Musculoskeletal disorders are among the most important causes of pain, disability, loss of work capacity, and reduced quality of life worldwide. They affect muscles, tendons, ligaments, joints, peripheral nerves, and supporting structures, with symptoms ranging from transient discomfort to persistent functional limitation. The public health burden is considerable because musculoskeletal conditions contribute substantially to years lived with disability, healthcare use, and indirect economic loss through absenteeism and reduced productivity [1]. In occupational settings, work-related musculoskeletal disorders are particularly relevant because they arise from the interaction of physical workload, work organization, individual susceptibility, and recovery patterns [2].

Manual workers represent a vulnerable occupational group because their routine duties often include lifting, carrying, pushing, pulling, bending, twisting, squatting, kneeling, standing for prolonged periods, and performing repetitive movements. Such exposures create cumulative mechanical loading on the spine and peripheral joints. Systematic evidence has linked heavy physical work, manual material handling, repetitive tasks, awkward postures, and vibration with musculoskeletal symptoms in several body regions [3,5]. The lower back, neck, shoulders, knees, wrists, and hands are frequently affected because these structures absorb repeated biomechanical stress during daily labour [6,7].

The clinical and occupational significance of musculoskeletal pain extends beyond pain reporting. Workers with persistent pain can experience reduced speed, impaired precision, poor endurance, disturbed sleep, and inability to maintain regular attendance. Multiple-site pain is especially important because it indicates wider biomechanical strain and has been associated with a greater risk of persistence and disability [7]. In construction and other labour-intensive sectors, overexertion and back injuries form a large proportion of work-related musculoskeletal events, while prolonged work experience and extended working hours further increase vulnerability [9,10]. These patterns are relevant in Indian manual work environments, where informal work, limited ergonomic training, irregular rest breaks, and delayed reporting of pain remain common challenges.

Reliable assessment of musculoskeletal symptoms is essential for workplace surveillance and prevention. Standardized body-region questionnaires such as the Nordic Musculoskeletal Questionnaire provide a practical approach for documenting pain distribution, duration, and functional consequences in occupational groups [4]. However, local data from semi-urban and coastal regions of Andhra Pradesh are limited. Regional evidence is useful because work categories, task intensity, rest patterns, and training exposure differ across settings. Therefore, the present study was conducted to assess the pattern of musculoskeletal pain and associated occupational risk factors among manual workers. The objectives were to estimate the prevalence of musculoskeletal pain, describe the anatomical distribution and severity of pain, document relevant occupational exposures, and analyse their association with musculoskeletal pain.

Study design and setting: This hospital-based cross-sectional observational study was conducted at Konaseema Institute of Medical Sciences & Research Foundation, Amalapuram, Andhra Pradesh, India. The study was carried out from April 2025 to September 2025. Manual workers from occupations involving regular physical labour were evaluated during the study period. A cross-sectional design was selected because it was suitable for estimating the burden of musculoskeletal pain and examining its association with current and past occupational exposures at a defined point of assessment. Study population and sample size: The study included 100 manual workers aged 18 years and above. Participants were recruited from workers engaged in construction work, loading and unloading, agriculture-related labour, manufacturing or factory work, and sanitation or housekeeping work. Workers who were willing to participate and had sufficient occupational exposure to manual tasks were included. Workers with recent major trauma, known inflammatory arthritis, neurological disease causing limb weakness, congenital deformity, malignancy, or postoperative musculoskeletal limitation unrelated to occupation were excluded to reduce misclassification of work-related pain. Data collection procedure: Data were collected using a predesigned structured proforma. Information included age, sex, body mass index category, type of manual work, duration of occupational exposure, average working hours per day, and key ergonomic risk factors. Musculoskeletal pain was assessed by asking about pain or discomfort in defined body regions, including low back, neck, shoulder, knee, wrist or hand, ankle or foot, and elbow. The body-region approach was based on the principles of standardized musculoskeletal symptom assessment used in occupational health research [4]. Pain severity was categorized as mild, moderate, or severe based on the participant’s self-reported intensity and effect on routine work. Pain duration was grouped as less than 1 month, 1 to 3 months, and more than 3 months. Operational definitions: Musculoskeletal pain was defined as self-reported pain, ache, or discomfort involving muscles, joints, bones, tendons, or related soft tissues during the reference assessment period. Multiple-site pain was defined as pain reported in two or more anatomical regions. Occupational risk factors included heavy load lifting, repetitive movements, awkward working posture, prolonged standing, frequent bending or squatting, inadequate rest breaks, use of vibrating tools, and absence of ergonomic training. These variables were selected because previous epidemiological studies and systematic reviews have described their relevance to work-related musculoskeletal disorders [2,3,5]. Statistical analysis and ethical considerations: Data were entered and analysed using descriptive and inferential statistics. Continuous variables were summarized as mean and standard deviation, while categorical variables were expressed as frequency and percentage. The prevalence of musculoskeletal pain was calculated as the proportion of workers reporting pain among the total study population. Associations between occupational risk factors and musculoskeletal pain were examined using the Chi-square test. Crude odds ratios with 95% confidence intervals were calculated to estimate the strength of association. A p-value below 0.05 was considered statistically significant. Ethical approval was obtained from the institutional ethics committee, and written informed consent was obtained from all participants. Confidentiality was maintained throughout the study.

A total of 100 manual workers were included in the study. The mean age of the study population was 38.9 ± 9.7 years. Males constituted 72.0% of the participants. The largest age category was 40-49 years, followed by 30-39 years. Most workers were engaged in construction work, loading and unloading, agriculture-related manual labour, and manufacturing or factory work. Forty workers had more than 10 years of occupational exposure, and 68 workers reported working for more than 8 hours per day. The baseline demographic and occupational profile is shown in Table 1.

Table 1. Baseline demographic and occupational profile of manual workers [n=100]

Table 2. Pattern and severity of musculoskeletal pain

Musculoskeletal pain was reported by 68 workers, giving an overall prevalence of 68.0%. Among symptomatic workers, moderate pain was the most common severity pattern, followed by mild and severe pain. Chronic pain lasting more than 3 months was observed in 34.0% of the total study population. Multiple-site pain was reported by 45 symptomatic workers, indicating that pain was frequently distributed across more than one anatomical region. Work absenteeism due to pain was reported by 24.0% of workers. The pattern and severity of pain are summarized in Table 2.

The lower back was the most commonly affected site, reported by 42.0% of workers. Shoulder pain was present in 29.0%, neck pain in 24.0%, and knee pain in 22.0%. Wrist or hand pain, ankle or foot pain, and elbow pain were less frequent but still contributed to the overall symptom burden. Since anatomical pain sites were recorded as multiple responses, the total percentage exceeds 100. The anatomical distribution of pain is presented in Table 3.

Table 3. Anatomical distribution of musculoskeletal pain [multiple responses allowed]

Occupational exposure assessment showed that heavy load lifting was present in 62.0% of workers, repetitive movements in 58.0%, awkward working posture in 55.0%, and prolonged standing in 61.0%. Frequent bending or squatting was reported by 54.0%, while 48.0% had inadequate rest breaks. Only 22.0% had received ergonomic or safe-handling training, and 78.0% had no ergonomic training. Musculoskeletal pain showed statistically significant associations with work duration of more than 10 years, working more than 8 hours per day, heavy load lifting, repetitive movements, awkward working posture, inadequate rest breaks, and no ergonomic training. The strongest associations were observed for absence of ergonomic training and heavy load lifting. Age 40 years or above and prolonged standing showed higher pain prevalence, but these associations were not statistically significant. The association between occupational risk factors and musculoskeletal pain is shown in Table 4.

Table 4. Association between occupational risk factors and musculoskeletal pain

Note: For each risk factor, the comparison category was absence of that exposure, except for age, work duration, and working hours where the reference categories were age <40 years, work duration ≤10 years, and working ≤8 hours/day, respectively.

The present cross-sectional study showed a high burden of musculoskeletal pain among manual workers, with 68.0% reporting pain in at least one body region. This finding is consistent with the broader understanding that manual workers are exposed to repeated biomechanical loading and have a higher risk of work-related musculoskeletal disorders [2,3]. The prevalence observed in this study was higher than that reported by Reddy et al. among construction workers in Chennai, where musculoskeletal morbidity was observed in 33.8% of participants [10]. Differences in pain definition, reference period, occupational mix, local work intensity, and ergonomic support can explain this variation.

Low back pain was the leading anatomical complaint in the present study, followed by shoulder, neck, and knee pain. This distribution is biologically plausible because manual labour commonly requires lifting, bending, twisting, carrying, and prolonged static loading. Hoogendoorn et al. reported strong evidence for manual material handling, bending and twisting, and whole-body vibration as risk factors for back pain [5]. Coenen et al. further demonstrated that cumulative low back load was associated with low back pain, supporting the role of repeated mechanical exposure [8]. The high proportion of low back pain in the present study therefore reflects the expected pattern in occupations dominated by physical workload.

Multiple-site pain was reported by two-thirds of symptomatic workers. This is clinically important because pain affecting more than one body region indicates wider exposure to biomechanical stress and can interfere with endurance, productivity, and recovery. Hartvigsen et al. highlighted that accompanying pain at multiple body sites increases the risk of persistent disabling low back pain [7]. In the present study, work absenteeism due to pain was present in 24.0% of workers, suggesting that musculoskeletal symptoms had practical occupational consequences and were not limited to minor discomfort.

Several occupational factors were significantly associated with musculoskeletal pain. Heavy load lifting, repetitive movements, awkward posture, longer working hours, inadequate rest breaks, and absence of ergonomic training showed meaningful associations. These findings agree with the systematic review by da Costa and Vieira, which identified repetition, awkward postures, heavy lifting, and heavy physical work as important biomechanical risk factors [3]. The association with shoulder pain patterns is also supported by van der Windt et al., who identified repetitive movements, vibration, and duration of employment as relevant occupational factors for shoulder pain [12].

The strongest association in the present study was observed with absence of ergonomic training. This finding has preventive importance because training, safe lifting technique, task rotation, use of assistive devices, and scheduled recovery intervals are modifiable workplace factors. Evidence from occupational research indicates that targeted prevention strategies and workplace-level ergonomic programmes are necessary to reduce musculoskeletal burden [13]. The findings also support the need for early screening of manual workers, especially those with longer work duration and prolonged daily working hours. A practical workplace approach should combine worker education, supervisor involvement, rest scheduling, and redesign of high-risk manual tasks.

Limitations

The study was limited by its cross-sectional design, which restricts causal interpretation. Pain and occupational exposures were self-reported, introducing recall bias and reporting variation. The sample size was modest and drawn from a single centre, limiting external generalization. Objective ergonomic assessment and clinical confirmation of musculoskeletal diagnoses were not performed. Psychosocial factors, job satisfaction, sleep quality, and income-related pressures were not assessed.

Musculoskeletal pain was common among manual workers, affecting more than two-thirds of the study population. Low back pain was the predominant complaint, followed by shoulder, neck, and knee pain. Pain was significantly associated with longer occupational exposure, extended working hours, heavy load lifting, repetitive movements, awkward posture, inadequate rest breaks, and lack of ergonomic training. These findings highlight the need for systematic workplace screening and preventive strategies. Ergonomic education, safe manual handling practices, task rotation, assistive devices, and scheduled rest intervals should be integrated into occupational health programmes for manual workers to reduce pain burden, absenteeism, and functional impairment. Periodic follow-up can track symptom progression and response to workplace changes.

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