muscles of the lower extremities was linked to a significant decline in physical function in SLE patients, particularly among the women who exhibited the lowest strength levels.³⁰ Importantly, in line with the literature, our findings indicated a relationship between lower muscle strength (knee extension) and the level of physical activity.

The reduced physical activity level in SLE patients initiates a vicious cycle, limiting their engagement in daily activities and subsequently diminishing their overall quality of life.^7,31 Several studies in the literature found a correlation between physical activity and pain,³² fatigue,³² and depression.³³ Jacobelli et al. observed diminished lung volumes, reduced chest compliance, and a decline in diffusion capacity among SLE patients. Notably, dyspnea emerges as the most prominent symptom.³⁴ Previous studies on different diseases have established a correlation between physical inactivity and the onset of dyspnea.^35,36 It is noteworthy, however, that we did not find any correlation between physical activity and pain, dyspnea, fatigue, or depression. This dicrepancy may arise from the variance in scales used to assess these parameters and difference in social environments of enrolled SLE patients. Furthermore, the level of disease activity, whether low or high, can also impact the correlation between these evaluations. Future studies should assess the correlation between physical activity level and pain, dyspnea, fatigue, or depression in patients with high disease activity and compare patients with low and high disease activity.

In a study by Legge et al., the reallocated time from sedentary behavior or light physical activity to moderate-to-vigorous physical activity was associated with lower blood pressure and lower estimates of 10-years cardiovascular risk in SLE.³⁷ This study identified that the level of physical activity affects knee extension strength, functional walking capacity, and its certain physiological findings (maximum heart rate, Δ heart rate, Δ dyspnea, QFM fatigue, and Δ QFM fatigue). When reviewing the literature on SLE patients, most studies have solely examined the correlation between physical activity levels and other symptoms.^18,32,33 However, to the best of our knowledge, our study is the first to investigate the effect of physical activity levels on other parameters such as functional exercise capacity and peripheral muscle strength.

The present study has several limitations. Firstly, our study data was collected at a single center, which may impact the generalizability of the outcomes. Secondly, the relationship between occupation and physical activity. The level of physical activity will be low, especially for office workers. Our study did not evaluate the distinction between time allocated for leisure and occupational physical activities among our SLE patients. Third, we did not include therapeutic characteristics into the analyzes like corticosteroid exposure. The most robust feature of the present study was the objective measurement of physical activity levels and comprehensive evalution of potential causative parameters on physical activity.

In conclusion, it was found that SLE patients with physical activity levels below 5000 steps had higher levels of pain and fatigue, along with reduced functional exercise capacity and knee muscle strength compared to those above 5000 steps. Physical activity levels showed correlations with exercise capacity, maximum heart rate, Δ heart rate, Δ dyspnea, QFM fatigue, Δ QFM fatigue, and knee extension muscle strength. Furthermore, the level of physical activity had a significantly correlated with these parameters. Patients might be advised to engage in daily exercises with progressive intensity and group exercise programs. In future studies, the impact of physical activity levels on other symptoms should be investigated using multicenter study groups with higher disease activity and larger sample sizes.

Footnotes

Acknowledgements

Thank you to all our patients in this study.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Fulden Sari

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