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Efficacy of structured exercise & relaxation techniques in managing post-COVID paraspinal myalgia in manual labourers of Belagavi, Karnataka: A quasi-experimental study
For correspondence: Dr Nirmala Subhash Anand, Department of Physiology, Jawaharlal Nehru Medical College Belagavi, KLE Academy of Higher Education & Research, Belagavi 590 010, Karnataka, India e-mail: drnirm79@gmail.com
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Received: ,
Accepted: ,
Abstract
Background & objectives
This study compared the effectiveness of Progressive Muscle relaxation technique (PMRT) and Spinal Muscle Training (SMT) against Standard Neurosurgical Care (SNC) for the management of post-acute-COVID-19 syndrome (PACS)-associated paraspinal myalgia (PM), via changes in serum interleukin (IL)-17 and functional independence measured by Katz index of activities of daily living (ADL).
Methods
Male manual labourers aged 40–50 yr with PACS-associated PM were enrolled and allocated to the experimental group receiving PMRT and SMT and the control group receiving SNC delivered via telerehabilitation over 12 wk. IL-17 and ADL were measured pre- and post-intervention. Data analysis involved paired and unpaired t-tests, with a P value < 0.05 being statistically significant.
Results
There was a notable decrease in IL-17 in the experimental and control groups, from (31.13±3.68 pg/mL) to (18.96±2.56 pg/mL) and (31.05±4.24 pg/mL) to (28.89±4.58 pg/mL), respectively. The experimental group's ADL scores increased from 2.93±0.94 to 5.03±0.85, while the control improved from 2.5±1.13 to 3.53±1.04. The experimental intervention was supported by large effect sizes and statistically significant differences in IL-17 reduction and ADL improvement on inter-group comparisons.
Interpretation & conclusions
The combination of PMRT and SMT was significantly efficacious than SNC at lowering systemic inflammation and improving functional independence in PACS patients with PM. This study also highlighted the role of telerehabilitation in intervention delivery to socio-demographically limited populations. Future studies should investigate long-term effects and generalizability to larger populations.
Keywords
Exercise therapy
myalgia
post-acute COVID-19 syndrome
progressive muscle relaxation
telerehabilitation
The worldwide COVID-19 pandemic has led to a spectrum of long-term health complications. Individuals recovering from recent infection may develop post-acute COVID-19 syndrome (PACS), characterized by persistent symptoms beyond four weeks1. A large subset of PACS patients have been previously reported to have musculoskeletal symptoms like fatigue, reduced strength, generalized myalgia, and impaired functional ability2. The back muscles are a common site of post-COVID myalgia, with approximately 30 per cent patients experiencing localized paraspinal discomfort3, termed paraspinal myalgia (PM). This leads to impaired mobility and reduced quality of life, posing a threat to populations with physically demanding occupations.
The pathophysiology of PACS remains incompletely understood. Proposed mechanisms include viral persistence4, immune dysregulation5, low-grade systemic inflammation6, mitochondrial dysfunction7, and autonomic disruption8. Elevated serum interleukin (IL)-17 and IL-6 have been reported in PACS patients9–11, linked to sustained inflammation and poor viral resolution12. IL-17 has shown highest serum concentration among cytokines11, making it a potential biomarker for therapeutic response assessment.
Current management of PACS-associated PM is largely symptomatic, highlighting the need for accessible, evidence-based strategies. Progressive muscle relaxation technique (PMRT)13 and spinal muscle training (SMT) have shown benefits in reducing pain and improving physical function in various clinical populations14–19. PMRT involves cycles of muscle tension and relaxation to promote neuromuscular recovery and stress relief13. SMT enhances spinal mobility and strength through targeted flexion-extension exercises. A combined rehabilitation protocol may benefit PACS-associated PM when delivered consistently under supervision.
This quasi-experimental study involved male manual labourers (aged 40–50 yr) from Belagavi, Karnataka, a population vulnerable to occupational disruption due to post-COVID musculoskeletal limitations. We evaluated the effectiveness of PMRT and SMT compared to standard neurosurgical care (SNC) in reducing systemic inflammation and improving functional independence, measured through serum IL-17 and Katz index of activities of daily living (ADL). Telerehabilitation was used to deliver these interventions to overcome the geographic and socioeconomic barriers20.
Materials & Methods
This was a 12 wk quasi-experimental, parallel-group study conducted from November 2023 to January 2024 at the department of Neurosurgery of a tertiary healthcare centre in Belagavi, Karnataka. The study received Institutional Ethics Committee clearance from KLE Academy of Higher Education & Research, Jawaharlal Nehru Medical College, Karnataka and adhered to the Indian Council of Medical Research Ethical Guidelines for biomedical research involving human participants (2017)21. The study objectives, protocols, and investigations were explained to the participants in their vernacular language, and written consent was obtained before enrolment.
The study evaluated the effects of a combined progressive muscle relaxation technique (PMRT) and spinal muscle training (SMT) versus standard neurosurgical care (SNC) on systemic inflammation and functional independence in male manual labourers suffering from post-COVID paraspinal myalgia (PM). A quasi-experimental design with a control group and an experimental group was considered appropriate and preferred over a randomized controlled trial, since random allocation was considered impractical in this situation where participants clustered naturally in outpatient department (OPD) timeslots and required timely care22–24. Participants were assigned based on OPD cluster scheduling, mirroring real-world telerehabilitation workflow while preserving patient autonomy in participation. To account for possible selection bias due to non-random allocation, extensive baseline data, including demographic and clinical variables, was collected to statistically confirm baseline comparability between the groups.
Sample size estimation
Using G*Power 3.1 software, assuming α = 0.05, power = 0.8, and an effect size of 0.7 (based on previous telerehabilitation and PMRT studies)25–27, a required sample size of 26 participants per group was calculated and adjusted to 30 per group to account for possible attrition.
Study participants
Participants were recruited from neurosurgery OPD using cluster-based sampling. Participant eligibility was validated through direct interviews and a review of their past medical records. Male manual labourers aged 40–50 yr, with confirmed history of SARS-CoV-2 infection and a clinical diagnosis of post-acute COVID-19 syndrome (PACS)1 with persistent PM (complaints of constant low-grade back pain in the paraspinal region, beyond 4 wk of acute COVID-19 infection) were included. Patients with significant comorbidities (e.g., diabetes, cardiovascular disease), autoimmune diseases (e.g., rheumatoid arthritis, myositis), recent muscle relaxant use, and females were excluded. Female participants were excluded to minimize variability in inflammatory response and exercise tolerance due to hormonal fluctuations associated with the perimenopausal transition28, which could potentially confound inflammatory markers. Additionally, the sample drawn from the inpatient and outpatient departments consisted predominantly of males, and retaining a homogeneous study population was necessary, given the limited sample size and quasi-experimental design.
Sixty participants were enrolled from the 127 screened individuals and were allocated to the experimental and control groups sequentially based on OPD cluster assignment with designated recruitment windows during the week for either group in a structured yet non-random manner. This approach preserved the practical integrity of telerehabilitation delivery and allowed for standardized implementation while minimizing bias through baseline equivalence checks.
Study phases
We divided the study into four phases. The first phase was carried out in the month of October 2023, which involved participant enrolment, allocation, and baseline assessment of patient demographics, occupational history, COVID-19 history, serum IL-17 measurement, and katz index of activities of daily living (ADL) scoring.
The second phase commenced immediately following patient allocation, with three in-person rehabilitation sessions for a week at the inpatient department to ensure that the participants understood their respective protocols before proceeding to the online telerehabilitation programme.
In the third phase, intervention delivery was performed via telerehabilitation over 12 wk from November 2023 to January 2024. Online sessions were held through Zoom video calls using participants' smartphones and devices provided by local primary health centres (PHCs). Three sessions were held weekly, each lasting 60 min. Trained physiotherapists supervised the participants to ensure adherence to the correct exercises and relaxation techniques.
The experimental group underwent a structured rehabilitation protocol of warm-up, exercise, and Progressive Muscle relaxation technique (PMRT). The exercises comprised collateral and spinal muscle training (SMT), which involved focused spinal flexion and extension movements. PMRT was delivered using the Jacobson Progressive Muscle Relaxation Technique13, with cycles of tension and relaxation of specific muscle groups in a specific order. The control group received conventional Standard Neurosurgical Care (SNC), comprising warm-up, basic stretching, and cooldown. Detailed rehabilitation protocols are presented in (Supplementary Tables I and II). The fourth phase involved post-intervention IL-17 and ADL assessments in both groups. A flowchart depicting participant progression is shown in figure.
- Flowchart of participant recruitment, eligibility screening, intervention allocation, and follow up in the quasi-experimental study. A total of 127 individuals were screened, 68 met the eligibility criteria via cluster sampling, and 60 participants were enrolled. All participants completed the 12-wk intervention and were included in the final analysis. PACS, post-acute COVID-19 syndrome; PM, paraspinal myalgia; IL-17, serum interleukin-17; Katz ADL, Katz index of activities of daily living; PMRT, progressive muscle relaxation therapy; SMT, spinal muscle training; SNC, standard neurosurgical care.
Outcome measures
Serum interleukin (IL)-17 levels were quantified pre-and post-intervention using the Abbkine EliKine Human IL-17 ELISA Kit, with a 7.8 to 500 pg/ml detection range and 4 pg/ml sensitivity. Functional independence was assessed using the Katz index of activities of daily living (ADL), which evaluates six daily life domains: dressing, transferring, bathing, continence, toileting, and feeding. Each function without assistance was scored 1, and dependence was scored 0. Higher total scores indicated greater functional independence.
Data analysis
Data were analysed using the IBM SPSS Statistics version 29. Normality of obtained IL-17 values and ADL scores was confirmed via Shapiro-Wilk test, to guide the choice of statistical tests. Paired t-tests were used for within-group comparisons and unpaired t-tests for between-group comparisons. Effect sizes were calculated using Cohen's d, interpreted as small (0.2), medium (0.5), and large (0.8). Statistical significance was set at a two-sided P value <0.05.
Results
A total of 128 individuals were screened, of whom 68 were found to be eligible and approached for participation. After accounting for refusals and incorrect contact information, 60 participants were successfully enrolled, with 30 in each group. Participants completed the study protocol with no loss to attrition during the 12-wk intervention period, and all enrolments were included in the final analysis.
Baseline demographic and clinical characteristics were comparable between the groups (Table I). Participants were male manual labourers aged 40–50 yr with no significant difference in mean age groups (P=0.442). There were no significant group differences in the duration since infection (P=0.791). Hospitalization due to COVID-19 occurred in 70 per cent of participants in both groups (P=1.000), and the proportion reporting symptom persistence beyond four wk was also similar between groups (P = 0.774). There was no significant difference in baseline serum IL-17 levels between the groups (P = 0.938). Baseline Katz ADL scores were also found to be statistically similar (P=0.114). Following the 12-wk intervention, both the groups demonstrated a marked reduction in IL-17 levels; reductions were statistically significant on assessment within the groups (P<0.001).
| Variable | Experimental group (n=30) | Control group (n=30) | P value |
|---|---|---|---|
| Age (yr) | 45.40±3.41 | 46.06±3.19 | 0.442 |
| Duration since COVID-19 diagnosis (wk) | 11.28±3.47 | 10.99 ±4.87 | 0.791 |
| Were hospitalized due to COVID-19 | 21 (70%) | 21 (70%) | 1.000 |
| Symptom persistence >4 wk | 20 (66.7%) | 21 (70%) | 0.774 |
| Baseline IL-17 (pg/ml) | 31.13±3.68 | 31.05±4.24 | 0.938 |
| Baseline Katz ADL score | 2.93±0.94 | 2.50±1.13 | 0.114 |
| Sex | All males | All males | - |
| Occupation | Manual labour | Manual labour | - |
| Substance use history | None | None | - |
Values are presented as mean±standard deviation. Unpaired t-test was used to compare continuous variables (age, duration since COVID-19, baseline IL-17, baseline ADL scores) between groups. Chi-square test used for categorical comparisons (hospitalization, chronic pain >4 wk). No between-group comparisons were required for sex, occupation, or substance use due to sample homogeneity. P value < 0.05 was considered statistically significant. IL-17, serum interleukin-17; Katz ADL, Katz index of activities of daily living
On comparison between the groups, the experimental group showed a greater IL-17 reduction (P<0.001). The effect size analysis revealed a large effect in the experimental group and a moderate effect in the control group (Table II). ADL scores improved significantly post-intervention in both groups (P<0.001) with a greater observed improvement in the experimental group (P<0.001). The measured effect size was large for both experimental and control groups, while the experimental group demonstrated a greater clinical impact (Table II). These results are illustrated graphically in (Supplementary Figs. 1–3).
| Group | Experimental group | Control group | Between group P value |
|---|---|---|---|
| Pre-intervention IL-17 (pg/mL) | 31.13±3.68 | 31.05±4.24 | 0.938 |
| Post-intervention IL-17 (pg/mL) | 18.96±2.56 | 28.89±4.58 | < 0.001* |
| P value | < 0.001* | < 0.001* | - |
| Cohen's d | 3.84 | 0.49 | - |
| Pre-intervention ADL Scores | 2.93±0.94 | 2.50±1.13 | 0.114 |
| Post-intervention ADL Scores | 5.03±0.85 | 3.53±1.04 | < 0.001* |
| P value | < 0.001* | < 0.001* | - |
| Cohen's d | 2.33 | 0.95 | - |
Values are presented as mean±standard deviation. Paired t-tests were used for within-group comparisons, and independent (unpaired) t-tests were used for between-group comparisons. Cohen's d was calculated to estimate effect sizes (> 0.8=large, 0.5=moderate, 0.2=small). A P value *< 0.05 was considered statistically significant
Discussion
This study evaluated a combined PMRT and SMT protocol for post-acute COVID-19 syndrome (PACS)-associated paraspinal myalgia (PM). The intervention significantly reduced systemic inflammation and improved functional outcomes compared to conventional standard neurosurgical care (SNC).
Studies have reported elevated serum pro-inflammatory cytokines, particularly IL-17, showed the most consistent elevation in post-COVID-19 patients with comorbidities11; therefore, IL-17 may be indicated as a suitable biomarker for assessing therapeutic response. Th17 cells and IL-17 drive chronic tissue inflammation and autoimmunity29. The observed IL-17 decrease likely reflects the attenuation of a core inflammatory mechanism, supporting the anti-inflammatory effects of PMRT and SMT.
During viral infections, proinflammatory cytokines triggers the HPA (hypothalamic-pituitary-adrenal) axis to release cortisol, which in turn regulates immune responses30. Chronic stress can impair this feedback loop, contributing to HPA dysregulation, persistent inflammation31, and immune suppression32. By reducing stress and normalizing cortisol responses, PMRT may have helped reduce inflammation. Relaxation therapies also increase vagal tone, activating the cholinergic inflammatory reflex33, which suppresses cytokine production, including IL-17.
While PMRT may act through neuroendocrine and vagal pathways, SMT likely works through myokine release during muscle contraction. IL-6, the principal exercise-induced myokine, mediates anti-inflammatory effects through the release of IL-1 receptor antagonist (IL-1ra) and IL-10, and inhibition of TNF-α34,35. It also promotes regulatory T (Treg) cells while suppressing pro-inflammatory monocytes and TLR signaling36. A recent study in COPD patients similarly reported that aerobic exercise increased Treg cells, lowered Th17 cells, and improved physical function37. The IL-17 reduction and higher Katz ADL scores in our cohort likely reflect on similar pathways, providing a strong basis for systemic immunoregulatory benefits of SMT.
Both groups showed improved functional independence, but the greater effect in the experimental group was likely attributable to the physiological and psychological effects of PMRT and SMT. PMRT has been shown to reduces stress, anxiety, and improves sleep among COVID-19 patients15,16. This may have facilitated better daily functionality in our PACS cohort. SMT improves spinal mobility and strength. Previous studies confirm that spinal flexion-extension exercises reduce low-back pain and disability17,18, directly supporting activities such as transferring, toileting, and dressing. This is consistent with our findings of improved ADL scores.
Telerehabilitation played a key role in enabling supervised rehabilitation beyond the rural socio-economic barriers, likely contributing to high adherence to the interventions.
The modest sample size and restriction to male participants aged 40–50 yr, inherently limited the generalizability of the results to broader populations. Lack of a comparison group receiving in-person rehabilitation makes it challenging to isolate the advantages of telerehabilitation. The quasi-experimental design lacked randomization, introducing possible selection bias despite efforts to maintain baseline group equivalence. Lastly, long-term follow up is needed to confirm the sustainability of clinical benefits. The limitations of this study should be considered as future research objectives, thus highlighting essential directions to optimize rehabilitation strategies for individuals affected by long COVID.
In conclusion, this study demonstrated that a combined PMRT and SMT protocol delivered via telerehabilitation effectively reduced systemic inflammation and improved functional independence in male manual labourers with post-COVID PM. These findings support integration of structured telerehabilitation into PACS care and highlight its potential as a scalable and cost-effective solution to extend rehabilitation services to underserved populations in the post-COVID era.
Acknowledgment
Authors acknowledge Dr. Prabhakar Kore Basic Science Research Center, KAHER University, Belgaum, Karnataka for helping with the biochemical investigations of the study. The technical support staff that helped conduct of this study are also acknowledged.
Financial support & sponsorship
The first author received funding support through the ICMR Short Term Studentship 2023 Grant (STS ID: 2023-09335).
Conflicts of Interest
None.
Use of Artificial Intelligence (AI)-Assisted Technology for manuscript preparation
We declare that OpenAI's ChatGPT-4 and Grammarly were used during the preparation of this manuscript. ChatGPT-4 assisted in refining the structure and clarity of the manuscript text, including language editing and drafting of narrative components. Grammarly was used for grammar and readability checks. All content was critically reviewed, edited, and approved by the authors to ensure accuracy and originality.
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